Archived posting to the Leica Users Group, 2001/03/19
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]I have bought a 12/5.6 Heliar to use for infra-red (among other things). Would it be practical to use a 25A or 87 gel on the rear element of this lens, rather than dangle the big stuff off the front. I was thinking of making a snug fitting cap/tube to put over the rear element prior to mounting the lens. This would have the appropriate filter gel on one end. It would need to be firmly attached to stay put and not foul the shutter of course. The reason I am posting this is that I am not sure what effect this will have on the light path through the lens in terms of "better or worse" than on the front. The cost of a 77mm filter up front will be far more than a small diameter gel at the rear, and it will also be far less obtrusive. What is the cost though in terms of image degradation? Is it viable or not? Mike Nicholls Canberra, ACT Australia mikenic@cyberone.com.au *My toys! My toys! I can't do this job without my toys!*