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03-24-2014, 06:54 AM   #1
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Takumar 500mm f/4.5 - FD mount?

I'm a Canon guy, but love Pentax Legacy glass. I picked up a Takumar 500mm 4.5 for a song, and I was expecting it to be an M42 mount. When it arrived, it was a Canon FD mount. Hmm. Ok, I figured this must be an M42 > FD adapter. But it doesn't appear to be an adapter, but that the rear section with the mount is original as an FD mount. I have come to the conclusion (although so far i haven't found any info to support this) that Pentax made an assortment of mount sections to be able to market across different platforms. Is this correct?

Does anyone know, or have you ever seen just the mount section available anywhere? Or, is there a way to modify/alter/dissassemble the mount section so I can convert it to M42 (preferred) or another mount?

Also, the lens takes a 127mm front cap. Is there a snowball's chance that I'll find one somewhere?

Thanks in advance!

03-24-2014, 07:24 AM   #2
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I think the Lens was altered, there was a Ebay add for such lens recently and I thought it mentioned altered mount. Saw this one recently see link and the altered lens was on the Similar Items list.. Pentax 500mm F4 5 027075002135 | eBay

Not much help but it has M42 mount,I have no interest in the above lens.
03-24-2014, 09:08 AM   #3
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That one looks like it comes apart very easily - his last picture looks like just the first group of elements removed from the main barrel. Odd.

I meant to take photos of it over the weekend, but life got in the way. Tonight I'll post up some pics of the mount assembly. It sure does look like it's original though, but a certain part of me says it's an adapter, as it say CF-P on the very back.
03-24-2014, 09:23 AM   #4
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The Takumar 500/4.5 and 1000/8 (M42) and the SMC Takumar 500/4.5 and 1000/8 (K) had a removeable mountor (you could actually own several lenses and swap the mountor among them). I once had a M42 Tak 500/4.5 for which the mountor had been 'converted' (i.e. molested) to Nikon bayonet. There was an article floating around the internet (maybe on MF Forum) that Associated Press had converted some of the Tak 500 and 1000 lenses to Nikon when they changed over around 1970.

Mine had a threaded pipe screwed into the end that accepted a T-mount > Nikon converter. Eric Hendrickson looked at the lens and made some adjustments so that a T > K converter allowed sharp but not infinity focus, but there was no way to restore the mountor. Finding a mountor today is just about impossible - you have to find a good lens and the wrong mountor, then a beater lens with the right mountor.

I lost interest in super-tele's - that's an entire skill all its own - on top of focusing problems with the K10D, so I sold the lens on. IIRC at the time the vlaue was around $325.

There's an entire thread about a member buying this lens on eBay and dealing with the molested mount. He bought a beater lens with a good mount, swapped the mounts, sold it to me and Eric worked on mine as well. Ironically, I got that Vivitar T > K adapter back when I bought the lens.

Last edited by monochrome; 03-24-2014 at 09:58 AM.
03-24-2014, 11:47 AM   #5
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Thanks monochrome. I saw that thread. I wonder what percentage of these (and the 1000mm) were butchered....
03-25-2014, 10:37 AM   #6
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Here's some photos of the mounting section. I have been able to get the very back ring off (that has the writing), but I can't separate/break ir down any further. It almost looks like the bayonet is screwed onto it, but I have tried everything to unscrew it to no avail. There are no screws anywhere (the 2 small dots on the front have no slot for a screwedriver/hex key/etc), and it really doesn't look like it can be broken down any further. Looks like OEM, but...? Anything I can do to make it more usable (M42/PK/etc)?


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500mm, 500mm f/4.5 fd, adapter, canon, fd, k-mount, m42, mount, pentax lens, section, slr lens, takumar, takumar 500mm f/4.5
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