Additive Color

[dehk]

Say I want to do some additive color, using black and white film with R G B filter. Do I want to expose them in the same exposure, or should I adjust according to the filter factors?

 

[E. von Hoegh]

Of course you apply the appropriate factors. You need to make three separate exposures in correct registry, too.

 

[holmburgers]

The goal is this: If you have a grey card or grey scale, you want the densities to be identical in all 3 negatives. With most films and filters this will require different exposures and could even require different development.

 

[dehk]

Thanks guys.

 

[E. von Hoegh]

Let us know what your results are, I'm becoming interested in this process. It may end up the only way to do color in the sheetfilm sizes.

Good luck!

 

[dehk]

Let us know what your results are, I'm becoming interested in this process. It may end up the only way to do color in the sheetfilm sizes.

Good luck!

It's going to be a while since I couldn't find my green filter, but will do!

 

[Old-N-Feeble]

Tri-color photography...

There are a couple of sets of filters for which all share the same filter factor... makes it far easier. But my darned memory... I "think" one set is a 29, 47 and 61?? Don't ask me to remember the filter factor...

 

[johnielvis]

all the tricolors are about a filter factor of 3 stops--check the old kodak publications for super xx for a starter on what is involved--that film was used for tricolor separations---they now recommend tmx as the best alternative for current films available

I've done it--and it works great...results are AWESOME--of course you must scan an put it together in the computer or get 3 slide projectors...I haven't done that yet but maybe some day....

anyways--use roll film--it's easiest to line up in a scanner, since the one axis is always lined up along the film strip direction, then you only need register in the other direction--sheet film, you must register in 2 directions and rotation too--much more difficult BUT the photoshop programs have this auto allign feature for stitching together photos and that makes it easy now.

it looks so kool when you do it

OH...another problem with sheet film is that registration is even more tricky (for larger sheets) when film sags differently between exposures---so that will mess things up too--you'll need one of them pressure film holders or a vacuum camera back for perfection---but, again, the photoshop software should take care to stretch and shring and rotate where it is necessary to make it eye-pleasing