The following is from "The Practical Accessories" publication by Franke & Heidecke:
"The infrared filter features special compensation for focusing difference between visible and infrared portion of the spectrum. Direct ground glass focusing may be employed with full assurance of sharp pictures."
You can read the entire document at: http://www.butkus.org/chinon/rollei/rolleiflex_acc/rolleiflex_acc.htmThe principle is that the IR filter is ground like a very slight version of a screw-on close-up filter.
Are you sure you had an "infrarot" filter and not just a deep red filter? An infrared filter should be opaque to visible light, so you would not be able to see anything through the viewing lens with the IR filter attached to it . . .
-Aaron On May 16, 2007, at 12:04 PM, Peter De Smidt wrote:
I've heard that claim but I don't believe it. How could it do that? Moreover, taking the filter on and off the viewing lens doesn't affect focus through the screen.
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