S-Log2 - 7Q best practices for exposure

berlinfool

berlinfool

Well-known member
Hi guys,
I'm still looking for the best practice to get the perfect exposure for S-Log 2
The fear of noice always made me overexpose but I don't think it's the solution.
When I apply the LUT in DaVinci most of the noise goes away.
I also found out during my research that most of the image information is in the lower light levels.
Does anybody has a good system?
My tools I use for exposure are my lightmeter, SmallHD DP6 and the 7Q

People tell me the LUT on the 7Q is useless but I'm not convinced.
 
Hey berlinfool,

I'll be the first to admit that I'm not the most experienced with Slog2 and 7Q, but I was doing a shoot this weekend, Slog2 to Cinema DNG (4K on the 7Q), and I found that my overexposed images were more gradeable than when I exposed skintones in the 38 IRE range. I was using false color and everything. The skintones when overexposed were graded to much better results...which I also thought to be a bit counter intuitive. Now, I know that there might not be as much room for grading if your shooting ProResHQ, but that has been my experience. And yeah, I haven't been using 7Q LUT. I can't wait unitl we can load our own LUTs!
 
There are 3 acceptable methods of exposure for Slog2. I won't go into the rationale, enough of that is available if you do a search( see Alister Chapman Blog).
Method 1-No LUT, expose 18% grey to 32 IRE, or 90% white to 59 IRE
Method 2-Rec709 LUT-expose 18% grey to 45, or 90% white to 90 IRE. Alister suggests, further, set EI to 800(1.3 stops overexposure)
Method 3-Rec709 LUT-expose caucasian skin tones to 65-70%
 
overexposing 1-2 stops is good way to reduce the noise but of course eats into your highlight latitude, so its a trade off to overexpose.

Also if you are shooting scenes with low contrast there is less reason to use the over-exposing method, because realistically you are further away from the noise floor anyways. Conversely if you shoot low-key scenes where there can be large pockets of blacks or shadows then noise usually rears its ugly head. The solution can be to light your shadows which reduces the scene contrast range, but lighting shadows etc.. may not always be practical.

It's ok to use generalized rules of thumbs like expose middle grey for 32% IRE, etc.. but in reality everything depends on the scene itself you are shooting. One size really doesn't fit all.

I wrote 'The Ultimate Exposure guide for the F5/F55 cameras' which many have found really practical and useful if you're interested. Its available for a really small price and applicable to all the Sony slogs currently available.

 
Cool - thank you everybody. I just made some tests and realized I don't have to worry about noise because there won't be any shadows - it's a bright fashion shoot. So I won't be overexposing - losing skin detail is a bad thing.
I realized the LUT on the 7Q is a better guide than the Slog2 image. The light meter is useless.
I'm going to check out that exposure guide.
In addition to all I will use prayer as well - haha.
 
berlinfool said:
Cool - thank you everybody. I just made some tests and realized I don't have to worry about noise because there won't be any shadows - it's a bright fashion shoot. So I won't be overexposing - losing skin detail is a bad thing.
I realized the LUT on the 7Q is a better guide than the Slog2 image. The light meter is useless.
I'm going to check out that exposure guide.
In addition to all I will use prayer as well - haha.
Click to expand...

Lol, i'm gonna check out the exposure guide as well.
 
Well this topic fits my question. In situations with lowcontrast/lots of light the overexposure trick will not always work or be neseccary but consider this clip: https://www.youtube.com/watch?v=6F2WG5bos8c

The set had a black background and I had to bump up the exposure to get the noise out of the black areas. Luckily the higlights that i got fit the DP's goal of crappy rgb TV. But i over exposed by opening the lens and this kills my DOF ofcourse 'cause with certain lenses or talent at a certain distance the DOF wil be as thin as paper. Yet there isnt much to do to overexpose. I could slow down the shutter but unless the camera is on a tripod and standing still i never go slower than 1/100. i always look at my wavefrom to see if it has a lot of info with a fat bar from 20 to 80IRE. take a look at this, from 1.00 its the Q7 and at the end i had a 62mm Minolta lens on the camera with no speedbooster etc: https://vimeo.com/145208538
 
You must log in or register to reply here.
Back
Top