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05-12-2008, 11:17 AM   #1
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Old lens, mount issue

I won a cheap lens on ebay (paid only 10) last weekend, which arrived today. All seemed interesting.

Lens is a Vivitar 70-210mm f4.5-5.6 MC, so nothing special, but in decent condition. Very clearly says P/K on the base, sold as a K mount lens. I have the K100D Super.

It doesn't mount. That is, it connects, it won't twist into place ( but I did manage to get a test shot off using it like that!). Here are a couple of (quick) photos showing the mount compared to that on my Pentax SMC-M 50mm f1.7 , you can see there is a difference.



So I am now wondering what is going on. Is there anything I can do, is it my mistake, or what? Get the feeling I've missed something.

05-12-2008, 11:19 AM   #2
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the solution is simple

take a file, and file away a chunk off that thing.

thats the only way.
05-12-2008, 11:34 AM   #3
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QuoteOriginally posted by Gooshin Quote
the solution is simple

take a file, and file away a chunk off that thing.

thats the only way.
I'd figured out that would work as a last resort! Its a fair chunk to remove, though, and I haven't got metalworking kit anyway.

But my question, then, if that is the only way, is where is all this talk of pentax k-mount compatibility, when lenses like this exist. How does one avoid this? (ant let's avoid the obvious "buy modern lenses" answer).
05-12-2008, 11:37 AM   #4
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QuoteOriginally posted by MrA Quote
I'd figured out that would work as a last resort! Its a fair chunk to remove, though, and I haven't got metalworking kit anyway.

But my question, then, if that is the only way, is where is all this talk of pentax k-mount compatibility, when lenses like this exist. How does one avoid this? (ant let's avoid the obvious "buy modern lenses" answer).
Before you take out your saw or file, I would recommend getting a small set of jewlers screw drivers and removing the shield totally.

The lens can actually work without it, and any filing should be done off lens, so the lens is not filled up with filings.

the mod takes about 10 minutes with a fine saw (hacksaw, coping saw etc, or possily even a very sharp knife, since this part is only aluminium any way.

If you cut the shield down to size and re-install it, cover the bare metal edge with black p paint to avoid internal reflections.

05-12-2008, 11:57 AM   #5
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[QUOTE=Lowell Goudge;
the mod takes about 10 minutes with a fine saw (hacksaw, coping saw etc, or possily even a very sharp knife, since this part is only aluminium any way../QUOTE]

MrA,
Lowell is correct about removing the baffle,but it is most likley made of brass, which is very hard. Remove the baffle and carefully trim the baffle to height of no more then 8mm above the bayonet mounting surface. I use a dremel tool with a cutoff disk. Finish the edge with a swiss file and use a black marker to finish the job. This will allow it to clear the interior of the mirror box,including the SDM contacts. From the photos, it souldn't even be required for this lens.

Dave
05-12-2008, 12:35 PM   #6
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Well that worked a treat - one borrowed razor saw later and all is well. That piece isn't brass, as it turns out, silver-coloured (so I could say steel but that'd be a guess). Lens mounts (and more importantly, perhaps, dismounts) perfectly. Now to play.

Thanks for the help.

Still interested in an answer to my question of why there are K mount lenses out there which don't fit, and how to avoid them.

Last edited by MrA; 05-12-2008 at 01:21 PM. Reason: typo
05-12-2008, 12:44 PM   #7
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first of all it IS a Vivivtar

second, i believe the extra space that is provided for modern (and pretty much all the other lenses) with the shorter lip is... used for something, i forget what tho, anyway the Vivtar i think was designed without that in mind...

or something...

i'm just digging the odd bits of info i have in the back of my head.
05-12-2008, 01:17 PM   #8
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QuoteOriginally posted by MrA Quote
Well that worked a treat - one borrowed razor saw later and all is well. That piece isn'tt brass, as it turns out, silver-coloured (so I could say steel but that'd be a guess). Lens mounts (and more importantly, perhaps, dismounts) perfectly. Now top play.

Thanks for the help.

Still interested in an answer to my question of why there are K mount lenses out there which don't fit, and how to avoid them.
For compatibility try this link

Pentax Lens/Camera Compatibility - Mark Roberts Photography

I hope you blacked out the cut metal, it will cause internal reflections if you did not

05-12-2008, 02:16 PM   #9
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QuoteOriginally posted by Gooshin Quote
first of all it IS a Vivivtar

second, i believe the extra space that is provided for modern (and pretty much all the other lenses) with the shorter lip is... used for something, i forget what tho, anyway the Vivtar i think was designed without that in mind...

or something...

i'm just digging the odd bits of info i have in the back of my head.
Soligor has it on some lenses too. The lense is still PK compatible, it's just that the DLSR's has less space inside the house then the older cameras.
05-12-2008, 02:23 PM   #10
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QuoteOriginally posted by Lowell Goudge Quote
If you look closely there is a link that describes this exact issue including a picture guide for where to cut!

Flange Fix for Vivitar Lenses - Mark Roberts Photography
05-12-2008, 03:07 PM   #11
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I saw that pic, which very reassuringly corresponds exactly to what I undertook earlier this evening. It's a handy site, I didn't have that link before.

Now I just have to wait for tomorrow evening when I can test the lens properly / in daylight.
05-12-2008, 07:36 PM   #12
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QuoteOriginally posted by Zewrak Quote
Soligor has it on some lenses too. The lense is still PK compatible, it's just that the DLSR's has less space inside the house then the older cameras.
It has to be cut back to fit on cameras fitted with the contacts for SDM, or used earlier for power zoom. FWIW, I have never heard of a Pentax or Takumar lens that would not fit without the fiddling.
05-12-2008, 09:03 PM   #13
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QuoteOriginally posted by Canada_Rockies Quote
FWIW, I have never heard of a Pentax or Takumar lens that would not fit without the fiddling.
That makes my head hurt... Can't quite figure out what you're sayin'.
05-12-2008, 11:50 PM   #14
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QuoteOriginally posted by Canada_Rockies Quote
It has to be cut back to fit on cameras fitted with the contacts for SDM, or used earlier for power zoom. FWIW, I have never heard of a Pentax or Takumar lens that would not fit without the fiddling.
I have only seen this in real life once though. It shouldn't be that common. I have no clue why they did it though, was it for Ricoh cameras? I know the Soligor zoom that I saw was used on a Ricoh back in the days.
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