dfreerider
Well-known member
I think Kanta Yamamoto handles the A7s, at least in Europe. Someone like Den Lennie would probably know how to reach him.
A7s highlight aliasing. Houston we have a problem
- Thread starter squig
- Start date
I think Kanta Yamamoto handles the A7s, at least in Europe. Someone like Den Lennie would probably know how to reach him.
Ian-T
Veteran
I like this.
paulcurtis
Veteran
Both the 700 and 100 do it as do many other cameras (the canons have their own issues with scaling too). It's an artefact of the scaling algorithm, it produces negative values at high contrast transitions. You used to be able to recreate it in Photoshop and you can certainly set something up in Nuke to mimic it. If you google it you should see a more detailed explanation. (if you look at ringing effects in wikipedia there is a section called related phenomena and there's talk of overshoot which is what it is, the algorithm creating negative lobes(values) that are turned into black - somewhere out there is a really good paper on it, with examples showing exactly what we're seeing - but i can't find it at the moment)
It's not to say that something can't be done about it, but it's been present all the time in all Sony cameras, so it must be a way that sony likes to scale.
The external recorder will show it too.
I'd guess that 4K out would not show it.
Same deal for the 700, everything but 4K RAW would show it, 4K RAW is clean in that regard (as is the 4K2HD mode) confirming it's not a sensor issue.
We found that Slog would minimise it simply because there's less of a harsh contrast usually.
So i'm 99% that's what's causing it, but i don't see why Sony couldn't have fixed it though...
cheers
Paul
It's not to say that something can't be done about it, but it's been present all the time in all Sony cameras, so it must be a way that sony likes to scale.
The external recorder will show it too.
I'd guess that 4K out would not show it.
Same deal for the 700, everything but 4K RAW would show it, 4K RAW is clean in that regard (as is the 4K2HD mode) confirming it's not a sensor issue.
We found that Slog would minimise it simply because there's less of a harsh contrast usually.
So i'm 99% that's what's causing it, but i don't see why Sony couldn't have fixed it though...
cheers
Paul
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Samuel H
Major Contributor
My take on why this doesn't appear in some shots: because in the original files the highlights are nowhere as bright as they should be to show the problem, only the grade turns them to near-white. Just speculation, though. I'd love to have a camera to play with... I'm gonna have no nails left when my a7s arrives.
NeedCreative
Well-known member
Between this camera and the GH4, I think everybody needs to chill out or up their budget!These incredible tools are under $3,000 and some have put them in the "not good enough" category already. If a camera does not create the image you are after, save up and buy a better one instead of trying to make a lesser model punch above its weight. Sorry to say this but this syndrome seems to get worse with every generation of improved cameras that are released.
FYI the now $12000 formerly $16000 C300 had pretty bad highlight aliasing when it first came out. Newer FW mostly rectified that, but even I still see it on occasion. What the a 7s is showing is very minimal.
FWIW the GH4 doesn't do it at all.
paulcurtis
Veteran
The effect would be generated in the camera, black ringing around extreme contrast areas (it happens with saturated colours too, in fact more obviously) so i don't think grading would change things that much.
Hopefully my A7s will appear next week, so i can side by side with the 700, 100 and whatever else i can find.
I suspect in day to day shooting it would be fine. I'm deep in post/vfx on a feature and i spend all day scrutinising footage - i don't see this as being a big deal compared to a lot of the problems i have to deal with, but it would be nice to avoid dealing with it in the first place.
cheers
Paul
Has anyone confirmed that the 4k and 1080p come from a 1:1 crop of the sensor?
Which would approximate a 1.1 horizontal crop over stills mode. I would assume and have assumed this is the case, but I have not heard anyone confirm it yet.
Sony reps constantly said that it was using the whole sensor. I hoped they were just simplifying things. It wouldn't make sense to downscale from an odd number when a 1.1 crop is so insignificant. And I would guess that it would increase the chance of downscaling problems. I also noticed a lot of mosquito type noise around edges and an overall digital look in Philip Blooms Brighton beach low light test. Even in the daylight shots. Although it was well shot there was just something that didn't seem right.
Obviously there are a lot of possible culprits for the things we are seeing. Camera settings, over exposing, posterization from grading, post sharpening, chroma sub sampling (which 4k would negate), camera processing, internet compression etc. But it would be good to eliminate the crop question.
Which would approximate a 1.1 horizontal crop over stills mode. I would assume and have assumed this is the case, but I have not heard anyone confirm it yet.
Sony reps constantly said that it was using the whole sensor. I hoped they were just simplifying things. It wouldn't make sense to downscale from an odd number when a 1.1 crop is so insignificant. And I would guess that it would increase the chance of downscaling problems. I also noticed a lot of mosquito type noise around edges and an overall digital look in Philip Blooms Brighton beach low light test. Even in the daylight shots. Although it was well shot there was just something that didn't seem right.
Obviously there are a lot of possible culprits for the things we are seeing. Camera settings, over exposing, posterization from grading, post sharpening, chroma sub sampling (which 4k would negate), camera processing, internet compression etc. But it would be good to eliminate the crop question.
This type of highligh fringing / aliasing is something that seems to be common across many Sony cameras http://vimeo.com/98791150 and was what killed my relationship with the FS700.
After years of trying to get a response, Sony reportedly said (in reference to the FS700) that is was a fundamental part of the sensor design limitations and wouldn't be fixed. They did, however, fix the same problem on the F5 within weeks of launch.
I seem to recall that Adam Wilt explained it was actually a mathematical rounding error with the way the signals from the sensor were being processed, and that caused over-white pixels adjacent to non-white pixels to be rounded to zero - but I can't seem to find where I read that. On the FS700 4k does not in itself help, but recording raw and allowing the Oddysy 7Q to do the debayering does fix the issue. That's not going to be an option for the a7S because it has no SDI outputs - only HDMI (no raw video).
I really wish Sony would fix this. It is one ugly, ugly artefact.
After years of trying to get a response, Sony reportedly said (in reference to the FS700) that is was a fundamental part of the sensor design limitations and wouldn't be fixed. They did, however, fix the same problem on the F5 within weeks of launch.
I seem to recall that Adam Wilt explained it was actually a mathematical rounding error with the way the signals from the sensor were being processed, and that caused over-white pixels adjacent to non-white pixels to be rounded to zero - but I can't seem to find where I read that. On the FS700 4k does not in itself help, but recording raw and allowing the Oddysy 7Q to do the debayering does fix the issue. That's not going to be an option for the a7S because it has no SDI outputs - only HDMI (no raw video).
I really wish Sony would fix this. It is one ugly, ugly artefact.
vincent thomas
Well-known member
I guess Sony is listening to us. I hope so. What would be the best way to "group" all our complains and wishes to be certain they will not be forgetten but arrive to the right sony's key people?
lonely complains here or there may be pointless, we need to go all together on this. Sony did a great job to this camera and i want to love it.
Let's make it even better!
vince*
lonely complains here or there may be pointless, we need to go all together on this. Sony did a great job to this camera and i want to love it.
Let's make it even better!
vince*
squig
Veteran
Once we've done a few more tests (4k especially) I can start a change.org petition. It'll be just like the good old days of petitioning for 24p on the 5D. I need more info about the feasibility of speeding up the sensor read time to reduce the rolling shutter, nobody wants to go back to jello cam circa 2008.
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Christopher Barry
Veteran
Get your sister home soon!
Christopher Barry
Veteran
Someone start a specific 'Sony a7S issues/fix' thread, post 1 reserved for issues list and updated. DVXuser forum members post issues in the specific thread, and post 1 updated by person interested to follow this up for a while, and then bring the thread to Sony reps attention or email post 1 to Sony reps in various territories? I personally think Sony have now moved on to the next batch of cameras with this new sensor tech. A few minor firmware tweaks may follow for the a7S. Still interested in a7S and Shogun, once up and running, or see what happens NAB2015. Shogun has longevity, multiple camera use.
Have a job or something to shoot today, and a7S fits the budget and specs, ROI should be covered by the time next cams may be promoted, assuming April 2015. If Sony announce new cameras before end of year, like the F5 and F55 were, then in a few months we might see FS100/700 announced. Not really relevant to me, I am interested in the now, a7S is more than enough as part of a 2 camera set.
Samuel H
Major Contributor
First: I really liked your explanation of how the downscale algorithm is probably the cause. I'll buy that for now
Then: what I mean is that the clips that don't show it may be clips where there are no extreme contrast areas at all... at least in the original footage (you can always grade a clip so that they appear)
I'm trying to get a loaner from Sony in the meantime, but the camera hasn't even launched here in Spain yet... and it won't do so until late July (not sure if that is the 23rd or the 27th)
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dustylense
Veteran
Hell, I walked into Samy's Camera and saw one on the shelf and bought it on site. And I walked into the camera store to return a rental gyro. Then I went and saw KISS in concert. So I got paid for shooting out of a helicopter, bought an A7s on the spot, and saw the greatest live show ever to been seen. Good day I would say.
Christopher Barry
Veteran
Rule of Three. All three acts appear positive, as such. Good day. 
NMSK
Active member
This highlight aliasing was a real bummer to recognise, so I'm cancelling my purchase plans until it's fixed. I absolutely cannot stand it on my FS700 (it's not as present on my FS100, but still a problem) and I expect I'd be consistently disappointed by it in the A7s also. I don't understand Sony - they pump the hell out of the fact that it's a low light camera, that's where most this fugly highlight aliasing is most commonly going to occur (building lights, neon signs, car headlights etc). I guess to them, they'd consider it a consumer camera, and that most users wont notice, or that the more knowledgable shooters will trade up to one of their professional cameras. Bad news though, the next large sensor Sony camera that doesn't do it is the F5, and it's 18+ grand. Sigh.
Please, if you start that petition, consider also asking them to fix it in the FS700 and FS100 also. The 5DIII doesn't have this problem, so why should people who've spent 2-4 times as much on dedicated video cameras have to deal with this ugly, unfixable artifact?
Please, if you start that petition, consider also asking them to fix it in the FS700 and FS100 also. The 5DIII doesn't have this problem, so why should people who've spent 2-4 times as much on dedicated video cameras have to deal with this ugly, unfixable artifact?
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photochris
Well-known member
Now that's a good day!
photochris has confirmed in another thread that in 1080p mode the A7s down-scales from the full width of the sensor rather than from a native 4k crop. Scaling from 4240 to 1920 is obviously not an integer multiple, so this fits well with the theory that the aliasing/edging issue is related to down-scaling.
Thankfully philiplipetz has confirmed that there is a 1.1x crop in 4k mode which means native 4k. No down-scaling needed. (apart from chroma channel)
This differs from the fs700 (that also shows the issue) in that the sensor resolution of the fs700 is 4352* 2662. So even in 4k on the fs700, down-scaling is needed.
I would therefore guess there is a good chance that the issue will not exist when shooting 4k from the A7s.
If this turns out to be the case, I would suggest firmware with “1.1 crop mode” for 1080p for people who understand this issue.
Thankfully philiplipetz has confirmed that there is a 1.1x crop in 4k mode which means native 4k. No down-scaling needed. (apart from chroma channel)
This differs from the fs700 (that also shows the issue) in that the sensor resolution of the fs700 is 4352* 2662. So even in 4k on the fs700, down-scaling is needed.
I would therefore guess there is a good chance that the issue will not exist when shooting 4k from the A7s.
If this turns out to be the case, I would suggest firmware with “1.1 crop mode” for 1080p for people who understand this issue.