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Quick review of A7S and GH4


jcs
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Stops are exponencial, 1 stop more is 2 times the light, 2 stops is 4 times the light. The difference between FF an m43 is 2 stops, if you get a 0.5 speedbooster the difference will be 0.

That would assume 0 transmission loss through the Speed Booster, and that you could get a 0.5 Speed Booster.  The ones I have seen for M 4/3 have been closer to 0.7, and one stop.  I've never seen any measurements as to what the losses actually are.

 

Michael

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The one video I've seen comparing the two side by side show very similar DR.  

 

I'm a bit lost. The big highlight of A7S was big large pixels (instead of 36MPx on Sony A7R). If DR is similar too GH4 which has finer pitch and also smaller sensor, what does the A7S has, apart from low ISO? Where are the 15+DR advertised?

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I'm a bit lost. The big highlight of A7S was big large pixels (instead of 36MPx on Sony A7R). If DR is similar too GH4 which has finer pitch and also smaller sensor, what does the A7S has, apart from low ISO? Where are the 15+DR advertised?

 

simple answer, I think we have to see more tests.  

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I'm a bit lost. The big highlight of A7S was big large pixels (instead of 36MPx on Sony A7R). If DR is similar too GH4 which has finer pitch and also smaller sensor, what does the A7S has, apart from low ISO? Where are the 15+DR advertised?

 

Maybe they changed their mind? Instead of high DR @ ISO100 (like most rivals) thay did good DR @ ISO100-25000

The same with Color Sensitivity according to dxomark.

 

So instead of 15 stops DR @ ISO100 and unusable ISO>3200 you have 13 stops DR @ ISO 100 and still nice 9-10 stops DR @ ISO 12000 (the same with color sensitivity)  [GH4 perfoms like that @ ~ ISO 1200]

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I revealed the answer to which camera was used for this shoot (originally planned for the A7S): '?do=embed' frameborder='0' data-embedContent>>

When I received the A7S shipping notice last week, we planned a shoot for Saturday. The camera was due Friday however apparently Sony(?) stopped B&H from shipping the cameras early; ours never made it out of the warehouse. B&H was kind enough to ship it out overnight at no charge on Monday. This review was from a few hours working with the camera.

 

 

My co-director-producer Elena loves the GH4 skin tones, as did our model. Elena never liked the FS700 (Sony) skin tones (and loves the 5D3 skin tones the best). I agree with them and feel that the A7S, once the proper settings are found (not using Slog2!) and likely one of the cine settings with natural color in-camera, will be a useful tool in the toolbox, especially for low light and/or more shallow DOF shots (I'm still waiting for the EF to m43 active SpeedBooster to come out).

 

It's really important to shoot people and skin tones to see how accurate a camera's color science is. Human beings are very well evolved to detect when skin tones are wrong or 'off', probably related to evaluating health (related to survival and reproduction).

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Which one has the best dynamic range? In the comparison, it seems to assume both GH4 and A7S have same dynamic range.

DXO Labs test result:
k5_gh4_a7s.jpg

We have to keep in mind that if we shoot slog2, the base iso is 3200, so in bright conditions a7s loses lots of DR compared to GH4 or itself.
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DXO Labs test result:
k5_gh4_a7s.jpg

We have to keep in mind that if we shoot slog2, the base iso is 3200, so in bright conditions a7s loses lots of DR compared to GH4 or itself.

What I like is that the A7S still has almost 10 stops at ISO 6400 and is maybe the only camera with at least 10 stops at ISO 3200 in Dxo's data base.

It is starting to look to me that while maybe designed as a hybrid with a video focus, it is getting rave reviews for stills but less than that for video.

 

It is/will seemingly take a hit from many people because it may not do 15+ stops of DR except under very specific circumstances (maybe) but ignoring that it will still have a higher DR than any camera near its price at ISO 1600 and up.

 

For live music, I am seriously considering replacing my A7 with an A7S for stills and the video will be better as well and good enough for me (since it will mostly be covers that I can't show anyway).

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Doing lower light tests with the GH4+Voigtlander 25mm @F.95 and the A7S with Canon 50mm F1.4 @ F2 (fairly equivalent in terms of FOV and DOF), the A7S does much better with noise control vs. the GH4 (as expected), however the GH4 does surprisingly well. In lower light shooting, the GH4 noise does go from nice monochromatic to colored, similar to the A7S (which is much less and better controlled). The GH4 is looking more detailed (4K => 1080p) and clear in bright light. The A7S is clearly better in low light; shooting handheld is tricky as rolling shutter is 30.5ms (vs 20.5ms for GH4 in 4K (13.7ms in 1080p)): http://www.dvxuser.com/V6/showthread.php?303559-Measuring-rolling-shutter-put-a-number-on-this-issue!

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Doing lower light tests with the GH4+Voigtlander 25mm @F.95 and the A7S with Canon 50mm F1.4 @ F2 (fairly equivalent in terms of FOV and DOF), the A7S does much better with noise control vs. the GH4 (as expected), however the GH4 does surprisingly well. In lower light shooting, the GH4 noise does go from nice monochromatic to colored, similar to the A7S (which is much less and better controlled). The GH4 is looking more detailed (4K => 1080p) and clear in bright light. The A7S is clearly better in low light; shooting handheld is tricky as rolling shutter is 30.5ms (vs 20.5ms for GH4 in 4K (13.7ms in 1080p)): http://www.dvxuser.com/V6/showthread.php?303559-Measuring-rolling-shutter-put-a-number-on-this-issue!

 

Finally direct GH4 vs A7S test.. Oh! Thanks! Do you know You will get millions of clicks if you publish it? ;)

Please do also DR test (extreme scene and GH4@100 , A7S@100, A7S@3200log2) and we will be happy as children..

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Guest Ebrahim Saadawi

Thank you, JCS

Please if you have the time, do a Dynamic range test and post it here.

Just a small clip looking outside a window at the same exposure settings,...

Side by Side ISO test would be greatly appreciated too! 

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