Since I'll be shooting with a C300 in 2 days from now I wonder whether there are different rules than usual when I use C-log instead of a normal colorprofile.

What is the right way to use (and expose) C-Log?

And is grading different too or not?
(I usually use Colorista and Magic Bullet Looks (not just the presets) to grade my EX1R-footage while using waveforms.)

Yes. When shooting log you have to consider that in order to record the increases dynamic range, each stop of exposure is allocated a very similar amount of data. But as each extra stop is a doubling of brightness range there is in effect more and more image compression occurring as the image brightness increases. For maximum grade ability, you don't want all your picture information up in the highlights. So generally with a log curve you will underexpose slightly compared to a standard gamma. The norm is to use a mid grey card and expose it so that it is at 38% and reflected white should be somewhere around 70%. Reflected white at 70% then allows headroom for direct light sources like the sky or reflections off shiny surfaces.

That's the theory at least, in practice things will vary from scene to scene, but the primary concern is to not overexpose and to keep highlights well controlled.

I'd also like to hear form others on this. I hear you on the grey/white card method but is there an easier way to get perfect exposure on the fly without a card in the scene? On the EX1, I set zebra 1 to 56 IRE and exposed for zebras on the brightest part of the subject's face (except dark skin people) and the results were always great. But you can't do that with the current C300 firmware. And I also don't like how zebra 1 & 2 look so similar. On the EX1, zebra 2 was much thicker which was fine because that was overexposed anyway.

Yes. When shooting log you have to consider that in order to record the increases dynamic range, each stop of exposure is allocated a very similar amount of data. But as each extra stop is a doubling of brightness range there is in effect more and more image compression occurring as the image brightness increases. For maximum grade ability, you don't want all your picture information up in the highlights. So generally with a log curve you will underexpose slightly compared to a standard gamma. The norm is to use a mid grey card and expose it so that it is at 38% and reflected white should be somewhere around 70%. Reflected white at 70% then allows headroom for direct light sources like the sky or reflections off shiny surfaces.

That's the theory at least, in practice things will vary from scene to scene, but the primary concern is to not overexpose and to keep highlights well controlled.

That's a great summarization. Cheers, Alister.

56 IRE for skin tones with standard gamma? That's quite low for a standard gamma, it's more common to use 65 IRE for skin tones. Is that a typo?

With C-log, skin tones I would place bright skin tones around 60IRE.

Nope not a typo. I got that number from an unusual source. It's what Marshall recommends for skin tones when using their false color feature. Looked great to me so I stuck with it.

So 60 in C-Log sounds good to me. Except the C300 only goes down to 70. :-/

Edit: 70 on zebras that is

Thanks for the quick and helpfull replies!

Since I'll be on a very tight schedule, I'm considering using a normal gamma instead of C-log.
(Practising C-log exposure has to wait, I guess ;-) )

i really do hope canon updates firmware so we can get zebras below 70

I've emailed pro support up here in Canada about the zebras under 70, and was told it would be forwarded to the correct people. Probably a good idea for everyone to do the same in their region.

Also brought up having selectable display of the SDI. For example only sending TC to the client monitor, instead of everything on the screen.

yeah,

i keep calling about once a week asking for a few things...most of them correctable with firmware.

I also really want them to make it so that when you split one source of audio to both channels, you can control the levels of the 2 channels seperately.

as it is now, when you split the one source the two channels are locked at the same volume.

I can't seem to assign two different functions to the wheel on the hand grip and the lower wheel on the body. Has anyone been able to do this? I would request that in a firmware update if it's not currently possible.

yes, thaat is my other request. i want to have iris on handle and ISO on the body

That's exactly what I wanted to do!

yup....would probably save me an hour over the space of a year...

I assigned ISO to button 1 so I can't say it'd save me an hour per year but it would be nice. Actually, if it could be assigned to color temp I'd probably do that as I do a lot of run & gun.

I can't seem to assign two different functions to the wheel on the hand grip and the lower wheel on the body. Has anyone been able to do this? I would request that in a firmware update if it's not currently possible.

Probably one of the most requested firmware tweak at this point. This will be very handy indeed, and once they fix this, I'll likely use the ISO wheel much more than I use the iris one. As a workaround, I mapped the MAG button #1 as ISO control, works quite well.

That's exactly what I've done as well. I just want an easier way to change color temp.

having used the C300 for a couple of shoots now, I think I can confirm that placing skin tones around 60IRE max is correct. using the waveform, I have been setting skin tones closer to 65+IRE, (which is what I have been used to with my Sony) and this has resulted in things being just a bit overexposed. from now on I'm going off the waveform at no more than 60IRE for skin tone. (this also seems consistent with the false color on my monitor)

I wouldn't trust Marshall for skin tone info. I saw an early version of the false color at a trade show 2-3 years ago and the flesh tone was set at 80! I took the rep aside and told them they were way off and he brought me over to their tech guy at the show who didn't have a clue. They changed it afterward to 55 - which I thought was too low.
I like 60-65 but people use their zebras a little differently anyway.

Hopefully their actual engineers are more in touch than their trade show tech guy.

Good point on using zebras. I am interested to know how you use yours at 60-65. When I had my EX1 zebras at 56, I would place zebras on the brightest part of light skinned peoples' faces. Again, I was happy with the results but maybe I was slightly underexposed.

Either way, we need expanded capabilities in the firmware. Here's a new one: when using aspect markers on the LCD, it would be nice to have the option to black out the video at the top and bottom. It would still record the full frame to the cards/outputs but it would be easier to frame things in camera.

Hi All,


Just took delivery on my Canon C100 and a Ninja2. ( delivered in a rush. Grateful to Joe at Abel, LA)
My first shoot in a couple of days will be interviews against a white background cyc, high key lighting.
I want the background to be textureless white (100% ?) Having never done this, I could use some clarity on setting up zebras and exposure for my interviewees.

Also, any advice for a first user of the Ninja2? I plan to shoot in 24P (60i) 24Mbps.

I plan to use an "interrotron" setup with an iKann iPad teleprompter.- hoping the interviewers face will be visible in this rig...given the bright studio.

Have any of you shot with this high key look?. I'd be interested in any advice. Thanks!

(Alister- I enjoyed your presentations at NAB this year. Great info. Did I hear that you are publishing camera profiles for the Canons as well as for the Sonys?)

Yes. When shooting log you have to consider that in order to record the increases dynamic range, each stop of exposure is allocated a very similar amount of data. But as each extra stop is a doubling of brightness range there is in effect more and more image compression occurring as the image brightness increases. For maximum grade ability, you don't want all your picture information up in the highlights. So generally with a log curve you will underexpose slightly compared to a standard gamma. The norm is to use a mid grey card and expose it so that it is at 38% and reflected white should be somewhere around 70%. Reflected white at 70% then allows headroom for direct light sources like the sky or reflections off shiny surfaces.

That's the theory at least, in practice things will vary from scene to scene, but the primary concern is to not overexpose and to keep highlights well controlled.