I recently got ahold of a Vivitar 28-85 f/2.8-3.8 which is made by Kiron for the Pentax K mount. I have been using it on my old MX body and it works great, but it is a pretty large and heavy lens (compared to my SMC-M lenses) and feels unbalanced on the tiny MX body.
I reality, I think I would rather use the lens on my 5DmkII as a fun walk around or even travel lens. I've read seemingly as much information as I can about removing the aperture lever so it will clear my 5D's mirror, but I cannot seem to find any clear instructions.
I also would like to know which adapter would be the best option for this lens. It has to be sturdy because the lens is heavy. I also want one that aligns properly at 12 o-clock if at all possible.
So have any of you alt shooters gone through the task of modifying a Pentax mount lens for use on Canon full frame cameras?
I have a number of converted Pentax K lenses that I use on FF Canon DSLR. The conversion process is also known as an "aperture leverectomy". The K to EOS adapters that I use are all relatively old, and all provide correct alignment of the lens aperture and focus index marks with the body. It's my understanding that some newer adapters have an offset angle that allows you to use at least some K lenses on FF bodies without the leverectomy, as the offset angle places the aperture lever and lever shield out of the way (which must he at about 12 o'clock). So, I guess if you want to buy a new adapter, you'll have to look for ones that provide the correct orientation.
Anyway, here's a bunch of links that you might find useful. The last one shows some leverectomy example photos.
Oh wow thank you Jim! That's probably the most helpful response I've ever gotten on this board before.
I'll pour over those links you provided, but that is an interesting thought about the adapter intentionally having the lens offset to make room for the mirror, I'll have to see at which point the lens clears the internal baffles.
Edit: Turns out it doesn't clear the mirror at any point, another interesting thing is that at infinity I have to pull the lens away from the camera a little bit to bring things into focus, I'm assuming the thickness of the adapter is what would allow infinity focus?
I have disassembled a Pentax lens before to try and repair the focusing of the lens as it was stuck between mfd and infinity. It wasn't too difficult to remove the lens mount if I recall, but I did lose some small pieces so I'll have to be careful.
As a side note, with the lens in question, do you think it's even worth the hassle of modification and permanently altering the lens thus prohibiting it from being used on Pentax bodies again?
AbramG wrote:
As a side note, with the lens in question, do you think it's even worth the hassle of modification and permanently altering the lens thus prohibiting it from being used on Pentax bodies again?
An aperture leverectomy doesn't prevent you from using the post-op lens on any Pentax body, it just means that you have to use "stop down" metering, (i.e. focus and compose wide open, then manually stop down to the "taking aperture" before taking the photo). On some Pentax DSLR, you have to use the 'green' mode (whatever that is) for correct metering, but you still have to use the "stop down" approach. AFAIK, most if not all of the modern Pentax DSLR can't use the manual aperture control lever anyway.
My personal preference is to simply snip off the protruding aperture lever with a pair of bull nose cutters. Sometimes it's easy to remove the plastic ring that has the aperture shield, in which case I do that, before snipping or grinding off the shield.
In my experience, an aperture leverectomy has no effect on the lens resale value, at all. I've done it to some pretty primo glass, including SMC Pentax 18/3.5, SMC Pentax-A 100/2.8 Macro, SMC Pentax 200/2.5 and SMC Pentax-A* ED 200/2.8. I've since sold all of them for about the same prices as the original costs for buying them. I'm currently looking for a SMCP-M* or -A* 300/4 lens. The first thing I'll do after unwrapping and inspecting it, is perform the leverectomy. I don't even use any anesthetic! Well, at least not on the lens.
