View Full Version : Efke PL25M for Red Rocks?

Steve Goldstein
7-Sep-2012, 16:33
This question is probably academic with the demise of PL25M and all other Efke products :(

Does PL25M's relative lack of red sensitivity make it preferable for shooting in the red sandstone areas of Utah, Arizona, and Colorado? I've heard that a strong green filter is useful in this situation as a red blocker, so it seems plausible that a film with less red sensitivity would be better able to differentiate the subtle patterns in the stone.

Yes, I could test it, but that would involve leaving my armchair in Massachusetts, and I'm out of vacation days this year so I wouldn't get the answer until well after all the remaining PL25M was hoarded.

10-Sep-2012, 07:19
It really depends on whether the colour variations in the rocks fall on the steep part of the frequency response curve of the film. If they all lie on the insensitive end of the spectrum with regards to that specific film, the whole area will be under exposed if shot at the *correct* exposure for that scene. Alternatively, if the red rocks, or what ever, lie well within the films response curve, the scene should render as normal. The picking out of details - that being variations in tones of the surface - will require them residing on the curve where there is a steep drop in sensitivity at the red end, thereby promoting contrast between the tones. To what extent this would be apparent on the final development, I don't know.

Drew Wiley
10-Sep-2012, 08:15
Efke 25 is orthopan, not ortho, so it does see red, but just not as far toward that end of
the spectrum as more typical pan films. I often carry a 58 green filter in the desert or analogous situations so that reddish rocks will not reproduce so light, if I don't want them
that way. In this case, the effect will be similar between Efke 25 and ordinary pan films,
though you will end up with an effective ASA around 6 once the filter factor is added.

Drew Wiley
10-Sep-2012, 09:31
PS - Fuji ACROS is also an orthopan film and much easier to handle than Efke 25. It has a
different curve shape than Efke but otherwise gives a similar value rendition to the hues.
I haven't used it much in the desert because it's hard to get in 8x10, but based upon
analogous situations in the mtns with 4x5, it would seem to be an excellent choice. It's
realistically a stop faster too.

Steve Goldstein
10-Sep-2012, 10:35
Thanks guys!

Drew, it was a comment you made in another thread relative to mountains that prompted my question. I'm in the Colorado mountains at least annually, and they don't strike me as especially red. What is it that sets PL25M and Acros apart in those situations?

Drew Wiley
10-Sep-2012, 11:09
Steve - what I reallly like about the orthopan films in the mtns is that they seem to render
the light a lot more realistically. Foliage colors in particular are a lot more buoyant. You
can get an analogous effect using a yellow-green filter on ordinary pan films, but it's not
quite as convincing. The sky seems to come out more atmospheric too. Just don't use anything stronger than a 25 red. A deeper 29 red will chop off about a zone in the shadows
because it just too sharp-cutting. It's just a different look overall; but between Efke 25
and ACROS, there are different personalities too. Efke has a longer exposure scale and higher contrast, but is trickier to handle and can be pretty damn slow to expose. ACROS
has a decent straight line once you kick the shadows off the toe, which for me, requires
an ASA of about 50.