How to adjust infinity on the lens

BrianSVP · Joined: 09 Jun 2023 Posts: 343 Location: Philadelphia

Congratulations on getting the front open! If you want to try to reassemble the helical without taking off the rear mount and removing the keys, here's how to do it:

On the front side helical with the larger threads, trace one of the threads around from the top to the bottom and count how many times you circle around the barrel over the course of the thread, (x) turns.

Now take the center ring and screw it into the rear half all the way. Then, back it off x turns + 1. Determine the correct orientation of the front half with respect to the keys. Make sure the aperture lever is on the correct side. Find the entry point roughly 1/8 of a turn past where you need to be, and insert the front half there. You'll likely bottom out the front half against the keys. now, turn the rear half until you get the keys lined up with the slots.

Once lined up, holding the front and rear halves in place, turn the ring to bring both halves together. As you advance it, make sure any internal linkages for the aperture mechanism are lined up correctly; you might want to look from the rear with the rear group removed if this is difficult to do with the group in. If it binds, don't force anything. Just back it off some and try again.

With a lens of this focal length, there is usually enough excess travel in the helical that it's not critical which entry point you use.

If you're unable to do it this way, you can remove the rear mount and keys, do each half of the helical separately, and then reinsert the keys. It can be easier that way if you are careful, but also runs the risk of aperture components flying off every which way, so it's worth trying it the above outlined way first.

kiddo · Joined: 29 Jun 2018 Posts: 1237

wow , thank you, i will need some more patience to try this (tomorrow), but iÂ´m having the issue with not recording the position of the entrance of the helicoid , there are 8 of them , i guess i will have to try each one of them until getting the proper thread, right?
the issue i had, after trying to mount it couple of time, it was that the aperture wasnt working properly, either wonÂ´t open all the way or not closing all the way, so i should start with leaving the A/M switch on M, right?

kiddo · Joined: 29 Jun 2018 Posts: 1237

Of course I couldn't have waited for tomorrow
I measured the thread for the larger helicoid and it only takes a full turn from one extreme to the other
For now, I was able to aligned it and put it back together, but it would reach infinity

kiddo · Joined: 29 Jun 2018 Posts: 1237

Stupid me, forgot to put back the rear element lol
So I've put it back together again and BINGO , infinity is working
But there's an issue with the aperture , only opens 1 step no more

The question is, before assembling the 2 helicoids, A/M switch should be M? Aperture ring wide open? That's how I've tried it , but there's something wrong
I guess I'll have to try it all over again, or only open it a little bit ?

BrianSVP · Joined: 09 Jun 2023 Posts: 343 Location: Philadelphia

What is probably going on is that either there is an aperture control lever on the mount side that is incorrectly positioned with respect to the silver open/close lever on the helical side, or the black aperture cam lever is not correctly slotted to the linkage on the ring. This is typically the challenge of attempting to re-set a helical without removing a mount.

If you take the back group out, you might be able to peek in and see what's not lining up correctly, then back the helical out past minimum focusing distance and attempt to line up things correctly. Otherwise, the easiest thing to do at this point would probably be to pull the mount off and re-position everything correctly.

As far as teh A/M switch goes, it probably matters less than having the lens set wide open when you try to re-seat everything, which is typically the easiest spot to do it.

kiddo · Joined: 29 Jun 2018 Posts: 1237

Thanks to your excellent advice, I was able to put back together this lens.
I haven't got chance te read your last post, but you were right, the A/M switch, has a little lever that controls another one from the aperture unit, so this one was bend, I had to straight it up a little bit and now everything is working properly, aperture, focus . There were still an issue when installing the last ring that has the rubber on it, tighting up the 4 screws way to much, would not allow the focussing ring to move at all, so I had to tight them evenly just the right amount to hold the focussing ring not to slip in the one underneath ,well that was curious .

BrianSVP · Joined: 09 Jun 2023 Posts: 343 Location: Philadelphia

Very welcome!

Yes, on lenses with set screws from the outside like this, overtightening the screws or having them tightened to different degrees can cause the outer ring to get slightly out of round and bind when turning. It's usually a good idea to count the number of turns when removing them so you can get everything balanced properly on reassembly.

kiddo · Joined: 29 Jun 2018 Posts: 1237

I didn't notice if it was the same before opening the lens.
If I over tight the screws ,the focussing ring will not move at all,if I don't tight them enough , the outer ring will slip on the focusing ring, so, should I unscrew them totally and count each thread for screw ?
I still don't understand why overnighting the screws wouldn't allow the focussing ring move at all, as the would only good the front side of the ring where withered a gap

BrianSVP · Joined: 09 Jun 2023 Posts: 343 Location: Philadelphia

Yes, just make sure that each screw has gone in the same amount so everything is balanced.

If you overtighten them, the circular shape of the ring starts becoming something more like a triangle, pushing the ring out at the points where the screws enter and causing it to bend inward midway between them. Depending on the lens design and tolerances, this can cause binding where surfaces that aren't supposed to be touching begin to rub against each other. Likewise, if the screws are not put in the same amount of turns, the whole ring can be off-center, which can also lead to binding.

kiddo · Joined: 29 Jun 2018 Posts: 1237

Thank you again for your patience and educational sharing ,that really helped me fix the mess I've got into.
I have to admit ,this is my first time working with helicoids , even though I've watched lots of videos how to do it, and to measure thicknesses and distances , and to mark exit point etc, it's a whole experience to do it by your own (in this case, I wasn't alone at all). Besides ,there are lenses that are not very common, even though they might share same construction . I wasn't aware that a basic cleaning for optical elements would imply opening the lens completely(almost ), like in this case.
Now I feel more motivated to change grease of the helios 44-4 k mount (scratches on the optical group,but mechanical is fine).
Wish you best.

BrianSVP · Joined: 09 Jun 2023 Posts: 343 Location: Philadelphia

Really, diving in is the best way to learn! Due to the cult reputation of the Helios lenses, there are tons of resources on them out there.

The 44-4, being a later design, is a lot more similar in construction to the Japanese lenses of the 70's and 80's than are the 44 and 44-2, making it IMO a lot easier to work on. The older designs are much more similar to pre-war German lenses, but with substantially worse construction and quality control. As Steve mentioned upthread, the screws on the earlier models can be a pain to deal with due to their tendency to rust, and also due to the fact that they are made of very soft metal and are easy to strip out. The 44-4 in my experience doesn't have these problems and should be pretty easy to handle after your experience with the Tamron.