Jump to content


Photo

Shooting a projected HD image on 35mm


  • Please log in to reply
10 replies to this topic

#1 Michael Rizzi

Michael Rizzi
  • Basic Members
  • PipPip
  • 33 posts
  • Cinematographer
  • LA

Posted 26 July 2006 - 07:16 PM

I have searched the archives but haven't quite found what I'm looking for. Hoping someone can help me out with this one.

I'm to shoot about a half an hour of HD acquired footage on 35mm, the HD footage will be projected on a screen. Think rear projection without anything in front, it's basically a poor man's telecine in reverse. This is to match other footage that was acquired on 35mm.

The issues I want to make sure I address are syncing, proper exposure, and color temp. I have gathered that using an LCD HD projector will eliminate any sync problems (yes/no?). As far as exposure, if the footage does not have a grey card at the head what other techniques might there be to get the proper exposure? And color temp...my understanding is that projectors are daylight balanced so an 85 filter over the projector??

Anything else I should be aware of? Screen size? Lenses? Shutter angles? Any thoughts are appreciated.

Thanks.
  • 0

#2 Michael Nash

Michael Nash
  • Sustaining Members
  • 3330 posts
  • Cinematographer
  • Pasadena, CA

Posted 26 July 2006 - 07:20 PM

Mike Rizzi, welcome! :D

I take it a proper film-out of the material is too expensive?
  • 0

#3 Michael Rizzi

Michael Rizzi
  • Basic Members
  • PipPip
  • 33 posts
  • Cinematographer
  • LA

Posted 26 July 2006 - 07:26 PM

Mike Rizzi, welcome! :D

I take it a proper film-out of the material is too expensive?



Of course. This is low budget you know!! :P
  • 0

#4 Laurent Andrieux

Laurent Andrieux
  • Sustaining Members
  • 1527 posts
  • Cinematographer
  • France

Posted 26 July 2006 - 07:58 PM

I

have gathered that using an LCD HD projector will eliminate any sync problems (yes/no?). As far as exposure, if the footage does not have a grey card at the head what other techniques might there be to get the proper exposure? And color temp...my understanding is that projectors are daylight balanced so an 85 filter over the projector??


I've never shot an LCD monitor but read here and there there was no flickering problem with such devices. (make a research on the site)

exposure : read the projected image with a spotmeter or reflective ligh meter.

projectors can be higher that 5500 (usually 6500 at least) but it should be possible to check and set this up in its menu. But if you shoot the projected image ful screen, you can as well put a 85 on the camera or shoot daylight stock (it's the finest grain)
  • 0

#5 Michael Rizzi

Michael Rizzi
  • Basic Members
  • PipPip
  • 33 posts
  • Cinematographer
  • LA

Posted 26 July 2006 - 08:18 PM

Thanks for the replies but I think I need to clarify something I wrote in the original post.

For exposure...naturally I am going to use a spot meter to find my exposure but the issue I'm worried about is not metering an image that is 18% grey and therefore either overexposing or underexposing the projected footage. I imagine that if somehow I projected color bars and then spot metered the middle grey bar I would get an accurate exposure. Does that sound logical?

-Rizzi
  • 0

#6 Michael Nash

Michael Nash
  • Sustaining Members
  • 3330 posts
  • Cinematographer
  • Pasadena, CA

Posted 26 July 2006 - 08:25 PM

I would think the hardest part would be trying to get the contrast right. If the projection contrast is too low, the white highlights won't look white on film (a dull gray-white instead). But if it's too high, then you'll just clip highlight detail. Same deal for blacks. And you'll also have to figure in where the 35mm print will clip the whites and blacks. So in other words, you really need to test.

I think the larger you can project the image, the sharper the end result will look. But naturally as the projected image gets bigger, the contrast and luminance gets lower. You should probably include a grayscale at the head of your HD playback tape, one that includes not only middle gray for color timing and exposure, but also some steps of white and black to judge contrast by.

But I've never filmed a rear-projection before (only video where it's easier to control the signal live). I didn't see much info on CML either. Maybe David Mullen remembers some tricks from old CineFX articles?


BTW Mike, have you seen this?
http://www.youtube.c.....h=sean lennon
  • 0

#7 Michael Rizzi

Michael Rizzi
  • Basic Members
  • PipPip
  • 33 posts
  • Cinematographer
  • LA

Posted 26 July 2006 - 08:47 PM

I would think the hardest part would be trying to get the contrast right. If the projection contrast is too low, the white highlights won't look white on film (a dull gray-white instead). But if it's too high, then you'll just clip highlight detail. Same deal for blacks. And you'll also have to figure in where the 35mm print will clip the whites and blacks. So in other words, you really need to test.

I think the larger you can project the image, the sharper the end result will look. But naturally as the projected image gets bigger, the contrast and luminance gets lower. You should probably include a grayscale at the head of your HD playback tape, one that includes not only middle gray for color timing and exposure, but also some steps of white and black to judge contrast by.

But I've never filmed a rear-projection before (only video where it's easier to control the signal live). I didn't see much info on CML either. Maybe David Mullen remembers some tricks from old CineFX articles?
BTW Mike, have you seen this?
http://www.youtube.c.....h=sean lennon



I have seen that...it turned out pretty good I think (i recognized some of our shots in there too!). And ironically the reason for my posting has to do with that project. The producer called me to do this HD to Film transfer thing from footage that has already been shot, so I have no idea what it is that I'll be shooting really. Small world I must say though.

-Rizzi
  • 0

#8 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 19769 posts
  • Cinematographer
  • Los Angeles

Posted 26 July 2006 - 11:56 PM

Seems sort of pointless to shoot HD and transfer it to film this way -- you're going to lose a lot of sharpness and contrast.

I haven't dealt with rear-projection myself yet.

In theory, LCD should be fine and not need syncing.

Yes, you can spot meter some part of the color bars or some part of the frame that seems close to 18% gray.
  • 0

#9 John Pytlak RIP

John Pytlak RIP

    (deceased)

  • Sustaining Members
  • 3499 posts
  • Industry Rep
  • Rochester, NY 14650-1922

Posted 27 July 2006 - 12:33 PM

I'm pretty sure the cinema grade Digital Cinema projectors that use three DLP chips produce an image that has minimal flicker issues when rephotographed onto 35mm film. Tone scale and color reproduction will likely need to be adjusted. Usually, the white point is near D6500K.
  • 0

#10 Laurent Andrieux

Laurent Andrieux
  • Sustaining Members
  • 1527 posts
  • Cinematographer
  • France

Posted 27 July 2006 - 01:01 PM

I'm afraid there is no 18 % grey on a color bar, depends on wich one you use but...

You can meter the white bar and consider it should be 2 or 3 stops over KL (depending on the stock you're using) and the black bar and consider it should be 3 stops under KL, or shoot at the mean value beetween these two...

When it's an image that is projected, not a color bars pattern, you can apply the same to white and black areas. You can also meter the skin of a carachter on a close up and consider it is about 2/3 to 1 stop over KL in its mean values and about 2 stops over in its highlights (where you'd get zebras if shooting video, you know, the front head, the nose...), but it depends a lot on the skin color and lighting...

If you don't find more than 6 or 7 stops beetween the blacks and the whites, exposing at the mean or 3 stops over the blacks or under the whites should give a decent result.
  • 0

#11 Michael Rizzi

Michael Rizzi
  • Basic Members
  • PipPip
  • 33 posts
  • Cinematographer
  • LA

Posted 27 July 2006 - 05:01 PM

Hey, thank you everyone for your help and sharing your knowledge. Unfortunately the shoot has been canceled (c'est la vie) but next time I'll know what to do!

-Rizzi
  • 0


Willys Widgets

Metropolis Post

Paralinx LLC

FJS International, LLC

Wooden Camera

Ritter Battery

Glidecam

Tai Audio

The Slider

rebotnix Technologies

Technodolly

Aerial Filmworks

Broadcast Solutions Inc

Abel Cine

Visual Products

Media Blackout - Custom Cables and AKS

Opal

Gamma Ray Digital Inc

Rig Wheels Passport

CineTape

CineLab

Tai Audio

FJS International, LLC

Rig Wheels Passport

Visual Products

rebotnix Technologies

The Slider

Broadcast Solutions Inc

CineLab

Paralinx LLC

Ritter Battery

Aerial Filmworks

CineTape

Wooden Camera

Opal

Abel Cine

Technodolly

Media Blackout - Custom Cables and AKS

Gamma Ray Digital Inc

Metropolis Post

Willys Widgets

Glidecam