FS7: Compression artefacts in high contrast areas shooting raw with the Odyssey 7Q+

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hauklien

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We have just started using our new Sony PXW FS7 and the XDCA-FS7 Extension Unit with our Odyssey 7Q+, shooting 2k/4k raw via SDI (.dng). We immediately noticed heavy fringing and compression artefacts along high contrast areas, extending into the shadow area. It looks like compression artefacts similar to that of heavily compressed jpg pictures. However, we are shooting RAW, so this should not be an issue as there should be no compression of raw files. Quoting from Sony's own brocure: "RAW is an uncompressed signal containing all the information from the sensor, and represents the highest quality recording capable from these camcorders, with the largest amount of data. RAW is not coded and should not be confused with XAVC."

Our current setup for testing is Canon 85 1.2L II with a Metabones speed booster. We have noticed that internal prores files do not have this issue, so we think that we can rule out lenses and accessories. We noticed that on 4k raw the problem is less visible, but it is still there. It's the 2k raw that suffers most from this issue, and we purchased this system with the Odyssey 7Q+ primarily to be able to shoot 2k raw. We could of course shoot everything in 4k raw, but that would give us other workflow challenges.

Basically this renders the camera's raw capabilities useless since we love shooting with high dynamic range scenes, high contrasts, sunsets, reflections, etc.

Does anyone else have this problem and/or a solution to this? Jim Beethe at Convergent Design says this is a Sony issue that has nothing to do with their recorder, and that the Odyssey records exactly what the FS7 is outputting. For the record, we have updated to the latest firmwares: Odyssey 7Q+ has 2015.8 (1098). PXW-FS7 has V2.10 dated July 2, 2015. XDCA-FS7 has V2.00 dated March 26 2015.

Do someone else have the same issue, or are we doing something wrong here? We are comparing with the Canon 5D mk3 and feel like continuing shooting Magic Lantern RAW...

See these screen grabs and judge for yourselves. Only thing done to these two .dng files is opening them in Adobe Camera Raw, pulling back highlights and up the shadows.
Full res versions here: https://www.dropbox.com/sh/s57fcsmycp2dkfc/AAAdjctMWdKtbvwRGIizFtBGa?dl=0

Screen Shot 2015-08-25 at 14.57.15.jpgScreen Shot 2015-08-25 at 07.55.45.jpg




 
I have uploaded some .dng files from the same sequences and a third sequence to the same Dropbox location for scrutiny.
Check out the contrast areas to see the ghosting and artefacts moving around there.
 
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It's worth noting the 2k "raw" isn't a center crop. I always though that must be a cheat, somehow. Essentially, you have to do something to convert a 4k sensor to a 2k output. Either you skip photosites, or you bin them together, or something. It's possible this is what's coming out of the camera and is a fault of Sony's implementation and not the O7Q. Hard to know from this end.
 
I doubt that what the FS7 outputs is a 2K crop. The more likely scenario is that it is doing a 4K -> 2K scale in camera and pixel binning might be involved. That could account for the pixelation and artifacting which I see as well. I can't test it on mine now since it is all packed up to go out on a job later today, but definitely worth looking at.

Firmware 3.0 will offer a true center crop so we need to wait to see if that will have any effect.

Ned Soltz
 
Viddovation said:
It's worth noting the 2k "raw" isn't a center crop. I always though that must be a cheat, somehow. Essentially, you have to do something to convert a 4k sensor to a 2k output. Either you skip photosites, or you bin them together, or something. It's possible this is what's coming out of the camera and is a fault of Sony's implementation and not the O7Q. Hard to know from this end.
Click to expand...

Isn't scaling from original 4K output to 2K done in Odyssey?
 
We’ve been using the FS7 + O7Q combo for months now, and been getting exceptional results. That being said, you do have to understand the limitations of your gear.


There is no reason to shoot in 2k RAW unless you are trying to record 240fps. You will not get a better image than the internal XAVC-I at HD. That being said, the O7Q’s 4k to HD mode will provide the best HD image from your setup.


Part of the problem is with the Camera’s 4k to 2k RAW conversion. You can see a post in which I highlight part of the problem here: http://www.dvxuser.com/V6/showthrea...l-Mann&p=1986528630&viewfull=1#post1986528630
I spoke to Sony about this at NAB, and they pretty much confirmed that it was an issue with the in camera downconversion process.



Mitch Gross weighs in a little later in the coversation: (http://www.dvxuser.com/V6/showthrea...l-Mann&p=1986528783&viewfull=1#post1986528783):
“I can tell you that 2K RAW from an FS7 (or an FS700 for that matter) will ALWAYS be a compromise format for a variety of reasons. You will always have better, cleaner imaging from 4K RAW sampled in post down to 2K. Of course that tops you out at 60p, but there are numerous issues involved in the process of turning the 4K sensor into a 2K one while maintaining the field of view. As to why there is an apparently superior result in the camera's internal XAVC recording we will continue to analyze, but we do find that Sony adds various compression and other video tricks into the signal before recording it.”


If you need to shoot at anything less than 240 (i.e. 61-180fps), I’ve found that the internal recording is superior to the 2k because of these problems. However, if you understand the limitations and you prep/light your scenes properly, you can definitely use the 240 2k RAW option successfully.

I am seeing some weird pixelation in your uploaded images that I haven't run across before. However, without knowing quite a bit more about your setup, it's hard to know what might be causing that.

Regarding the question "Isn't scaling from original 4K output to 2K done in Odyssey?" The answer is yes. If you feed the Odyssey 7Q a 4k signal it can record 4k or downconvert to 2k. However, if you are feeding it 2k RAW, then the camera is doing the downconvert.
 
Like Christopher said, it sounds like the issue is that the camera is being set to send out 2K RAW. But to clarify the last line of his post, I don't believe the Odyssey has a 4K RAW > 2K RAW internal conversion mode. What it *does* have is 4K RAW to 2K/HD ProRes.

I would avoid putting the camera into 2K RAW mode, at least until Sony comes up with a 2K Crop mode. 4K RAW to ProRes is pretty great on the Odyssey7Q and would give you robust files without these artifacts.
 
The bars come from Convergent Design's Raw Bundle "watermark" for the Oddyssey 7Q+. You need to pay a $1000 licence fee to get rid of that bar if you want to shoot raw and 240 fps. We want to make sure it's worth it before we pay that fee by doing some testing. The rest of the image should be just like it would be if you pay the licence fee.
 
hauklien said:
The bars come from Convergent Design's Raw Bundle "watermark" for the Oddyssey 7Q+. You need to pay a $1000 licence fee to get rid of that bar if you want to shoot raw and 240 fps. We want to make sure it's worth it before we pay that fee by doing some testing. The rest of the image should be just like it would be if you pay the licence fee.
Click to expand...

Gotcha.
 
I shot this as a test about a month ago to compare two shutter angles at 240p. I figured you might like to see what other people's 240p footage is looking like. This was shot outside on a sunny day with the FS7 and O7Q.

https://vimeo.com/134620886
password: balldrop
 
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