AndreeOnline
Veteran
You're welcome to tell us what you think about the image I posted. Where do you find the differences in the image (100% crop) between ProRes and AVCHD. And how do you think they hold up with the mid tones lifted?
C100: When you don't need an external recorder and when you do
- Thread starter RZE
- Start date
It's obvious the AVCHD suffers from a little color noise but once darkened in post a lot of it becomes "hidden" and once played back as video these artifacts would become even less apparent.
If this was shot in C-LOG I think the image was over-exposed between 1 to 2 stops. I threw the frame in FC just to have a look at a WM and see what kind of levels were there before any grading. Have a look and see what you guys think:
According to Canon's white paper on C-LOG (see the table below I put together based on the white paper) middle grey should read around 32.8%. Blacks should reach down in the 12% ~ range, and nothing brighter than "white" should exceed 62.7%. Looking at the image we can see that the back of her neck is almost 26% higher than what "white" itself should read on a scope and the shadow side of her face is sitting around where middle grey should land ~ approx 32.8%
The debacle however is that if you over-exposed and need to darken your image in post you actually end up "eliminating" some noise, where-as if you under-exposed and need to boost exposure in post you will amplify any noise or codec artifacts.
Your references are for 320 iso not 850, I shot at 850, Clipping is much higher on the ire scale for 850. It is overexposed by 1-1.5 stops. I set middle grey to 45 IRE instead of 32 because there was a lot of fuss about underexposed this and that
starcentral
Veteran
The major difference I see is all in the shadows, you can see a lot of noise increase when the mid-tones were boosted up. Details in the dark part of the hair or around the sweater start to get pixely and look like RGB noise. In the final image however, you can "barely" see a difference and once the frames are playing back 24fps a lot of these kinds of artifacts can be hard to spot.
Obviously when you boost tones in post it will always increase the noise levels not decrease, which is why I think building a profile where your mid-tones are boosted in camera (or flat profile) is always better because generally you will be darkening and bringing them down in post - hence decreasing noise. LOG does this in essence but way more by giving you more equal data bits to work with throughout the entire tonal range.
The chart has nothing to do with ISO it simply shows the relationship between black, middle grey, 90% white and max brightness (highlight before clipping) when shooting in LOG mode on a C100. If you shot in REC709 or some other gamma the corresponding values would be entirely different in how the camera sees them.
As you probably already know when you change the ISO value in LOG mode what it effectively does is increase or decrease the number of stops you have above or below your middle grey point. If you are a DP this an extremely powerful feature because it allows you to select exactly what you want to protect for without having to cheat and shoot using different middle grey values and then push/pull it in post to bring it back to normal.
If you shot 850 ISO in LOG you would have gained a bit at the upper range but then by placing your middle grey at 45 IRE instead of 32 IRE you would have counteracted that and then some.