I'm more than a little sceptical as to the improvement with APO process lenses vs. "ordinary" lenses.
First of all the wavelengths that available (not HIE) IR films are sensitive to are so close to visible red light that even a non-achromat would have negligible focus shift.
Second, "APO" process lenses are corrected for blue, green and red light when used at 1:1. That is no guarantee that they will be reasonably well corrected for IR, or at other ratios.
I'll try when the sunlight returns - with 150mm APO-Lanthar, Germinar-W, Symmar, Tessar, and a (non-achromat) 14cm Ernemann Doppel-Objektiv which arrived yesterday. I doubt there will be visible differences in sharpness, except with the Ernemann.
-- Ole Tjugen, Luddite Elitist
Ole, a couple of quick points.
First of all, I tried near focus and I tried far focus with the Rollei IR film. Notice I did not say that no refocus is necessary, what I said is that I find it to be negligible. It was noticeably less of an issue than with other lenses that I have used... various schneiders and nikkors.
Second, the film I mentioned, Rollei IR, is a near-IR film... really what you might call edge red or extended red. I did not claim that there will be no refocus with a deeper IR film such as HIE or digital IR. But as you know, the basic issue here is n as a function of lambda, and in an APO lens, you don't have n(lambda)=constant across the visible range and then suddenly, drastically, it goes to crap as soon as you get to 800nm. Again one has to bear in mind what lambda range one is talking about. With HIE and digital you are seeing out to about a micron or more. Not so with Rollei IR and SFX and all that.
I use apo process lenses for near UV and near IR stuff and have had good success, even working wide open, even using swings and tilts. People should simply try for themselves.
Couple examples where I was shooting a 360mm apo-nikkor wide open with liberal swings to test...
In both cases the optimal focus was predicted by my ground glass to be dead center and then I made a line of good focus across each frame with a swing...
Last edited by keithwms; 01-27-2008 at 10:45 AM. Click to view previous post history.
Reason: added examples
Some plastic holders are not IR opaque. They can allow some IR light to come in from the plastic holding them together. I have not had fogging from the slides, but the edges have been horribly fogged in the past. I have never had issues with wood holders.
One of the challenges with IR film is getting enough shadow detail. As with normal film, one can easily get enough exposure for the highlights, but if there is not enough exposure for the shadows, no amount of development can bring it back.
I have had a wide range of ISO's from IR films. As fast as 200 ASA from Kodak's film to as slow as 1/2 ASA with the Maco film. It takes some testing.
Best of luck
Thanks a lot. Guess I'd better get two boxes - one for testing and one for shooting!
Ekfe IR film is very slow. If I remember rightly, I expose it at EI 6 with a Hoya RM72 filter.
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IR in 4x5
I've just picked up a box of Efke 4x5 after running out of HIE 35mm.
I can report there is NO problem in handling the holders outdoors. No problem with my bellows either -- although holders and bellows are only a couple of years old. If you are worried, waste a sheet by leaving the holder outside for half an hour -- I think you'll probably be okay. Daylight is UV heavy.
I'm using a Lee 87 filter, but, my god, the ISO seems to be about 1 for me. I've blown about 10 sheets so far and still haven't anything with enough density to print properly. I'm into reciprocity failure adjustment on every exposure.
I'm switching to deep red filter to nail that first and then I'll get back to the Lee filter.
I wish I could get more 4x5 HIE. I still haven't gotten comfortable with the efke stuff (though I've only shot a few sheets so far). It sure does need a pretty low sensitivity rating to get the shadow detail up, which of course means clouds & trees and stuff move more than you might want. With HIE, even stopped down and with a deep red on, you can get < 1 second exposures pretty easily.
The universe is a haunted house. -Coil
Originally Posted by David William White
It depends on the holders, slides and bellows. For sure the 5 bump fidelity holders are ok. Best to test rather than ruin allot of film. Concerning bellows for example, I have been told that the sheepskin on my Tachihara isn't IR safe. I will check it, of course to be sure.
Curious how the UV in daylight relates, regarding IR?
Fidelity holders were fine for me also.
"He took to writing poetry and visiting the elves: and though many shook their heads and touched their foreheads and said 'Poor old Baggins!' and though few believed any of his tales, he remained very happy till the end of his days, and those were extraordinarily long "- JRR Tolkien, ' The Hobbit '.
He probably mis-spoke there, Jason.
It's a certainty that some holders are not as safe as others. To that end I would always recommend a test of the holders you plan on using. Better safe than sorry.