I’ve dabbled in infrared photography a few times, originally using Maco 820c. The results were varied and I didn’t shoot it often enough to get a good feel for it. More recently, I bought some Efke IR820. If you’re reading this post, you presumably know vaguely about the film already, so I won’t go on about it.
I decided to make a renewed attempt to understand how to expose the film reliably so I can start taking decent shots with it. I don’t have a proper light meter. If I can be bothered to carry my DSLR, it makes an excellent spot and average meter. If not, I use an iPhone app called Pocket Light Meter, which is surprisingly good.
There are various methods of metering for infrared film. The light meters in some SLRs can meter infrared accurately through the filter; unfortunately the one in my Canon AE-1 Program doesn’t. Some photographers work out an “effective ISO speed” for their combination of film and filter, and use this with an unfiltered light meter. Different forums recommend different effective speeds and it’s hard to compare filters. The only way to work out what’s best for you is to sacrifice a couple of rolls to trial and error.
I am using a generic 720nm filter, which is a little stronger than a Hoya R72. The most comparable branded filter is a Wratten #88A. Refer to this comparison of infrared filters if you need to work out which type you’ve got.
Using Efke IR820 with an #88A filter, I decided to start with a speed of roughly 1.5 ISO. If using my DSLR’s light meter, this means metering at 100 ISO and then adding 6 stops of exposure. If using my iPhone light meter, I can meter as low as 6 ISO and then add 2 stops. I bracketed my exposures by varying amounts, and recorded the exposure information, and the way I arrived at it.
I decided not to “waste” the film by risking taking badly-exposed artistic shots, but instead to take technically interesting shots that included foliage, sky, clouds, concrete, water, and other materials as a learning exercise. Once I’ve learnt the right effective film speed and the right amount of compensation for my meter readings, it’ll be easy to go out and take well-exposed shots almost every time. Then I can focus on taking artistic photos for publication.
My procedure was like this:
- Take one frame without the IR filter, using the camera’s meter set to ISO100. This is to rule out development errors later on.
- With the filter on, take infrared photos using any method you like for metering. This might include using the camera’s meter, a handheld meter, intuition, the sunny-16 rule, or something else.
- Bracket the exposures by ±2 stops, so you have a choice of exposures to study later.
- Record what each exposure was of, the aperture, the shutter speed, and importantly, how you arrived at the exposure. I kept a table like the one below (and these examples are a selection of my actual data).
- After developing, and making sure the unfiltered exposure is correctly exposed and developed, I inspected each negative and decided which were under- or over-exposed, and which ones were OK. Then I have a handy reference of which metering methods gave the best results.
|1||Bridge over river||2″||f/8||TTL w/o filter @ ISO100, +6 stops||OK|
|3||Weir||2″||f/22||TTL w/ filter @ ISO100||Under|
|23||Brandon Hill||1/8||f/4||Meter @ ISO6, +2 stops||OK|
|26||Pastel houses||1/8||f/5.6||Meter @ ISO6, +4 stops||Over|
|30||Rooftops||1″||f/8||Meter @ ISO6, +3 stops||OK|
From studying the data I gained from these 39 exposures, the best-exposed images were achieved with a handheld meter set to ISO6, and then adding 2 or occasionally 3 extra stops of exposure. This indicates that the effective film speed of Efke IR180 with an #88A filter is ISO1.5 – ISO0.75.
The reason that the exposure compensation varied between 2-3 stops is probably due to the makeup of the composition of each scene. Foliage comes out near-white in the infrared region, but is relatively dull in the visible spectrum. The handheld light meter wouldn’t take account of this, so scenes with a lot of foliage probably need +2 stops added. Scenes that include a lot of sky, which is rendered black in infrared, will probably need +3 stops.
To see all of my favourite shot from the roll, see my photo blog.