[MilkaSchokoHase87]

Hey Pentaxians,

I bought a cheap (? 250€! ) 50mm F1.2, unfortunately with a lot of fungus inside.
No Problem for me, I thought. I often dissambled and assembled manual pentax lenses but never had this problem:
I never put out the lens barrel. So now I have to re-calibrate and adjust the lens.
Never did this before and I tried so many positions but not get it beack to basic settings.
I thought measuring the distance from top to back would be alright. Otherwise I used a white marker to mark the transitions - i forgot it. I forgot to make fotos too .

BUT: the lenses are free of fungus now .

Can someone please help to assemble the lens? Some tips and tricks? are there special positions of tubus/lens barrel too look for.

Pictures would help a lot, if possible.

If I will get it back to genuine settings, I will Dissamble the whole lens again and make fotos of the complete Dissamble/Assemble for all Users and the Dissambly Data Base.
So every tip and trick you will give is a great help for everyone.

If someone will not give these information to everyone, please write me a PM. If you not want to have published your knowledge let me know also, and I will conceal the information to adjust in the Dissambly Data Base.

Great Thanks to all Answers,

Milka

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[Tonytee]

Have you tried fishing around on Youtube? There are many great videos showing how to repair many types of photographic equipment. Hope this helps.

Antonio

[MilkaSchokoHase87]

Not for the 50mm F1.2

[sergysergy]

dcshooter may help. send him a message

[niceshot]

did you take apart the helicoil?

[Not a Number]

If by original settings you mean infinity focus then you either need a collimator or focus on a distant object. Adjusting the infinity focus should be pretty much the same as with other lenses of the same focal length in the model series (e.g. SMC 50mm f1.4). Depending on the design of the lens this is done with the outer barrel focusing ring removed. Once set, slip the focusing ring on - align the infinity mark with the focus indicator mark and tighten the screws that anchor the ring to the barrel of the helicoid mechanism. Some lenses you can't get at the helicoid barrel to turn it so you have loosen and tighten the anchors to turn the helicoid barrel beyond the stops on the focus ring.

Provided you reassembled the helical barrels in a position where the travel is enough for infinity and close focus. If not you have to reassemble this at the proper entry points.

There is a thread on how to DIY collimate using a film SLR body. Or just use a distant object that is focused at infinity on a same focal length lens.

[MilkaSchokoHase87]

For a better communication lets please use the following numbers of the picture for the description, or give me the name of the parts please. I did never heard the words holicoid or barrel. sorry =(

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[Kerrowdown]

What number is the wee man in the top left.

Looking at all these bits, is why I'd put mine in somewhere if anything needs done.

[Not a Number]

Part #2 should break down into two major components:
a. outer focus ring (where the textured grip goes)
b. the outer barrel of the helicoid. You can see the silver helicoid threads

The outer ring should be held in place by 3 screws. Remove these 3 screws and the focus ring should slip. Reassemble the two barrels of the helicoid. Reassemble the rest of the lens except for the focus ring (call it 2b). Mount the lens on a camera body, adjust the focus on a distant object that focuses at infinity. Slip 2b onto the barrel - align the marks to infinity. Replace the screws. Check infinity focus as well as minimum focus. Loosen screws and adjust as necessary.

If you can't get infinity or minimum focus it is because you didn't start the helicoid at the correct entry point. Disassemble the helicoid and try again. If you didn't make markings to help you find the correct entry point it is just a matter of trial and error.

Since you have the helcoid apart you may as well clean it and re-grease the threads. It should be possible to clean all the lens elements without taking the helicoid apart.

In this thread on disassembling the 50mm f1.2 lens the third to last and following pictures show the removal of the focus ring. The last photo shows the helicoid assembly without the focus ring.
https://www.pentaxforums.com/forums/114-maintenance-repair-articles/278469-pe...mbly-pics.html

Although this is for the 28mm f3.5 the basic design is the same lacking some of the extra rings and screws. See photo 5 in the sequence on which screws hold the focus ring.
https://www.pentaxforums.com/forums/54-pentax-lens-articles/179912-pentax-k-2...-cleaning.html

[Audi 5 cyl]

You have 8 different positions to start screwing part 1 into part 2. Screw it in, assemble, test. If it does not work, disassemble, screw it in, assemble and test. If you are lucky, hit and miss will give you results relatively fast. And that is pretty much what I would advise you to do.
Alternative is to look around the web for a picture of the lens at infinity and estimate the length of the part 1 that is visible in the front when screwed into the part 2 and then test trying to achieve that without a complete assembly.

Hope it works for you. If not, I'll be happy to liberate you of your tortures at a buying price

Regards,
Marko

[MilkaSchokoHase87]

Hey,
here is a step by step assembling of the 50mm F1.2 lens. I did not know where the failure is but at the end I did get near infinity but no close focus at 0.45m, just up to 0.6m (see pics).
The last pictures are taken with K3 at infinity (F1.2 - F2 - F2.8 - F4) and at close focus (F1.2 - F2 - F2.8)

[MilkaSchokoHase87]

here is part II

[MilkaSchokoHase87]

here is Part III

[MilkaSchokoHase87]

here are some examples taken at infinity and maximum close focus (between 0.55 and 0.6m). on K-3.

close focus @ F1.2 / F2 / F2.8
infinity @ 2 / F2.8/ F4

Hope you can find the error in my Assembling to solve the problem. Great thanks for all your answers.

[niceshot]

congrats nice job, and rewarding too.