From cdfk@hplb.hpl.hp.com Fri Aug 26 18:11:30 1994 Newsgroups: rec.photo Path: news.ifm.liu.se!liuida!sunic!trane.uninett.no!eunet.no!nuug!EU.net!howland.reston.ans.net!math.ohio-state.edu!sdd.hp.com!hplabs!hplextra!hplb!cdfk From: cdfk@hplb.hpl.hp.com (Caroline Knight) Subject: Draft IR FAQ Sender: news@hplb.hpl.hp.com (Usenet News Administrator) Message-ID: Date: Tue, 23 Aug 1994 07:48:04 GMT Nntp-Posting-Host: cknight.hpl.hp.com Organization: Hewlett-Packard Laboratories, Bristol, England X-Newsreader: TIN [version 1.2 PL0.7] Lines: 311 WWW: http://math.liu.se/~behal/photo/IR-faq-draft Sometime ago I promised to write an IR FAQ. I wrote this and sent it out to various people but have had no replies. If you can help with the gaps or put me right where what I wrote is wrong - please do! As to where it should end up I assume that all FAQs once real should be posted to rec.photo.help Draft Infra-Red Photography FAQ ------------------------------- This FAQ is intended to draw together net.wisdom on the topic of infra-red photography. I had a rather bumpy start so got more than the average amount of advice on the subject. Putting together this FAQ is my thank you to everyone out there who helped and encouraged me, including but not limited to: andpph@ritvax.isc.rit.edu (Andy) bud@sr.hp.com (Bud Noren) craig@ecel.uwa.edu.au (Craig Richmond) dr8192@albnyvms (david rosen) icajay@aol.com (ICA Jay) kbw@bnr.co.uk (Kieran Wills) monson@mycroft.ece.orst.edu (Ty Monson) paulb@cyberspace.com (Paul Butzi) ricks@vader.nrl.navy.mil stai@dt.wdc.com (Jeff Stai) stmwang@hubcap.clemson.edu (Sam Wang) There are currently some blanks that I would like to fill. These are shown by <>'s with text inside indicating what sort of thing I'd like to fill that slot with. Any corrections/additions or other comments are welcomed. Please send to cdfk@hplb.hpl.hp.com This FAQ is organised into the following topics: -- Why IR? -- Subjects -- What about heat? -- Which IR films? - the options -- Which cameras? -- Which lenses? -- Buying and storing -- Loading -- Exposing - filters, rating, focusing -- Flash -- Developing -- Printing These cover most of the topics of the frequently asked questions about IR photography on rec.photo -- Why IR? Infra-red photography uses films that are sensitive to both the light we can see and some of the shorter length infra-red radiation. There are scientific uses for such films but here the main use is to expand our range of picture making media. Some people just try IR once as a novelty others get hooked on the effects and exploit it as their main film, especially Kodak's High Speed Infra-Red black and white film. -- Subjects Everything looks odd on colour IR film. The following remarks relate to black and white IR film. Vegetation and sky look very different from normal therefore incorporating either or both into your pictures will take advantage of the effect of IR film. Vegetation comes out bright, clear sky comes out dark - clouds stay light. Skin also looks different IR film can be used for interesting portraits. Topics suggested are: * Graveyard shots - grass will go almost white leaving the tombstone floating in an eerie space, similarly for standing stones. * Derelict buildings covered in creepers - again the contrast of stone and vegetation * People on the beach - sky and skin, water reflecting sky * Nudes in a landscape - skin and vegetation and/or sky * Haze reduction - only reduces blue haze, but try it * Hot houses - vegetation Hints * There is more IR about when there is bright sunlight. This doesn't mean you should avoid using IR film in other conditions but that the effects are stronger when the sun is out. * A flash will increase the amount of IR as well as visible light. -- What about heat? Thermal radiation will not show up; IR films are not sensitive to a long enough wavelength to show such things as heat patterns. Heat will however tend to increase the fogging of the film. Keep film as cool as possible and avoid leaving in hot places like in a car on a hot day. -- Which IR films? - the options There are two black and white IR films. One from Konica and one >from Kodak. There is one colour IR slide film from Kodak. Konica Infrared B&W This is available in 35mm and 120 formats. It is not so grainy as the Kodak film, though still grainy. It is less sensitive to IR so the effects are less exaggerated. However it is also less prone to fogging from stray-light whilst loading and less likely to fog due to heat . Its latency is greater thus get better results if it is not possible to develop immediately. It is also a much slower film . Process using ordinary black and white developers. Kodak High Speed Infra-Red black and white film (HIE 135-36) This is available in 35mm only. It seems to be more commonly available than the other IR films. It is grainy, sensitive to IR down to and is the most used IR film. It has no anti-halation layer thus increasing the need for care when loading and unloading to avoid fogging. Process using ordinary black and white developers. Examples given: * HC-110 dil B for 6 mins * ID 11 for 11.5 min * Agfa Rodinal 1:50 for 10 min [The datasheet mentions the developers D-76, HC-110 (dilution B) for scientific uses and D-19 for maximum contrast. Time depends on temperature and size of tank.] Your favourite black and white developer will probably work though you may have to experiment to find the right times. Kodak's Colour Infra-Red Slide film This is available in 35mm . This is processed using E4. There are very few labs which still offer this old method. . You can also process it at home using an E4 kit, Tetenal make one . -- Which cameras? You cannot use IR film in all cameras. For instance, you cannot use it in any of the Canon EOS models which have an IR optical film loading mechanism (eg Elan/100, A2E/5 but okay in 10s/10 and older models). . [About 4 mm. So you will get a frame that is 20mm x 36mm. I think the 4mm is in the bottom of the image (top of the film in the camera). (source: postings in Usenet)] Also some camera backs may not be opaque to IR, especially some plastics. You also need manual focusing unless using a very wide lens with small aperture. Hints: * Mask off any window showing film cassette * Use 35mm film wound onto a spool with backing paper to load up a medium format camera (do this all in absolute darkness!). Get pictures which use whole of film surface including the film between sprocket holes. * Turn an old compact (eg Olympus Trip 35) into an IR camera - cut a circle of gel to cover lens but not light sensor, set aperture to small (check this works by looking through camera unloaded and set different apertures, press shutter, look for difference in size and listen for different shutter speed) and focus near infinity. Use a manually set ASA/ISO to bracket. -- Which lenses? For ease of focus use wide angle to increase depth of field but don't be put off from using any other lens. It is easiest to use lenses which are marked with a little red mark to show how to correct them for IR focusing. You can use AF lenses to focus then put into manual and reset (so long as they can be overridden). -- Buying and storing Buy only from places that keep the film refrigerated (or frozen). [Kodak advises keeping the B&W film at 13 celsius or less.] Keep your own film cold until needed. Allow to warm up to room temperature before loading (to avoid condensation). This is one film not recommended as a mail-order item... If you cannot process immediately return the film to the fridge/freezer. -- Loading The general advice is to load in total darkness, especially the Kodak high-speed IR b&w film. However I have had no fogging through loading in a room which is not pitch black - darkened just not total. This avoids embarrassing problems like putting ones fingers through the shutter ... Unload in similar conditions. Return the film to its original container until processing. -- Exposing - filters, rating, focusing All IR film is sensitive to BOTH some IR and visible light. To increase the IR effect one reduces the amount of blue and green light reaching the film, or you can block all visible light and record only IR. On the black and white films use a red filter. Which red filter you use will effect the amount of non-IR light that is also recorded. On colour IR film use a deep yellow filter to reduce the amount of blue - otherwise the results will have a strong blue cast. Film Filter Nominal ISO/ASA non-TTL TTL* Konica Kodak b&w Without filter 80 Wratten #25A 50 400 ** Wratten #29 50 Wratten #87 25 (opaque to visible light) R2 50 [* if you are using a TTL meter, the meter sees less light than there is, so you should increase the sensitivity marked by the filter factor. So as the filter factor for the #25 is 3, you should incres 3 stops from ISO 50, that is ISO 400. ] [use this numbers as a starting point. bracket around them or make tests] [** (from a Usenet posting): "I read an article (I guess it was in one of the latest PHOTO + Labor, german) stating that you can use TTL metering for the Kodak IR film. But, as the light sensor built in the cameras are less sensitive to IR than they are to visible light, you have to set the ASA setting on your camera to values between 300-1000 ASA (depending on the type of camera you use)." ] Kodak colour Whichever filter you use it is worth bracketing as more than one exposure can give you interesting effects - you may end up with several usable results from the same scene. Some people recommend bracketing over 5 stops. Another reason for bracketing is that the level of IR radiation is not exactly proportional to visible light thus one's exposure meter can only give an approximation. The amount of IR that reaches your camera is also effected by the distance that it travels through the atmosphere. Thus the distance of your subject will also alter your exposure, follow the guidelines on the enclosed data sheet. If you must expose through the lens (and the filter) you will need to adjust the working ISO as the meter is seeing less light though you are (hopefully) still getting all the IR available (limited by the sensitivity of the film and the characteristics of the filter). Thus you need to increase the ISO by however many stops of light your filter blocks eg lose 2 stops, go from 50 to 200. If using an opaque-to-visible-light filter (eg Wratten #87) on an SLR you will need to compose without the filter so also set the exposure manually at this point. The exact point of focus will depend on which filter you use as this dictates which wavelengths are most prominent in your image. Most people move towards or to the red infra-red mark on most lenses. If your lens is missing this mark then nudge it to a slightly closer focus. To improve apparent sharpness use a small aperture to increase depth of field. -- Flash Flash emits IR along with visible light. You should calibrate your flash for IR film through test exposures. You can use a filter over the flash to reduce or eliminate the visible light output. Hint * Two strips of unexposed but developed E6 film can be used as an approximation to a Wratten 87 (for more info contact: Andy on andpph@ritvax.isc.rit.edu). [Be careful on the frequency of flash use. Someone reported that his SB-24 overheated when using this technique.] -- Developing Process as soon as possible. This is good advice for any film but especially for IR film which seems to be more prone to fogging and more forgetful than other films! Take even more care than usual when loading the film onto a spiral. (I have found that I can get away with putting the leader onto the spiral in a darkened, but not totally dark, room.) Beware that not all changing bags and not all tanks are opaque to IR film. Some people insist on using an aluminium tank but I have not had any problems using my plastic tank (I do not leave the film in for long and do not put it in direct sunlight etc). Develop as appropriate to your film (see under description of film). -- Printing Choose your basic printing exposure to bring out the characteristics you were using - keep vegetation light and skies dark. This can lead to high-key light portraits, dark moody landscapes and ethereal vegetation. Experiment with your negs! As with any black and white print you can also tone or tint the picture to increase its mood or highlight a particular element. -- ----------------------------------------------------------------- Caroline Knight HPLabs Bristol UK cdfk@hplb.hpl.hp.com -----------------------------------------------------------------