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# Thread: I miss Color EIR film

1. Of course, even if you use the same film for all the component shots, you will need different exposure compensation factors for the different filters. Density versus exposure is not constant from blue to IR for any film.

To make life as easy as possible, what you want is a film that has roughly equal density per exposure at the three (or four) center wavelengths of your filters. That's why I was thinking of superpan or similar.

My guess is that if you shoot the IR separation frame with an rm72 filter then you'll need about 3 or 4 stops extra exposure time for that versus the red, green, and blue shots. For red you'll need, what, 2 stops exposure compensation typically. For green and blue you likely need a bit less compensation.

Idea: if you wanted to make life really easy, you could combine your r,g, and b filters with an ND filter of appropriate optical density. Then you'd be shooting the visible shots and the shot with the IR filter at the same exposure time.

Don't tie yourself in knots over it though, as long as you have good density in all the frames, you'll be able to handle the slight differences in density during the combination phase. I'd start by determining the optimal compensation factor for whatever IR filter you use, and then let that determine how you approach the other frames.

2. Here's some info for reference....

There are two sets of tri-color separation filters.

25 red, 58 green & 47B blue - Convenient because all filters share a filter factor of 8 (3-stops)

29 red, 61 green & 47B blue - Purer color separations, larger color gamut (the 25/58 set has over 6% overlap while this set has less than 1% overlap)

How many permutations are there for different ways to mix the colors? You've got 4 inputs, R/G/B/IR and you've got 3 outputs, R/G/B.... anyone better at math than me?

3. Another option for combining separation negatives.... on RA-4 no less!

http://www.apug.org/forums/forum40/8...ml#post1065949

4. Dean Bennici has got 500 rolls of fresh Aerochrome film for \$24.50 plus shipping from Europe. It will run out quick and believe me I'd buy it, but I've got 4 rolls stockpiled and not even an MF camera!

No need to miss it any longer.

5. Originally Posted by keithwms
What about making up your own colour separation images including a separation for IR by shooting a panchromatic/IR film with different filters? E.g. you could use r,g,b, and IR filters, shoot three or four separate frames, and then combine them as you wish to produce a colour neg or positive. It could be done in a purely analogue way. Since the IR films on the market are really edge-visible, I think I'd be tempted to shoot with g and b filters and use an IR filter for red + IR.
That is exactly what I was going to suggest. It is a PITA, but if you want to do it you can. It needs to be an IR film that also has full panchromatic sensitization, i.e. HIE would not work because it is not sensitive to the entire visible spectrum. For grain with a more intense IR effect, go with the Efke IR film, and for sharpness with less IR, go for the Rollei. It will require some testing to figure out how to expose through each filter to get the proper color balance, but you can do it. In a recent thread I posted the info from the data sheet about how the emulsions and their sensitivity are structured with EIR.

Of course, you are limited to static subjects with this method, and it is tons of work.

If you are into alternative options, you can figure out what to do on the computer by looking at the data sheet for EIR. It tells you what colors in reality are rendered as what colors on the film, and you can monkey around and do that on the computer. To talk about that option in depth, try DPUG.

6. I think it's a really cool idea. S. Frizza posted an example above in post #16 with this idea. It'd be really easy to do in a dye-transfer or other assembly method.

And I think that for landscapes it might be worth the effort to make 3 exposures. Neater yet, get a hold of a 'repeating back' from days of yore.

7. I just had a thought that it would be interesting to do the R-G-B separations on a very sharp and fine grained film, and to do the IR separation with the Aura film, and/or slightly out of focus.

As for the person who said this is not possible, it is actually how color photos were shot until color film was invented. And even after color film was invented and the capturing of images started to take place in one exposure, several photo printing processes relied on darkroom separation from the in-camera positive. It is also the way that litho printing, screen printing, etc. has been done and is still done to this day, though computers are used 99 percent of the time now to do the separations. I am sure you have heard the term CMYK. Well, that is the same thing Keith is talking about, basically.

You make a filtered shot for each primary color of light, onto black and white film. Then you print each of these in register onto the printing material. This is actually the most accurate and controllable way to make color prints, as one can control the density and contrast of each layer individually.

When going back to a positive, you can assign whatever color you want to each separation neg; it doesn't have to be C for the R-filtered shot, Y for the B-filtered shot, and M for the G-filtered shot. Not being so is how EIR worked the way it did. It was called a "false color" film because of this.

So, using a different process, one should be able to get close to the effect of EIR, using only black and white films. You just have to know exactly how EIR rendered false color in order to do it, so you can assign the "right wrong" color to each separation.

Another option for the OP would be to shoot one shot on transparency film, and one on IR film in camera. Then do the R-G-B separations from the transparency in the darkroom. Of course, you lose a lot of the contrast control through exposure and development that is available with b/w films. But your object does not have to be as still this way (only still enough for two exposure, not four), and the shooting routine doesn't involve as much monkeying around.

8. From individually taken separation negatives, you could even make a 4-color print using R, G, B and IR, which isn't feasible with integral film. One could make all kinds of different false color images.

9. Originally Posted by holmburgers
From individually taken separation negatives, you could even make a 4-color print using R, G, B and IR, which isn't feasible with integral film. One could make all kinds of different false color images.
That is the best for replicating EIR, I think. Though the film used blue sensitization on all of three layers, that could be taken care of with the additional B-filtered separation shot.

Shooting them is not the hardest part. Registration on printing is. And what printing process will be used? Gum bichromate? A whole other learning curve. RA4 paper with registered enlarged contact negs? It might be the most feasible, but would definitely take more than your standard contact printing frame. You'd have to build (or purchase) a registration punch and easel that is designed specifically for contact printing. Registering in-camera film to an easel with your standard enlarger and neg carrier is going to be a bear. Registration marks on the film lined up with marks on a registration easel, perhaps...but it is registration by eye/hand, which is bound to introduce lots of human error.

My question would be, what did you do with your EIR transparencies? Did you scan them to print them? If so, then staying 100 percent analog makes no difference anyhow. Just go the Photoshop route (on DPUG).

10. I've only got a handful of EIR transparencies, and so far I've only scanned them. In fact, I'm not even setup for color printing, but I'm making progress on a dye-transfer scheme.

A 2-hole punch can work for registration, and you can find pins at the hardware store to hold the pieces together, but it's much easier w/ large format negs. 35mm would be a bear indeed. Historically though, hand-eye registration has worked and worked well. I guess it's a question of how patient are you?

But projecting onto RA-4 would most certainly require a pin registered carrier or some ingenious scheme. I shudder at the thought...

The color transparencey plus b&w IR film is a good idea. That'd be really easy to manipulate in post.

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