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05-02-2013, 09:59 PM   #1
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smc pentax-a 1:1.7 50mm lens on a Canon 6D?

I'm brand new to the forum. I just bought a Canon 6D and entered the world of digital photography. However, I'd really love to use my SMC Pentax-A 1:1.7 50mm lens on my 6D. What kind of mount do I need to get to do this? I also have a Tokina zoom that I'd like to use as well. I get a little confused about exactly what kind of mount I need for my Pentax 50mm to fit properly. Any help would be appreciated!


05-02-2013, 11:32 PM   #2
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Suggestion: to use Pentax K lenses on a full frame Canon body you will probably have to modify the lens or the body to prevent mechanical interference.

Sell the Pentax A 50mm for $80 or so and either buy a second hand Canon EF 50mm f/1.8 for roughly the same amount, or pick up a Pentax M 50mm f/1.7 or an SMC Takumar 55mm f/1.8 for somewhere closer to $40. The M series lens is optically the same as the A, minus some electronics you don't need on a Canon body. I don't believe the 55mm Takumars need any modifications other than an M42-EOS adapter for use on a full frame Canon body.
05-02-2013, 11:34 PM   #3
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you cant really use it without destroying the lever on the back of the lens.

Forget about it Least one more piece of pentax glass gets lost for all :P

If you had google tho, you would have found this..
05-03-2013, 01:29 AM   #4

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I have the A50/1.7 modified for a 5D.
There is no other way other than chopping off the aperture lever.
You also need to remove the lever guard (this is easy, just 3 screws)
I used a fungused M50/2 aperture lever and chopped that instead (they were the same).

As suggested above, you are better off just using the EF50/1.8 (real cheap, but real crappy build too, but it does its job as a fast 50)
Otherwise, get a 7 element version of the S.Takumar 50/1.4 or a S.Takumar 55/1.8
I have the 55/1.8 and its very nice on the 5D.

FYI, and perhaps its my copy, but I've compared the EF50/1.8 vs the A50/1.7 and 55/1.8.
The 55/1.8 was the best (size, build, rendering, sharpness wide open, MF smoothness)
The EF50 was the sharpest, but it was dimmer by 0.5 to 0.7 stops at all apertures I tested up to f4.
It also seemed to have a bit more DOF at all tested f-stops.
The A50/1.7 is a bit better for colors and rendering to me (characteristically Pentax) (as well as the 0.5 stop difference I observed) vs the EF50/1.8.
Of course the 2 Pentax have smoother far MF than the EF50.

But don't compare, and the EF50/1.8 is cheap and does the job like any fast 50mm.

Last edited by pinholecam; 05-03-2013 at 01:50 AM.
05-03-2013, 02:33 AM   #5
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Trade the A50/1.7 for a M50/1.7 (or M42 55/1.8) and cash.
You will find many takers.


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