M'Ate Posted November 24, 2006 Share #1 Posted November 24, 2006 Advertisement (gone after registration) This might be a little off the wall, if it is don't flame me, but I haven't seen it poposed anywhere else. Is there any reason why an IR filter couldn't be mounted behind to the rear element and inside the camera rather than before the front element ? This approach is quite common with large format lenses and leaves the lens without a pink glow. Whilst the right sizes might not be available at the moment, designing and manufacturing a filter should be quite simple. The cost of a much smaller filter could also be lower. Looking at my 50mm Summilux there's room for it inside the throat without it reducing the lens to sensor distance. If there's an obvious reason why this couldn't happen I'd be pleased to know. Link to post Share on other sites More sharing options...
Advertisement Posted November 24, 2006 Posted November 24, 2006 Hi M'Ate, Take a look here IR filter alternative location ?. I'm sure you'll find what you were looking for!
carstenw Posted November 25, 2006 Share #2 Posted November 25, 2006 Some other lenses have less room, and the rays of light hit at a sharp angle, eliminating the possibility of a hot-mirror filter. I wonder if there is room inside the middle of the lens somewhere. Link to post Share on other sites More sharing options...
stewardrobbins Posted November 25, 2006 Share #3 Posted November 25, 2006 A more difficult but less "messy" solution might be to coat all new lenses with anti-IR coating. Perhaps older lenses could be coated as well... Link to post Share on other sites More sharing options...
ho_co Posted November 25, 2006 Share #4 Posted November 25, 2006 Is there any reason why an IR filter couldn't be mounted behind to the rear element and inside the camera rather than before the front element ? This approach is quite common with large format lenses and leaves the lens without a pink glow. I've seen some lenses that have built-in filters. Do the large-format lenses require a filter to work correctly? Or on the other hand are they symmetrical designs? Only guessing, understand, but it seems to me that if you put another piece of glass into a focused column of light you'll introduce aberrations dependent on the thickness and refractive index of the glass. That is, the filter couldn't just be an add-on to an existing design; the lens would have to be designed specifically to incorporate the filter as an extra element. Just a guess. --HC PS--I'm sure Leica has considered every alternative for the IR problem, and I'm sure the front-mounted IR-cut filters are the best solution. It's fun to speculate, but I'm ready to go with the plan Leica has given us! Link to post Share on other sites More sharing options...
erl Posted November 25, 2006 Share #5 Posted November 25, 2006 As I recall, the Hasselblad 40mm distagon has such a system. It comes supplied with 3 or 4 filters that screw to the back element of the lens. When you don't use a filter it is necessary to fit a 'dummy' filter, all of which supports HC's theory re. focussed light paths. Cheers, Erl Link to post Share on other sites More sharing options...
Riley Posted November 25, 2006 Share #6 Posted November 25, 2006 its common for mirror lenses to use a filter inbetween lenses this is facilitated by a draw that slides in and out of the top of the lens body Riley Link to post Share on other sites More sharing options...
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