SLog2: internal codec test

R

rotierney

Active member
As I wait impatiently for the arrival of my 7Q I thought I would test SLog2 with just the internal AVCHD codec. I wanted to really challenge the dynamic range and roll off so I filmed in a forest above Wellington called Mount Victoria (which also happens to be the place where a few scenes of Lord of The Rings were filmed). It was a sunny day for most of the shoot which created a good challenge but as I got to the top there was a little high cloud.

I did a relatively quick grade to see how it would stand up and I have been quite surprised. See for yourself (download enabled).

I intend to redo the grade tomorrow when I get more time but until then and will also be doing more tests around skin tone and of course the inevitable slomo.

 
I've done a ton of test shots also with SLog2 and AVCHD and so far am pleased with what I'm getting. You can see the DR improve immensely when switching between normal profiles and SLog2. I don't find it to be hard to grade, stands up quite well unless you're trying to do Sin City. Makes it hard to get excited about spending 5-10K extra for 4K and/or raw, when it's only going to DVD and broadcast rather than a 40 foot theater screen.

Interesting thing is that in Slog2 mode, you can shoot a high DR scene, like inside a church with stained glass windows and no interior lighting, expose the windows a bit blown out so you can see the interior, then in post bring down the highlights and the detail in the windows , to some extent, can be recovered.
 
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I think it works decent if you don't add too much saturation, which makes for blocking pretty quickly with the internal codec. It's fine for most stuff I do since I tend to keep saturation low, but you definitely cannot do any David Lachapelle type stuff with intense, super saturated color; at least with the internal codec. With 7Q, SLog will probably be a lot better.

The DR and lowlight is insane though with SLog
 
Just seeing how much detail is retained from shadows to highlights makes me happy I sent the cam in.
 
I just recently shot a music video where about half of it was a dark bedroom and dark forest, but I opted to not use Slog2. I haven't used it enough to really be confident that it wouldn't end up noisy/blocky in some of the dark scenes. In hindsight, looking at some of the footage, I exposed a bit brighter in the dark scenes to retain shadow detail but I may lose some highlight detail (which Slog2 would have probably saved for me.

Has anyone found dark scenes with Slog2 to be noisy? Or do you just expose a bit to the right and darken it?
 
what software do you use to bring down the highlights? or in premiere, what effect? I use the colorista and it seems to work well, but it doesn't just take the highlight and lower, it kinda does the overall video.
 
If one considers that an S-shaped curve in the semi-log domain was applied to the capture, it follows that an inverse needs to be applied in post to "undo" the effect. I always use a custom made s-curve, reshaping head and tail, as well as an intermediate point. Saturation adjust to taste and voila. Implied in all this is the necessity to be able to watch RGB histogram as well as luma wfm, to keep values legal.
 
dapoopta said:
what software do you use to bring down the highlights? or in premiere, what effect? I use the colorista and it seems to work well, but it doesn't just take the highlight and lower, it kinda does the overall video.
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I graded inside of Premiere Pro CC using just a fast color corrector and a LUT. It's important to place the FCC before the LUT is applied and then you can adjust the contrast of the image to suit the LUT. NOt the best way of doing it so will be doing a proper grade in resolve today
 
What's your workflow with Premiere and Resolve since Resolve doesn't support AVCHD footage? Do you transcode to another format for it?
 
Essami said:
What's your workflow with Premiere and Resolve since Resolve doesn't support AVCHD footage? Do you transcode to another format for it?
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For AVCHD,when importing into Resolve, I transcode with Adobe Media Encoder, first. Avid Media Encoder v7 will injest AVCHD directly. However, I, rarely, capture to AVCHD. My standard process uses a Pix740 external recorder and DNxHD. This allows direct import into Resolve and fast import into Avid.
 
cuervo said:
For AVCHD,when importing into Resolve, I transcode with Adobe Media Encoder, first. Avid Media Encoder v7 will injest AVCHD directly. However, I, rarely, capture to AVCHD. My standard process uses a Pix740 external recorder and DNxHD. This allows direct import into Resolve and fast import into Avid.
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What format do you transcode to?

Is there a way to transcode only the timeline clips individually and open in resolve as individual clips?
 
Another way might be to use Premiers "send to speedgrade" That will make a DPX sequence than Resolve should be able to read.
I've done so for my grader who uses Assimilate Scratch - and it worked like a charm - complete with transitions and so. But as I said I haven't tested it in Resolve, but give it a try.
 
I read this from your other post which Sony stated to you: "Basically, for exposure, you need to adjust Zebra down to 48% (nominal 50% would be OK), otherwise the highlights will blow out and defeat the purpose of SLog."

Hey Ro, what did you set your Zebras to? Correct me if I'm wrong, but setting your Zebras low will make you UNDER expose, correct? I seem to notice that under exposing, especially in low light causes a lot of noise, but I need to test it more.

But great test Ro, and curious as to your Zebra settings.
 
gene_can_sing said:
I read this from your other post which Sony stated to you: "Basically, for exposure, you need to adjust Zebra down to 48% (nominal 50% would be OK), otherwise the highlights will blow out and defeat the purpose of SLog."

Hey Ro, what did you set your Zebras to? Correct me if I'm wrong, but setting your Zebras low will make you UNDER expose, correct? I seem to notice that under exposing, especially in low light causes a lot of noise, but I need to test it more.

But great test Ro, and curious as to your Zebra settings.
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Essami...
AME will batch import individual clips and export to the codec of your choosing. Since I use Media Composer, I always export to DNxHD, either OP1a or OP Atom. If I'm feeding Resolve, I use OP1a, then export out of Resolve to OPAtom.

Gene...
I think you quoted one of my earlier posts. I've revised my exposure process with Slog2. You're quite right that underexposing introduces a lot of noise in post when I bring the exposure up. Overexposing is equally undesireable because it throws away useful range and detail in the hilites. The old expression, "perfect is close enough" applies. I watch the histogram and set the shadow values right before they start clipping. That seems to be the best procedure. Another method is to turn on automatic exposure to see where the FS700 wants to set the exposure. Sony has kept the auto exposure so it works quite well with the Slog2 profile.
 
tscav said:
Another way might be to use Premiers "send to speedgrade" That will make a DPX sequence than Resolve should be able to read.
I've done so for my grader who uses Assimilate Scratch - and it worked like a charm - complete with transitions and so. But as I said I haven't tested it in Resolve, but give it a try.
Click to expand...

I tested with a very simple 4 edit points sequence and it worked well! Thanks for the tip! :)
 
I have zebra on my Pix240 set for 50%; and to 100% in-camera. But, honestly, I'm not watching the zebra as much as the histogram. Generally, I'd guess that my 18% grays are coming out at 50%, pretty much as you'd expect for non-Slog footage. This may not seem rational, but, it's what's working best for me. I'd rather overexpose a tad than under.

Then in post, I build a custom curve for every shot. This seems to give me the most predictable results with nice shadows(not crushed) and well defined detail in the hi-lites. I've noticed that when using curves, it's impossible to get crushed shadows without also severely compressing the rest of the image. So, I have to go back in to "offset" to get the final look in the shadows I want. Then a tweak to the midrange gamma by putting a midpoint on the curva and dragging it down. Followed up with a little saturation tweak
 
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To me some of the footage looked great, and some (like the long shot of the city) a little flat, unless you're shooting for a certain mood. My takeaway: if you have an impossibly high dynamic range, switch to Slog in a heartbeat. I would love to know at what point Slog falls apart in grading.
 
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