A7s FF vs APS-C Request

S

Simon Shasha

Well-known member
Just a request to any A7s owners out there - if possibly, and if time permits, could you please do a comparison of dynamic-range and noise of A7s in Full-Frame mode vs APS-C mode.

Would be forever grateful! :)
 
I'll see what I can do for you tomorrow. I get a lot of shade and direct sunlight on the back deck. Won't be pretty but it will be a good torture test :)
 
I have no idea how to measure dynamic range, but as far as noise and ISO goes, it looks like Full Frame mode is close to one stop less noisy than APS-C mode. BUT, everything we shoot on the A7s is 60p and there's a HUGE advantage to shooting 60p in APS-C mode: There's FAR less moire and aliasing in APS-C mode than in full frame mode at 60p. As in pretty much none. It's very noticeable in full frame mode at 60p (I think there's none in 24p and 30p modes, but again, we only shoot 60p so that's all I tested). I just did these tests today shooting a little box with small words on it on a shelf with my APS-C lens and Full Frame lens side by side (at relatively the equivalent FOV) and it was really obvious when I saw the results. Like, shockingly obvious. There was so much moire that it made the tiny words on the box impossible to read so essentially it made the APS-C mode look way more detailed to my eye because those "little details" weren't distorted. For me and what I do, having about as much noise at 25k ISO in APS-C mode as full frame mode has at 50k ISO suddenly became less important to me when I saw how much better the moire is in crop mode. I mean 25k ISO is still pretty good and I mean, c'mon...that's 25k ISO!!! Wow! There's a youtube video online showing the difference in noise as you go up the ISO scale between full frame and aps-c which scared me into thinking I HAVE to get full frame lenses. But then this all happened. If you don't shoot 60p, then I'd say the extra stop of noise-free shooting in full frame mode is nice. Hope that helps!
 
How to check whether DR is the same in FF and APS-C modes:

* Set the camera ready for a static shot with some areas in sunlight and some shadows. Nothing special, the typical backyard will do. Make it an f/16 1/50s shot. Make the composition in APS-C mode but with a FF zoom set close to its widest (e.g. 24-70 set at 35mm).
* Record that in APS-C mode, then in FF mode adjusting the zoom to keep the framing (in the previous example, ~53mm), without moving the camera or changing anything else.
* Without changing anything else, switch to f/4 1/50s (that's overexposed by 4 stops). Record again in APS-C mode and in FF mode, adjusting zoom to keep the same framing.
* Without changing anything else, switch to f/16 1/1600s (that's underexposed by 4 stops). Record again in APS-C mode and in FF mode, adjusting zoom to keep the same framing.

You'll end up with 6 clips that will allow you to see if the black clipping point and the noise floor is the same in both modes, or if FF has an advantage (my guess: same highlight clipping, a stop less noise in the shadows in FF).

If you want to know exactly how much difference there is, record all the middle steps between f/16 and f/4 for the overexposure tests, and between 1/50s and 1/1600s for the underexposure test, and see which settings give you the same highlight clipping and the same noise floor.
 
Swink said:
This might answer some of your questions: https://www.youtube.com/watch?v=9olGx_L_ftI
Click to expand...

Swink!

Thanks so much for doing that! Much appreciated!

It seems the APS-C is nosier...which is a bit of a let down. It's still great of course, but definitely nosier than the FF mode. I'd be curious to see the noise of APS-C vs FF at night against something like a clear sky.

I've got a bunch of APC-C E-mount lenses and the Sigma 18-35mm F1.8. Hope APS-C holds up well at 6400 - 10,000ISO (which I think is where I'll be for a lot of the shooting I do for work).

Thanks again!
 
Simon Shasha said:
Swink!

Thanks so much for doing that! Much appreciated!

It seems the APS-C is nosier...which is a bit of a let down. It's still great of course, but definitely nosier than the FF mode. I'd be curious to see the noise of APS-C vs FF at night against something like a clear sky.

I've got a bunch of APC-C E-mount lenses and the Sigma 18-35mm F1.8. Hope APS-C holds up well at 6400 - 10,000ISO (which I think is where I'll be for a lot of the shooting I do for work).

Thanks again!
Click to expand...

Considering you'd open up the lens on APS-C 1-2 stops to match FF DOF it's not noisier at all.
 
squig said:
Considering you'd open up the lens on APS-C 1-2 stops to match FF DOF it's not noisier at all.
Click to expand...

True. I agree.

I find my Sony 35mm F1.8 OSS, Sony 50mm F1.8 OSS, and Sigma 18-35mm F1.8 all sharp wide-open on my Sony A6000 (and that's taking photos at 24MP). I'm pretty sure I'll be able to shoot with them at F1.8 in APS-C mode on the A7s wide-open and keep the ISO in check. Either way, I still find ISO 10,000 in APS-C mode rather clean. Leagues upon leagues ahead of all previous camera's I've owned (7D, 60D, GH3, GH4), and the 1DMK4 that I used to rent a lot.
 
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