This post is a collection of various technical notes about this great black and white film. I've been using it extensively for a while now, as it's wonderful film, both as a general-purpose medium-speed black and white film, and also for its extended infrared sensitivity.
However, by virtue of not being made by one of the larger film makers (i.e. Kodak, Fuji, Ilford), it's not super widely available or very popular, and as a result, it can be a bit hard to find data on it. I'll be collecting what I've found here, in the hopes that the great google machine indexes this and makes it a bit easier to find.
Rollei Infrared 400 is marketed under the Rollei name, but only by license. It has no other relationship with the old camera company. It is made by Hans O. Mahn & Co. KG of Stapelfeld, Germany, under their Maco Photo brand.
Currently (as of 2019) you can get it in 35mm (36exp), 120, and 4x5" (25 sheets).
Rollei Infrared 400 is, as its name suggests, sensitive to infrared light. Maco describes it as "hyper-panchromatic". It's pretty evenly sensitive to all colors of visible light from 350nm (near-UV) to 650nm (middle red), and then sensitivity starts to fall off roughly linearly until 780nm. It then has low sensitivity up to about 820nm. Without any filters it behaves like an ISO 400 panchromatic black and white film.
With a Hoya R72 infrared filter (which starts at 750nm), it behaves like an ISO 25 film (4 stops slower). Of course, care must be taken, because light meters are measuring the brightness of a scene using only visible light.
Reciprocity Failure / Schwarzschild Effect
When making long exposures, film generally needs to be exposed for longer than your light meter might suggest, and this property of a film is called "reciprocity failure", or the "Schwarzschild effect". Rollei IR400 has really bad reciprocity failure.
The effect is described by an exponential equation: for exposures >1 second, take the exposure time your light meter suggests, and raise it to some power P, which varies depending on the film, and expose the photo for that amount of time instead. Most films have a P-value something like 1.3 — 1.4-ish.
Rollei Infrared 400 has a P-value of 1.52. This is derived from looking at the German-language data sheet provided by Maco Photo (from April 2015), which contains the following table (translated):
|Metered Time||Actual Time|
|1/1000 sec — 1/2 sec||same|
|1 sec||1 — 2 sec|
|2 sec||3 — 4 sec|
|4 sec||8 sec|
|8 sec||24 sec|
|15 sec||60 sec|
|30 sec||180 sec|
From this you can extrapolate out additional times using the formula.
These times are taken from a listing on a box of 4x5 sheet film. There are other (conflicting!) times listed on Maco Photo's data sheet. I suggest if in doubt, go with what came with your film; it's possible that the emulsion has changed over time.
For more formulas provided by other people, see the Massive Dev Chart
All times assume EI 400 (or EI 25 if using infrared filter) and 20°C unless specified.
|Rollei Supergrain 1+9||10:00|
|Rollei Supergrain 1+12||12:00|
|Rollei Supergrain 1+15||15:00|
|Rollei RLS 1+4||18:00||24°C|
|Ilford Ilfotech DD-X 1+4||10:00||I have tested this one|
|Ilford ID-11 Stock||12:00|
|Ilford ID-11 1+1||16:00|
|Ilford Microphen Stock||12:00|
|Ilford Microphen 1+1||16:00|
As you can see, Rollei IR400 is a bit slow to develop.