A short film we shot using the Sony A7S II showing off its low-light capabilities and slow-motion footage.
First things first, there are reports of a ‘black sunspot’ issue with the A7S, and whilst we didn’t have the option to test the camera on a bright sunny day, we found we were able to replicate the effect using the LED light from a smartphone.
As other websites, including EOSHD, who first seem to have encountered the problem, have noted, the issue seems to only occur when shooting at 25fps. Switch to 24, 30, 50, 60 or 100fps and it isn’t there. This is why the problem hasn’t been reported as much from the US – most videographers will be using 24fps or 30fps, to mimic film or to work in an NTSC format.
I found the effect to be quite difficult to replicate. The light source needs to be very bright and clear. I tried pointing the camera at a lightbulb and even a very high powered studio light, and was unable to see the black sun spot. Presumably any slight diffusion reduces the effect.
However, an LED light, in the form of a smartphone flash/torch did make it occur, though I found that it was more magenta than black and it was worse when the LED was perfectly in focus.
If you are shooting point light sources, for now I would switch to 24, 30 or 50fps. The good news is that given it isn’t visible in those other frame rates it should be something that can be fixed in firmware. There is also the option of software correct. You should be able to track it out and bleach it white in After Effects, and Da Vinci resolve even has a tool to remove specifically this effect.
We contacted Sony regarding the black sunspot issue and were told that
‘We have confirmed this phenomenon and are now analyzing it to develop a firmware solution to solve it. We will be in touch as soon as we are ready to confirm timings for this update’
We’ll keep you updated when we find out any more as to when the firmware update will be available.
Sony has now released a firmware update for the A7S II sunspot issue. Impressively it has taken them only around a week from acknowledging the problem, to making the fix available.
Sony will release a firmware update for the α7S II camera on 20th November, 2015. It is designed to eliminate the occurrence of a black spot that may appear in frame when shooting in a specific set of high intensity light conditions. The new firmware, version 1.10, will be available for download through Sony’s e-support site http://www.sony.eu/support/ on the product page for model “ILCE-7SM2”.
Otherwise the image quality is pretty good. The 4k mode from the A7S II has a full sensor readout, without pixel binning, so aliasing isn’t noticeable. The readout from the whole sensor is then downsampled, producing very sharp 4K footage, and then obviously the shallow depth of field that is offered by the large sensor offers that cinematic effect that we are no used to from the use of DSLR cameras for filmmaking.
Switch to the 100fps mode and the sensor only reads out an area that produces a 2.2x crop, narrowing the field of view. We did notice that in this mode noise can be a little more of an issue, obviously there is relatively less light hitting the sensor due to the faster 1/200th sec shutter speed we were using, and the footage also doesn’t benefit from downsampling. In addition it may be that the processing required for shooting at this high speed means that the noise reduction has to also be reduced. Either way it is a little more noticeable, but using Neat Video we were able to reduce the noise in shadow areas easily enough.
There are some very impressive videos showing just what the Sony A7S II can do in virtually no light, by cranking up the sensitivity to huge ISOs. However, realistically you wont be doing this, as although noise is well handled, it is there, you can see and I’m sure you don’t want to spend extra hours processing footage. Ideally you want to be shooting up to around ISO 12, 800 if you are looking to make the most of the footage and keep noise to a minimum.
As we said earlier, there is quite a knack to shooting using the S-Log modes. S-log 2 is certainly the more forgiving of the two, whilst S-Log 3 produces such flat footage that you really want to only use where you have some footage that already has a lot of contrast in it. Get to grips with ho wto expose S-log 2 by overexposing as much as you can without blowing all the highlights and you will be rewarded with some footage that can be nicely graded. Do spend some time learning how to get the most from it in your chosen editor/grading software as you don’t want to be lifting the shadows too much to make them brighter. With the native value being ISO 1600 that shadows can be a little noisey and you will want to be knocking them back a little rather than lifting them, but that is the whole point of S-log 2 and shooting bright and flat.
As for rolling shutter, yes if we wiggle the camera from side to side or do very quick pans it is noticeable. This doesn’t mean that the A7S II is completely unusable for panning shots, it just means that you need work out a good steady speed that you can pan without it being an issue. Rolling shutter correction should be able to take the edge off too. Let face it, most videographers aren’t shooting loads of quick panning shots, but if you do then the A7S II may not be for you.
Once again it is worth adding that the Picture Profile settings really do offer the ability to get some great looking footage straight out the camera.