I’ve been using Camrade bags for years. They are tough, protect my gear well without being heavy and clunky like pelicases and other hard shell cases. In addition they don’t scream “expensive equipment here”. They just look like large holdalls. One of the best features is the use of dividers, pads and inserts that are attached with velcro that allow you to reconfigure the bags for different applications.
One thing I often do is carry my camera in a standard carry-on bag when I’m flying. Meanwhile my tripod goes in the camera bag in the hold. When I get to my destination the tripod comes out of the camera bag, I re-arrange the dividers and the camera then lives in the camera bag until I need to fly again. This is so easy to do with the Camrade bags. Although the bags look like soft bags they are extremely ridged. The sides, top and bottom have hard inserts in them that can withstand very large loads, they are strong enough for you to sit on them without collapsing. The bags have strong carry straps and come with a high quality, removable camera strap. There are mesh pockets on the outside as well as on the inside of the lid for those little accessories and bits and pieces that would otherwise get lost. Another bonus is a 90% white card for white balance and use as an exposure reference.
Here’s a video of the medium size Camrade CB-HD bag, designed to take the PXW-FS7 or other similar digital cinema cameras. It’s a bit taller than some of their other bags so perfect for cameras rigged up with base plates and matte boxes.
This is part 1 of two articles. In this article I will look at what timecode is and some common causes of timecode drift problems. In part 2 I will look at the correct way to synchronise timecode across multiple devices.
This is a subject that keeps cropping up from time to time. A lot of us camera operators don’t always understand the intricacies of timecode. If you live in a PAL/50Hz area and shoot at 25fps all the time you will have few problems. But start shooting at 24fps, 23.98 fps or start trying to sync different cameras or audio recorders and it can all get very complicated and very confusing very quickly.
So I’ve written these notes to try to help you out.
WHAT IS TIMECODE?
The timecode we normally encounter in the film and video world is simply a way to give every frame that we record a unique ID number based on the total number of frames recorded or the time of day. It is a counter that counts whole frames. It can only count whole frames, it cannot count fractions of frames, as a result the highest accuracy is 1 frame. The timecode is normally displayed as Hour:Minute:Second:Frame in the following format
RECORD RUN AND FREE RUN
The two most common types of timecode used are “Record Run” and “Free Run”. Record run, as the name suggests only runs or counts up when the camera is recording. It is a cumulative frame count, which counts the total number of frames recorded. So if the first clip you record starts with the time code clock at 00:00:00:00 and runs for 10 seconds and 5 frames then the TC at the end of the clip will be 00:00:10:05. The first frame of the next clip you record will continue the count so will be 00:00:10:06 and so on. When you are not recording the timecode stops counting and does not increase.
With “Free Run” the timecode clock in the camera is always counting according to the frame rate the camera is set to. It is common to set the free run clock so that it matches the time of the day. Once you set the time in the timecode clock and enable “Free Run” the clock will start counting up whether you are recording or not.
HERE COMES A REALLY IMPORTANT BIT!
In “Free Run” once you have set the timecode clock it will always count the number of frames recorded and in some cases this will actually cause the clock to drift away from the actual time of day.
SOME OF THE PROBLEMS.
An old problem is that in the USA and other NTSC areas the frame rate is a really odd frame rate, it’s 29.97fps (this came about to prevent problems with the color signal when color TV was introduced). Timecode can only count actual whole frames, so there is no way to account for the missing 0.03 frames in every second. As a result timecode running at 29.97fps runs slightly slower than a real time clock.
If the frame rate was actually 30fps in 1 hour there would be 108,000 frames. But at 29.97fps after one real time hour you will have only recorded 107,892 frames, the frame counter TC, won’t reach one hour for another 3.6 seconds.
DROP FRAME TIMECODE.
To eliminate this 3.6 seconds per hour (relative to real time) timecode discrepancy in footage filmed at 29.97fps a special type of time code was developed called “Drop Frame Timecode“. Drop Frame Timecode (DF) works by: every minute, except each tenth minute, two timecode numbers are dropped from the timecode count. So there are some missing numbers in the timecode count but after exactly 1 real time hour the time code value will increment by 1 hour. No frames themselves are dropped, only numbers in the frame count.
WHEN TO USE DROP FRAME (DF) OR NON DROP FRAME (NDF).
Drop Frame Timecode is only ever used for material shot at 29.97fps, which includes 59.94i. (We will often incorrectly refer to this as 60i or 30fps – virtually all 30fps video these days is actually 29.97fps). If you are using “Rec Run” timecode you will almost never need to use Drop Frame as generally you will not by syncing with anything else.
If you are using 29.97fps “Free Run” you should use Drop Frame (DF) when you want your timecode to stay in sync with a real time clock. An example would be shooting a long event or over several days where you want the timecode clock to match the time on your watch or the watch of an assistant that might be logging what you are shooting.
If you use 29.97fps Non Drop Frame (NDF) your cameras timecode will drift relative to the actual time of day by a minute and a half each day. If you are timecode syncing multiple cameras or devices it is vital that they are all using the same type of timecode, mixing DF and NDF will cause all kinds of problems.
It’s worth noting that many lower cost portable audio recorders that record a “timecode” don’t actually record true timecode. Instead they record a timestamp based on a real time clock. So if you record on the portable recorder for lets say 2 hours and then try to sync the 1 hour point (01:00:00:00 Clock Time) with a camera recording 29.97fps NDF timecode using the 1 hour timecode number (01:00:00:00 NDF Timecode) they will be out of sync by 3.6 seconds. So this would be a situation where it would be preferable to use DF timecode in the camera as the cameras timecode will match the real time clock of the external recorder.
WHAT ABOUT 23.98fps?
Now you are entering a whole world of timecode pain!!
23.98fps is a bit of a oddball standard that came about from fitting 24fps films into the NTSC 29.97fps frame rate. It doesn’t have anything to do with pull up, it’s just that as NTSC TV runs at 29.97fps rather than true 30fps movies are sped up by 0.1% to fit in 29.97fps.
Now 23.98fps exists as a standalone format. In theory there is still a requirement for Drop Frame timecode as you can’t have 0.02 frames in a timecode frame count, each frame must have a whole number. Then after a given number of frames you go to the next second in the count. With 23.98fps we count 24 whole frames and the increment the timecode count by one second, so once again there is a discrepancy between real time and the timecode count of 3.6 seconds per hour. The time on a camera running at 23.98fps will run fast compared to a real time clock. Unlike 29.97fps there is no Drop Frame (DF) standard for 23.98, it’s always treated as a 24fps count (TC counts 24 frames, then adds 1 to the second count), this is because there is no nice way to adjust the count and make it fit real time as there is with 29.97fps. No matter how you do the math or how many frames you drop there would always be a fraction of a frame left over.
So 23.98fps does not have a DF mode. This means that after 1 hour of real time the timecode count on a camera shooting at 23.98 fps will be 00:01:03:14. If you set the camera to “Free Run” the timecode will inevitably drift relative to real time, again over the course of a day the camera will be fast by almost one and a half minutes compared to a real time clock or any other device using either drop frame timecode, 24fps or 25fps.
So, as I said earlier 23.98fps timecode can be painful to deal with.
24fps timecode does not have this problem as there are exactly 24 frames in every second, so a video camera shooting at 24fps should not see any significant timecode drift or loss of timecode sync compared to a real time clock.
It’s worth considering here the problem of shooting sync sound (where sound is recorded externally on a remote sound recorder). If your sound recorder does not have 23.98fps timecode the timecode will drift relative to a camera shooting at 23.98fps. If your sound recorder only has a real time timecode clock you might need to consider shooting at 24fps instead of 23.98fps to help keep the audio and picture time codes in sync. Many older audio recorders designed for use alongside film cameras can only do 24fps timecode.
In part 2 I will look at the correct way to synchronise timecode across multiple devices.
By the time you get to read this you may already know almost everything there is to know about the PXW-FS7 II as it has been leaked and rumoured all over the internet. But I’m under a Sony NDA, so have had to keep quiet until now.
And I’ve been told off for calling it a MKII, the correct name is PXW-FS7 II. Sorry Mr Sony, but if you call it FS7 II, most people will think the “II” means MKII.
The FS7 camera is a mature product. By that I mean that the early bugs have been resolved. The camera has proven itself to by reliable, cost effective (amazing bang for the buck really). To produce great images and 4K files that are not too big. It can do slow-mo, 4K, 2K, HD and raw via an adapter and external recorder. As a result the FS7 is now one of the top choices for many broadcasters and production companies. It has become an industry standard.
The first and most important thing to understand about the FS7 II is that it does not replace the existing FS7. I would have preferred it if Sony had called this new camera the “FS7 Plus”. The “II” designation (which I take to mean MKII) implies a replacement model, replacing the MKI. This is not the case. The FS7 II is in fact a slightly upgraded version of the standard FS7 with a few hardware improvements. The upgrades make the MKII quite a lot more expensive (approx 10K Euros), but don’t worry. If you don’t need them, you can stick with the cheaper FS7 MK1 which remains a current model. In terms of image quality there is no real difference, the sensor and image processing in the cameras is the same.
So what are the changes?
The most obvious perhaps is the use of a square rod to support the viewfinder. This eliminates the all too common FS7 problem of sagging viewfinders. As well as switching to a square rod each of the adjustments for the viewfinder mounting system now has a dedicated clamp. Before if you wanted to slide the viewfinder forwards or backwards you undid a clamp that not only freed off the sliding motion but also controlled the tilt of the screen. So it was impossible to have the fore-aft adjustment slack for quick adjustments without the viewfinder sagging and drooping.
With the MkII you can have a slack fore-aft adjuster without the VF drooping. Overall the changes to the VF mounting system are extremely welcome. The VF mount on the Mk1 is a bit of a disaster, but there are plenty of 3rd party solutions to this. So you can fix the problems on a MKI without having to replace the camera. In addition, if you really wanted you could buy the FS7 II parts as spare parts and fit them to a MKI.
The Lens Mount.
The next obvious change is to the lens mount. The FS7 MK1 has a normal Sony E-Mount where you insert the lens and then twist it to lock it in to place. The FS7 II mount is still an E-Mount but now it has a locking collar like a PL or B4 mount. This means that you have to insert the lens at the correct angle and then you turn a locking ring to secure the lens. The lens does not rotate and once locked in place cannot twist or turn and has no play or wobble. This is great for those that use a follow focus or heavier lenses. BUT the new locking system is fiddly and really needs 2 hands to operate. In practice you have to be really careful when you mount the lens. It’s vital that you align the white dot on the lens with the white dot on the mount before you twist the locking ring.
As you rotate the locking ring a small release catch drops into place to prevent the ring from coming undone. But if the lens isn’t correctly aligned when you insert it, the lens can rotate with the locking ring, the catch clicks into place, but the lens will just drop out of the mount. When inserted correctly this mount is great, but if you are not careful it is quite easy to think the lens is correctly attached when in fact it is not.
Variable ND Filter.
Behind the lens mount is perhaps the most significant upgrade. The FS7 II does away with the rotating filter wheel and replaces it with the variable ND filter system from the FS5. I have to say I absolutely love the variable ND on the FS5. It is so flexible and versatile. You still have a 4 position filter wheel knob. At the clear position the ND filter system is removed from the optical path. Select the 1, 2 or 3 positions and the electronically controlled ND filter is moved into position in front of the sensor. You then have 3 preset levels of ND (the level of which can be set in the camera menu) or the ability to smoothly control the level of ND from a dial on the side of the camera. Furthermore you can let the camera take care of the ND filter level automatically. The real beauty of the variable ND s that it allows you to adjust your exposure without having to alter the aperture (which changes the depth of field) or shutter (which alters the flicker/cadence). It’s also a great way to control exposure when using Canon lenses as the large aperture steps on the Canon lenses can be seen in the shot.
Another physical change to the camera is the use of a new arm for the handgrip. The new arm has a simple wing-nut for length adjustment, much better than the two screws in the original arm. In addition you can now use the adjuster wing-nut to attach the arm to the camera body and this brings the hand grip very close to the body for hand held use. This is a simple but effective improvement, but again 3rd party handgrip arms are available for the base model FS7.
The viewfinder loupe has seen some attention too. The standard FS7 loupe has two fiddly wire clips that have to be done up to secure the loupe to the viewfinder. The MK2 loupe has a fixed hook that slips over the top lug on the viewfinder so that you now only need to do up a single catch on the bottom of the loupe. It is easier and much less fiddly to fit the new loupe, but the optics and overall form and function of the loupe remain unchanged.
As well as the loupe the FS7 II will be supplied with a clip on collapsable sunshade for the viewfinder. This is a welcome addition and hand held shooters will no doubt find it useful. When not in use the sunshade folds down flat and covers the LCD screen to protect it from damage.
The number of assignable buttons on the FS7 II is increased to 10. There are 4 new assignable button on the camera body where the iris controls are on the original FS7. The Iris controls are now on the side of the camera just below the ND filter wheel along with the other ND filter controls. These buttons are textured to make them easier to find by touch and are a very welcome addition, provided you can remember which functions you have allocated to them. It’s still a long way from the wonderful side panel LCD of the PMW-F5/PMW-F55 with it’s 6 hotkeys and informative display of how the camera is configured.
Tucked under the side of the camera and just above the power switch there is now a small green power LED. The original FS7 has no power light so it can be hard to tell if it’s turned on or not. This little green light will let you know.
The last hardware change is to the card slots. The XQD card slots have been modified to make it easier to get hold of the cards when removing them. It’s a small change, but again most welcome as it can be quite fiddly to get the cards of an FS7.
A further change with the FS7 II is the addition of Rec-2020 colorspace in custom mode. So now with the FS7 II as well as Rec-709 colorspace you can also shoot in Rec-2020. I’m really not sure how important this really is. If Sony were to also add Hybrid Log Gamma or PQ gamma for HDR then this would be quite useful. But standard gammas + Rec2020 color doesn’t really make a huge amount of sense. If you really want to capture a big range you will probably shoot S-Log2/3 and S-Gamut/S-Gamut3.
So – the big question – is it worth the extra?
Frankly, I don’t think so. Yes, the upgrades are nice, especially the variable ND filter and for some people it might be worth it just for that. But most of the other hardware changes can be achieved via 3rd party accessories for less than the price difference between the cameras.
With all the financial turmoil going on in many countries right now I think we can expect to see the cost of most cameras start to rise, including the original (but still current) FS7. This may narrow the price gap between the FS7 MKI and FS7 MK2 a little. But an extra 3000 Euros seems a high price to pay for a variable ND filter.
In some respects this is good news as it does mean that those that have already invested in an FS7 MKI won’t see that investment diminished, the MK1 is to remain a current model alongside the souped up MK2 version. Now you have a choice, the lower cost workhorse FS7 MK1 or the MK2 with it’s variable ND filter and revised lens mount.
Sony have released firmware update version 4.0 for the PXW-FS7. This new firmware brings some welcome updates to the FS7 including the ability to move the focus magnification area away from the center of the screen. Other new features include true 24p (as well as 23.98fps).
1. Support for Flexible Spot in Focus setting.
2. Support for XAVC-I 4K 24.00P.
3. Display for Video Signal Monitor is improved.
4. Operability of S&Q setting by assignable button is improved.
5. Remove Basic Authentication from items saved in all file.
6. Auto knee stability is improved.
7. Overall stability and operability of the camera is improved.
As the owner of a Sony AX100, which is a really great little 4K and HD camcorder I wasn’t really all that excited when I saw the first prototype of the X70 at Broadcast Asia back in June. You see in the past Sony have done this many times, taken a high end consumer camcorder, updated the firmware, added a handle and then sold it for a higher price as a pro camcorder. In the past, there has in reality been little difference between the cheaper consumer model and the more expensive pro version.
The PXW-X70 is different. This is much more than an AX100 with new firmware. For a start the body of the camera is quite different. The right hand side of the X70 is quite different to the AX100. It has a much fatter hand grip. This makes the camera much easier to hold comfortably for long periods. It also makes space for a full size HDSDI output and a full size HDMI output. But the differences don’t stop there.
On the top of the hand grip there is a large assignable button that is normally set to act as a control for the focus magnification function. This button falls immediately under your index finger when your shooting. In front of this is a new larger and easier to use zoom rocker and then in front of that is another assignable button, this one set as a one push auto iris button – very nice!
At the back of the handle there is a small joystick that ends up under your thumb (just where it needs to be). This joystick can be used to navigate through the cameras menu system. So, without taking your hand out of the hand grip you can check focus, zoom in and out, set your exposure and go through the menu system. If only it was this easy on all of Sony’s cameras! Ergonomically this camera is really good, especially when you consider how small it is.
The camera has a nice 12x stabilised, optical zoom lens, behind which sits a 1 inch 20 megapixel sensor. In video mode about 14 million pixels are used, so even in 4K (there will be a paid 4K upgrade option next year) there are more pixels than needed for full resolution. Rather than let this extra resolution go to waste you can activate Sony’s “clear image zoom” function that works seamlessly with the optical zoom to give you a 24x zoom range in HD.
The clear image zoom really is remarkably transparent. If you look hard enough at the image, on a big screen, when it’s zoomed all the way in you can just about discern a very slight softness to the image, but frankly I don’t think this is any worse than the softness you might see from a compact optical 24x zoom. It certainly doesn’t look electronic and unless you have side by side, with and without test clips I don’t think you would know that the clear image zoom has been used.
If 24x is not enough there is also a further digital extender, controlled by a button on the right side of the lens that doubles the digital zoom. This you can see, the image is a little degraded at 48x, but it’s not terrible, might be handy for a breaking news story where you can’t get close to the subject.
As well as the optical stabiliser in the lens the camera also has a switchable electronic stabiliser. The active steadyshot is very effective at smoothing out even the shakiest of hands. But it does tend to hang on or grab hold of the image a bit. So when you do deliberately move the camera it tends to try to stabilise the scene until it can no longer correct for the cameras movement at which point the scene is suddenly released and starts to move. If your using a tripod you definitely want to just use the standard steadyshot and not the active mode.
The pictures are recorded using either XAVC, AVCHD or standard definition DV to SD cards. For XAVC you must use SDXC cards, but these are cheap and readily available these days. There are two card slots and you can choose between relay record where the camera will switch from slot A to slot B once A is full, or you can make two simultaneous recordings on both cards at the same time. This gives an instant backup if you need it.
XAVC HD RECORDING:
The XAVC HD recordings are 10 bit 422 long GoP at 50Mb/s, 35Mb/s or 25Mb/s. The quality of the 50Mb/s recordings is amazing with no compression artefacts that I can see (there must be some, I just can’t see them). Even the 25Mb/s recordings look really good. You can shoot at up to 60fps in 60i mode and 50fps in 50i mode. In 60i mode you also have 24fps.
Considering this is a highly compact, single chip camera the images it produces are really very good. They don’t have that typical small sensor camera look. The pictures are remarkably noise free at 0db and largely free of artefacts. I tend to find that small handycams often suffer from what I would describe as “busy” pictures. Pictures where perhaps there is a lot of added sharpening or where the pixels are read in special ways to make a sharp picture. This makes edges slightly flickery and gives the pictures a tell tale small sensor look. The X70 with it’s big sensor and abundance of pixels just doesn’t have this “busy” look.
The pictures really look like they come from a pro camera. Occasionally very fine, high contrast details like white text on a black background can look a little busy, but this is very minor. Dynamic range is quite respectable, it’s not as good as a PMW-300, but not too bad for a compact handycam (I estimate about 10 to 11 stops of DR).
One thing I did find with this camera is that because there is so little noise and the codec is so good, you could quite comfortably shoot about a stop darker than you would normally and then just bring the image up a bit in post. Shooting a little darker helps the camera handle bright highlights and then in post you can just bring up the shadows and mid tones with a simple colour correction to give a nice exposure. I wish I had realised this when I shot the demo video. I would have exposed a little on the dark side and then tweaked the shots in post. There’s so little noise at 0db and so few artefacts that the image holds up to this really well. If your using auto exposure you can set an exposure offset to allow for this in the menu.
The X70 is pretty sensitive and 9db of gain is quite useable, so shooting indoors in a typical home or at a wedding venue without extra lights should be no problem. Ramp it up to +33db and it see’s better in the dark than I do, but there is a fair bit of noise at +33db.
As well as being generally rather sensitive the PXW-X70 also has a nightshot mode that bypasses the cameras IR filter and includes a switchable infra-red light, so you can shoot in total darkness if you want.
To see what you are shooting there is a 3.5″ LCD panel. This panel is higher resolution than the one on the AX100 and gives a sharp and pretty accurate image. On the back of the camera there is a small OLED viewfinder. This little OLED is pretty good. It has great contrast and is pretty sharp for a small finder. It’s a great feature on bright sunny days when the LCD can become harder to see.
CRISP, SHARP IMAGES:
The HD images are crisp and sharp without any obvious sharpening, almost certainly a result of having a 4K ready sensor. The lack of obvious detail correction helps give the pictures a pleasing, more filmic look. The camera has picture profiles so if you want you can soften or sharpen the images if you choose. As well as detail and aperture controls there are also controls for gamma (standard, still, Cinematone1, Cinematone2, ITU709) and color. The color controls are similar to those on the FS700 where you can adjust the saturation as well as R, G, B, C, M, Y and K brightness. In addition there is a choice of 6 different preset color modes plus black and white.
The camera can be controlled either fully automatically or fully manual as well as various in between modes. There is a switch on the back of the camera to switch between auto and manual. In manual you can control the iris, shutter and gain by pressing one of three buttons along the bottom edge of the camera and the using a small wheel just below the lens to set what you have selected. In practice this actually works quite well. There is another button for white balance control on the side of the camera with the usual presets plus auto white balance. Just under the Manual/Auto switch there is a selector for the built in ND filters. I recently purchased a A7s DSLR type camera and I had forgotten what a fiddle it can be to use a camera that doesn’t have built in ND’s. So it’s really good to see proper ND filters on the PXW-X70 as they really help you manage your depth of field.
On the lens there is a single large control ring that can be used to focus the lens or to act as a manual zoom ring. The focus is responsive and although I don’t normally like round and round servo focus rings this one wasn’t too bad.
There really is so much to this camera that it would take a small book to go through all the features. For example there’s the touch screen LCD that can be used for touch to focus or touch to expose where you just touch the part of the screen you want to expose or focus on. There’s a full set of exposure and focus aids including peaking, histogram, zebras etc.
On the top of the camera you have Sony’s new MI shoe (Multi-Interface) for connecting accessories like the supplied handle with XLR audio inputs. The supplied detachable handle is really well made and very secure when attached. One small note is that by default when you attach the handle to the MI-shoe the camera switches to XLR audio automatically by default. So if you don’t actually have a mic connected to the handle you won’t have any audio as the internal mic gets shut off. You have to go in to the audio section of the menu to enable the internal mic if you want to use the handle but want to use the built in mic.
If you want to do time-lapse or slow stuff down the camera has S&Q motion that goes from 1fps to 60fps at 1920×1080.
The camera has WiFi and NFC and allows remote control via Content Browser Mobile and simply touching an NFC enabled phone or tablet against the side of the camera will pair the camera with the phone or tablet. In the future following a firmware update you will be able to use the camera to stream your content live via U-stream.
Finally – build quality. It’s really well made. It feels nice and solid, it feels like it will really last. Don’t tell Sony, but I dropped the camera from waist hight while I was using it. It survived, no problem at all.
In conclusion: This is a nice little camera. It’s very easy to operate. The picture quality is very good for such a compact camera, the only thing that lets it down just a bit is the highlight handling. But the camera is so clean that you can afford to expose a little lower to compensate for this. Since shooting the demo video I have been playing with the picture profiles to help with the highlight exposure and I found that bringing up the black gamma really helps as it lifts the mid range allowing you to expose slightly lower.
The large sensor, combined with the switchable built in ND filters gives you much greater control over the depth of field than normally possible with a compact handycam.
I think you have to remember that this is a small camera. It isn’t a PXW-X180 and it never will be, but if your budget is tight and you want an easy to use compact camera this could be the one for you. I think it would be a good fit as a “B” camera or for use in lower budget corporate productions. In addition the PXW-X70 would be a good camera to give to PA’s and producers or to hand off to inexperienced shooters for fly-on-the-wall productions.
One way to reduce the noise in a video camera image is to reduce the cameras gain. One way to increase the brightness of the image is to add gain.
We all know that increasing the gain to lets say +6db will increase noise and generally the reverse holds true when you reduce the gain, the noise typically reduces and this may be helpful if you are going to do a lot of effects work, or just want a clean image.
However in most cases adding or removing gain reduces the cameras dynamic range as it will artificially clip or limit your low key or high key parts of the image. The maximum illumination level that a camera can capture is limited by the sensor or the gamma curves that the camera has. The black level or darkest part of the image is the point where the actual image signal compared to the sensor noise level is high enough to allow you to see some actual picture information (also known as noise floor). So the dynamic range of the camera is normally the range between the sensors noise floor and recording or sensor clipping point.
To maximise the cameras dynamic range the designers will have carefully set the nominal zero db gain point (native ISO) so that the noise floor is at or very close to black and the peak recording level is reached at the point where the sensor itself starts to clip.
The gain of the camera controls the video output and recording level, relative to the sensors signal level. If you use -3db gain you attenuate (reduce) the relative output signal. The highlight handling doesn’t change (governed by the sensor clipping or gamma curve mapping) but your entire image output level gets shifted down in brightness and as a result you will clip off or loose some of your shadow and dark information, so your overall dynamic range is also reduced as you can’t “see” so far into the shadows. Dynamic range is not just highlight handling, it is the entire range from dark to light. 3db is half a stop (6db = 1 stop) so -3db gain reduces the dynamic range by half a stop, reducing the cameras underexposure range without (in most cases) any change to the over exposure range, so overall the total dynamic range is reduced.
When you add gain the reverse happens. Generally how far the sensor can see into the shadows is limited by the sensors noise floor. Add 6db of gain and you will make the darkest parts of the image brighter by 6db, but you will also raise the noise level by the same amount. So while you do end up with brighter shadow details you can’t actually see any more picture information because the noise level has increased by the same amount. At the top end as the brightest sensor output is mapped to the maximum recording level at 0db, when you add gain this pushes the recording level beyond what can be recorded, so you loose 6db off the top end of your recordings because the recordings and output clips 6db earlier. So positive gain maintains the same shadow range but reduces the highlight recording range by 6db.
However you use it gain tends to reduce your dynamic range. Adding gain to cope with poor lighting tends to be the lesser of the two evils as generally if your struggling for light then overexposure and blown out highlights is often the last of your worries.
Negative gain is sometimes used in camera to try to reduce noise, but the reality is that you are loosing dynamic range. Really a better solution would be to expose just a tiny bit brighter and then bring your levels down a bit in post production.
Well I’ve just returned home from NAB and a week of Tornado Chasing in the USA. For the Tornado chasing I was shooting in 4K using my Sony F5. I’ve shot run and gun with my F3 and FS700 in the past when shooting air-shows and similar events. But this was very different. Tornado chasing is potentially dangerous. You often only have seconds to grab a shot which involves leaping out of a car, quickly setting up a tripod and camera and then framing and exposing the shot. You often only have time for one 30 second shot before you have to jump back into the car and move on out ahead of the storm. All of this my be happening in very strong winds and rain. The storms I chased last week had inflow winds rushing into them at 50+ MPH.
The key to shooting any thing fast moving, like this, is having whatever camera kit your using well configured. You need to be able to find the crucial controls for exposure and focus quickly and easily. You need to have a way of measuring and judging exposure and focus accurately. In addition you need a zoom lens that will allow you to get the kinds of shots you need, there’s no time to swap lenses!
For my storm chasing shoot I used the Sony F5 with R5 recorder. This was fitted with a Micron bridge plate as well as a Micron top cheese plate and “Manhandle”. Instead of the Sony viewfinder I used an Alphatron viewfinder as this has a waveform display for exposure. My general purpose lens was a Sigma 18-200mm f3.5-f6.5 stabilised lens with a Canon mount. To control the iris I used a MTF Effect iris control box. For weather protection a CamRade F5/F55 Wetsuit. The tripod I used for this shoot was a Miller 15 head with a set of Carbon Fibre Solo legs.
Overall I was pleased with the way this setup worked. The F5’s ergonomics really help as the logical layout makes it simple to use. The 18-200mm lens is OK. I wish it was faster for shooting in low light but for the daytime and dusk shots, f3.5 (at the wide end) is OK. The F5 is so sensitive that it copes well even with this slow lens. The CamRade wetsuit is excellent. Plenty of clear windows so you can see the camera controls and a well tailored yet loose fit that allows you to get easy access to the camera controls. I’ve used Miller Solo legs before and when you need portability they can’t be beaten. The are not quite as stable as twin tube legged tripods, but for this role they are an excellent fit. The Miller 15 head was also just right. Not too big and bulky, not too small. The fluid motion of the head is really smooth.
So what didn’t work? Well I used the Element Technica Micron bridge plate. I really like the Micron bridge plate as it allows you to re-balance the camera on the tripod very quickly. But it’s not really designed for quick release, it’s a little tricky to line up the bridge plate with the dovetail so I ended up removing and re-fitting the camera via the tripod plate which again is not ideal. The Micron Bridge plate is not really designed for this type of application, when I go back storm chasing in May I’ll be using a baseplate that locks into a VCT-14 quick release plate, not sure which one yet, so I have some investigating to do. The VCT-14 is not nearly as stable or as solid as the Micron, but for this application speed is of the essence and I’m prepared to sacrifice a little bit of stability. The Micron bridge plate is better suited to film style shooting and in that role is fantastic, it’s just not the right tool for this job.
The MTF-Effect unit is needed to control the aperture of the Canon mount lens, it also powers the optical image stabiliser. But it’s a large square box. I had it mounted on the top of the camera, not in the best place. I need to look at where to mount the box. I’m actually considering re-housing the unit in a custom made hand grip so I can use it to hold the camera with my left hand and have iris control via a thumbwheel. I also want to power it from one of the camera’s auxiliary outputs rather than using the AA batteries internally. The other option is the more expensive Optitek lens mount which I’m hoping to try out soon. I’m also getting a different lens. The Sigma was fine, but I’m going to get a Sigma 18-250mm (15x) f3.5-f6.5 for a bit more telephoto reach. The other option I could have used is my MTF B4 adapter and a 2/3″ broadcast zoom, but for 4K the Tamron will have better resolution than an HD lens. If I was just shooting HD then the broadcast lens would probably be the best option. After dark I swapped to my Sigma 24-70mm f2.8 for general purpose shooting and this worked well in low light but with the loss of telephoto reach, I need to look into a fast long lens but these tend to be expensive. If you have deep enough pockets the lens to get would probably be the Fujinon Cabrio 19-90 T2.9, but sadly at the moment my budget is blown and my pockets are just not that deep. The Cabrio is very similar to an ENG broadcast lens in that it has a servo zoom, but it’s PL mount and very high resolution. Another lens option would be the Canon CN-E30-105mm T2.8, but overall there isn’t a great deal of choice when it comes down to getting a big zoom range and large aperture at the same time, in a hand-held package. If I was working with a full crew then I would consider using a much larger lens like the Arri Alura 18-80 or Angenieux Optimo 24-290, but then this is no longer what I would consider run and gun and would require an assistant to set up the tripod while I bring out the camera.
From an operating point of view one thing I had to do was to keep reminding myself to double check focus. If you think focus is critical in HD, then it’s super critical for 4K. Thunderstorms are horrid things to try and focus on as they are low contrast and soft looking. I had to use a lot of peaking as well as the 1:1 pixel function of the Alphatron viewfinder, one of the neat things about the Alphatron is that peaking continues to work even in the 1:1 zoom mode. As I was shooting raw and using the cameras Cine EI mode to make exposure simpler I turned on the Look Up Tables on the HDSDI outputs and used the P1 LUT. I then exposed using the waveform monitor keeping my highlights (for example the brighter clouds) at or lower than 100%. On checking the raw footage back this looks to have worked well. Quite a few shots needed grading down by 1 to 1.5 stops, but this is not an issue as there is so much dynamic range that the highlights are still fine and you get a cleaner, less noisy image. When shooting raw with the F5 and F55 cameras I’d rather grade down than up. These cameras behave much more like film cameras due to the massive dynamic range and raw recording, so a little bit of overexposure doesn’t hurt the images as it would when shooting with standard gammas or even log. Grading down (bringing levels down) results in lower noise and a cleaner image.
So you can run and gun in an intense fast moving environment with a large sensor camera. It’s not as easy as with a 2/3″ or 1/2″ camera. You have to take a little more time double checking your focus. The F5 is so sensitive that using a F3.5-F6.5 lens is not a huge problem. A typical 1/2″ camera (EX1, PMW-200) is rated at about 300 ISO and has an f1.8 lens. The F5 in Cine EI mode is 2000 ISO, almost 3 stops more sensitive. So when you put an f3.5 lens on, the F5 ends up performing better in low light, even at f6.5 it’s only effectively one stop less sensitive. For this kind of subject matter you don’t want to be at f1.8 – f2.8 with a super 35mm sensor anyway as the storm scenes and shots involved work better with a deep focus range rather than a shallow one.
Having watched the footage from the shoot back in HD on a large screen monitor I am delighted with the quality of the footage. Even in HD it has better clarity than I have seen in any of my previous storm footage. This is I believe down to the use of a 4K sensor and the very low noise levels. I’d love to see the 4K material on a 4K monitor. It certainly looks good on my Mac’s retina display. Hopefully I’ll get back out on the plains and prairies of Tornado Alley later in May for some more storm chasing. Anyone want to join me?
With winter well upon us I thought it would be good to share some of my arctic shooting experience. I’ve shot in temperatures down to -40c in the arctic in winter.
Overall modern tapeless cameras do OK well in extreme cold. The most reliable cameras are larger solid state cameras. Larger cameras cool slower than small ones and larger cameras will hold on to heat generated internally better than small ones.
Condensation is the big deal breaker. When you take the very cold camera inside into a house/hotel/car/tent you will get condensation. If the camera is very cold this can then freeze on the body of camera including the glass of the lens. If there is condensation on the outside of the camera, there will almost certainly also be condensation inside and this can kill your camera.
To prevent or at least reduce the condensation you can place the camera in a large ziplock bag BEFORE taking it inside, take the camera inside in the bag. Then allow the camera to warm up to the ambient temperature before removing it from the bag. Peli cases are another option, but the large volume of the pelicase means there will be more moisture inside the case to condense and the insulating properties of the case mean that it could take many, many hours to warm up.
I don’t recommend storing a cold or damp camera in a Pelicase (or any other similar waterproof case) as there is nowhere for the moisture to go, so the camera will remain damp until the pelicase is opened and everything dried out properly.
Rather than moving a camera repeatedly from outside to inside and repeatedly generating risky condensation you should consider leaving the camera outside. You can leave the camera outside provided it does not get below -25c. Below -25c you risk the LCD panel freezing and cracking. LCD panels freeze at between -30 to -40c. If you are using a camera in very cold conditions and you notice the edges of the LCD screen going blue or dark you should start thinking about warming up that LCD panel as it may be close to freezing.
LCD displays will become slow and sluggish to respond in the cold. Your pictures may look blurry and smeary because of this. It doesn’t affect the recording, only what you see on the LCD.
Very often in cold regions houses will have an unheated reception room or porch. This is a good place to store your camera rather than taking it inside into the warm. Repeatedly taking a camera from cold to warm without taking precautions against condensation will shorten the life of your camera.
If you can, leave the camera on between shots. The camera generates some heat internally and this will prevent many issues.
Li-Ion batteries are effected by the cold but they are not nearly as bad as Nicads or NiMh batteries which are all but useless below freezing. li-Ion battery life gets reduced by between 25 and 50% depending on how cold it is. Down to about -10c there is only a very marginal loss of capacity. Down to -25c you will loose about 20%-30% below -25c the capacity will fall away further.
Keep your spare batteries in a pocket inside your coat or jacket until you need them. After use let the battery warm up before you charge it if you can. Charging a very cold battery will reduce the lifespan of the battery and it won’t fully charge. One top tip for shooting outside for extended periods is to get a cool box. Get some chemical hand warmers and place them in the cool box with your batteries to keep them warm. If you don’t have hand warmers you can also use a hot water bottle.
Watch your breath
If your lens has and snow or ice on it, don’t be tempted to breath or blow on the lens to blow the ice off. Also try not to breath on the lens when cleaning it as your warm breath will condense on the cold glass and freeze. Also try to avoid breathing out close to the viewfinder. A small soft paint brush is good for keeping your lens clean as in very cold conditions you’ll simply be able to brush and snow or ice off. Otherwise a large lens cloth.
Conventional rain covers become brittle below about -15c and can even shatter like glass below -20c. Special insulated cold weather covers often called “polar bears” can be used and these often have pockets inside for chemical heat packs. These are well worth getting if you are going to be doing a lot of arctic shooting and will help keep the camera warm. As an alternative wrap the camera in a scarf or cut the sleeves of an old sweater to make a tube you can slide over the camera. If you have a sewing machine you could make a simple cover out of some fleece type material.
Your lens will get cold and in some conditions you will get frost on the front element. To help combat this wrap some insulating fabric around the body of the lens. Wrist sweat bands are quite good for this or an old sock with the toes cut off.
Plastics get brittle at low temperatures so be very gentle with anything plastic, especially things made from very hard, cheap plastic. The plastic Sony use appears to be pretty tough even at low temps. Wires and cables may become ridged. Be gentle, bend then too much and the insulation may split.
Other considerations are tripods. If outside in very low temps for more than 30mins or so the grease in the tripod will become very thick and may even freeze, so your fluid damping will become either very stiff or freeze up all together. Contact your tripod manufacturer to see what temperatures their greases can be used over. Vinten and some of the other tripod companies can winterise the tripod and replace the normal grease with arctic grease.
Looking after yourself.
I find that the best way to operate the camera is by wearing a pair of large top quality mittens (gloves are next to useless below -15c), consider getting a pair of Army surplus arctic mittens, they are very cheap on ebay and will normally have an additional “trigger finger”. This extra finger makes it easier to press the record button and things like that. If you can get Swedish or Finnish military winter mittens, these are amongst the best. I wear a pair of thin “thinsulate” gloves that will fit inside the mittens, i can then slip my hands in and out of the mittens to operate the camera.
I keep a chemical hand warmer inside the mittens to warm my fingers back up after using the camera. The hardest thing to keep warm is your feet. If you’ll be standing in snow or standing on ice then conventional hiking boots etc will not keep your feet warm. A Scandinavian trick if standing outside for long periods is to get some small twigs and tree branches to stand on and help insulate your feet from the cold ground. If your feet get cold then you are at risk of frostbite or frost nip. Invest in or hire some decent snow boots like Sorel’s or Baffin’s. I have an arctic clothing guide here; Arctic Clothing Guide |
I was asked by my good friend Rene of Camrade to take a look at some of their new products. So over the next couple of weeks I’ll be looking at the CB Single III camera bag, the PMW F3 rain cover and a new PL lens adapter for the Sony FS100. First I’m going to take a look at the camera bag.
I’ve had Camrade bags before and they have always lasted well, standing up to the knocks and bumps that go along with lugging kit all over the place. I was in the market for a new bag for one of my PMW-F3’s, so I was sent the CB Single III bag. From the outside this is a functional looking bag with a large mesh pocket on one side and further external pockets on the other side and at one end. It has a nice well padded chunky carry strap that is comfortable to use.
The top of the bag opens up with a dual zipper system that gives you completely un hindered access to the bags interior. This is great for run and gun where you may need to quickly grab the camera from the bag and you don’t want to have to squeeze it out through a small opening. The interior of the bag has various dividers that are secured by velcro, so you can customise the layout to suit your needs. One of the dividers forms a clever storage box to one side of the bag. I’ve found this particularly useful with the F3 as I can safely store my Genus 4×4 Matte Box and a couple of DSLR lenses in here.
Then my batteries, other bits and bobs and the rain cover fit comfortably in the end compartments. This bag really works well with the F3 alloying you to get a complete basic shooting kit into one bag without the bag being too big or bulky.
It’s not perhaps the most fancy or sophisticated of bags, but in terms of practicality and functionality it works very well indeed. There is a strap in the main compartment to hold the camera secure if your really going to be bouncing it around. The base and sides of the bag are all semi ridged and have a good layer of shock absorbing foam in them. With one of these bags typically costing a very affordable $200 it really does represent good value for money.
I was asked in some post comments whether the a 50mm PL mount lens would give a wider picture than a 50mm DSLR lens. This confusion comes about I believe because of all the talk about focal length conversion factors. I don’t think this concept is well understood by some people as the implication is that somehow the lens is changing when its used on different cameras, when in fact it’s the camera that is different, not the lens.
It is important to understand that a 50mm lens will always be a 50mm lens. That is it’s focal length. It is determined by the shape of the glass elements and no matter what camera you put it on it will still be a 50mm lens. A 50mm DSLR lens has the same focal length as a 50mm PL mount and as a 50mm 2/3″ broadcast lens. In addition the lens focuses a set distance behind the rear element, agin the distance between the rear element and where it focuses does not change when it’s put on different cameras, so an adapter or spacer must be used to keep the designed distance between the lens and sensor, this distance is called the “flange back”.
The key thing is that it’s not the lens or it’s focal length that changes when you swap between different cameras. It is the size of the sensor that changes.
Imagine a projector shining an image on a screen so that the picture fills the screen. The projector is our “lens”. Without changing anything on the projector what happens if you move the screen closer or further away from the projector? The image projected on the screen will go in and out of focus, so that’s not good, we must keep the projector to screen distance constant, just like the lens to sensor distance (flange back) for any given lens remains constant.
What happens if we make the screen smaller? Well the image remains the same size but we see less of it as some of the image falls of the edge of the screen. If our projected picture was that of a wide landscape then on the reduced screen size what would now be seen would not appear less wide as we are now only seeing the middle part of the picture. The width of the view would be decreased, in other words the FIELD OF VIEW HAS NARROWED. The focal length has not changed.
This is what is happening inside cameras with different size sensors, the lens isn’t changing, just how much of the lenses projected image is falling on or off the sensor.
So the multiplication factor should be considered more accurately as being applied to the camera, not the lens and the multiplication factor changes the field of view, not the focal length.
So whether it is a PL mount lens, a Nikon or Canon DSLR lens or a Fujinon video lens, if it’s a 50mm lens then it’s a 50mm lens and the focal length is the same for all. However the field of view (width and height of the viewed image) will depend on the size of the sensor. So a 50mm PL lens will give the same field of view as a 50mm DSLR lens (no matter what camera the lens was designed for) on the same video camera.
The only other thing to consider is that lenses are designed to work with certain sizes of sensor. A lens designed for a full frame 35mm sensor will completely cover that size of sensor as well as any sensor smaller than that. On the other hand a 2/3? broadcast lens will only cover a 2/3? sensor, so if you try to use it on a larger sensor the image will not fill the frame.
The sensors in the Sony F3 and FS100 are “Super 35mm”. That is about the same size as APS-C. So lenses designed for Full frame 35mm can be used as well as lenses designed for 35mm cine film (35mm PL) and lenses designed for APS-C DSLR’s such as the Nikon DX series and Canon EF-S.