Archived posting to the Leica Users Group, 2000/01/23
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 07:18 PM 23/01/2000 +0000, Joe B. wrote: I might set up a test at some point to see if I can find a focusing shift with filters, caused by the filter itself, on the Noctilux. This really wouldn't be an issue except that I really like the strange look of infrared Ektachrome through this lens. It would be nice to know for sure. ::::::::::::::::: I'd like to see the results. My working hypothesis might be that good quality optical glass, mounted properly (exactly perpendicular to the lens axis), will not cause a focusing shift in the IR, but it still is worth testing. Several months ago the LUG carried a discussion about image degradation with UV filters and Leica lenses. Some people said that they were planning to do controlled tests, looking for differences in images shot with and without UV filters. Has anyone done these tests? If so, what is the verdict on this? I wish I had some way to scan film. I could show you some shots taken with the 35 Summilux ASPH and a red 25 filter, which show just how badly the filter can cause an image to break up! I didn't have a clue what was going to happen beforehand (one lament about no preview capabilities with a rangefinder) otherwise I would have removed the filter and done some comparison shots. Strong backlighting, sun in frame, snow-covered contrasty subject ... the filter killed it, but was "necessary" to get the contrast in the sky I was aiming for. If I get time, I'll do some comparison shots using a naked lens (sounds like fun eh?) and one with a UV added. Blowing up a small section of frames processed and printed identically should help to show what happens.