Tag Archives: viewfinder

My Exposure Looks Different On My LCD Compared To My Monitor!

This is a common problem and something people often complain about. It may be that the LCD screen of their camera and the brightness of the  image on their monitor don’t ever seem to quite match. Or after the shoot and once in the grading suite the pictures look brighter or darker than they did at the time of shooting.

A little bit of background info: Most of the small LCD screens used on video cameras are SDR Rec-709 devices. If you were to calibrate the screen correctly the brightness of white on the screen would be 100 Nits. It’s also important to note that this level is the level that is also used for monitors that are designed to be viewed in dimly lit rooms such as edit or grading suites as well as TV’s at home.

The issue with uncovered LCD screens and monitors is your perception of brightness changes according to the ambient viewing light levels. Indoors in a dark room the image on it will appear to be quite bright. Outside on a Sunny day it will appear to be much darker. It’s why all high end viewfinders have enclosed eyepieces, not just to help you focus on a small screen but also because that way you are always viewing the screen under the very same always dark viewing conditions. It’s why a video village on a film set will be in a dark tent. This allows you to then calibrate the viewfinder with white at the correct 100 NIT level and then when viewed in a dark environment your images will look correct.


If you are trying to use an unshaded LCD screen on a bright sunny day you may find you end up over exposing as you compensate for the brighter viewing conditions. Or if you also have an extra monitor that is either brighter or darker you may become confused as to which is the right one to base your exposure assessments on. Pick the wrong one and your exposure may be off.  My recommendation is to get a loupe for the LCD, then your exposure assessment will be much more consistent as you will then always be viewing the screen under the same near ideal conditions.

It’s also been suggested that perhaps the camera and monitor manufacturers should make more small, properly calibrated monitors. But I think a lot of people would be very disappointed with a proper calibrated but uncovered display where white would be 100 NITs as it would be too dim for most outside shoots. Great indoors in a dim room such as an edit or grading suite but unusably dim outside on a sunny day. Most smaller camera monitors are uncalibrated and place white 3 or 4 times brighter at 300 NIT’s or so to make them more easily viewable outside. But because there is no standard for this there can be great variation between different monitors making it hard to understand which one to trust depending on the ambient light levels.

Understanding Sony’s Viewfinder Display Gamma assist.

Most of sony’s cameras that support S-Log3 or Hybrid Log Gamma also have a function called Viewfinder Display Gamma Assist.

Viewfinder Display Gamma Assist allows you to monitor with the cameras built in LCD screen or viewfinder with the correct brightness and contrast range when using gamma curves that are not directly compatible with these Rec-709 screens.

Whenever you try to view a gamma curve that is not normal Rec-709 on a Rec-709 screen the brightness and contrast that you will see will be incorrect. The most common scenario is perhaps viewing S-Log3 without any form of LUT. In this case the images will look less bright and have less contrast than they should and this makes judging exposure difficult as well making it less easy to see focus errors.

With a camera like the FX6 or FX9 most people will use the cameras CineEI mode and add a LUT to the viewfinder image to convert the S-Log3 to something that looks more contrasty and on the FX6 and FX9 the default LUT is “s709”.  However s709 is not the same thing as Rec-709 (Note that with the FX6, because LUTs are always available in the CineEI mode, viewfinder display gamma assist is not available in the CineEI mode of the FX6, you should instead use a LUT).

I think a lot of people think that the default s709 LUT is the same as Rec-709, it’s not, it is very different. They look very different and result in quite different brightness levels when exposed correctly. s709 when exposed correctly will put skin tones somewhere around 50-60% and white at 78%. If you expose s709 using normal Rec-709 brightness levels (70% skintones, 90% white) this is actually over exposed by just over 1 stop. As a result if you expose the s709 LUT, using Rec-709 levels, and then turn off the LUT and instead use Viewfinder Gamma Assist, the gamma assist will look wrong, it will be too bright and may look washed out and this is simply because the exposure IS wrong.

Almost always, if the viewfinder display gamma assist looks wrong, the exposure is wrong. When it looks right, the likelihood is the exposure is right.

A few things to understand:
  • The viewfinder is a Rec-709 range display device only capable of showing Rec-709 range and colour.
  • Feed true Rec-709 to a Rec-709 device and you will have a correct looking image with “normal” brightness, contrast and colour.
  • Feed S-Log3 to a Rec-709 device and you will have an incorrect dull, flat looking image due to the gamma miss-match between the capture gamma and display gamma.
  • Feed S-Log3 to a device with S-Log3 gamma and you will once again have the correct brightness and contrast as there is no longer a gamma miss-match (S-Log3 only appears to be flat due to the gamma missmatch between S-Log3 and Rec-709, use the right gamma and you will see that it is not actually flat).

Viewfinder Display Gamma Assist works by changing the gamma curve used in the Viewfinder to a gamma curve similar to S-Log3. When you view S-Log3 with a monitor with S-Log3 gamma you will have the correct contrast and brightness, so correct exposure will look correct.

But because the cameras LCD display screen can only show 6 to 7 stops you don’t get the full S-Log3 viewing range, just the central mid range part that is the direct equivalent of Rec-709. This very closely matches what you see if you use the Sony 709(800) LUT to convert the S-log3 to 709. The 709(800) LUT converts S-Log2 or S-Log3 to vanilla Rec-709 (70% skintones/90% white) with a knee that provides a slightly extended highlight range. It is broadly comparable to how most conventional Rec-709 cameras will look. So as a result viewfinder display gamma assist and Sony’s 709(800) LUT’s will look almost identical, while the s709 LUT will (and should by design) look different.


Viewfinder Display Gamma Assist is extremely useful for scenarios where you do not have a LUT option such as when shooting in CineEI in HD with the FX9. It can help you make good exposure assessments. It can make it easier to see when you are in focus. But it isn’t a LUT, so can’t be applied to the cameras outputs, only the built in viewfinder. Additionally if you use zebras, the waveform or histogram, gamma assist has no effect on these so you must remember that you are still measuring the levels of the actual recording gamma, not Rec-709 levels.

Viewfinder Gamma Assist is useful not only for shooting with S-Log but also when shooting using HLG (Hybrid Log Gamma). HLG is an HDR gamma curve and because the LCD viewfinder isn’t HDR you can’t correctly monitor HLG directly. Viewfinder Gamma Assist allows you to monitor with the correct brightness and contrast when shooting HLG making it easier to confidently get the correct exposure levels, as much like S-log3 the levels required for the correct exposure of HLG are quite different to Rec-709.

One last thing: NEVER use Viewfinder Gamma Assist with a LUT at the same time, this will result in a completely incorrect looking image and could result in very bad exposure as a result.

Vocas FX6 LCD Support Bracket – Brilliant!

A common complaint with the FX6 is that the pivots on the LCD screen are quite weak. So if you add a heavier sun shade or a magnifier loupe the screen tends to tilt and flop around. Vocas have come up with a really rather brilliant LCD support bracket that works in tandem with the existing LCD mount to turn it into a beautiful fluid damped  system.

The support bracket fits on the supplied 15mm rod normally used for the LCD screen and the the LCD screen assembly slides into the support system. It takes only seconds to fit and remove and no tools are needed so if you do want to take it off at any time you can.

Once fitted you can then add a loupe such as the FX9 loupe or another 3rd party magnifier. The support bracket incorporates a fluid damped pivot that takes the weight of the LCD and stops it sagging or drooping but at the same time allows you to adjust the angle of the screen easily. If you do need to lock it in place there is a locking screw, but normally you don’t need to use this as the fluid damping holds the screen in place very nicely.

You should note that the screen will only tilt up and down when you use the support bracket, so you can no longer fold it flat against the side of the camera, but if you are using a loupe, you can’t do that anyway.

I really like this bracket. I does add a little bit of weight, but if you are using a loupe it really adds a quality feel to the way the LCD screen moves. If you are working handheld without a loupe then it takes seconds to remove it.

For more details take a look at the video.

 

Yes, You Can Use The FX9 Viewfinder With The FX6

FX6FX9VF1 Yes, You Can Use The FX9 Viewfinder With The FX6
The viewfinder assembly from the FX9 fitted to the FX6

 

Good news, you can use the FX9’s viewfinder assembly on the FX6. Not just the loupe/magnifier, but the entire viewfinder including the LCD. It all fits straight on to the FX6 and is full functional. Overlays, menus and the touch screen are all good. The only small thing is the display is initially upside down, but that is easily resolved using the “rotate” switch that is at the bottom of the FX9’s LCD screen.

So – if you have an FX9 and an FX6 you can swap viewfinders between both cameras. We already know that if you simply add the loupe/magnifier from the FX9 to the FX6’s LCD that it fits, but tends to be a bit “droopy” because of the weak hinges on the FX6 LCD.  You can  buy the FX9 LCD as a spare part along with the loupe if you want, but it won’t be cheap!

FX9-LCD-on-FX6-600x401 Yes, You Can Use The FX9 Viewfinder With The FX6

Are We Missing Problems In Our Footage Because We Don’t Use Viewfinders Anymore?

I see it so many times on various forums and user groups – “I didn’t see it until I looked at it at home and now I find the footage is unusable”.

We all want our footage to be perfect all of the time, but sometimes there might be something that trips up the technology that we are using. And that can introduce problems into a shot. The problem is perhaps that these things are not normal. As a result we don’t expect them to be there, so we don’t necessarily look for them. But thinking about this, I also think a lot of it is because very often the only thing being used to view what is being shot is a tiny LCD screen.

For the first 15 years of my career the only viewfinders available were either a monocular viewfinder with a magnifier or a large studio style viewfinder (typically 7″).  Frankly if all you are using is a 3.5″ LCD screen, then you will miss many things!

I see many forum post about these missed image issues on my phone which has a 6″ screen. When I view the small versions of the posted examples of the issue I can rarely see it. But view it full screen and it becomes obvious. So what hope do you have of picking up these issue on location with a tiny monitor screen, often viewed too closely to be in good focus.

A 20 year old will typically have a focus range of around 12 diopters, but by the time you get to 30 that decreases to about 8, by 40 to 5 and 50 just 1 or 2. What that means (for the average person) is that if you are young enough you might be able to focus sufficiently on that small LCD when it’s close enough to your eyes for you to be able to see it properly and be able to see potential problems. But by the time you get to 30 most people won’t be able to adequately focus on a 3.5″ LCD until it’s too far from their eyes to resolve everything it is capable of showing you. If you are hand holding a camera with a 3.5″ screen such that the screen is 30cm or more from your eyes there is no way you can see critical focus or small image artefacts, the screen is just too small. Plus most people that don’t have their eyesight tested regularly don’t even realise it is deteriorating until it gets really bad.

There are very good reason why viewfinders have diopters/magnifiers. They are there to allow you to see everything your screen can show, they make the image appear larger, they keep out unwanted light. When you stop using them you risk missing things that can ruin a shot, whether that’s focus that’s almost but not quite right, something in the background that shouldn’t be there or some subtle technical issue.

It’s all too easy to remove the magnifier and just shoot with the LCD, trusting that the camera will do what you hope it to. Often it’s the easiest way to shoot, we’ve all been there I’m sure. BUT easy doesn’t mean best. When you remove the magnifier you are choosing easy shooting over the ability to see issues in your footage before it’s too late to do something about it.

How We Judge Exposure Looking At an Image And The Importance Of ViewFinder Contrast.

This came out of a discussion about viewfinder brightness where the compliant was that the viewfinder on the FX9 was too bright when compared side by side with another monitor. It got me into really thinking about how we judge exposure when purely looking at a monitor or viewfinder image.

To start with I think it’s important to thing understand a couple of things:

1: Our perception of how bright a light source is depends on the ambient light levels. A candle in a dark room looks really bright, but outside on a sunny day it is not perceived as being so bright. But of course we all know that the light being emitted by that candle is exactly the same in both situations.

2: Between the middle grey of a grey card and the white of a white card there are about 2.5 stops. Faces and skin tones fall roughly half way between middle grey and white. Taking that a step further between what most people will perceive as black, something like a black card, black shirt and a white card there are around 5 to 6 stops and faces will always be roughly 3/4 of the way up that brightness range at somewhere around about 4 stops above black . It doesn’t matter whether that’s outside on a dazzlingly bright day in the desert in the middle East or on a dull overcast winters day in the UK, those relative levels never change.

Now think about this:

If you look at a picture on a screen and the face is significantly brighter than middle grey and much closer to white than middle grey what will you think? To most it will almost certainly appear over exposed because we know that in the real world a face sits roughly 3/4 of the way up the relative brightness range and roughly half way between middle gray and white.

What about if the face is much darker than white and close to middle grey? Then it will generally look under exposed as relative to black, white and middle grey the face is too dark.

The key point here is that we make these exposure judgments based on where faces and other similar things are relative to black and white. We don’t know the actual intensity of the white, but we do know how bright a face should be relative to white and black.

This is why it’s possible to make an accurate exposure assessment using a 100 Nit monitor or a 1000 Nit daylight viewable monitor. Provided the contrast range of the monitor is correct and black looks black, middle grey is in the middle and white looks white then skin tones will be 3/4 of the way up from black and 1/4 down from white when the image is correctly exposed.

But here’s the rub: If you put the 100 Nit monitor next to the 1000 Nit monitor and look at both at the same time, the two will look very, very different. Indoors in a dim room the 1000 Nit monitor will be dazzlingly bright, meanwhile outside on a sunny day the 100 Nit monitor will be barely viewable. So which is right?

The answer is they both are. Indoors, with controlled light levels or when covered with a hood or loupe then the 100 Nit monitor might be preferable. In a grading suite with controlled lighting you would normally use a monitor with white at 100 nits. But outside on a sunny day with no shade or hood the 1000 Nit monitor might be preferable because the 100 nit monitor will be too dim to be of any use.

Think of this another way: Take both monitors into a dark room and take a photo of each monitor with your phone.  The phone’s camera will adjust it’s exposure so both will look the same and the end result will be two photos where the screens will look the same. Our eyes have iris’s just like a cameras and do exactly the same thing, adjust so that the brightness is with the range our eyes can deal with. So the actual brightness is only of concern relative to the ambient light levels.

This presents a challenge to designers of viewfinders that can be used both with or without a loupe or shade such as the LCD viewfinder on the FX9 that which be used both with the loupe/magnifier and without it. How bright should you make it? Not so bright it’s dazzling when using the loupe but bright enough to be useful on a sunny day without the loupe.

The actual brightness isn’t critical (beyond whether it’s bright enough to be seen or not) provided the perceived contrast is right.

When setting up a monitor or viewfinder it’s the adjustment of the black level and black pedestal which alters the contrast of the image (the control of which is confusingly called the brightness control). This “brightness” control is the critical one because if the brightness adjustment raises the blacks by too much then you make the shadows and mids brighter relative to white and less contrasty, so you will tend to expose lower in an attempt to have good contrast and a normal looking mid range. Exposing brighter makes the mids look excessively bright relative to where white is and the black screen surround is.

If the brightness is set too low it pulls the blacks and mids down then you will tend to over expose in an attempt to see details and textures in the shadows and to make the mids normal.

It’s all about the monitor or viewfinders contrast and where everything stits between the darkest and brightest parts pf the image. The peak brightness (equally confusingly set by the contrast control) is largely irrelevant because our perception of how bright this is depends entirely on the ambient light level, just don’t over drive the display.

We don’t look at a VF and think – “Ah that face is 100 nits”.  We think – “that face is 3/4 of the way up between black and white” because that’s exactly how we see faces in all kinds of light conditions – relative levels – not specific brightness.

So far I have been discussing SDR (standard dynamic range) viewfinders. Thankfully I have yet to see an HDR viewfinder because an HDR viewfinder could actually make judging exposure more difficult as “white” such as a white card isn’t very bright in the world of HDR and an HDR viewfinder would have a far greater contrast range than just the 5 or 6 stops of an SDR finder. The viewfinders peak brightness could well be 10 times or more brighter than the white of a white card. So that complicates things as first you need to judge and asses where white is within a very big brightness range. But I guess I’ll cross that bridge when it comes along.

Pxw-fx9 Viewfinder Mounting

After playing with a number of FX9’s I have noticed that the way you arrange the viewfinder rods can alter whether the viewfinder sits level or may tilt just a tiny bit. Based on experimentation with several cameras I believe the orientation of the rods and clamps shown in the pictures here works best to ensure the VF stays level.

DSC_0623-1024x576 Pxw-fx9 Viewfinder Mounting
I believe this is the best orientation for the FX9s viewfinder support bars.
DSC_0621-1024x576 Pxw-fx9 Viewfinder Mounting
Another view of the FX9 support bars.
DSC_0619-1024x576 Pxw-fx9 Viewfinder Mounting
Arranging the FX9 support bars this way seems to minimize any VF tilt.

PXW-FS5 Screen Protector updated images.

Here are some updated pictures of the screen protector for the FS5 that I sell via Shapeways. It’s not an exciting product, it’s just a clip on plastic cover that protects the LCD panel from damage when you are not using the camera. I travel a lot with my camera and the unprotected LCD screen is very vulnerable and could easily get scratched or worse still smashed. Arriving for a shoot and finding the FS5’s LCD screen smashed would be a disaster!

If you want one for yourself you can order them through my Shapeways store: https://www.shapeways.com/shops/alisterchapman

AJC05188 PXW-FS5 Screen Protector updated images.
PXW-FS5 screen protector front view.

AJC05190 PXW-FS5 Screen Protector updated images.
PXW-FS5 screen protection cover clipped on to the LCD screen.

AJC05192 PXW-FS5 Screen Protector updated images.
PXW-FS5 clip on screen saver attached to the LCD.

When is a viewfinder a viewfinder and when is it just a small monitor?

It’s interesting to see how the term viewfinder is now used for small monitors rather than monocular viewfinders or shrouded dedicated viewfinders. Unless the a monitor screen is properly shielded from external light then you can only guess at the contrast and brightness of the images feeding it in anything other than a dim/dark room.

This is one of the key reasons why for decades viewfinders have been in fully shrouded hoods, snoots or loupes. As one of the key roles of a viewfinder is to show how your recordings will look for exposure assessment, if it doesn’t have a full shroud then in my opinion it isn’t a viewfinder, it is simply a monitor and exactly what your images will look like is anyones guess depending on the ambient light conditions. Furthermore even a young person with perfect can’t focus properly at less than 6″/150mm and that distance increases with age or in low ambient light. So most people will need a loupe or magnifying lens to be able to make full use of a small HD LCD for critical focus. In order to be able to see the sharpness of an image you need contrast, so an unshaded LCD screen on a sunny day will be next to useless for focus – perhaps this is why I see so many out of focus exterior shots on TV these days?

To be truly useful a viewfinder needs to be viewed in a controlled and dark environment. That’s why for decades it has been normal to use a monocular viewfinder. The eyepiece creates a tightly controlled, nice and dark,  viewing environment. This isn’t always convenient. I will often flip up or remove the eyepiece for certain types of shot. But – if you don’t have the option to fully shade the viewfinder – how do you work with it on a sunny day? On a camera like the FS5 I often find myself using the small, enclosed viewfinder on the back of the camera when the sun is bright. These tiny built in viewfinders are not ideal, but I’d rather have that than a totally washed out LCD or trying to shoot with a jacket over my head as my only option.

So next time you are looking at upgrading the monitor or viewfinder on your camera do try out a good 3rd party monocular viewfinder such as the Zacuto Gratical or Zacuto Eye. Perhaps consider a Small HD monitor with the  Side Finder option. Or an add-on monocular for the existing LCD panel. Without that all important shading and magnification it isn’t really a viewfinder, it’s just a small LCD monitor and in anything other than a very dim environment it’s always going to be tough to judge focus and exposure.

What’s wrong with my viewfinder, my old camera had a much better viewfinder!

This is something that keeps popping up all over the place and it’s not just one camera that attracts this comment. Many do, from the FS5 to the FS7 to the F55, plus cameras from other manufacturers too.
One common factor is that very often this relates to the newer super35mm cameras. Cameras designed to give a more rounded, film like look, often cameras with 4K or higher resolution sensors.
I think many people perceive there is an issue with their viewfinder because they come to these new high resolution, more rounded and film like cameras  from traditional television centric camcorders that use detail correction, coring and aperture correction to boost the image sharpness.
SD and even HD television broadcasting relies heavily on image sharpening so that viewers perceive a crisp, sharp image at any viewing distance and with any screen size (although on really big screens this can really ruin the image).
This works by enhancing and boosting the contrast around edges. This is standard practice on all normal HD and SD broadcast cameras. Especially camera that use a 3 chip design with a prism as the prism will often reduce the images edge contrast.
As most people will prefer a very slightly sharpened HD image or a heavily sharpened SD image over an unsharpened one, it’s sharpened by default. This means that the images those cameras produce will tend to look sharp even on screens that have a lower resolution than that of the camera because the edges remain high contrast even when the viewing resolution is reduced and as a result look sharp.
Most current manufacturer supplied LCD EVF’s run at 1/4″ HD with 940 x 560 pixels (each pixel made up of an RGB 3 dot matrix). In addition many of the 3rd party VF’s such as the very popular Alphatron are the same because they all use the same mass produced, relatively low cost panels – panels that are also used for mobile phones and many other devices. 
 
The problem then is that when you move to a camera that doesn’t add any image sharpening, if you view the cameras image on a lower resolution screen the image looks soft because — it is. There is no detail correction to compensate. Incidentally this is why often these same cameras can look a bit soft in HD and very soft in SD compared to other traditional or detail corrected cameras. But, that slightly softer, less processed look helps contribute to their more film like look. This softness and lack of sharpening/processing is particularly noticeable if you use the focus mag function as you are then looking at an enlarged but completely un-sharpened image.
 
It could be argued that the viewfinder should sharpen the image to compensate. Some of the more expensive viewfinders can do this using their own sharpening processes. But the image that you are then seeing is not the picture that is being recorded and this isn’t always ideal. If it is over done then it can make the entire image look sharp even when it isn’t fully in focus. Really you want to be looking at exactly the image that the camera is recording so that you can spot any potential problems. But that then makes focussing tricky.
 
There are a few 3rd party viewfinders such as the Gratical that have higher resolutions. The Gratical and Eye have screens that are 1280×1024, but in normal use you only use 1280×720 for the image area. This certainly helps, but even the 1:1 pixel zoom on these can look soft and blurry as you loose the viewfinders peaking function when you crop in.
 
Sony’s Venice and the F55/F5 can use Sony’s new DVF-EL200 OLED viewfinder. This costs around £4.5K ($6K) and has a 1920×1080 screen. It’s a beautiful image, but even this needs a fairly good dose of peaking to artificially sharpen the image to be able to see that last critical bit of focus. Again when you zoom in the image looks soft and a bit blurry (even on a Venice) as the camera itself is not adding any sharpening. The peaking function on the DVF-EL200 is quite sophisticated as it only enhances the highest frequency parts of the image, so only sharp edges and fine details are boosted.
 
Go back to the days of black and white tube viewfinders and these used tons of peaking to make them useable. Traditional SD and HD cameras add sharpening to their pictures, but most of our modern large sensor 4K camera do not and as a result often the viewfinder images appear soft compared to what we used to see on older cameras or still see today on cameras that do sharpen the pictures.
 
All of this makes it hard to nail your focus, especially if shooting 4K. Even with a DVF-EL200 on a Venice I struggle at times and rely heavily on image mag (which is still difficult) or better still a much larger monitor with a good sun shade and if necessary some reading glasses to allow you to focus on it up close.

So before you get too critical of your viewfinders performance do also consider all of the above. Try to see how another similar viewfinder looks on your camera (for example an Alphatron on an FS7). Perhaps try a higher resolution viewfinder such as a Gratical, but don’t expect miracles from a small, relatively low resolution screen on a modern digital cinema camera. This really is one of those areas where you can’t beat a big, high resolution screen.