A Fun, Funky Filter for Shooting Digital Infrared

Dave Powell replied:

Comment posted: 26/06/2025

Much appreciated, Thorsten! The camera is one of the greats of the CCD era!

Dave Powell replied:

Comment posted: 26/06/2025

Thanks so much Ben... glad you enjoyed it! Yes... 'chrome should come back!

Dave Powell replied:

Comment posted: 27/06/2025

Isn't it though?! Maybe the lack of color stems from the emulsion's design. According to my 1940s Kodak Reference Handbook, Kodachrome consisted of three superimposed (monochromatic) layers that were selectively and equally sensitized to red, green and blue light. Corresponding dyes were attracted to these layers during processing. The manual's color-sensitivity charts also indicate that the effective sensitivity curves for the three colors were identical. I've noticed that the CoolPix 990's R-G-B histograms for files shot through a regular R72 glass filter are usually spread out, with blue shifted to the left, green in the middle and red farther to the right (or sometimes with completely overlapping blue and green curves to the left of red). But the curve "mountains" for IRs shot through Kodachrome were usually identical and positioned right on top of each other. Which kind of supports Kodak's claim of equal sensitivity by design. Oh yes... and I too did not expect the emulsion's optical clarity! Thanks Tony!

Dave Powell replied:

Comment posted: 27/06/2025

Thanks Alexander! That shot and the second were where I first noticed the images' great tonal range. And I agree about the "look." It is quite "filmic" and a great surprise. Extraordinary results from an essentially "free" filter!

Dave Powell replied:

Comment posted: 27/06/2025

Thanks Dave! And you ask a most interesting question. I turned Google's AI crawler loose on it, and received the answer that the slide wouldn't have the same kind of "cutoff" values as glass filters like the R72. That's because Kodachrome's colors come from layers of pigment dyes added to the emulsion base during development. So the nature of the dye lots and thickness of their application could create varying cutoffs for different black slides. However, I did find an online estimate that the spectral sensitivity of Kodachrome 25 Daylight film (across all wavelengths) in normal use ranges from around 380 to 720nm. Theoretically, it looks like Kodachrome should block infrared bandwidths. But again, the bandwidths that make it through a black slide seem to be affected more by the thickness of the applied dyes than their inherent optical sensitivities.

Gary Smith replied:

Comment posted: 27/06/2025

I figured with all that math and physics, you'd have a better answer than that... :-)

Dave Powell replied:

Comment posted: 27/06/2025

I did have an additional thought though! The best explanation for the black slide's monochrome results may simply be that dyes of each color are applied evenly across its entire surface. Kodachrome was actually a multi-layer monochrome emulsion that was developed in color chemistry. But I didn't do so well in chemistry, and still don't have an explanation for why IR gets through... when the sensitivity charts I've seen suggest that it shouldn't! Perhaps it's an unanticipated effect of densely layering the three dyes... sort of like people who in the past have made UV-bandpass filters using colored markers on glass. I tried that too, but wasn't overly impressed with the results!

Dave Powell replied:

Comment posted: 27/06/2025

Thank you Ibraar! I'm working on an article now that will have some Marsden-style images in it. Or more precisely, "Edgy Marsden"! It suggests ways of "making" abstract photos that are beyond just "taking" them. It'll probably appear sometime this fall. I hadn't intended for the results to be Marsden-esque. But some turned out that way!

Ibraar Hussain replied:

Comment posted: 27/06/2025

Nice Nice!!!!!! Man I'm looking forward to em!! By the way I now have 4 Marsden's books. Bastard was a genius

Ibraar Hussain replied:

Comment posted: 27/06/2025

Got two rolls of the cloest I could get to IR film on a budget, Rollei retro 80s, with a red 25 filter it'll give an approximation minus the halation. and going to copy you!

Dave Powell replied:

Comment posted: 27/06/2025

Fascinating, my friend. Maybe another post there!

Ibraar Hussain replied:

Comment posted: 27/06/2025

Don't expect me to get anywhere near the magic you've made here man!

Dave Powell replied:

Comment posted: 27/06/2025

Aw... Thanks! But that film and filter can do amazing things! ;-)

Dave Powell replied:

Comment posted: 28/06/2025

Thanks so much Michael... I'm very glad you liked the images. And what you say makes so much sense! It's likely that Ektachrome would behave the same way, even though its slides were structured differently. With Kodachrome, colored dyes were added to the surface of the slide during processing, but they were built into the R-G-B layers of Ektachrome. One would think that the dyes would have needed to provide the same IR-pass-through to protect both types of slides. Thanks again!

Michael Flory replied:

Comment posted: 28/06/2025

You've inspired me to go back and try some more IR. I've played with several point-and-shoots and once led a class in removing the IR cut filter from them, but the best solution I found (short of an expensive SLR conversion) was a Sony DSC-F828, which had a "night mode" that moved the IR cut filter out of the way, and a neutral-density filter, as Sony had locked the camera at 1/30 sec, aperture wide-open, after it was discovered that women's polyester swimsuits were IR-transparent! I might have used an IR-bandpass filter to block the visible spectrum as well.

Dave Powell replied:

Comment posted: 28/06/2025

Great idea Michael! I used a DSC-F707 to take the photo that I Photoshopped into the "Autumn Emerging" image described HERE. If you haven't already, you may also want to try the famous "magnet hack" that temporarily moves the 828's hot mirror out of the way, and reportedly lets you shoot infrared at the camera's best-quality apertures and shutter speeds. My above-linked article contains a link to a 35mmc article about that hack. And another interesting article about it is HERE. Best of luck with your experiments!

Michael Flory replied:

Comment posted: 28/06/2025

What a wonderful picture! I just looked back through scores of digital IR photographs and I couldn't find any labeled "DSC-F828" so I guess I'll have to go through the EXIFs. What I did find was a lot of shots taken with a Coolpix 990! I just looked, it and the DSC-F828 are right there on the shelf, along with a Coolpix 995. I don't think I ever tried the magnet hack on the F828, though I remember hearing about it.... I might have tried it with a magnet that was too weak, but I have a couple of rare-earth magnets extracted from an old hard drive stuck to the fridge now. I emailed a very good friend a couple of IR shots that I took of the beautiful lake on which his house sits and he said "send more!" So I've spent the afternoon assembling ten color IR shots I took in 2013 intending to assemble them into a panorama, converted them from livid pink to sky blue (for the sky and the lake) and IR-white (for the trees), and finally patched them together into a 10400x1248 image. Now I just have to see if I can get the old Epson Stylus Photo 2200 to work with roll paper. I'm going to take one or another of the cameras with us next time we go to our friend's house. I'm thinking this all might even make a follow-up to your IR article. Now if I can only find the scans (or the slides) from the color infrared shots I took in the Everglades in 1970...

Dave Powell replied:

Comment posted: 28/06/2025

Glad you like it, Michael! You might even want to do an article about printing your huge panorama on roll paper! Even if readers don't own a 2200, the general experience and observations would be interesting. I too have a 2200 and roll-paper attachment, but haven't yet used the attachment. Have you tried to order ink for the 2200 recently? Once Epson quit selling and supporting it, the inks disappeared from Staples and most online camera vendors. I've had to buy ink "sets" on eBay to keep using the 2200. So sad... it's such a wonderful machine. I have two more 990-based articles in 35mmc's release queue for July. And you might also enjoy THIS earlier article shot in Paris. The 990's "native" IR colors are so special, when compared with other cameras!

Michael Flory replied:

Comment posted: 28/06/2025

I just saw your post from a week ago. I'm glad to hear you've been able to get some ink for the 2200. I'll have to try. I've just been using up a stash of 2200 ink I put aside when I realized they would doubtless drop it soon. But I may have to shell out for a new printer anyway. Three of the four 2200s I had just were beyond my ability to declog and persuade to feed paper. I think the last one will be OK with some more yellow ink and maybe I can get that roll printer attached to it. The Paris series is just gorgeous. I see it has that truly wonderful shot of Notre Dame. I've never thought to do IR there, though I've taken a lot of photographs over the years. Our corner of Brooklyn doesn't compare with Paris but I did get out with the DSC-F828 today. Now I just have to find the Memory Stick adapter.

Dave Powell replied:

Comment posted: 28/06/2025

Yes Michael, I too may have to spring for a newer model when my 2200 inks run out. And I'm so happy you liked the Paris series! The Notre Dame shot might even be "historic" now!