Archived posting to the Leica Users Group, 2003/12/07
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 6:15 PM -0600 12/7/03, robertmeier@usjet.net wrote: >Does anyone know if Leica ever made an infrared filter like the one Rollei >made? The Rollei filter is distinguished for two things: it is all but >opague, only passing the infrared wavelengths, and it is slightly ground to >compensate for the different focus point needed for infrared light, so no >compensation is needed on the focus setting. Since with a Rollei, like a >Leica, you don't view through the taking lens (and the filter), the opague >filter works all right. I would love to use such a filter on my Summircon >50, and I might have to tape my Rollei Bayonet II filter on to it (the >diameters are just about identical). Leica made IR filters, generally equivalent to Wratten 89B, but with no optical adjustment such as the one for the Rollei. The latter works even less well for the Leica than the Rollei. A focus adjustment is lens dependent, filter dependent and film dependent. If the Rollei filter is made for a specific lens, it's important to find out what film it's made for. Most likely HIE, but not necessarily. Again, note that this only works for a specific lens formula. The possible variations is the reason that Leica no longer puts an IR correction mark on the focussing mount of lenses. You gotta find it for yourself, for your parameters. With Leicas, the fact that the filter could be used on a variety of different lenses means that no specific optical adjustment should be made in the filter, but that tests should be made with the specific lens/film combo for each filter. On a related note, last weekend my son and I were playing with his Panasonic LikaLeica, and discovered that it had significant sensitivity even with an 87C filter. An 87 seemed the best match for the camera, or possibly an 88A (which we didn't try). Reasonable exposure times, and a very clear IR effect. The strange thing was that if you used an 89B, the picture came out red, but if you used an 87C, it came out B&W. There must be firmware in there that switches to B&W past a specific spectral response; it means that the Panasonic engineers were planning for this camera to be useable in the IR. - -- * Henning J. Wulff /|\ Wulff Photography & Design /###\ mailto:henningw@archiphoto.com |[ ]| http://www.archiphoto.com - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html