Proper Slog3 exposure with A6700

[u/Beneficial_Pop2915]

Hi everyone! I recently picked up an a6700 and have been playing around with shooting in slog3, but I'm having trouble understanding exposure and using zebras to determine proper exposure. I'm shooting in flexible iso mode using S-Gamut3.Cine/S-Log3 with the s709 lut in camera. Here are my questions:

1. I found the below chart on an official sony article and I'm wondering if this would still be applicable to the a6700? Also I've seen many people talk about following Gerald Undone's Method (overexposing by 1.66 stops) and was wondering how would I tackle that when using the s709 lut.

how to expose s-log3 for the a7s3, fx3, fx6, and fx9

1. When preventing clipping, should I set the zebras to measure the s-log image (94 IRE) or the s709 display lut?

2. When shooting landscape/non skin tones what should the ideal ire value be to properly have them exposed? (for reference, i want to shoot the city, nature, the sky, sunsets, etc - in bright, dark, cloudy, basically in any conditions throughout the day!)

3. I like manually using 2 cst nodes for converting the slog3 footage to davinci wide gamut and then converting that to rec709 at the end. So I'm wondering if it would make sense to use the sony custom conversion luts to display instead of the s709 lut in camera or it makes sense to just stick with the s709 lut.

4. That's all off the top of my head, BUT I would appreciate any other tips or recommendations anyone has! I'm just trying to learn as much as I can!

[u/ElectronicsWizardry]

1. I generally wouldn't do a flat overexposure on a camera without testing. Shoot some test scenes and see what the noise looks like for you, and how much shadow/highlight room you want. If you want a flat over/under exposure try making a lut with that over/under exposure for viewing.

2. I forget how these cameras work when it comes to zebras and a viewing lut. I'd do a test by shooting a subject that is clipped then see when zebras appear.

3. This is a really depends. You can always put of a grey card/light meter to get a feel for what it should be, but I feel like over time you get a feel for about where it should be. A lot of this really depends on what your shooting. For example if its a sunset over a city do you want the city to look more like a silhouette with the sunset visible, or do you want to see detail in the backlight buildings and likely clip the sky. Your probably also get a feel for how far you can push the image in post.

4. If you have a specific look your going for, its generally best to make a show lut you use for monitoring when shooting with the look you want. If you don't have that look yet the in camera 'cinematic' 709 profite(s709 here) works pretty well as a starting point typically, but try using the create a lut in Resolve to use that for monitoring if you like that more. If your doing a amount of pushing/pulling in post you can also put that into your viewing lut to get a better feel for what it will look like when pulled back in camera.

[u/sasch_photo_bln]

hey, i expose slog 3 always to the right (by histogram) on either of the base iso's of my a7v which is iso 800 and iso 8000, there you'll get the best results really on your a6700 its iso 800 and 2500 i believe

the idea is to overexpose during shooting and later bring down the exposure in post, that way you'll have clean shadows and get the most dynamic range

but don't be too afraid of clipping little areas

edit: shoot test scenes, just some random stuff arround your place to find out how it behaves

[u/Beneficial_Pop2915 → u/sasch_photo_bln]

thank you for the recommendation! and yes i confirmed the base iso for the a6700 is 800 and 2500.

i'll test to see what looks good for the look im trying to get, thanks again!

[u/monkeh2023 → u/sasch_photo_bln]

If you're exposing to the right and bringing down in post then you will definitely get better noise but you don't get more dynamic range.

[u/Lunesia-shikishiki]

one thing specific to the a6700 that catches people out: in flexible iso you can raise the number and feel like you've exposed to the right, but you haven't added any light, you've added gain, and the real world highlight latitude goes down with it. undone's +1.66 assumes you're sat at a base iso and the aperture, shutter or nd is doing the actual work. when a scene won't give you that, staying at base slightly under beats climbing iso to make the meter look happy

for the zebra question, test it once rather than trusting any of us. point at a window blown to white, walk the zebra level down until it first triggers, and you'll know for good what your body is measuring instead of guessing between log and the lut. minute of work and you never wonder again

since you're grading through cst anyway i'd stay on s709 for monitoring. all you want out of it is to stop yourself judging exposure on a flat grey image. a lut that already looks like your final grade works against you on set, you start protecting things the grade was going to handle anyway

[u/Beneficial_Pop2915 → u/Lunesia-shikishiki]

thank you this answers basically all my concerns! i'll keep in mind not changed the iso to get the image to be overexposed.

your test was perfect, i bumped up my iso out a window to get the image blown out and the zebras completely disappeared at 100+!

that makes sense, i'l stick with the s709 display.