S-Log2 + a7s (Please educate me!)

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evanburke

Member
Is S-Log2 a flatter profile that you have to correct to a proper contrast in post?

If so, isn't that pretty hard to do when you're only recording 8bit video? Isn't that going to leave you with shredded, banded footage?

I need some education when it comes to S-Log2. :(
 
Basically yes, but no not really. I shoot Slog2 to AVCHD (half the bitrate of the A7S's XAVC-S) a lot more lately and have not really had any problems so far. It's worth it for the image quality improvements. People get all worried about 8bit but most of the LCD screens you've are looking at and have been looking at for the past 10years have been 6-bit... Yes it may be limiting for some applications and for some people, and some people are very concerned about numbers because other people tell them they should be, but I have yet to see banding or artifacting after grading SLOG2 footage shot in AVCHD. Then again I don't push Slog2 too far usually, just restore saturation and black level and it already looks way better than any other gamma mode available on my FS700.
 
nyvz said:
Basically yes, but no not really. I shoot Slog2 to AVCHD (half the bitrate of the A7S's XAVC-S) a lot more lately and have not really had any problems so far. It's worth it for the image quality improvements. People get all worried about 8bit but most of the LCD screens you've are looking at and have been looking at for the past 10years have been 6-bit... Yes it may be limiting for some applications and for some people, and some people are very concerned about numbers because other people tell them they should be, but I have yet to see banding or artifacting after grading SLOG2 footage shot in AVCHD. Then again I don't push Slog2 too far usually, just restore saturation and black level and it already looks way better than any other gamma mode available on my FS700.
Click to expand...

+1

if you know what your doing you won't have any problems
 
it's a lot wider than normal profiles, which means it preserves more of the sensor's DR, and yes, that means it's spread thinly over the 256 values of an 8-bit codec, but if that codec is good and doesn't create artifacts it may not be a big problem

or maybe it will

the proof is in the pudding, and we shall know soon enough
 
This is some test footage from the Sony FS700.

It's S-Log2, just recorded as AVCHD to the camera's internal codec (no 4k, no RAW).

https://vimeo.com/75311478

Would that be a fair comparison to the kind of image quality and dynamic range I should expect from the Sony a7s?
 
I know he was shooting at 50Mbps using XAVC to SD cards...

But man some of that footage looked only just 'ok'.
 
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Ok, you were correct! *Minimum* ISO of 3200!

What the hell, why a base/minimum ISO of 3200 just to be able to shoot S-log2??
 
Fs700 slog2 operates at ISO 2000 as optimal standard.. A7s ISO goes up to 400000 so considering that I would think 3200 is quite low to make sure all it's shadow latitude is present.
 
Keep in mind ISO is somewhat arbitrary. It only means where middle grey falls, not where any other part of the tonal range. And for Slog2 middle grey is arbitrarily in a different place, so if you expose like other gammas (by eye on monitor) it will feel more like ISO500. When I use slog2 on the fs700 in auto exposure I have to set to about +1.5ev offset if I want a middle grey of 40-50% instead of the designed 32%.
 
seems like they put twice number as base ISO of S-Log2 for final product the market.
I will go check the store right now and see whats up with.
 
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