In this blogpost I want to built upon my earlier blogpost about the exposure latitude on the Panasonic GH4 and how to do an exposure latutide test.
I ended this blogpost wondering how well the Sony A7s would perform when I would do the same test with this camera and here it is, I have created a new updated version of the comparison that includes the results of the Sony A7s.
Exposure Latitude on the Sony A7s
The most optimal results in terms of dynamic range are to be expected when shooting with the SLOG2 picture profile on the A7s, this is PP7 (Picture Profile 7) in the menu of the camera. So the first test that I did was with this Picture Profile but since SLOG2 works only with a minimum of ISO3200 I also wanted to check out how well another Cine Picture Profile would perform, so I also did the test with PP6 that has a Cine2 gamma.
As you saw in the video the results are:
|Picture Profile||Usable Exposure Latitude|
|SLOG2 (PP7)||8 stops|
|Cine2 (PP6)||8 stops|
So was there no difference at all?
Difference between shooting SLOG2 and other picture profiles on the A7s
In terms of whole stops both the profiles I tested were the same (in my opinion) but there definitely was a difference between the two of them:
- SLOG2 has a lot more room to play with in the highlights
- Cine2 has a lot more room to play with in the shadows
I thought overall the SLOG2 picture profile performed slightly better, I was in doubt about the 4 stops underexposed on with the SLOG2 footage, if I would have judged that as usable then the SLOG2 Picture Profile would have gotten 9 stops of usable exposure latitude, but I didn't do that because I thought it had too much noise, especially in certain colours.
How to set exposure on the A7s with SLOG2
With all the DSLRs I have regularly shot with (Nikon D7000, Nikon D800, Panasonic GH4, A7s with picture profile other then SLOG2) you need to protect the highlights because there is always more room to play with in the shadows.
The only camera that was different in this respect was the Blackmagic Pocket Cinema Camera, there were a lot of times where I thought I was heavily overexposing but that really gave the best image when handled in Resolve.
When shooting SLOG2, as you can see from this test, there is a lot of room in the highlights, more room then in the shadows, so you need to protect your shadows a lot better. On my Nikons I liked to underexpose a little so I could clearly see details in the highlights, but when shooting with the A7s in SLOG2 I need to trust on the zebra's and set exposure to the point where it doesn't clip any highlights or clips just the highlights that can be clipped (like specular highlights), often times the exposure meter in the camera says that I am 2 stops overexposed but that's fine in this case.
When shooting outdoors one time, I had forgot to change my zebras setting from 100+ back to 100 and I was shooting SLOG2, I was way overexposed, but in this case too much, because I had lost part of the highlights because I was relying on the zebra setting which was not set correctly, so definitely set your zebra's too 100 or lower and not to 100+ when shooting SLOG2.
The Exposure Latitude of the Sony A7s compared to the Arri Alexa / Amira Sensor
In my previous blogpost I wrote in my conclusion that the A7s had an advertised dynamic range of 15.5 stops, I thought I got that from the specs at the B&H page at that time, but those numbers are not on there anymore.
I think this was a little too much, DXOMark rated the sensor in the A7s to a somewhat disappointing 13.2 stops of dynamic range (when you compare it to the earlier advertised 15.5 stops), while Cinema 5D has it rated at 14.1 stops.
Cinema 5D also has rated the dynamic range of the Amira at 14.5 stops, so when we compare both of these numbers there is almost no difference. But when we look at the usable exposure latitude the difference is about 3 stops:
This difference is probably due to the internal processing of the images in the camera and to the codec in which the images are being recorded, it's pretty logical that the Alexa / Amira has a lot more processing power and better codecs than the Sony A7s.
Nonetheless the A7s performs incredibly well for such a small full frame camera and this is only for exposure latitude but it does some other things very well too, for example, the resolution and the resolved resolution in 1080p is excellent as well.
Full Exposure Latitude Comparison Table Arri Alexa, Sony A7s, Panasonic GH4, Nikon D800 and Blackmagic Pocket Cinema Camera
|Nikon D800||6 stops|
|Panasonic GH4||7 stops|
|Arri Alexa||11.5 stops|
|Sony A7s||8 stops|
Had I hoped for a better result? Ofcourse I did. But am I dissapointed by the results? No, I'm not. I really love this camera, it's amazing what this camera is capable of in terms of specifications but what matters most of all is what images it is capable of producing and that is absolutely amazing.
For the testing that I have done, there are countless times when I have shot with no picture profile at all on the A7s, when paired with my Leica Summicron 35mm F2.0 lens and Voigtlander E-mount to Leica M mount Close Focus Adapter, this camera has produced some amazing images for me and it definitely is my number one camera right now.