More Gemini, Samurai, AC-Log and S-Log sample frame grabs. See download box at bottom of post.
I had thought, when I first wrote this post that I had discovered a strange issue where the 444 RGB recordings from the Gemini had more dynamic range than 422 recordings. I didn’t think this was right, but it was what my NLE’s (FCP and CS5.5) were telling me. Anyway to cut a long story short, what was happening was that when I dropped the Gemini RGB files into the timeline the levels got mapped to legal levels, i.e. nothing over 100% while the YCbCr 422 clips go into the timeline at their original levels. The end result was that it appeared that the 422 clips were clipping before the 444 clips. Thanks to Waho for suggesting that it may be a conversion issue with the frame grabs, I was able to see that it was simply the way the NLE’s (both CS5.5 and FCP were behaving in the same way) were clipping off anything in the 422 clips above 100% both in the frame grabs and also on the monitor output. As the RGB files were all below 100% they were not clipped so appeared to have greater dynamic range.
Anyway….. below is a new set of frame grabs layered up in a single photoshop file showing how the various codecs and recorders and codecs perform. The levels in these have been normalised at 100% to avoid any dodgy clipping issues. I’ve included F3 Cinegamma 4, plus my AC-Log picture profile, plus Samurai ProRes, Gemini S-Log and F3 Internally recorded S-Log of a very extreme contrast situation. Use the link below to download the photoshop layers file. You’ll need to me a registered user to access the link.
Well the new year is less than a month away and at this time every year I start to consider my product of the year. To qualify the product must be available for general purchase within the year, so the C300 can not be included. In the running at the moment:
PMW-F3, FS-100, Convergent Design Gemini, Atamos Ninja/Samurai, Matrox Ultra Studio, F65 (if it ships before year end). Media Composer 6, Zacuto EVF, Cineroid Metal EVF.
Anyone think I should be considering anything else?
I spent most of the morning at the Visual Impact C300 open house. They had 3 C300’s on show. One on a camera set alongside an F3 and an Alexa, the other was a very simple handheld configuration for people to play with and a 3rd on a stedicam rig.
What impressed me the most was how nice the camera was to hand hold and how good the rear viewfinder is. You certainly don’t need anything extra to shoot with it.
On the camera set I was a little less impressed. At the beginning of the day when I first quickly looked at the 3 monitors I could see no obvious difference between any of the cameras. The monitors were fairly small 20″ Panasonic monitors. However when I went back to take a closer look, for some reason the C300 looked a little soft or not quite in focus. No matter how I played with the focus, the edges of the image looked soft compared to the F3 next to it. Both the F3 and the C300 had Arri 32mm master primes so they should have been similar. I was told all the cameras were set up with standard gammas, but looking at the C300 it looked quite flat, so perhaps it was setup with the Canon Log gamma and the resulting lower contrast was making the image appear softer. There were so many people at the event that it was difficult to really get at the camera to figure out what was going on. I don’t think something was quite right, I’ve seen better from the C300. I asked if I could record some footage but was told that this was not possible on this occasion as these are pre-production cameras. Shame, I had a pocket full of CF cards and SxS cards. Anyway I have been promised a test shoot very soon.
I really hope that the softness was a peculiarity of that particular camera or the way it was set up as the C300 would for me be fantastic for my storm chasing and extreme weather assignments. I’d love to take one up to Norway in January to see if it sensitive enough to shoot the Northern Lights without having to resort to slow shutters or long exposures (Stop Press… I’ve placed an order and hope to have one in time for Norway). I’ve done the math, and according to my calculations it should just about be sensitive enough at 22,000iso with a f1.4 lens to shoot the Aurora in real time. It would be really cool to try and stream the Aurora live from Norway in January. On other assignments I could shoot using Canon L series glass or my B4 to Canon adapter and get broadcast ready material without needing an external recorder. I still think the Sony F3 with S-Log and an external 444 recorder is capable of a better image, but that’s a significantly more expensive package and more cumbersome, power hungry etc. It’s horses for courses. The C300 for me looks to be fantastic for simple, fast, easy shoots where shallow DoF is desirable, while I would continue to use the F3 where the extra bulk of an external recorder and the slightly more complex S-Log workflow will not be an issue as I think the ultimate image quality will be better. I might just have to place an order for one, especially as the price will be less than anticipated. The price I was offered from Visual Impact today was £9995, available from mid January…. Just in time to take to Norway????
Note: There is something up with the frame grabs. For some reason they are very dark. I’ll look into this in the morning and get some more accurate grabs online.
First of all let me say thanks to Ben Allan on CML list for getting me thinking about this. He has already started experimenting with creating a log style Picture Profile for the EX1. All the setting you’ll find here are my own work and based on tests done with real scenes and some dodgy home made latitude test charts 😉
Ben’s musings on CML made me consider what S-Log is. In essence it is nothing more than a clever gamma curve that allows you to capture a greater dynamic range than is normally possible with conventional gamma curves. The reason why the standard gamma dynamic range is normally constrained is in part simply because if you record too large a dynamic range and then show it on a conventional monitor or TV, it simply does not look right. So to make it look right it must be graded in post production. In order to do a significant grade in post, the quality of the recording has to be good enough to withstand a fair bit of pulling and pushing. As a result 10 bit recording is recommended (however it is still possible to work with lot with top quality low noise 8 bit recordings, not that I would recommend this). Anyway as both the standard PMW-F3 and EX1/EX3 have 10 bit outputs I decided to see if it was possible to come up with a picture profile that would mimic a Log curve and then see if it actually brings any real world advantage.
Genuine S-Log, mid grey @38%
First up I experimented with the F3. I already have the S-Log option, so this gave me a benchmark to work against. To mimic S-Log you need to increase the gamma gain at the lower end of the curve, you can do this with the Black Gamma function. I know that with S-Log the cameras native ISO is 800 as this is the sensitivity at which maximum dynamic range can be realised with the F3’s sensor. So I started my experiments at 800iso. I could bring up the shadow detail with the Black Gamma but I notice that I appeared to be trading off some highlight handling for shadow information, so while the images kind of looked like S-Log, they did not really gain any latitude.
AC-Log v1. Very similar to S-Log, same exposure as S-Log
During this process I realised that my mid range sensitivity was now a lot higher than with genuine S-Log, so I decreased the camera gain so I was now at 400iso and started tweaking again. Now with Black Gamma all the way up at +99 I was seeing around 1 stop further into the shadows, with no impact on highlight handling.
When I tested my new Picture Profile on a real scene, exposing as you would S-Log with mid grey at 38% I was very pleased to find some very similar images that do grade quite well. As well as the Gamma tweaks I also incorporated a few other changes into the profile to increase the overall grade-ability.
CineGamma 4, mid-grey at 38%
There is a definite improvement in shadow reproduction. It’s not as good as real S-Log, but it does give a very useful improvement for those without S-Log. One interesting point is that the exposure between the two log frame grabs posted here is not changed, so even though the camera is set at 400iso, when the picture profile is applied the camera behaves more like an 800iso camera and exposure should be set accordingly. I think my PP (which you can download at the bottom of the page) brings a little under a one stop improvement in DR, real S-Log is about 2 stops.
If you click on the image captures you can view them full frame. When you compare the AC-Log and Cinegamma 4 images you should be able to see more shadow detail in the tree on the right of frame with the AC-Log yet the sky is further from clipping as well.
So what about the EX1 and EX3, can the same be done for them? Well this is much more of a challenge as the EX cameras are much noisier. Simply bringing up the Black Gamma does help you see into the shadows a bit better but it comes at the cost of a lot of extra noise and really makes it un gradable. Normally I don’t recommend using negative gain as it can reduce the dynamic range of the camera. But I figured if I use negative gain and then increase the gamma gain that should cancel out any dynamic range loss. To then avoid the usual -3db reduction in highlight performance I adjusted the overall gamma gain to return the peak output level to 109IRE. After a bit of fiddling around with my test charts and waveform monitors I could see that it was possible to gain a small amount of dynamic range, a little under 1 stop, however there is an overall increase in the noise level of about +4db. Now that doesn’t sound too terrible, but to gain the extra stop of DR you have to under expose compared to standard gamma’s, typically with S-Log you would put mid grey at 38% (use the centre spot meter on the EX1/EX3 and a grey card). This works reasonable well with this fake log picture profile. The problem however is that when grading you may find that you have to add still further gain to bring skin tones to a normal level and this will accentuate the noise. You could use something like the Neat Video plugging to reduce the noise and in this case I think this sudo Log picture profile could be handy in tricky lighting situations. The EX1R Log picture profile, to work correctly MUST be used in conjunction with -3db gain, any other gain setting and you will loose dynamic range. Again like real S-Log, 10 bit external recording is desirable, but why not play with the picture profile and try it for yourself. It is a bit experimental, I’m not convinced that the extra stop of DR is worth the noise penalty on the EX1R, but then I’m spoilt as I have an S-Log F3.
I have uploaded both the F3 and EX1R picture profiles into a single zip file that you can download below. You will need to have an account on xdcam-user.com to download them, or register for a new account first. Un-zip the package and copy the SONY folder to the root of an SxS card, so you should have both a BPAV folder and a SONY folder in the root directory. The cameras will need the latest firmware versions to load the single profile directly. In the Picture Profile menu choose an empty PP and then in the bottom PP menu chose “load”.
I have created a single photoshop file with multiple layers each containing some of my codec test results. Layers include, Uncompressed DPX, Samurai ProRes, ProRes HQ and DNxHD 185 encodes from the DPX and F3 Internal Mpeg 2 @ 35Mb/s. By zooming in and turning layers on and off in Photoshop you can quickly see the differences in the quality. One thing this highlighted was some duplicated pixels in the DPX files from the Gemini. This issue has now been fixed.
I’ve been playing with the Sony 3D link kit for the F3. I’m still discovering some of the fine details of how and what exactly it gives you, but what I will say right now is that it really, really simplifies 3D with a pair of PMW-F3’s.
The kit comprises of a couple of SxS cards with the software keys required to activate the cameras plus a special cable that connects the two cameras together. After loading the software keys on to both cameras you get an additional menu option to activate the 3D link in one of two modes, master or slave. With one camera connected to the other and one set as master, the other as slave the first thing that happens is that the cameras will sync with each other. My initial testing indicates that this is more than just Genlock, it appears to be full shutter sync. I’ve tried a few fast shutter speeds and so far have not seen anything to suggest the shutters are not in sync, but a proper test is still needed to confirm this.
Other things that happen is that the cameras will both go in and out of record in sync and the timecode of the master camera is used by the slave. If you change the shutter on the master camera the slave also changes. I’m still learning more about the way the 3D link system works and I really like it a lot. Anyone doing a lot of 3D work should seriously consider it. It is pricey at around $5k for the kit for a pair of cameras (although it does also include a couple of SxS cards) but the stable sync, dual start/stop and small things like the sync shutter speed changes does remove another set of things to worry about during your 3D shoot.
It’s really flattering to find that XDCAM-USER has passed another milestone. Last month the site received 518,817 hits from 62,310 visits. Please, please let me know what you want more of, is it reviews, tech notes, or just my random ramblings? I’ve got some really exciting projects lined up for next year including a super 35mm 3D music video shoot, Northern lights workshops (sold out), 3d and Cinematography workshops, a feature shoot for big screen release and much much more.
I got the opportunity to shoot a quick test with one of Sony’s new SR-R1 recorders while in Dubai. The SR-R1 will have a street price in the region of $18k USD and a 256GB SR Memory card will cost around $7,500 USD!!! The big selling points of SR Memory are it’s speed and reliability as each cartridge (bigger and chunkier than most memory cards) contains a solid state raid array. However, while the price of the SR-R1 recorder is not in itself unreasonable, I feel the cost of media is sky high. So with that in mind I wanted to see how it compares overall to the Convergent Design Gemini which is a cheaper solution. The Gemini costs about $6k with a 256Gb SSD running at around $750 USD.
One thing to take into account is the true cost of storage on these two devices. While the Gemini media is cheaper, you do require a lot more of it per minute. If your shooting 444, 1920×1080, 24p then your looking at around 750GB per hour which equates to a cost of around $2,250 per hour. The SR-R1 recording SR-SQ which is the standard quality setting (440Mb/s 444) will fit a little over an hour of material on a single 256GB card, so SR Memory works out at around $7,000 per hour, almost 3 times as much as the Gemini. Of course in both cases you will re use your media many, many times, so in the long run compared to tape the media costs may not be quite so scary.
So what do you get for all this extra money with the SR-R1? Well you do get a faster workflow. The SR Memory cards can operate at upto 5Gb/s, so with more compact SR-SQ material, on paper at least, a transfer speed of around 10x real time should be possible. However in reality transfer speeds will be much lower than this as there just aren’t the data interfaces currently available that can sustain this. Still the transfers will be a lot faster than the Gemini which in a perfect world would also max out at 5Gb/s but again in reality will be somewhat slower, but due to the much larger files size. Even in a perfect world the Gemini, uncompressed, would probably at best reach 2x real time. Being realistic with well setup systems you should be able to get 1.5x real time with the Gemini and 5x realtime with SR-SQ. Now this could be a big time saving on a large project and you have to consider this. You also have to figure out how your going to store the Gemini data long term as don’t forget you probably want at least two copies. Now one of the ways to use the Gemini is to do a first encode as you copy the material of the SSD’s and this can seriously reduce your storage requirements and actually speed up your transfer speeds.
But what about image quality? Well the Gemini is uncompressed, so there is no difference between your recordings and what comes out of the back of the camera. This really is as good as you can get. The SR-R1 recording SR-SQ is compressing the data by about 4.5:1. That’s not that high by todays standards, but it is still a fair amount of lossy data squashing. Comparing Gemini DPX files and SR-SQ files it is very difficult to see any difference. There’s no added noise as occurs when you use ProRes and compression artefacts are hard to find. Look hard enough with a highly detailed image or lots of motion and you can find a bit of mosquito noise, but it’s very, very minor and I’d be more than happy with the material, even for high end productions.
So in summary the Gemini offers a perfect copy of the camera output, for a lower initial outlay and has cheaper media. But the workflow is a bit slower and you must consider how you will archive your data. The SR-R1 is more expensive, as is the media. It produces a near perfect copy of the camera output and has a fast workflow with files that are more compact and thus easier to store and work with.
The Gemini also has the benefit of a great LCD screen, while the SR-R1 is more like a traditional VTR. Gemini uses a lot less power, SR-R1 has a fan and is more power hungry. For me, the Gemini is the winner, the image quality really is as good as it gets. For production companies working on multiple projects or long form films the SR-R1 may be preferable simply because file management may prove to be easier.
TEST TO COMPARE A PMW-F3 RECORDING ON ATAMOS SAMURAI, CONVERGENT DESIGN GEMINI and INTERNALLY.
Now I thought this would be simple. Set up my PMW-F3 with a Convergent Design Gemini and an Atamos Samurai and shoot a few shots so that I could compare the output from each recording codec. Well, the shoot side of things went just fine, a couple of different shots recording to DPX on the Gemini, ProRes on the Samurai and the internal recordings on the F3. The shots were exposed using a grey card exposed at 38%. The F3 was set to output 444 Dual Link S-Log.
However all sorts of strange things are happening when I bring the clips into my edit applications. What’s worse I get different results with different apps. For example bringing in all the material in to Adobe CS5.5 results in different luma levels for all the clips. Not only that, I also created some ProRes 4444 clips from the uncompressed DPX files and these are different again. This makes it really hard to analyse the footage when black levels are different or brightness and saturation are different. Heck all the clips were shot at exactly the same moment in time or at least within a few seconds of each other. The ONLY difference should be between the quality of the recordings. This is just more Apple Quicktime weirdness making my life difficult.
Anyway, after much head scratching and trying FCP, Avid and Premier to view the clips I was able to draw some useful conclusions which I’ll share with you here. Now the first, which may seem obvious, is that of the bunch, the Convergent Design Gemini DPX files are without doubt the best. They have zero artefacts and no added noise. After that though things become much more confusing!
Now you would expect (or at least I expected) the F3’s internal 8 bit recordings to be the worst of the bunch as all the others are 10 bit and much higher bit rates, but you know what the F3 recordings stand up really well. Why? Well in the tests I did the S-Log footage really didn’t need much of a grade to produce a nice looking image, so the clips were not being pushed very hard. One thing I’ve noticed about ProRes in the past and once again noticed in these tests, is that it’s noisy, or at least adds noise on the first encode. When you look at the Grey card in the frame grabs you can see that all of the ProRes clips show more noise than the DPX files or the F3 internal recordings, I conclude from this that ProRes is adding noise.
So in a low motion, fairly static scene the F3 recordings hold up impressively well against the ProRes ones. However I also know from experience that when you start adding in a lot of motion to a scene that 35Mb/s Mpeg can start to soften a little and in extreme circumstances really struggle and this is where ProRes starts to win as the extra data the HQ version uses really helps.
Going back to the clips from this test and looking more closely at the my wife’s face there is a difference in the way the EX codec and the ProRes codecs look. The ProRes is showing a little less blockiness and this would be a big help if you were harding the material harder. Again the clear winner is the DPX files from the Gemini, but then what do you expect!
So these are my conclusions from this test:
The Gemini DPX files produce the cleanest most gradeable images.
ProRes is noisy compared to the original source.
F3 S-Log recordings using the internal codec can be graded successfully by small amounts without obvious degradation, but I would not recommend it as you never know how much the colourist may want to push the material.
I need to shoot more challenging scenes for this type of test.
Registered users can download a 45MB zip file containing full resolution frames, graded and un-graded recorded using the Gemini, Samurai and F3. If you are not a registered user you will get the option to create an account.
I’ve been testing and using a Gemini with my S-log equipped PMW-F3 for a month now and I have to say that every time I use the combo the image quality amazes me.
The Gemini firmware has been updated many times in that month, but I can report that the latest release is nice and stable and delivering the goods. The gemini is remarkable easy to use, the on screen menus are clear and concise. Talking of the screen the LCD is very good indeed. It is clearly visible even in bright direct sunlight. I’ve also been using some other external recorders with screens and the Gemini stands out as a clear winner in this regard.
Power consumption is very good. I’m using Swit 86U batteries with a D-tap to power both the F3 and the Gemini and I get around 2 hours from a fully charged battery. This keeps the size and weight of the rig very manageable, no need to upgrade my tripod or use special mounts for the Gemini, it sits very nicely on the F3’s handle. You can still use the full kit handheld without needing to use a shoulder mount or wear the recorder in a rucksack or similar.
Now.. there are some important things to consider with the Gemini. It is a high end production tool at a low end price. You do get high end, beautiful image quality and you get the same kind of files as you’d use for high end movies and commercials. These DPX files are basically sequences of uncompressed still frames. If you are considering the Gemini you do need to think about your workflow. You will be generating some damn big files, 750GB per hour and that presents a few issues.
Don’t expect to transfer your material to a laptop hard drive in real time. The Gemini uses ultra fast SSD’s because regular hard drives are not fast enough for 444 uncompressed data, so you just won’t get real time uncompressed copies to a laptop drive. It’s taken me up to 3 hours to copy an hour of footage to a fast single hard drive. If you want real time or faster transfers of uncompressed 444 (from ANY device) then your going to want a nice big, fast, raid array, that’s just a fact of uncompressed life.
One option with the Gemini is to convert your files to a compressed codec as you transfer from the SSD’s. This can actually end up faster than doing a straight copy as with a fast computer the material can be pulled of the SSD quickly, encoded and then the more compact file written to a conventional hard drive. For this to be effective I recommend at the very least a dual core i5 2.3Ghz machine. For current model MacBook and iMac users you will be able to use the Sonnet Echo Express thunderbolt to express card adapter along with a Sonnet Express34 to dual eSata adapter to get fast transfers (available December).
I’ve been transcoding to ProRes 4444 and the results are superb. Avid Media Composer 6 now includes a 444 codec but I have not tested this yet. My i7 iMac will encode from uncompressed to ProRes 444 at around realtime speeds.
Another thing you must consider is that because DPX is a stills sequence, there is no audio. At the moment the Gemini does not record audio, so I record both in camera with audio plus the DPX files on the Gemini. It’s pretty straight forward to sync them up in post. There will be a firmware update in the future to add audio recording to the Gemini, so this is just a temporary issue.
So, being realistic about things. The Gemini 444 is a great device. It’s uncompressed so the image quality is fantastic. But you must consider that this is a very high end uncompressed recorder and with any uncompressed HD recorder you will end up with big files. I won’t be using the Gemini for everything I do, the workflow doesn’t suit fast turnaround productions and frankly it’s overkill for web videos etc. But when quality is paramount the Gemini truly excels, performing as well as devices costing many times more, yet offering one of the best LCD’s, very low power and it is a featherweight in comparison to some of the other external brick recorders.
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