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Sony A7S - does it have Super 35mm 4K mode too?


Andrew Reid
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Sony A7S APS-C mode

One of the enigmas emerging from the A7S is whether you can shoot 4K in APS-C crop mode as well. This would allow the use of standard Sony E-mount / NEX lenses, Canon EF-S and Nikon DX lenses, even PL cinema lenses on the full frame sensor.

Sony's information (above) implies that is the case with "both resolutions available at both full frame and APS-C size".

I dug a little deeper to find out more...

Read the full article here
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The info on that picture clearly says "both resolutions available at both full-frame and APS-C", but it contradicts what I've heard Sony reps say in other videos. Besides, 4K is actually 12Mpixels, which is the whole sensor in full-frame stills mode.

 

I'm afraid 4K is going to be full frame only...

 

Still, this camera has the potential to make my working life so much easier and better. If only we could see some real life tests regarding rolling shutter -my biggest fear with this camera-, dynamic range and usable ISO. No point having 400.000 expanded ISO if only up to 32.000 ISO is acceptable -would still be great, though-.

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...No point having 400.000 expanded ISO if only up to 32.000 ISO is acceptable -would still be great, though-.

 

Have you seen the ISO 12,800 video? That stuff looks smooth as glass, even with YouTube compression artifacts! Looks better than my Canon 60D ISO 400!

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So for stills, that APS-C bit of the sensor is about 5Mps - I've got a tonne of glass for my NEX 7 and I wonder how viable this is for stills in crop mode - I suspect the answer is that it'll be great, plenty of pixels but it will place a demand on getting it right in the camera rather than in lightroom!

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From the way they're explaining it they'll get 1080p in APS-C mode by scanning all the pixels in the APS-C window then downscaling, just like a camera would take a jpeg picture, downscale it, and save it at 1920x1080. 

 

I DON'T think it will use the RX-10 method, which I think is binning, albeit binning without column or row skipping. If you read the fine print of Sony's description of the video mode on the RX-10 it says they "use" every pixel for their video, that's carefully and cleverly worded, they've never said the RX-10 takes a full sensor scan then downsamples that for video.

 

What I think the RX-10 does is use a fine binning mode that incorporates every pixel into it but at the end of the day it's still binning. For instance a red pixel would probably get binned with 3 surrounding reds to get a summed readout, etc. It's faster and easier than getting a discrete reading from every single pixel, and if the RX-10 were doing it that way Sony like the a7s does they would have been shouting it from the rooftops like they are now.

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^ I'm in the same boat. The GH4 looks great... but after the reading about the 96fps not being the same quality as 60 or 24... I'm a little more interested in this machine. I'd definitely rather have higher quality 60fps over higher sub-par FPS.

 

Forgive me for maybe not reading all the info on this... but does the A7S export any 60fps signal to external recorder?

 

Plus, if the new processor in this is as good as it sounds... the 120fps, even in 720p might be really quite usable.

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but of course sony has to limit it for not reason and only outputs 8bit hdmi. How much dynamic range can your really squeeze into slog2 at 8bit?

Quite a bit if exposed right, especially in SLog2. I work with C Log on C300s all the time and its DR is quite good and decently grazeable. Wouldn't surprise me if it gets btw 13-14 stops.

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To me it really would make sense for them to sample UHD 4k at 1 to 1 crop (and to also downscale this for 1080p)  which is roughly a 1.1* crop which is practically nothing anyway.    As opposed to sampling the full 4240 pixel width and downscaling to 3840, which would be more processor intensive and would seem to me to have a higher risk of image issues.

 

In fact, the 1.1 crop is so slight that my guess is that sony might think no need to mention it.  Not that its a bad thing, just that it makes it more complicated to explain.   Much easier to sell "a full sensor readout",and then put the 1.1 crop in the fine print after nab or at least after the first few days.

 

On the other hand an apc crop, as the article says, has 2768 horizontal pixels which is sufficiently greater than 1920 to make a downscale sensible.

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Same pixel density as Alexa (also a sony sensor). Let the inaccurate rumors begin. (C300 has same pixel density as 5D Mark II....)

 

Quite a bit if exposed right, especially in SLog2. I work with C Log on C300s all the time and its DR is quite good and decently grazeable. Wouldn't surprise me if it gets btw 13-14 stops.

 

It would surprise me... Canon Log (not Log C) is 12 stops, no more. But it is still disruptively better than dSLR video (10 stops or less with poor tonality). CX00 has great DR, but still no more than Epic, slightly less than F3, significantly less than F5/5 and Alexa.

 

If SLOG 2 matches F5 or even F3 dynamic range this will surpass CX00 and Epic... Dragon/F5/Alexa league (though Alexa distributes the curve better than anything else). Sony has better color than Red, worse than Alexa and Canon. This could easily have the best IQ short of the Alexa for any price. Haven't used the Dragon yet, to be fair.

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I am going to buy this and within my circle of professional photographer friends this camera is a hot topic. There was some mention of the camera handling 2.7k internally? It would be nice if this was an option to record at that res. Mostly im interested in the low light performance for photos with this camera as I mostly do events photography where flash is quite often not allowed.

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I am going to buy this and within my circle of professional photographer friends this camera is a hot topic. There was some mention of the camera handling 2.7k internally? It would be nice if this was an option to record at that res. Mostly im interested in the low light performance for photos with this camera as I mostly do events photography where flash is quite often not allowed.

 

The camera handles 4K internally it just doesn't encode it, instead it sends the debayered final image to the HDMI port instead (uncompressed).

 

Can't compress the 4K image to XAVC...

 

This feature is reserved for their cheaper cameras like the AX100 ;)

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The info on that picture clearly says "both resolutions available at both full-frame and APS-C", but it contradicts what I've heard Sony reps say in other videos. 

 

Correction. Just saw another video in which the Sony rep said the camera can record 4K in APS-C mode with some internal upscaling. Seems like they wanted to include such a possibility in case you had to shoot 4K and were stuck with APS-C lenses, but... Will the upscaling be good enough to make the use of those lenses worth it?

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