I'm in the process of building a bunch of 5X7 pinhole cameras, and I'd like to outfit them with red 25 (or better, red 29) filters. Is there some brand of polyester filter that I can cut into pieces for this purpose? Searched around a little, but it seems like everything comes in kits. And I looked at rubylith, but optically it won't work.

Additionally, will it matter if the filter is installed inside the camera, instead of in front of the pinhole, or does it matter?

Thanks up front for any advice here.

g'day Rich

as far as i know it shouldn't matter, filtering wise, where the filter is placed in the light path

why not just mount a filter inside the camera, either permanently or temporarily

Ray

Well, I have red 25s on all my other cameras, so I'm just thinking of building a little slot on the inside of the cameras to drop them in. But then I couldn't have them on the 4X5's at the same time. That's why I'm wondering about about some mylar or acetate that I can cut up and permanently install inside the box. I just don't know what will give me a 25 or 29 red and be optically acceptable.

Rosco makes a couple of red filters, 90 Red (Rosco #4690) and, Storano Red (Rosco #2001) that might work, the Storano red is a deep red and very similar to the safety filter under my enlarger lens. There is also a 60 Red (Rosco #4660) that is a stop lighter than the 90 which may or may not work ... it looks a tad orange. I know b&h sells smaller squares for a reasonable amount.

(and if you contact rosco directly they'll send you a sampler for free)

You could try Lee polyester filters, they come in 4x4 and I think 3x3. I know B&H carries them, and IIRC Calumet carries them branded under their own name. They come in pretty much all standard colors, I'm sure you could get a 25, and I'd be very surprised if you couldn't find a 29.

Peter

Thanks for those refs, pretty much what I'm looking for. I figure 2cm squares would be enough for each box, so just one 4X4 would do it.

A word of caution.....the filter must be SPOTLESS. I put one behind my pinhole and it picked up even the smallest piece of dust and lint, talk about crappy looking negatives. Now I hold it in front and the shake of my 54 year old hands, especially at 0f eliminates the problem.