Thoughts On The Sony A7s Camera by Michael Head
I once had a cinematography professor tell me that the video DSLR trend is just a fad. But for whatever reasons, camera manufacturers didn't hear his message.
New and more powerful cameras are coming out everyday, and each model strives to be better then the one before it. This makes it hard to be a tech-nerd in the film industry! (I want ALL this gear!)
One DSLR-style cameras with excellent video features is the Sony A7s.
The A7s comes out of the Sony A7 mirrorless SLR camera family that includes the A7 and the A7r. Both of these are great full frame (large sensor) cameras. While it might seem odd at first, the A7s, has the smallest number of pixels, weighing in with 12 MP.
However, while it is “only” 12 MP, it is a full 4K sensor – which means the pixels are bigger and can therefore actually be more sensitive to light then the same sensor with more MP.
How much more sensitive?
Some early tests have shown video taken in the woods at night with no lights.
And the image OVEREXPOSES – in the DARK!
http://youtu.be/XgbUgNiHfXM
As filmmakers, we live in an interesting time.
The extended ISO of the A7s's sensor lets you record downsampled 1080P video at up to 409,600 ISO (yes, you read that right) and 60 frames per second (720P up to 120! FPS). That's an amazing sensor.
The Sony A7s Camera
Although shooting that high of an ISO is not likely to happen often, it is an amazing option for making sure that dark shadow in the corner of your room is only a jacket and not a vampire or something. And surprisingly the sensor doesn't line-skip like many of the popular video DSLRs. This means moire and alaising are reduced.
But that's not all!
The full frame sensor gives you the same depth of field you can get with other Full Frame sensors, but it also will shoot in a crop sensor (x1.6) mode. In other words, you can choose to use a smaller sensor size. Why might you do that?
Some lenses don't cover full frame sensors, and those lenses can still be used on the A7s. In effect, you can double your number of lenses using full-frame lenses and the crop fame shooting. Your 35mm full frame sensor can shoot as a 50-ish (56mm) lens is crop sensor mode. While this does affect your depth of field, it's a nice for those with limited budgets.
Sony also seems to have moved away from the A-mount lenses. Instead, the A7s has an e-mount, which has numerous adapter options for almost any lens.
Another video-centric feature is the inclusion of S-Log 2 built in. That's right, the flat Sony picture profile that was included in the FS700's $400 upgrade is built. If you haven't seen what S-log is capable of in the hands of a skilled shooter, do some research on Vimeo – it's an amazing option.
The Good of The Sony A7s:
– Full-frame (and crop) 4k Sensor with no line skipping 1080P/60fps internal video
– Ultra-HD 4K Output through HDMI (see wrap-up)
– Highly adaptable e-mount len mount
– S-Log 2 picture profile (native 3200! ISO) at around 13 stops of dynamic range
– Clean ISO up to 64000 (although I still don't recommend shooting that high)
The Not So Good of The Sony A7s:
– No 4k Internal (see wrap-up)
– Extremely sensitive sensor (a Sony quality) means you need to invest in some quality ND filters
– Limited Battery Life
Final Thoughts on The Sony A7s:
I asked Philip Bloom about the dynamic range, and he said that it gets up to about 13 stops. This is a similar dynamic range to the outstanding Blackmagic Pocket and Cinema Cameras.
While the The Sony A7s is priced between the Blackmagic 2.5K and 4K Production cameras, it has a 4K powerhouse of a sensor and I am very excited to see what good cinematographers can do with it. Internal downsampling is nice, but being able to output full Ultra-HD 4K over HDMI is a great option.
