Pentax 67 105mm 2.4 - Part 1 Disassembly 

My friend I landed on this video just for a problem on infinity focus problem in my 105/2.4 lens. Do you have any more information?

@@TheFelipemahler I too have the same lens with no focus to infinity, have you found a solution, and if so, any chance you could share your findings?

@@SmalltimR any update? I am having the same problem right now

@@r2r0TV Yes, absolutely. As it turns out, it was the outer rear element that was inverted - someone took the lens apart to clean it I'm guessing, and when they re-assembled it, they inverted the rear element in what I'd call the stack. Which was apparent, as the ring which held the element has a chamfer for notch that will only fit the element one way, and yet, the person put it in backward. Anyways, long story short and a few tools later, and the lens focus is now perfect - as I was able to adjust the helicoil screws to calibrate the focus using a 67 to K-mount digital adapter (for real-time calibration), without issue. Following this, I also completely cleared the yellowing in the rear elements using a small UV lamp from Amazon, after leaving both sit above the lamp for a few days. - hope this helps and if you have any questions, please do not hesitate to ask ps. I suck a fixing things and had low expectations for this lens, but I'm happy to say that I was able to fix this without any issues whatsoever, even with my limited skills

@@SmalltimR so so helpful!! I have a 90 and 55mm and they both focus perfectly, except my 105. im going to give it a try! I hear u can adjust the infinity focus? I know I have to take out the front plate with the lens info and underneath there is some screws! from there I do not know what to do!

Smart decision

I use iFixit mako driver kit

@@yorgic thank you!

you can just unscrew the rear element with a lens spanner if removing the rear element is the only thing you're trying to do.

@@andrewharrington795 Bad luck, it was not on the rear element. But one the one after that. It's a piece of two elelments together. Maybe glued/bonded/cemented (?) together. No idea how fungus could get there. But apparently it can. Any idea whether those two lens elements are actually cemented? Or just very tightly together?

@@caleidoo in my copy of the lens I was able to disassemble the rear group from it's housing. Threads were tight but I didn't encounter any glue there or on the glass itself.

@@andrewharrington795 Strange. The final group is held together, so a sub group of three, where only the last can be removed from the rest. What remains is the two lens other elements tightly together. See optical formula: skrasnov.com/wp-content/uploads/2017/03/pentax-67-105mm-f24-formula.png I haven't used brute force yet - I would need tools and I'm afraid to damage it. They look really tight, I can only see a small line between the two metal barrels of the elements. On the other hand, if there's fungus, there should be a way to open it. And if they are cemented, there would not be fungus in between, correct?

@@caleidoo Did you remove the ring surrounding the rearmost element with a lens spanner? That should allow that one to come out and give you access to the rearside of the other two, which is where I found fungus in my copy. Here's the ring I am talking about: imgur.com/a/c9i1VtK

Is just need twist the focus ring to a correct angle to take apart front elements and lens-body

I used a piece of rubber (bicycle tube).

@@yorgic Oh I see, so just creating enough friction with the front ring made it possible?

You have to carefully take out the front ring with a rubber tool (4:50). Then remove the cover (4 screws). Inside the gap there are 3 screws, loosen them to adjust infinity focus. Tight the screws when it's ready.

@@yorgic Awesome - do you know what size is used for this particular lens? According to Pentax forums, the filter size is reported to be 67mm, though I'm not sure if that reflects on the tool as well, or if it needs to be another size?

@@SmalltimR I think 60 or 62mm for the tool

@@yorgic Hi, I just wanted to update and say that I received the tool and have successfully removed the ring. With that said, and after loosening the three screws inside the lens, I was able to adjust the focusing ring, though it would appear that the lens cannot focus any further than approximately 4 feet when the helicoil is maxed out Any ideas what might cause this? Or how I could fix it? As it stands, the lens is effectively a macro lens

Part 2 shows the right position for the helicoids. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-mE_9uzmmGls.html