Filter to make IR Flash

I'm intersted in trying infrared flash photography. I want to use my Olympus XA2 or XA4 and A16 flash, and go out shooting in public at night. What sort of filter can I put over the flash? I read a blog post recently that suggested that I can use an Ilford SFX A filter. They were cheap, but Amazon has long since sold out of them, and I can't find them elsewhere.

So I'm looking for some other inexpensive alternatives -- improvised ones if necessary. What kind of filter can I put over the flash? For lack of anything better, someone suggested that black trash bag material would work and even black electrical tape. Will it really?

Thanks...

I'm looking into the same thing. So far I've found that Freestyle has gel filters equivalent to Wratten 87 and 87c for quite reasonable prices (US$26.99 for 4x4 inches). A gel 89b is available from Kodak (B&H has them, for instance) but it's expensive, north of US$60 for 3x3 and US$100 for 4x4.

I can't figure out whether the SFX filter is equivalent to 89b or not.

-NT

Very simple solution. You need to tape a polyester Wratten or Lee Infrared filter over your strobes lens.

3 inch: http://www.bhphotovideo.com/c/product/292664-REG/LEE_Filters_87CP3_3_x_3_Infrared.html

4 inch: http://www.bhphotovideo.com/c/product/102760-REG/LEE_Filters_87P_4x4_Infra_Red_87.html

Your Infrared film should see the IR strobe, but make sure you do testes before an important shoots.

Not to follow up to myself, but I did a little more poking around and found this promising article:
http://amasci.com/amateur/irgoggl.html

The author apparently has combined multiple layers of "Congo Blue" and "Primary Red" visible-light filters to get something that's visually opaque but passes IR from about 720 nm---basically the equivalent of an 89b. I'm going to have to try this.

-NT

I am afraid that if you filtered the little flash on an XA, you'd have almost no light hitting your subject. I would suggest something that has more power.

I think that you are about 40 years too late with this idea. Just get out your Speed Graphic and your Graflite and use some GE #5R flashbulbs with your infrared film.

Yes, the flash must have IR output at an amount useful to you. After all, most flash units were designed to have maximum output in the visible range.

There is some IR output from standard flash units. You can feel the heat on some. If you cannot feel heat when you test flash your strobe, then there is probably little or no IR output.

PE

2F/2F said:

I am afraid that if you filtered the little flash on an XA, you'd have almost no light hitting your subject. I would suggest something that has more power.

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It's been done successfully before:
http://www.kpraslowicz.com/2009/11/29/infrared-flash-photography-with-an-olympus-xa2/

I do intend to try it with a higher-output flash, though.

-NT

you can use blank (developed but unexposed) E6 film. 35mm if you have a small flash, or 120 if your flash is larger. Just take and attach two strips of either to the front of your flash and there you go IR filter. IDK about the actual spectral emission of using E6, but it has always worked good for a buddy of mine.

I think using a flash with IR would be a waste of good IR film. Unless you want specific skin tones I see no reason to do this. Also at night you won't get the full IR 'effect' because there is no sunlight. You would be better off using an ordinary bw film, and saving the IR for daylight subjects. (IMO).

ntenny said:

It's been done successfully before:
http://www.kpraslowicz.com/2009/11/29/infrared-flash-photography-with-an-olympus-xa2/

I do intend to try it with a higher-output flash, though.

-NT

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I am not really sure that he is getting much of an IR effect in those shots. Some black eyes and a little bit of glowing skin is all I see. There appears to be plenty of visible light exposing his film, as well as the IR and near IR.

Also, read how close he has to be to his subjects to make the little flash work.

Also, focus shift for different wavelengths definitely is an issue with both Ekfe and Rollei IR films, despite what he sez. Check out this link: http://www.digitaltruth.com/products/product_tests/infrared_film_007.php.

2F/2F said:

I am not really sure that he is getting much of an IR effect in those shots. Some black eyes and a little bit of glowing skin is all I see. There appears to be plenty of visible light exposing his film, as well as the IR and near IR.

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Hmm, they look to me fairly similar to what Weegee got with IR flash---no obvious screaming IR effects, but a little bit of the "zombie eyes" look. But it's not clear to me what circumstances he's shooting in---my plan is to do some controlled experiments in really dark circumstances and try to get a good understanding of what's going on.

Also, focus shift for different wavelengths definitely is an issue with both Ekfe and Rollei IR films, despite what he sez.

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I don't think he disputes it, it's just that he's shooting with a scale-focus camera and relying on DOF to cover for focussing errors and shifts. I've done the same thing and gotten away with it.

Also, shouldn't the focus shift depend more on the filter than the film?

-NT

2F/2F said:

I am not really sure that he is getting much of an IR effect in those shots. Some black eyes and a little bit of glowing skin is all I see.

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The goal with my infrared experimenting wasn't about the Infrared Effect, but instead, to be able to shoot in situations where the unsuspecting subjects' pupils will be wide open without ruining their ability to see all night by blinding them with a full power flash. Trust me here, the SFX A covered flash is very, very, very, very, very, very dim compared to an unfiltered flash. Unless the subject is looking directly at my my camera, they are clueless. And ifthey are looking directly at it, they don't see a big blue spot for the rest of the night.

Without Kodak HIE film available, I found that using 87 filter with SFX or Rollei IR film just doesn't work. For SFX and Rollei film you need a 72 filter. All my experimenting with the 87 ended in failure. Before I found some SFX-A filters to use, my original plan of action was to get some of the cheap Chinese 72 filters off eBay and grind them down to fit over my flash.

ntenny said:

I don't think he disputes it, it's just that he's shooting with a scale-focus camera and relying on DOF to cover for focussing errors and shifts. I've done the same thing and gotten away with it.

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Exactly. I've been using this IR method for a little over a year now and focus shift included, just about all of what I shoot is acceptably sharp for my needs.

Some are really on.

And some are a little off.

But here here is the deal. The ones which are a little off are still acceptable to me. I scale focus when I shoot with non IR film, and I scale focus with it. Both yield results that work. If you require absolute & perfect sharpness, then this style of shooting probably isn't right for you.

I love it though and can't wait for Halloween--best damn IR shooting day of the year.

ps: A larger collection of images I've made over the past year using this methodology can be found here.

Kip, someone on your blog suggested covering the flash with black garbage bag material. I'm curious to hear more about this or any other DIY solution from household or easily attainable materials.

Like you, I'm interested in nighttime flash photography without blinding my subjects more than any classic infrared effect.

bvy said:

Kip, someone on your blog suggested covering the flash with black garbage bag material. I'm curious to hear more about this or any other DIY solution from household or easily attainable materials.

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I haven't tried any DIY methods aside from the exposed E6 film. That didn't work well with the near-IR films that are easy to get. I just bought a bunch of of the SFX-A filters while they were available so I wouldn't run out anytime soon.

I think the guy on my website used the trashbag to simulate an 87 filter, which probably won't get you very far unless you can track down some HIE film. I tried an 87 with the Efke Infrared film and it just wasn't fast enough to get results with a small strobe.

Kip, glad you came along. I don't know why it didn't occur to me to think that the guy who did the IR-flash experiments would be on APUG...

Sjixxxy said:

I think the guy on my website used the trashbag to simulate an 87 filter, which probably won't get you very far unless you can track down some HIE film. I tried an 87 with the Efke Infrared film and it just wasn't fast enough to get results with a small strobe.

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I've been looking into the filter options. Ilford indicate (in the data sheet for the SFX 200 film) that the SFX filter is similar to an 89B / R72, but it's not clear if they really mean "equivalent" (cutoff at 680 nm, 50% transmission at 720 nm). But it sounds at least plausible than the (expensive) 89B gel would work.

Interestingly, Dead Link Removed says that the combination of two Wratten primary-colour filters will make a working IR-pass filter, transmitting "relatively freely" from somewhere around 700 nm. That sounds promising to me, and the Lee primary-colour polyester filters aren't expensive---I'll probably try this combination first.

-NT

ntenny said:

Interestingly, Dead Link Removed says that the combination of two Wratten primary-colour filters will make a working IR-pass filter, transmitting "relatively freely" from somewhere around 700 nm. That sounds promising to me, and the Lee primary-colour polyester filters aren't expensive---I'll probably try this combination first.

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Definitely let me know how that works out for you. I get e=mails from time to time asking for alternatives to the SFX-A, would love be be able to actually provide one to those people.

blade_o said:

you can use blank (developed but unexposed) E6 film.

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I have used this method for several different and unmentionable things.

The mention of IR flashbulbs got me thinking and I found this comment over at RFF (http://www.rangefinderforum.com/forums/archive/index.php/t-35227.html)

"Weegee often used infrared bulbs, like for such things as taking photos of couples carrying on in theaters and such. From what I heard he made these by dipping ordinary flash bulbs in some kind of very deep red (infrared) dye. From what I remember from a thread on another system, these did emit a visible, but not obviously bright, deep red flash."

Some flashbulb guns are very tiny. Not like the typical "40's press photographer" look; the Honeywell Tilt-a-Mite, among others, is the same size or smaller than most modern, hi-end strobes.

Anyways, something to think about.... you'd have a lot of range with this method.

Well, I have some preliminary, albeit negative, results to report.

I got hold of a Nissin 4500 GTE flash (a pretty convincing flash: its guide number in feet is 148, and if you fire it at an unsuspecting person, it takes them quite a long time to recover themselves and beat you up) and made an IR filter for it out of Primary Red and Congo Blue theatrical gels. (They're really cheap; I think it cost me US$8 for each 20x24" sheet.)

Two layers of blue and one of red produces a filter that on paper should start transmitting fairly freely above circa 700 nm, and that to the eye looks indistinguishable from an 89B. The flash at full power, through this filter, is quite noticeable but not disturbing; you'd never overlook it, especially in a dark room, but it doesn't leave an afterimage or create a visible floodlighting effect. Adding a third layer of blue produces something a bit darker to the eye and reduces the flash visibility quite a bit.

I shot a roll of Efke IR 820 with a mixture of frames assuming guide numbers of 40, 28, and 20 (five feet from the subject, at f/8, f/5.6, f/4, which is the limit of the lens I was using---well, it goes to 3.5, but the difference seemed unlikely to be significant). I had pretty high hopes, but unfortunately the roll developed clear, so I'm going to assume that either the film was too far past date (dated February 2009, but kept refrigerated; its contemporaries have been fine) or the film just isn't sensitive enough even for this rather potent flash.

I'll try the Rollei IR400 film next. At some point I might try the Efke film again, leaving the shutter open in a dark room and firing the flash multiple times to see if I can get anything to come out at all.

-NT

Thanks for the follow up. Sorry it didn't go well, but I'm very curious to hear about your results with the Rollei film. Please continue to keep us posted!

Yes. Use the Rollei film. My results with Efke was just as tragic.

Kip, did you work out the approximate effect of the filter on guide number?

-NT

holmburgers said:

The mention of IR flashbulbs got me thinking.... by dipping ordinary flash bulbs in some kind of very deep red (infrared) dye...

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Yes, I'm quoting myself.....

And although no one jumped at my flash-bulb idea, I figured I'd continue the research and include it here just for reference. So incase you guys get the itch, the info will be here.

Anyways, I discovered this product by Rosco designed specifically for dipping bulbs for scenic applications. http://www.rosco.com/us/scenic/colorine.cfm

Using the same idea as mixing a red & blue gel, you could mix red & blue 'colorine' and presumably get a visibly opaque coating, that would hopefully have some IR transmittance.

I've emailed them once, and they pointed me towards some strobist kit... *ahem* ... no thanks I said flash bulbs lady!



Anyways, I'm hoping she'll be able to give me a tech pub or something with the characteristic curves. But from a design standpoint, you'd want these bulbs to transmit as much IR as possible to cut down on overheating. So there's hope yet.