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02-13-2012, 08:09 AM   #1
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Tokina 500mm mirror lens - front filter thread size?

Anyone know what size the front filter threads are on a Tokina 500mm f8 mirror lens? I know it's larger than 72mm.

Cheers,
Bobbo :-)

02-13-2012, 10:05 AM   #2
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I do own this lens and its manual. Tokina DOES NOT RECOMMEND the use of front filters.

It uses special 35.5mm filters which are fixed AT THE REAR of the lens, using the special tool delivered with the lens. These filters are part of the optical system, and one of them must ALWAYS be mounted - and it MUST be a Tokina one designed for use with that lens, as thickness, glass chemistry, and position are part of the optical formula. The manual says any other filter (or no filter at all) may degrade the performance of the lens considerably. Together with the lens Tokina delivered one set of filters (1 Skylight and 2 ND filters (2x and 4x). 2 more sets (one for s/w, one for colour) could be purchased seperately, each consisting of 4 filters.

Edit: I measured the front thread, which is meant to be used for the special lens hood ( a cylinder as long as the lens). It is either 72mm or 71.5mm, but the pitch could be different from the standard, to prevent users to abuse it for filters.

Last edited by RKKS08; 02-13-2012 at 10:20 AM.
02-13-2012, 11:08 AM - 1 Like   #3
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QuoteOriginally posted by RKKS08 Quote
I do own this lens and its manual. Tokina DOES NOT RECOMMEND the use of front filters.
<snip>
It is either 72mm or 71.5mm, but the pitch could be different from the standard, to prevent users to abuse it for filters.
My Tokina 500/8 has a 75mm x 1.00 pitch thread for the metal hood on the front of the lens, which is completely non-standard for any filters (almost all filters are .75mm thread pitch). This effectively prevents the mounting of any filter directly to those threads on the lensbody.

However, as RKKS08 states above, the hood itself has a threaded interior at the base that is 72mm and looks to be .75 thread pitch. You'll have to very carefully lower your 72mm filters *into the hood* and screw them on to face front or the hood cannot be mounted. Doing this would also remove the ability to reverse the hood and further degrade the sharpness and brightness of this lens (which isn't tops already)... so, really, don't use any front filters on the Tokina 500/8!

**On the plus side, this thread got me to try a 72mm pinch cap on the reversed hood, and it works much better than the plastic slip-on cap from Tokina (which always slides off in the bag)! Thanks for that!

Last edited by panoguy; 02-13-2012 at 11:18 AM.
02-13-2012, 12:22 PM   #4
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Original Poster
Thanks for the info, guys. My wife wanted a UV filter on the front to protect the lens, but I guess that's a no-go. The original Tokina cap does kinda suck.

On the plus side, the lens is reasonably sharp. Not equal to the Tair, but still... quite decent. Much better than the cheap mirror lenses.

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