Exposing for ProRes?

[Mark Kenfield]

Hi Guys,

Just wondering if people would care to share how they expose their BMCs when shooting in ProRes. And particularly, how you expose with lenses that don't have iris rings?

I've got a couple of primes (35mm, 85mm, 135mm) that are fine, and I have manual control over, but my wider lenses are all iris-ring-less zooms (Tokina 11-16mm, Nikon 17-55mm), and apart from having them wide-open (at f/2.8) or closed right down (at f/22) I don't know what my iris is.

I'd love to hear any tricks people have for exposing for ProRes without knowing your iris!

I've also got the joy of having to match my exposure with an F3 which will be our A-cam. So any suggestions for figuring out what my exposure would be would be a big help. The only solution I can think of at the moment is setting Zebras on both cameras at the same level and roughly matching the cameras together using that - I'd much prefer a more elegant solution if someone has one though!

Cheers

[Chris Medico]

This guy could become your best friend in your situation:

http://www.bhphotovideo.com/c/product/330874-REG/Lastolite_LL_LR1250_EZ_Balance_Grey.html
Using a grey/white card to get your exposure set then shooting BOTH sides after you have your exposure will be very helpful in getting the shots tweaked in during post.

[Mark Kenfield]

Thanks Chris,

I've already got the EzyBalance card (never leave home without it), but although I can set my exposure easily with the F3 and CP.2s, it's setting the exposure for the BMC when I don't have an iris measurement to go by that I'm concerned about.

[John Richard]

It sounds like you have not loaded firmware version 1.2 onto the BMCC.

1.2 gave this camera the capability to display the iris setting for any lens that the BMCC can communicate electronically with. The Tokina 11-16mm iris setting displays on the BMCC LCD as well as thru a monitor connected via the SDI port.

[Mark Kenfield]

Hi John, the camera is up to date. All of my stills lenses are Nikon F-mount though - so they connect to the camera via a dumb adapter (so no iris readings on the camera itself).

Which is why I really wanted the MFT version to be out by now - so that I could just stick the CP.2s on it and not have to worry about this stuff!

[Chris Medico]

Originally Posted by Mark Kenfield

Thanks Chris,

I've already got the EzyBalance card (never leave home without it), but although I can set my exposure easily with the F3 and CP.2s, it's setting the exposure for the BMC when I don't have an iris measurement to go by that I'm concerned about.

Since you have a grey card and if you know the gamma curve in the camera it should be a pretty simple thing to estimate your iris setting from the video signal.

Start from a known iris setting then shift the exposure on the card down till you reach the stop you want. If you do that under controlled conditions you should be able to put some witness marks on the lens adapter for reference.

[Chris Barcellos]

I shot ProRes film setting last week, and broad daylight situations, I just adjusted aperture on my lenses until I lost zebras, which were set at 100 % This left me with detail in the sky still, while still leaving me detail in shadows too. I got in trouble when I wanted to take the f-stop higher by two stops after the zebras disappeared and I lost too much in shadow, though sky looked great. Camera in ProRes still seems to have a pretty wide latitude and using zebras seems to work just fine because you can bring out detail in highlights in post.

Camera really needs ASA 50 and ASA 100 to allow a little more aperture control in daylight. I like to shoot my old Nikon lenses at around F4 to F11 for best lens performance, but in bright daylight conditions at 200 ASA, I usually get stuck up at around f 16 to F22. I did have to adjust shutter angle to 90 or 45 degrees too, in those situations.

Alternative is to set everything where you want it, and mount a variable adapter and rotate it for exposure adjustment. I am not tickled with the way my cheapy variables seem to muddy the images, so I need to get a better variable in my kit.