Centre filters for UWA lens - rear element instead of front

[Drew Wiley]

Only filters on the front, Alan. That's the only place they belong. There are a handful of really huge MF telephoto lenses which are so big (nearly 10 inches front diameter) that filters simply won't work on the front, so are specially engineered for rear ones. That's the case with certain very long focal length Pentax 6x7 lenses which almost resemble telescopes. I don't know if similar RB lenses exist or not; but I'm quite sure you wouldn't own anything that huge, heavy, or expensive anyway.

[Bob Salomon]

Only filters on the front, Alan. That's the only place they belong. There are a handful of really huge MF telephoto lenses which are so big (nearly 10 inches front diameter) that filters simply won't work on the front, so are specially engineered for rear ones. That's the case with certain very long focal length Pentax 6x7 lenses which almost resemble telescopes. I don't know if similar RB lenses exist or not; but I'm quite sure you wouldn't own anything that huge, heavy, or expensive anyway.

Also with some very short lenses like the 30mm Zeiss Distagon for Rollei and Hasselblads.

[Dan Fromm]

Drew, you may be thinking of the Reflex Nikkors (500 mm, 1000 mm and 2000 mm), which take small filters in the rear. They must be used with a filter in place. The filter set includes clear, red, yellow and several NDs of various densities. These are all for 35 mm F-mount SLRs.

[Bob Salomon]

Drew, you may be thinking of the Reflex Nikkors (500 mm, 1000 mm and 2000 mm), which take small filters in the rear. They must be used with a filter in place. The filter set includes clear, red, yellow and several NDs of various densities. These are all for 35 mm F-mount SLRs.

So did a 300mm Nikon which was not a reflex design. Heliopan even made a polarizer in a drawer for it.

[Drew Wiley]

No Dan, I was not thinking of Reflex Nikkor. Everything Nikon is tiny compared to P67 equivalents, which even at the rear of their long teles take rather big filters, at least in the case of the Pentax Takumar series. The newer EDIF series is a little different, but still huge compared to 35mm lenses. I have a Nikon F adapter for my 300EDIF; that's fun wildlife combination, though I rarely use it because I seldom print 35mm shots. Gratefully, their 300's accept standard 82mm filters on the front of the lens. It when you get to 600mm and beyond that things get crazy big.

[Alan Klein]

Alan - Don't worry about that. I already did plenty of testing with the 90/4.5 + CF + contrast filters too. Just go ahead and focus first, then add the filters. But REAR mounting filters on a lens is a no no unless otherwise specified. There are some modern lenses which are less than ideally corrected, especially at the widest apertures, and can exhibit a bit of focus shift between different colors of very deep contrast filters, even high quality glass ones mounted on the front. So when in doubt, carefully test. It's more likely to be a problem with MF lenses.

I wasn't clear with my question. What did you mean with MF lenses. Do you have to focus MF lenses after the filters are put on the front? Or is it acceptable to focus first and then add the filters on the front?

[Bernice Loui]

Sinar shutter has a rear filter holder for 103mm Sinar glass or square gel filters.
Zodiak 30mm f3.5 fish eye for Pentacon six has filters in the rear similar to the Zeiss fish eye for Hasslblad (image quality wise, both are surprisingly similar).

Canon 35mm fish eye, built in filter wheel at the rear of the lens.
Canon and many other telephoto lenses over 300mm and similar zoom lenses.
Canon FD 200mm macro has a filter holder at the rear of the lens.

Schneider 110mm & 150mm SSXL has a threaded rear element for filters..

Kinoptik 9.8mm T2.3, Tegea has a rear gel filter holder slot.

Rear of the lens filter is quite common.


Bernice

[Bob Salomon]

I wasn't clear with my question. What did you mean with MF lenses. Do you have to focus MF lenses after the filters are put on the front? Or is it acceptable to focus first and then add the filters on the front?

No, you focus with the filter in place as it is part of the optical system of the lens, if a filter came with the lens from the manufacturer. Otherwise you would be out of focus by the amount the filter shifts the focus plane.
A better example might be that glass plate on Hasselblad Polaroid backs. Since the film plane of a Polaroid back is different then the roll film back Hasselblad used the glass plate to shift the focus so it would be acceptably sharp for test shots with the lenses it was recommended for.

[Bob Salomon]

I wasn't clear with my question. What did you mean with MF lenses. Do you have to focus MF lenses after the filters are put on the front? Or is it acceptable to focus first and then add the filters on the front?

You should focus with the filter in place. Especially as some cheaper filters can play havoc with focus.

[Alan Klein]

Holy cow. I've never ever considered that. Half my pictures must have been focused before putting the filters on. I use good filters like B+W or Nikon. Is this something I can check live to see if I see a difference? After all, if it's still in focus after I put the filter on requiring no change, then it shouldn't matter for future use. After all, the whole point of spending extra money for a brighter lens that's heavier is to make it easier to see, compose and focus. If I have to add a 1 1/2 stop polarizer on beforehand, I've defeated the whole point and spent money for nothing.