Filter to make IR Flash

Mike Wilde · Oct 4, 2010

holmburgers said:
Yes, I'm quoting myself.....

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!

Heylloyd's web site discusses this idea for making red safelights sucessfully.

The key is to find a theatrical distributor. I am fortunate Rosco has a dsitribution agent (actually one of their own reps) here in the GTA. Things might be a bit harder to find at your end.

I wish I had the time to try this out, because I have about 250 M2/M3 bulbs in stock, and a pal looking to unload about 30 rolls of Ilford SFX in 120.

holmburgers · Oct 4, 2010

Mike, thanks for the heads up. I can't seem to find anything about safelights on that website however. Got a link?

edit: found some stuff via the "googles" ... durrr

further edit: Ok, Rosco got back to me w/ a bunch of worthlessness and apprently they don't have any transmission data on their colorine product as it's meant for "entertainment". Indeed, this Hey Lloyd guy is a big proponent of making your own safelight bulbs this way. I found a few older forum posts where he talks about it. He claims that transmittance is free past 650nm but I don't know what he's basing this off of.

Testing is the only option at this point, it appears.

holmburgers · Oct 5, 2010

:wizard:

"...At the suggestion of A. Barrett, the Kodak Research Laboratories in England worked out a formula for an infrared-transmitting lacquer which could be applied to flash bulbs for candid photography and for photography in blackouts when regulations forbade the use of visible flashes. The formula was published in 1940 by Morris and Spencer."

Morris, R B, and Spencer, D A, "Dazzle-Free Photoflash Photography", Brit. J. Photo., 1940, 87, 288-289

If anyone has easy access to this article, please post it. In the meantime, it's on my library list.

ntenny · Oct 5, 2010

Mike Wilde said:
The key is to find a theatrical distributor. I am fortunate Rosco has a dsitribution agent (actually one of their own reps) here in the GTA. Things might be a bit harder to find at your end.

It looks like mainstage.com, the site I got my gels from, sells colorine. I've only had the one transaction with them but it was unobjectionable, for what that's worth.

-NT

mhcfires · Oct 5, 2010

holmburgers said:
:wizard:

"...At the suggestion of A. Barrett, the Kodak Research Laboratories in England worked out a formula for an infrared-transmitting lacquer which could be applied to flash bulbs for candid photography and for photography in blackouts when regulations forbade the use of visible flashes. The formula was published in 1940 by Morris and Spencer."

Morris, R B, and Spencer, D A, "Dazzle-Free Photoflash Photography", Brit. J. Photo., 1940, 87, 288-289

If anyone has easy access to this article, please post it. In the meantime, it's on my library list.

My son is a research librarian, I'll ask him if he can locate the book.

m

sun of sand · Oct 6, 2010

i bookmarked a site with an IR coating recipe so its out there
where it is in my bookmarks is anyones guess

id do a search on IR coating

holmburgers · Oct 6, 2010

Hey y'all,

I was able to find the above mentioned article. And I had to break out the micro-film at the library no less! What a trip that was..

Given in the article are complete instructions for making several types of lacquers. Of note is the one for infrared transmittance only, which emits no visible light. But perhaps more intriguing is another dyed lacquer that appears deep purple and is meant to be used with for normal panchromatic films.

The impetus for concocting these lacquers is to avoid "dazzling" your subjects; that is to say blinding the hell out of them with a huge flash bulb!

Basically, they say that we are most sensitive to green & yellow, and that this region of the spectrum accounts for most of the "flash blindness" that occurs with bright flashes in dark surroundings. By utilizing a deep purple filter, you're shooting by the red & blue light only; in a region of the spectrum that is much less irritating and noticeable to your subjects.

So, regardless of whether we're dipping flash bulbs or putting filters over electronic flashes, using a violet filter might be a simpler solution than going to such lengths for pure, invisible IR flash. (not that it's not worth pursuing in itself)

I'll try to scan and post the article to my galleries at some point. PM me if you're interested.

2F/2F · Oct 6, 2010

I am interested. I have a plethora of big-ass flashbulbs that would be perfect for coating, as they are so powerful that they will make up for a lot of the light loss.

It seems that there would have been over-the-reflector IR filters as well in the days of IR flashbulbs. There were certainly over-the-reflector blue filters and clear protectors (the latter used in case of the flashbulb shattering), so an IR one would not have been much of a stretch. An IR line placed on any focusing scale adjacent to the line for visible light would allow one to adjust focus relatively quickly. (I am thinking Technika or Speed Graphic.)

holmburgers · Oct 6, 2010

Funny you should say that... actually, another application they mentioned was dyeing the cellophane safety bags (designed to capture shattered bulbs). You dye one bag with the purple-panchro dye and then you dye another bag with yellow; put the yellow over the violet and you get the IR only filter.

holmburgers · Oct 6, 2010

(there was a url link here which no longer exists)

greybeard · Oct 6, 2010

An interesting thread.

In the 1960s, military-surplus IR filters from "snooperscopes" were available quite cheaply, and it was something of a fad to put one over the reflector of a Graflex Stroboflash or a Speed Graphic bulb flashgun. This was for nature photography, Weegee-style theater photography, and for the embarrassment of teenagers in parked cars. The lore at that time was that you could see the flash only if you were looking directly at it when it fired; how this translates to the spectral sensitivity of modern IR films is a good question.

The filters (I actually have a couple somewhere, although I've never tried the IR photography with them) are about five inches in diameter, with a rubber grommet rim a quarter of an inch or so wide. They are molded, not ground and polished, and went over an incandescent-bulb lamp for night combat.

nworth · Oct 6, 2010

If you look hard, you can find the equivalent of 87 and 89 filters in large sheets. 87 filters used to be available in 5-1/4 inch round safelight filter form, and there may still be some hiding somewhere. These filters can be used over a light source to make photographs in the dark (or nearly dark for the 89). I also came across this formula for coating flashbulbs. It is more or less an 89 filter. It could be coated on glass or plastic to be placed over a light source.

Recipe for Coating Flash Bulbs with Infrared Paint
From a 1970 photo-lab-index, "Blackout Coating for flashbulbs".

Eosin 2524 60 grains 4.0 grams
Tartrazine N. 250 88 grains 6.0 grams
Coomassie Violet RS 60 grains 4.0 grams
Lissamine Green 146 grains 10.0 grams
Gelatin (hard) 6+3/4 ounces 200.0 grams
Glycerin 3+1/4 fl. Oz 100.0 cc
Add cold water to make 32 ounces 1.0 litre

"The gelatin is first soaked in half the quantity of water for one hour, then warmed to 120 degrees F (49C) and stirred until dispersed. The dyes are dissolved separately in small quantities of water at not above 150 degrees F (65C). Each dye is mixed with a small quantity of the gelatin solution to prevent precipitation when they are later mixed. The glycerin is diluted with another small portion of water, then all ingredients are mixed and brought to the final volume with water at 120 degrees F (49C).

"If necessary the mixture is filtered through two layers of muslin to remove air bubbles, then cooled to 96 degrees F (36C). At this temperature the flashbulbs are dipped in the mixture until completely covered. On removal from the solution they are drained for a few seconds, then inverted and the remaining solution is permitted to spread back over the surface rather than draining. They should appear almost black and it should be impossible to see within the bulb. Drying takes about 24 hours. These bulbs may then be used with any regular infrared film for photography in complete darkness.

"The formula above is a British formula and the dye materials mentioned are of British manufacture... American dyes are...

Then it lists different companies with some equivalent products. I'm a couple blocks from Aldrich Chemical Co. and they carried all the materials. Based on quantities that were available it would cost about $100. I wonder if there is somewhere to buy the dyes at lesser purities. Anyway here are some equivalent dyes that are listed then in the book: Tartrazine N. 250 = Tartrazine Conc. or Wool Yellow X Conc.; Coomassie Violet RS = Pontacyl Violet 4BL, Conc. 125 percent or Formyl Violet S4B or Wool Violet 4BN; and Lissamine Green = Pontacyl Green SN Extra or Wool Green S. All the "wool" colors were supplied by National Aniline Corp in NY. I kept the capitalization and abbreviation the same as the text pretty much, so thats all the clues you get. Are there any chemists in the crowd?
Well, glycerin and gelatin are common, cheap and safe enough. I wouldn't think that dyes would be that expensive, but the ones from chemical supply houses are very pure and somewhat expensive. Maybe a mixture of common clothing dyes would work... or maybe one part lime jello, one part grape jello and...
If you try out this recipe please let me know how you get on.

Ref: Last Updated: Tuesday, September 28, 1999
(http://www.cocam.co.uk/CoCamWS/Infrared/IRpaint.htm)

2F/2F · Oct 6, 2010

Thanks. Just giving it a quick glance, it seems like the same formula that holmburgers posted in his other thread. I have a '61 Photo-Lab Index. I will look. It probably has the same formula.

holmburgers · Oct 7, 2010

Ok, I've done a little bit of checking for the availability of these products. Here's what I've found thus far:

Eosin - Used in histological staining; two types Eosin Y & B.
Dead Link Removed
http://secure.sciencecompany.com/Eosin-Y-Stain-15ml-P6366C669.aspx

These are both 1% solutions of Eosin Y. Know idea is that's what we need or not.

Tartrazine - A.K.A. Yellow 5... think Mountain Dew!
Dead Link Removed

Coomassie Violet - Not looking good...
http://www.sigmaaldrich.com/catalog...7|FLUKA&N5=SEARCH_CONCAT_PNO|BRAND_KEY&F=SPEC
http://en.academic.ru/dic.nsf/enwiki/441852 (good information, absorptions, etc.)

Lissamine Green - A tad expensive it appears.
http://www.artchemicals.com/SearchResults.asp?Search=lissamine
http://en.wikipedia.org/wiki/Light_Green_SF_yellowish (alternative names)

Ok, that's all for now.

2F/2F · Oct 7, 2010

Looks like over-the-reflector filtration is a better option.

holmburgers · Oct 7, 2010

I wonder if methyl violet couldn't just be substituted for coomassie violet, as it appears to be easily available. Why would the cellophane covers (see (there was a url link here which no longer exists)) not require the Lissamine green, eosin or Coomassie violet dyes?

Of course, I have no idea of the chemistry involved.

ntenny · Oct 8, 2010

Well, I got some of the Rollei film and ran a smoke-test roll this evening. The good news is that, as others have found, it works; but I'm still losing a *lot* of speed to that filter. The flash has a guide number of 148 (feet) at ASA 100; with the Rollei film, and a filter on the flash consisting of two layers of Congo Blue gel and one layer of Primary Red, I find that the equivalent guide number seems to be about 16!

The attachment is the best shot from the roll: four feet away at f/4. This is a neg scan, so it's fairly forgiving of the thin negative, but you can see every little fleck of dust as a result. I'd say this negative might be printable with some effort; most of the rest are probably impossible to print conventionally.

Research continues! I'm wondering now if I can drop one of the layers of blue filtration, and how much difference it will make if I do.

-NT

mhcfires · Oct 8, 2010

You might try and find some 5R flash bulbs. I used them with much success about 45 years ago. If I remember correctly, they worked pretty well.

m

Sjixxxy · Oct 8, 2010

ntenny said:
The flash has a guide number of 148 (feet) at ASA 100; with the Rollei film, and a filter on the flash consisting of two layers of Congo Blue gel and one layer of Primary Red, I find that the equivalent guide number seems to be about 16!

Sounds like you are getting a lot less light then with an SFX Filter. I've been using a flash with a GN of 60 at ASA 100. Four feet at f/4 tends to give me negatives where the subject is of a nice density on the film.

holmburgers · Oct 28, 2010

Just wanted to follow up on this and see if anyone had thought about trying a purple filter instead of an IR one. The idea is that the human is disproportionately sensitive to yellow/green, whereas typical panchromatic film is more evenly distributed.

Check this out... http://upload.wikimedia.org/wikipedia/commons/e/e9/Eyesensitivity.png

A purple filter would avoid that whole peak area; so the effect is that you aren't blinding your subjects but you're getting a healthy does of photographic light.

So unless you're looking for (a) the IR look, or (b) complete stealth, the purple could be an ideal solution for not annoying your subjects. And remember, Halloween is coming!

ntenny · Oct 28, 2010

I haven't had time lately to pursue this project further, but after looking at some filter spectra I ended up thinking that it might work better to use a Rose Indigo filter than Congo Blue; the former passes low-IR to high-red at a much higher level, and while the resulting flash would probably be more visible to the eye, it looks like it should be a LOT more visible to the film. When I find a local theatrical-supply company and some spare time, I'll try out that version.

Or does someone have a few spare SFX gels to sell me?

-NT

mhcfires · Oct 28, 2010

ntenny said:
I haven't had time lately to pursue this project further, but after looking at some filter spectra I ended up thinking that it might work better to use a Rose Indigo filter than Congo Blue; the former passes low-IR to high-red at a much higher level, and while the resulting flash would probably be more visible to the eye, it looks like it should be a LOT more visible to the film. When I find a local theatrical-supply company and some spare time, I'll try out that version.

Or does someone have a few spare SFX gels to sell me?

-NT

You should try and find some 5R flash bulbs. I remember using them in the early 1960's to take pictures at parties when using IR film. It worked pretty well, no one realized they were being photographed.

holmburgers · Oct 28, 2010

They are few and far between and quite expensive unfortunately. The few I've seen for sale are like $50 for a pack of 6 or whatever. You might be able to get lucky on eBay someday but it's not sustainable solution. However, you can always make your own.... (dazzle-free flash photography - articles section)

ntenny · Oct 28, 2010

holmburgers said:
They are few and far between and quite expensive unfortunately. The few I've seen for sale are like $50 for a pack of 6 or whatever. You might be able to get lucky on eBay someday but it's not sustainable solution. However, you can always make your own.... (dazzle-free flash photography - articles section)

I couldn't read all the scanned text, but I didn't see any statement of what wavelength the coating starts to pass at---I'm afraid it might work with HIE but not with anything currently available. (Leaving aside the question of getting the dyes.) Same concern about #5R flash bulbs---do we know that they put out enough low-IR for current films?

Layering theatrical gels is easy as pie and the spectra are available, so I'm pursuing that route for now, although I applaud you and the other intrepid people working on coatings.

-NT

holmburgers · Oct 28, 2010

I can email you the texts if you'd like. No transmissions are stated in the paper, IIRC, and you raise a good point about modern IR films vs. the old ones. I believe that you could tweak the dye content though to compensate. I'd love to find a source with good, hard data about dyes and their transmission values.

I'll see what I can dig up about ye old IR films.

******************************
update (wow the internet is amazing...)

Ok, this is from 1951:

"The fast infra-red plates have been improved slightly and the I-Q plate with maximum sensitivity between the M and the Z has been reinstated. Of particular interest among the infra-red plates is the 103-U which as high sensitivity between 7000 and 7500A where there is a gap in the emission of the night sky.
Eastman Kodak Co., Rochester, N. Y. "
Astronomical Journal, Vol. 56

'A' means angstroms (å), and 7500 angstroms is equal to 750 nanometers. Therefore, it appears that the old IR emulsions weren't particularly spectacular; on par with current available films.

Filter to make IR Flash

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