Pentax Super Takumar on 6D issues

[Lee Lounsbury]

Recently purchased an adapter to use some old pentax glass on my 6D. Crazy sharp and fairly cheap nowadays...

Anyway I found that upon focusing the Super-Takimar 35mm f/2 to infinity, the back element of the lens protrudes just enough to lock up the mirror after firing a shot. Upon focusing the lens a bit closer, the mirror falls back down. Tested this a couple of times, and I found no damage to the mirror, or to the back of the mirror assembly.

Should I be concerned about this, or is this just a minor inconvenience?

 

[Valvebounce]

Hi Lee.
I would be extremely concerned about this, if the mirror won't fall back, it must have forced its way past on the way up! There is such speed and the force of the mechanism to open the shutter and therefore inertia from the mirror opening that a slight interference will not stop the mirror, but only a spring* (and gravity) to return it, also the back of the lens is acting like a ratchet, smooth ramp to push past, hard edge preventing return.
Yes you should be worried about this in my opinion.
*I have not investigated the driving forces I took a guess, but I stand by the geometry.

Cheers, Graham.

Recently purchased an adapter to use some old pentax glass on my 6D. Crazy sharp and fairly cheap nowadays...

Anyway I found that upon focusing the Super-Takimar 35mm f/2 to infinity, the back element of the lens protrudes just enough to lock up the mirror after firing a shot. Upon focusing the lens a bit closer, the mirror falls back down. Tested this a couple of times, and I found no damage to the mirror, or to the back of the mirror assembly.

Should I be concerned about this, or is this just a minor inconvenience?

 

[Lee Lounsbury]

Well looks like this has now become a video only lens..

Thanks for your answer!