Trichromatic Photography

[C_Remington]

What's the gum process?

Shoot three images, each with R, then G, then Blue filter..
Print R negative on R colored gum, then G negative on G colored gum, etc?

Lots of info on digital process only.

[Bob Salomon]

When CBS introduced their color TV system it was using a tricolor filter wheel placed in front of the tube. For some reason the NBC system won the race.

[Jim Jones]

Lou Charno was doing expensive dye transfer portraits with a tri-color camera in Kansas City until the mid or late 1980s when Kodak discontinued the glass plates she was using: http://tech.groups.yahoo.com/group/d...r/message/1120.

[photoevangelist]

I did it with some 35mm Kodak color separation movie film in my M6 with R G B filters and combined them in Photoshop. It's fun, but I've been getting deeper into large format (as mentioned can be used with any B&W pan films and any format as well). I should do some more. There are some quirky results when things move during the course of time.


Trichromy Test #21 by Lee Smathers, on Flickr

Check out the yellow ghost on the left:

Trichromy Test #14 by Lee Smathers, on Flickr

[Drew Wiley]

Ideally you don't choose just any pan film. The curves have to match the whole distance, regardless of the significant variables how they respond to different hard
filters and potentially also different amounts of development per matched contrast too. In traditional methodology, long straight line films like Super XX and Kodak
Color Sep film were used. Today TMax films are highly compliant to such usage. Other types of film might require significant retooling in PS to get the curves matched. Simple in principle, but takes a lot of experimenting and preferably a densitometer to do accurately. Then you still have to potentially tweak or mask
the results to match the idiosyncrasies of the tricolor print medium, depending on what you're trying to achieve.

[sanking]

What's the gum process?

Shoot three images, each with R, then G, then Blue filter..
Print R negative on R colored gum, then G negative on G colored gum, etc?

Lots of info on digital process only.

This article by C. Anderson provides a nice summary of the color gum process.

http://www.alternativephotography.co...romate-process

Sandy

[Wayne]

There is a previous and rather extensive thread on the subject in this forum.

Where.

[sanking]

Where.

Perhaps this one.

http://www.largeformatphotography.in...ight=tri-color

Sandy

[Wayne]

Must be. Thanks.

Perhaps this one.

http://www.largeformatphotography.in...ight=tri-color

Sandy