C100: Spot metering

jonnyh1968

jonnyh1968

Well-known member
The c100 has the ability to go into spot metering mode (and a little man icon appears on the left of the screen). There is not, however, any type of marker or box telling me what area of the screen is "spot" metered. What area is it? The center? What if you magnify the image? The manual simply tells us how to turn it on - it does not actually say how to use it.

I want to expose my subjects face at 18% grey. My subject's face represents maybe 20% of the screen area and is rarely in the center of the frame.

Also, second question, does the EOS standard gamma on a c100 offer a greater dynamic range than on a 60D or 7D (which uses EOS standard gamma by default). OR do I need to go into Wide DR or Cinema mode to get the greater dynamic range in the C series.


Any help greatly appreciated. Thank you.
 
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Well on the DR question I would tell you to use C-Log if you really want to take advantage of the image. It's easy to grade and get the contrast back, but at least using C-Log and Cinema Lock you can get the most information possible. If I bought a C300 or C100 I wouldn't even think about using the standard gamma. Odds are it's DR will be similar to your DSLR...don't expect it to be much more. Unless I was handing footage over quickly to someone and having that DR didn't matter, C-Log would be all I use.

Just my opinion of course. :)
 
Another opinion here =)

I'd say the default gamma for internal recording should be Wide DR. It's specifically made to maximize DR in a output ready format.

Log gamma sounds really great, but we're shooting into 8 bits here. I'm not going to rule it out for AVCHD use, but the risk is that that our 8 bits, originally optimized for around 6 stops of DR don't have the reserves to take care of the whole Log process.

With Log gamma you are going to compress most of your image into essentially few discrete levels—a subset of the 256 available.

A profile like Wide DR that more fully uses the 256 levels will give you better tonality and you don't risk the flatness in tones that you risk with Log.
 
About the spot metering, I think you're confusing it with the "spotlight" light metering mode. It's on page 61 of the manual. I don't believe there is a spot metering mode, like on a DSLR.
 
Spot metering - Thanks drummondb. Yes, you are correct it is called "spotlight" light metering mode (as the manual infers 'in the case you are using a spotlight') ... so what does this mean? That it hones in on the brightest spot in the frame and meters that area? Whatever. So, there is no internal meter for selecting a specific area. And 'Average' or whatever its called just gives us an average of the whole frame regardless of whats in it or what our subject is? I guess I need to buy a light meter. Wow, never thought I'd say that. But, I guess there is Zebras... that helps. I put facial highlights at 70% on my Panny HPX170.

Wide DR - Thanks AndreeOnline, I think I might have to agree with you. With only 8 bits and 4:2:0 to work with, forcing us to color correct seems risky. Wide DR seems pretty good.

Thanks everyone.
 
Don't forget about the built-in waveform monitor. I've heard a cinematographer say he barely uses his light meter when he has access to a waveform monitor.
 
Spotlight seems to favour the centre of the image as you would expect with most spot metering modes. You can enable the centre cross in the marker menu to give you an aiming tool if required. As said above though, the waveform is a better tool by far, although for somebody coming from DSLR's I can see how the exposure bar would feel more familiar. I quite like the fact that you can use the spot metering to get correct exposure on skin tones and then check the waveform to see where that puts the rest of the image.
 
AndreeOnline said:
Another opinion here =)

I'd say the default gamma for internal recording should be Wide DR. It's specifically made to maximize DR in a output ready format.

Log gamma sounds really great, but we're shooting into 8 bits here. I'm not going to rule it out for AVCHD use, but the risk is that that our 8 bits, originally optimized for around 6 stops of DR don't have the reserves to take care of the whole Log process.

With Log gamma you are going to compress most of your image into essentially few discrete levels—a subset of the 256 available.

A profile like Wide DR that more fully uses the 256 levels will give you better tonality and you don't risk the flatness in tones that you risk with Log.
Click to expand...

I would have to disagree with you on all accounts. The 8-bits will hold up fine. I've graded C-Log C100 footage and it works just fine. The C300 is 8-bit with 422 and higher bit-rate and grades wonderfully well in C-Log. I agree with Noel that if you aren't doing an insane amount of grading, Wide DR is a waste compared to what C-Log can afford you. That's my opinion at least.
 
AndreeOnline said:
Another opinion here =)

I'd say the default gamma for internal recording should be Wide DR. It's specifically made to maximize DR in a output ready format.

Log gamma sounds really great, but we're shooting into 8 bits here. I'm not going to rule it out for AVCHD use, but the risk is that that our 8 bits, originally optimized for around 6 stops of DR don't have the reserves to take care of the whole Log process.

With Log gamma you are going to compress most of your image into essentially few discrete levels—a subset of the 256 available.

A profile like Wide DR that more fully uses the 256 levels will give you better tonality and you don't risk the flatness in tones that you risk with Log.
Click to expand...

Truth.
 
My experience is that Wide DR exposes to just below highlight clipping, and that it will deliberately crush shadows to give smooth highlights. When you have indoor lowlight with a few bright practicals unavoidably in the frame it produces too much shadow mud for my taste unless you correct thebexposure to delibrately overexpose the bright practicals. However, sometimes I have untrained camera operators using our cameras to film events (we frequently volunteer our equipment to record spiritual/religous events), and then I find I must set it to C Log for the best results with auto iris. otherwise the shadowed faces and clothes are buried by Wide DR being optimized for highlights. So, when I shoot I use Wide DR in indoor low highlight and adjust aappropriately for the luminance range in the shot and what I need to preserve. It is great then, but without exposure compensation Wide DR is not as optimal as Cinema C Log for low light indoor scenes with large luminance range where the desired focus is more into the dark range.
 
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