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A more realistic impression of the Sony A7S low light performance at ISO 12,800


Andrew Reid
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Guest Ebrahim Saadawi

I've seen clean 50.000 ISO and usable 100.000 on youtube from the A7S! I haven't seen that kind of low-light performance from any 1D or D4 (given we're viewing both on youtube / noise-reduction, the A7s seems miles ahead of anything else)

I think maybe high ISOs in video mode have some magic in-camera noise reduction that doesn't exist in the full resolution still images.

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It's funny how some people they're trying to reduce A7s qualities in favor of GH4... It feels urgent to prove GH4 is finally up there with the big boys...

Right now 1080p is the reality and in 1080p world GH4 is nothing really special. Even a seriously compromised camera like 5DmkIII from 2+ years ago still holds its own against GH4. As for GH4's low light capability it's still stuck in 800 iso from back in the day... However, I really believe that GH4 is a great camera but a bit overhyped. On the other hand A7s is not out yet so we can only speculate. Enough is enough with biased conclusions, it is just a matter of time before we know what is all about.

Be patient 4K is not there yet and by the time it will be there will be much better cameras than GH4, A7s etc. 

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My FS700 has 14-stops DR however clients love the 5D3 RAW image and like the GH4 better as well.

No it isn't and never was.

 

The FS700 was never factually rated at 14 stops (i.e. film), or else more Cinematographers would've used it by now. Instead it's used as more of stop gap between DSLRs and the bigger digi-cinema bodies (Red, Alexa, F5, etc.). THOSE camears are rated between 13 and 14 stops.

 

I've seen A LOT of tall claims on this forum from you guys about your cameras being 13-14 stops with zero discernible proof beyond personal claims. Factually, the FS700 has anywhere from 11-12, just like the FS100 did and so does the GH4.

 

The gross exaggerations from you guys are ridiculous. I understand that you need to justify your purchases to yourselves (and to one another, akin to hardware posturing), but let's at least keep clean perspectives and refrain from....lying.

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Read that, and though he claims to be able to count 14 stops -only 11 usable-, I look at the picture and count no more than 11. Just like the A7S might be impressive but I doubt it will have 14 stops in video. If it had 13 stops without the hassle of RAW, I'd be more than satisfied.

 

 

This tests shows the FS700 to have 11.5 stops, which would put it in the same league and market segment as the C100.

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Here is what Adam said:

 

 

 

I count 14 stops of dynamic range, with perhaps 11 of them being "paycheck stops". Crikey!

[Art Adams defines the terms paycheck stops and gravy stopsPaycheck stops are those you have to capture, "otherwise your paycheck stops". Any stops beyond those are gravy stops.]

The other gammas may lose as much as one stop of total range (oh, the horror of having a mere 13 stops!), and the contrastier ones may "only" have about 9 paycheck stops; overall, this camera does a great job of capturing as much of the tonal scale as possible and making it available through the cine gammas' S-curved compression or the video gammas' knee functions. Art has a full writeup on the FS700's dynamic range.

 

He states that 11 are 'required for a paycheck' and anything beyond is 'gravy'. He counts 14 stops, then counts 13 with  different gammas.

 

Art Adams did his own analysis- 13-14 stops with 'perhaps 12 usable': http://provideocoalition.com/aadams/story/cameras_sony_fs700_dynamic_range_presentation/P2

 

This kind of discussion is similar to discussing resolution charts: some people call the end of resolution at the beginning of first artifacts, some at the extinction of detail, others in between. In any case, they both stated 14 stops is what they can see; how much is usable is up for debate. If they couldn't see 14 stops, there would be no point making those statements.

 

In any case, the FS700 has more DR than the 5D3 or GH4. The point was DR is less important than color science.

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Suddenly everything under 14 stops of Dynamic range looks little. While not so long ago the Professional RED Epic MX was doing between 11 and 12 stops of dynamic range, and that seemed perfectly fine. 

 

http://provideocoalition.com/aadams/story/next_stop_the_last_stop_red_mx_latitude_tests/P2

 

Vision 2 was the first time even film stock really exceeded 10 stops of usable information, even then only available when digitally processed. 

 

MX has the same DR as C300, 11-12 stops. Red was never good in this respect (until now at least), but since dSLRS are so bad it seemed great.

 

15.3 is insane. Alexa is 14-15. F3 and F5 12-13. Most of that unusable. Sony handles highlights terribly (over-sharpened, over-saturated), hopefully they will implement the modified SLOG3 curve on this. F5 with SLOG2 clips horribly while Alexa (older Sony sensor) clips beautifully.

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If you read the ARRI website about the Alexa sensor you will understand how it can deliver more than 14 fstops. There is two readouts from the sensor, two outputs merged inside the camera. It is something like the RED X, but different.

 

The sensor technology available today cannot deliver more than 11 - 12 usable fstops DR for compressed video. RAW is another story, but not so much different...

 

To reach the 16 fstop DR dream wich makes possible to record the bright sky with clouds and the living room inside the house without add light at the same time we need another sensor technology, or two streams merged inside the camera, or record the two streams as a side by side image to merge in computer...

 

Something new will come with the quantum dots and organic sensors or with real time HDR video as shown by toshiba new smartphone sensors.

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Agreed, a straight (standard) jpeg out of the camera is "probably" the best basis for a quick mark one eyeball analysis.  

 

Problem we've been having is this constant skewing of data for "expected" performance.  We've had so many "internet activists" propping up one brand over another that its becoming more "brand religion" that's based on erroneous (or misinterpreted) testing methods.  I had one guy  (from this very board) telling me that real world jpegs out of the GH4 bore no relationship to actual 1080p footage, because you can down-sample this and add that to make it look spiffy.  That's no basis for testing anything, we need a realistic base measurement, a realistic starting point.

 

It'd be interesting to see a (standard profile) jpeg comparison from a 5D3, A7S & GH4 now, maybe throw in an A7R for giggles too.  I'm a 5D3 stills guy who also shoots the A7R and differences based simply on noise characteristics (based on RAW files in Aperture) are negligible.   

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If you read the ARRI website about the Alexa sensor you will understand how it can deliver more than 14 fstops. There is two readouts from the sensor, two outputs merged inside the camera. It is something like the RED X, but different.

 

The sensor technology available today cannot deliver more than 11 - 12 usable fstops DR for compressed video. RAW is another story, but not so much different...

 

To reach the 16 fstop DR dream wich makes possible to record the bright sky with clouds and the living room inside the house without add light at the same time we need another sensor technology, or two streams merged inside the camera, or record the two streams as a side by side image to merge in computer...

 

Something new will come with the quantum dots and organic sensors or with real time HDR video as shown by toshiba new smartphone sensors.

 

While the Alexa does seem to have the most DR to me (two stops better in highlights at least, 1/2 stop better in shadows than the MX) in my experience shooting with it, what sets it apart is how cleanly the highlights clip into white rather than into over-sharpened/over-saturated color, but Red has really improved in this respect. Also the Alexa looks better under tungsten. The Dragon seems to be a move in the right direction, though. The C300 in wide DR mode is pretty decent in this respect, too. 5D III raw has maybe 11 stops useable, but pretty darned good, on par with Red MX but noisier shadows and the color is handled really well in ACR but the highlights are UNDERsaturated, weirdly.

 

The CX00 seems to raise gain in each channel independently in hardware or something, but it does a great job under different white balances.

 

I don't see the appeal of 16 stops of dynamic range because a projected stock has what? 6-7 stops of contrast and my monitor has maybe 8-10? So it begins to look flat, and few scenes approach that number, but I agree that the Alexa is still the reigning champion.

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Guest Ebrahim Saadawi

That 12800 ISO still looks very disappointing. From my experience with the 1DC, it's way less noisy at 12800 there than on the A7S example above. And the C100/300 at 20.000 look less noisier than this with way less hedious RGB noise.

In fact that example above doesn't even look way different from 12800 ISO on a good modern APS-C sensor!

I expect the A7S to deliver far better 12800 ISO.

Something is off about this.

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I don't see the appeal of 16 stops of dynamic range because a projected stock has what? 6-7 stops of contrast and my monitor has maybe 8-10? So it begins to look flat, and few scenes approach that number, but I agree that the Alexa is still the reigning champion.

 

I talked about 16 fstops DR because this is what I can get with the old Canon T3i 600D using a good pictue style to lift the shadows and bring highlights down to allow 11 fstops dr combined with the hdr video 80/2500 iso to add more 5 fstops.

 

This way I can shoot in light situations where even Alexa would fail... No way to compare the image quality from Alexa to T3i, but it works for indie production.

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I talked about 16 fstops DR because this is what I can get with the old Canon T3i 600D using a good pictue style to lift the shadows and bring highlights down to allow 11 fstops dr combined with the hdr video 80/2500 iso to add more 5 fstops.

 

This way I can shoot in light situations where even Alexa would fail... No way to compare the image quality from Alexa to T3i, but it works for indie production.

 

Sounds impressive! That easily beats anything else out there. How many situations have you encountered when you needed that my dynamic range, though? Usually when the Alexa is blowing out it's in a situation in which I'd want it to, anyway.

 

I am surprised you are getting 11 stops from the t3i to start with though? I found it to provide 8-9 at best with neutral or technicolor picture style. To be fair, I have not A/Bed it with the Alexa, nor shot charts. Great camera nevertheless!

 

And to be fair, nothing compares with the Alexa. :)

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I pointed the T3i to the computer monitor and filled the computer monitor with a 255-255-255 white image. from the dark monitor to the white image in the monitor I have 9 fstops. So maybe you are correct, it is 9 fstops. 9 from the picture style + 5 from the magic lantern hdr video, it is 14 fstops total, pretty good for the cheap T3i.

 

When I was developing a picture style to get the most possible DR I lifted the shadows to the point before the sensor started to show vertical paterns and I bring down the highlights to a point before I hurt the textures. Without flatten the image.

 

If you shoot inside a room, inside a house with an open window, or inside a car or a bus with a sunny day outside, this amount of DR is useful. Also at night, dark streets with light lettering panels. On vimeo there are lots of magic lantern hdr videos online, you know.

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That 12800 ISO still looks very disappointing. From my experience with the 1DC, it's way less noisy at 12800 there than on the A7S example above. And the C100/300 at 20.000 look less noisier than this with way less hedious RGB noise.

In fact that example above doesn't even look way different from 12800 ISO on a good modern APS-C sensor!

I expect the A7S to deliver far better 12800 ISO.

Something is off about this.

 

It's just bad JPEG processing. A dpreview user posted A7s raws today (http://***URL removed***/forums/post/53852362). I processed the ISO 12,800 through 408,9600 raws in Iridient and posted the JPEGs here: http://***URL removed***/forums/post/53855688

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This video shows that in iso 51200 the image starts to tremble near the lamps. So probably after denoise the edges of objects will keep trembling. so maybe my supposition was correct, the maximum safe iso will be aound 25600 / 32000.

 

Also the difference from slog2 to other was a small lift in shadows so maybe dro5 will be better to get almost same dr without flatten the image.

 

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So you get a very usable 25,600 ISO in video and even 51,200 if necessary... I don't see a problem with that. We all knew that 400,000 ISO was just a "wow factor" spec. Most modern cameras are really noisy at 6,400 ISO so yes, it is a big improvement that has practical use, even if it's not even close to what sony marketing claims. The same applies to DR, you will not have 15 stops in video mode but 12-13 usable stops would still be great...

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