Help exposing Infrared b/w film, please.

[PHOTOTONE]

OK, this is a follow up post to my post stating that I received the free trials of the new Maco Infrared film.

I have never exposed infrared film, but I just ordered a "black" filter from B&H.

How does one determine exposure?

Any special filmholder loading advice or use of 4x5 advice? I am well skilled in using large-format cameras and materials in general, just not infrared.

 

[PHOTOTONE]

As an additional comment to my post above, I will probably be using my Graflex Super Graphic camera with an assortment of leaf-shutter lenses that I normally use for my other personal location photos. I doubt the type of camera makes a difference, but I thought I would add this info, just in case.

 

[Ryuji]

There is no good, systematic way to expose infrared film. Most, if not all, photographers rely on experience and hunch in determining exposures, and most are happy with the results. When beginning, it's a crapshoot; best to start with 35mm or 120 size before getting to 4x5.

I have had a plan to make an IR-specifc light meter, which could be used to get a dead-on exposure every single time, once film and meter are matched. However, this project is currently not moving forward. I'd be happy to share the idea with other people, or I would be happy to accept donation of necessary materials to see the feasibility...

 

[PHOTOTONE]

yes, well I got this free sample and it is just 4x5..so I don't have any format choices..I either test this, or don't at all.

 

[Ryuji]

Yeah it's a rather tricky situation. I wish they made Polaroid Type 55 Infrared, so that you can burn a few sheets in the field. A modified version of Sunny f/16 works when sun is up high and there is no cloud covering the sun. I like Konica IR 750 at 1/8 second, and Kodak HIE at 1/60 second, both at f/16. Maco, I do not know... Unfortunately. Maybe you can open the film all way, make one 1/60 exposure, close half way and make another exposure at 1/15, and guess from there.

Either that, or cut a sheet into small pieces in total darkness and test using MF or 35mm cameras. MF cameras with 6x9cm sheet film back are useful for this.

You know, modern people are obsessed with Zone system, spot meter, sensitometry and exact contrast control and what not, but with multicontrast paper and now a good film-oriented flatbed scanner like Epson Perfection V700/750, you don't need to worry too much about being a stop off...

 

[Ian Grant]

Go look on the internet, I guess its the new EFKE film so data will be available.

There was a excellent article about the film in B&W magazine recently, I rarely change films but when I tried Kodak's IR film it behaved exactly as the reviews & tests.

Ian

yes, well I got this free sample and it is just 4x5..so I don't have any format choices..I either test this, or don't at all.

 

[PHOTOTONE]

Go look on the internet, I guess its the new EFKE film so data will be available.

Ian

In the cover letter I got with the free sample they state positively that it is NOT the new EFKE film, rather they state that it is made for them by Agfa/Gevaert in Belgium. So info on the Efke film would not be suitable.

I was just asking for help in exposing IR film in general, as I have never done it before, although I have plenty of experience with large format.

 

[Murray@uptowngallery]

http://www.pauck.de/marco/photo/infrared/comparison_of_films/comparison_of_films.html

http://www.a1.nl/phomepag/markerink/irfilter.htm

Try and figure out what filter you REALLY have. See above links.

Remember IR focus shift (remember seeing a red line on some SLR lenses?).

Someone else told me he stops down considerably when he adds a slight focus offset. (compensatory gamble).

If you sample is one sheet, I guess you can research first.

If your IR stock is too precious, and you have a non-plastic 120 camera, you could try a roll of the 120 IR stuff first.

 

[winger]

I've only used HIE and with a red #25, so I don't know if that will apply at all to this film. I've used different methods of guessing the exposure, but it's still a crapshoot. When it's sunny (noon in New England), setting the iso at 200 and the aperture at f16 has given me decent results. I think the shutter speeds were from 1/15 to 1/125 then. The Laurie White book on infrared (I think it's the Infrared Photography Handbook) has some good practical info, if you can find that. One suggestion she has (assuming HIE and a red #25) is to shoot at 1/125 at f16. If you can correlate that to your film and speed, then you've got a starting point at least. With 4x5, you don't have to shoot all of it at once, so you can figure out a little faster what's working. With 35mm, it's 36 shots unless you respool the film.

 

[colrehogan]

Which black filter did you order from B&H? You have to keep in mind that some filters may be too dark for the film, i.e. they might not transmit light in the film's usable wavelength range.

With the Maco 820c IR, I found that 1/2 sec. at f/16 (or 1 s @ f/22) gave nice results with either an 88A or an 87 filter on a sunny day (with my back to the sun).

 

[htmlguru4242]

Exposure with B&W infrared is tricky, and requires alot of fiddling and experimentation to get right on any consistent basis. Two or three years ago when I was experimenting with it, I brought along a second camera, photographed the scene in IR and visible light, and logged the light conditions and exposures in a notebook. This gave me something to compare it to, and helped alot. Other than t hat and just tweaking around with it, there's really no sure-fire exposure method. I do remember that in bright sun, Konica IR was about 1/30 second at f/5.6.

I'd second the idea to cut up a piece of the 4"x5" sheet and put it in an MF or 35mm camera.

Ryuji, I like the IR exposure meter idea. I think I'm going to grab some stuff and fiddle with that this summer!

 

[Ryuji]

Ryuji, I like the IR exposure meter idea. I think I'm going to grab some stuff and fiddle with that this summer!

Pick a cheap meter that uses a silicone photo diode, not CdS or GaAs or silicone PIN photodiode. Naked silicone photodiodes have sensitivity peaks in the IR region and the sensitivity (when looked by energy) goes down as the wavelength goes down, because the number of photons per unit energy goes down, and the diode converts photon for electron basis. The efficiency of conversion also gets worse as the wavelength goes down, because of the excess energy more likely to get the photon wasted due to a mechanism called "recombination." This may not be intuitive for people who didn't study solid state physics but it's a sort of reciprocity failure-like mechanism.

Anyway, silicone photodiode meters ALWAYS have to have a blue filter in front of the photodiode, or the filter is built into the sensor component.

What needs to be done is to remove the blue filter, and place an IR filter. Ilford used to make (do they still? I'm not sure) IR filters in sheets. Get that and cut a small piece out of the corner.

The rest is calibration of the meter sensitivity to the film sensitivity.

It would be so awesome to be able to measure IR exposure in both incident and reflection modes!!!

 

[Helen B]

There are a few threads on converting exposure meters over on photo.net. Here is one recent thread and another.

Best,
Helen

 

[Murray@uptowngallery]

There is a guy selling 'German glass filters', not real well specified, but single-spec choices of '760 nm', '850 nm' and '950 nm, reasonably priced on eBay as Y2KREX.

I chose the 760 as my best guess closest thing to an 87, in 49 mm (front & rear threads) for $9.99 + 3.00 ship.

Sadly, they seem to be marketed to doofusses who put them on camcorders for nerdish voyeurism. Seller communication via eBay is non-existent, but sales rating is excellent. He may not understand all the technical questions I asked about them, or he doesn't bother to read the eBay messages.

Anyway, I got it in reasonable time, in a hard case, with foam case liners stamped with size and wavelength. The filters themselves are unmarked and you have to specify what cutoff you want or you get a random one. I did not get an answer whether the cutoff wavelength is 50% transmission or 0%. I assume 50% and am told by someone else that with IR filters, the attenuation dropoff is pretty steep (but is that log or linear?).

The 760 nm filter (to my eyes), viewing a 60 W light bulb in a sun-illuminated room (open curtains), showed a dim dark red bulb shape. Under better conditions, more (filament?) might be visible. I guess this is a mileage-may-vary scenario, and too subjective to estimate what filter it's equivalent to. He just lumps them all into one group, comparing them to the common photographic IR filters available.

Murray

 

[Roger Hicks]

I chose the 760 as my best guess closest thing to an 87, in 49 mm (front & rear threads) for $9.99 + 3.00 ship.

Dear Murray,

I'm sure you know all this but I'll stick it in for others. 760nm is pretty high and I don't think it would work at all with some films: Ilford's filter is about 715nm (T50 in both cases). Maco sometimes states the very longest wavelength usable, not the dye peak.

Cheers,

R.

 

[Mick Fagan]

I have had great success with Kodak's infrared film and a Hoya R72 filter, which filters out all but the infrared rays above 720nm.

I live at 38 degrees latitude, this is reasonably relevant information for the following suggestions. Remember this is for Kodak's infrared film.

Clear sun Summer 1/125 f/16

Clear sun Winter 1/125 f/11

Cloudy bright 1/60 f/11

Overcast 1/30 f/11

The best way to see if there is much infrared light around, is to hold the filter up to an eye, block out all other light, then scan the view, you will be very surprised at what you see. You will see certain areas of vegetation looking almost white and other plants will not have much at all.

I have not used a meter of any description for years for infrared, just the above exposing parameters.

I cannot claim responsibility for the suggestions. I did a 3 hour infrared course at a local adult education centre many years ago, it was run by a well known local Kodak scientist. The figures were his, which he had worked out after a fair amount of usage of this film and some inhouse testing I suspect.

I have had roll after roll of near perfect infrared negatives, using this exposure technique.

Mick.

 

[wirehead]

Pick a cheap meter that uses a silicone photo diode, not CdS or GaAs or silicone PIN photodiode. Naked silicone photodiodes have sensitivity peaks in the IR region and the sensitivity (when looked by energy) goes down as the wavelength goes down, because the number of photons per unit energy goes down, and the diode converts photon for electron basis. The efficiency of conversion also gets worse as the wavelength goes down, because of the excess energy more likely to get the photon wasted due to a mechanism called "recombination." This may not be intuitive for people who didn't study solid state physics but it's a sort of reciprocity failure-like mechanism.

Silicon! Not silicone!

Silicone is what gives the ladies the big boobies.
Silicon is what gives you your computer so you can download pictures of the afforementioned women.

 

[keithwms]

I haven't had too much trouble getting IR exposures right. Starting with a new film or new filter, I simply waste a sheet doing strip tests. Recently I was rushed and did some developing in the field and that wasn't so hard. If you're using roll film, just waste a roll and bracket like nuts. Thus you can obtain a film/filter compensation values such as EV+6 or EV+8 and after that it's pretty easy.

If you're over or under by a stop or two it usually isn't a disaster. If you do shoot roll film and bracket, I'd suggest bracketing by at least ~2 stop increments, you won't see much difference in density otherwise. It's not like shooting slide film, it is bit more forgiving, fortunately!

One of the trickier bits of using IR film is that some minor clouding (probably invisible to you) can cut the ground-level IR down quite a lot. So when I go out for IR shooting I simply watch the cloud patterns, looking for sunny 16 light and also avoiding situations in which very thin, high clouds might intercede. But it hasn't been a big issue for me, I haven't felt the need to use an IR meter.

 

[htmlguru4242]

Good idea, Ryuji.

I actually have a sheet of infrared filter plastic. A company called Astra Products makes plastic sheet filters for display applications. I grabbed a sample of a few of theirs. One of the ones i have is, in my experience, nearly Identical to my Hoya RM72 (in transmission, not optical quality). They're a little fuzzy for photography, but it'd be ok for a filter on a sensor.

I was actually thinking of designing the whole thing from the ground up, making it supercomplete and full-featured. There's a photosensor that TI sells, with linear response to incoming light intensity; it has usable response all the way out to ~920 nm. I was thinking about building something like this around some digital components; perhaps even a microcontroller (or an FPGA if I can hunt down one of my electronics guru friends).

We shall see. If I get it done I'll post my results.

 

[wirehead]

Should just require a single microcontroller and some LEDs. FPGA is overkill. A microcontroller tends to have a D/A converter built in, wheras a FPGA tends not to.

 

[Helen B]

...I haven't felt the need to use an IR meter.

I have two of them, and I hardly ever bother using them. As I mentioned in the photo.net threads I gave a link to, I have converted a Pentax Digital Spotmeter and Minolta Booster II to IR use by replacing the existing filtration with a short wave pass filter, and an IR-pass filter in the case of the spotmeter (the Booster gets used with a camera filter over it).

One small drawback with the spotmeter is that the SWP filter needs to more-or-less match the film in use and the IR-pass filter needs to match the IR-pass filter on the camera, if you want the meter to work for a wide range of sources*. For example: mine is matched to an 87C/093 with HIE - a film that is now only available in 35 mm, for which I can also use the TTL meter in my M6 or M7 quite well (set to EI 1600 for an 093 filter, by the way). For the Booster II mod, I made the SWP filter more easily interchangeable.

Most photographic meters have some residual IR sensitivity so they can be calibrated for use behind an IR-pass filter without any other modification. This works fairly well as long as the proportion of radiation the meter is seeing to the radiation the film is seeing stays about the same.

If you read the photo.net threads you will see that the lux meter suggested for modification by Adrian Allen (or was it designed by Adrian Wilson?) is really cheap - less than $30. I've just bought the same-price replacement for that meter to test, if I ever find the time. My current, higher priority project is to modify a Sinar Booster I. I might actually use that.

*Obviously you can't put the IR-pass filter in front of the lens, though you could put the SWP filter in front of the lens. A 25 mm diameter SWP filter is about $90)

Best,
Helen

 

[htmlguru4242]

Hmm, its probably pointless to design a dedicated IR one from the ground up, but I think I'll try it anyway.

And wirehead, you're probably right. LEDs could provide the exposure info. easily, or I have a bunch of superEasyToControl LCDs banging around ... argh the ideas, they keep coming

 

[wirehead]

Well, the goal would be to design a minimalist meter that can be made at home.

Basicly, a microcontroller, a photosensor, a display, and as few other parts as possible.

I've been toying with it... I've been yearning to do some electronics hacking of late...

 

[Doug Webb]

With films similar to this film, I have had good success with exposures ranging from 1/8 second at f32 to one full second at f32 when using an 89b Wratten equivalent filter. (Filters like a Wratten 87 will not result in an image with many of the newer infrared films because these filters don't pass the wavelengths the films are sensitive to.) The light conditions were all clear days with bright sun with sun high in the sky. If you want to be sure to get at least one good negative from a single composition, I would recommend making one exposure at 1/8, one at 1/4, one at 1/2, and one at a full second. Start developing the negative with the shortest exposure, then reduce development on the longer exposures if you get decent shadow detail on the early negatives but the highlights are blown past what you are looking for. I develop with XTOL 1:3 for 14 minutes at 68 degrees. I can send you a photo as an attachment if you are interested.
Good Luck,
Doug Webb

 

[Helen B]

Here, to the best of my knowledge, are the 50% transmission wavelengths for some common filters, to the nearest 5 nm. Heliopan filters are given their Schott RG numbers, which correspond to the 50% transmission wavelength.

Wratten # 25 (Old designation: A): 600 nm
Wratten # 29 (Old designation: F): 620 nm
B+W 091 (Schott RG630): 630 nm
B+W 092 (Schott RG695): 695 nm
Wratten # 89B: 715 nm
Hoya R72: 720 nm
Wratten # 88A: 745 nm
Wratten # 87: 795 nm
B+W 093 (Schott RG830): 830 nm
Wratten 87C: 850 nm

All Wratten data from Kodak Photographic Filters Handbook, B-3, 1992

The B+W Handbook gives the Schott glass used for each filter. The Schott website gives complete spectral data, but it isn't really necessary for obtaining the 50% transmission values.

Best,
Helen