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02-04-2011, 06:56 AM   #1
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Help with fitting 6x7 lens to K fitting

G'Day All

I have picked up a SMC Takumar 6x7 f4 600 mm lens to use with a K-x and K200D.
The problem i have is that there appears to be a piece missing from the back of the lens. What i would like to know is .

what is missing ?
Where if possible can i get it?

Thanks Mick

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02-04-2011, 07:50 AM   #2
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I have this lens and there is nothing missing.

The inner ring is to hold the 77mm filters inside the lens. The lens is mounted on a Pentax 6x7 on the outer mount. You just screw the outer ring on the mount, there is no security.

Now, it's a big tricky to mount this lens on a K-mount camera. Most 6x7 to K adapters (from 3rd parties) have only the inner mount for the 6x7 part, so it is not possible to mount this lens with such an adapter.

Anyway this SMC Takumar 6x7 600 F4 is a good lens but has far too much of chromatic aberations for satisfying results on a digital Pentax APSC. Lets just say that it's good accross the 6x7 image circle, but not good enough for the center magnification of a 10Mpx + APSC digital sensor.
02-04-2011, 08:13 AM   #3
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Thanks for your answer. After stumbling around the net for an hour or so i had just come to the conclusion that ineed an outer bayonet adapter. Now to find one at areasonable price.

02-04-2011, 08:47 AM   #4
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Pentax 67 6X7 lens adapter to pentax K PK K20D K200D - eBay (item 380108865601 end time Feb-24-11 12:30:26 PST)

seems to have the outer bayonet.

02-04-2011, 11:02 AM   #5

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That is a really huge lens. I hope you're not expecting more than a 600mm + 1.5 crop factor for focal length out of it.
02-04-2011, 02:37 PM   #6

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Pentax's K Mount Adaptor does have outer bay tabs on it, so it can be used with the 600mm. It should be remembered that the longitudinal chromatic seen on the 600 is way reduced when stopping down. This is because the degree of color correction varies with lens zone. The ridiculous color fringing seen at f/4 almost completely vanishes by f/22. In flat lighting situations, you may not see any fringing even wide open. High constrast is another story. I can't tell from your picture but there should be a light baffle in the rear of the 600 that is basically a metal piece with a square hole with rounded corners. If you are considering using the rear filter bay, I suggest using multi coated filters only. The uncoated ones cause reflections that show up on the film/ sensor. I use my 600 with the 6x7 body and a Leicaflex body, mostly for birds but also for sunsets, Bobcats and lightning.

Last edited by desertscape; 02-04-2011 at 02:46 PM.

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