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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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Sony A7S rig

All the high ISO footage from the Sony A7S so far have been highly compressed and streamed on YouTube. Here we have not one but two stages of very aggressive noise reduction being applied to the images. If you want to see it without the heavy compression removing all trace of noise, here's a full resolution JPEG shot at ISO 12,800 from the camera courtesy of DCFever...

You can download it below...

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Granted I'm still thinking in terms of a 1080p world, but I still think the A7s could be great beyond ISO 12,800 if it retains enough luma detail.  NeatVideo seem to require sharp source footage in order to do its magic.  So if the 4k starting point gives lots of luma information but but smudgy chroma, it might still work great with noise reduction.  

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Guest Ebrahim Saadawi

I would be very disappointed if it's just as sensitive as a 1DC/D4... I mean yes these are incredible low-light cameras but the A7s has been marketed as the absolute best, as the newest technology, as being able to shoot the stars at night, and basically see in the dark!

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I played with the 12MP JPEG in ACR- highlights are clipped and not recoverable- DR looks similar to 5D3 in that shot. Noise cleaned up OK using ACR tools, however image then looked over-processed (Neat Video would work better along with temporal NR).

 

I shot a clip with the GH4 at ISO 1600 and lit it with a single LED (iPhone 5S). After Neat Video NR and bringing up the levels in post, it looks pretty good compared to the A7S examples so far. I would expect the A7S to do better in any case, however if Neat Video is needed in both cases and the final results look similar, the A7S's utility over the GH4 in low light would then be lessened. The FS700, especially with SpeedBooster is pretty good in low light, all the way up to ISO6400 (still needs NR in post at that level).

 

So far most of the A7S demo shots have been with locked off (tripod) or very low camera motion. It would be helpful to see typical handheld (with and without a rig) shots. While it would be nice to have a 5D3 replacement at 50Mbps (vs. 5D3 RAW at ~64GB per 12min), I almost pre-ordered the A7S but am holding off until it's released and actual end-user videos are posted. Also curious about the A7S XLR audio attachment (release date and cost).

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5D3 H.264 needs decent sharpening in post: still not super detailed, but is workable if using sharp lenses.

5D3 RAW sharpened in Resolve or (even better), ACR, is very solid for 1080p. A sharpened 5D3 RAW shot compares very well to even a 4K GH4 shot projected on a 20' 4K screen (saw this in person).

 

14-bit 5D3 RAW still looks great compared to the GH4 4K and A7S (examples so far):

 

Still no direct competition at that price point for 5D3 RAW color, color science and decent 1080p resolution. The workflow and disk space requirements are another story (I'm shooting mostly with the GH4 now).

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I obviously have absolutely nothing to back this, but, I have a feeling, that the noise reduction and sensor read-out for video is smoother than for stills. Also, in the Comparison video, at upto ISO 25600, the A7S clearly had more details in the trees and the Caesar's Palace sign-board. Also, I found the dynamic range noticeably greater, and therefore, it looked brighter than the Mark iii. 

 

Also, after 25,600, the image quality didn't seem to deteriorate any further, and it seemed as usable at ISO 25,600 as it was at ISO 1,02,400. After that it looked like a 640p video. Beyond that it looked like the GH4 at ISO 3200, the only difference being, that it has insane Noise Reduction happening internally, so much so, that the noise didn't seem organic at all. 

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the pixel density in a7s compared to a6000 shows the a7s pixels area is 4.7 times larger. in cameralabs iso video tests the maximum quality iso with perfect denoise is 3200 for a6000 and 6400 gives good quality with small trembling in shadows after denoise. 3200 x 4.7 is will give us iso 16000 for great denoise in a7s. and the safe limit will be 6400 x 4.7 = 32000 iso maximum when the quality after denoise will show some trade off.

 

I do not expect more than 11 or 12 fstops dr with slog2. i think neutral or standard profile with contrast 0, dro level 5 and superwhite recovery in post will be better than slog2 for good dynamic range without flatten the image. more than 11 or 12 fstops we will see in the next generation of sensors, maybe quantum dots sensors, maybe organic sensos, maybe hdr sensors with dual stream merged inside camera.

 

a6000 with a good focal reducer will be the low budget a7s.

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Still no direct competition at that price point for 5D3 RAW color, color science and decent 1080p resolution. The workflow and disk space requirements are another story (I'm shooting mostly with the GH4 now).


Exactly. I'm talking about internal codecs with no external hassle at this point. 5d3 IQ on h264 is crap compared to gh4. Raw for 5d3 is great but a huge pain in the ass for workflow. I don't know why people are so concerned with "low light" performance... Even on my 5d3 I can't remember shooting over 800iso.
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the pixel density in a7s compared to a6000 shows the a7s pixels area is 4.7 times larger. in cameralabs iso video tests the maximum quality iso with perfect denoise is 3200 for a6000 and 6400 gives good quality with small trembling in shadows after denoise. 3200 x 4.7 is will give us iso 16000 for great denoise in a7s. and the safe limit will be 6400 x 4.7 = 32000 iso maximum when the quality after denoise will show some trade off.

 

I do not expect more than 11 or 12 fstops dr with slog2. i think neutral or standard profile with contrast 0, dro level 5 and superwhite recovery in post will be better than slog2 for good dynamic range without flatten the image. more than 11 or 12 fstops we will see in the next generation of sensors, maybe quantum dots sensors, maybe organic sensos, maybe hdr sensors with dual stream merged inside camera.

 

a6000 with a good focal reducer will be the low budget a7s.

 

 

The Dynamic range of the GH4 is rated at 12.8 stops (http://www.dxomark.com/Cameras/Panasonic/Lumix-DMC-GH4) and the A7S is rated at 15.3 stops according to Sony themselves

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Both the A7s and GH4 likely have the same/simiilar quantum efficiency, and the A7s likely has a High ISO read noise/DR advantage. Based on this and scaled to their respective sensor size differences the A7s will hold a 2EV noise advantage over the GH4 in stills, and this advantage should apply to video as well since both cameras sample the entire sensor. Subjective differences will come down to only how noise and detail are balanced by their respective noise reduction algorithims.

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