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how to stop lens changing focus when setting aperture?
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PostPosted: Sun May 18, 2014 9:55 am    Post subject: how to stop lens changing focus when setting aperture? Reply with quote

I have a beautiful Canon LTM f3.5/135mm lens. Both focus ring and aperture ring feel as if working perfectly well, not loose nor hard. However I am used to focus wide open and set aperture after. If I do this with this lens setting the aperture will turn the focus ring and put it out of focus again. Is this a well known problem with some lenses? How to best avoid this? ( besides setting the aperture first, which I have to do now )
As mentioned I feel that both rings work normally. But in search for a solution, if I wanted the focus ring to become harder, how to do that? Not sure if I want to try to take out helicoid grease, make it dry doesn't feel right. Or de-clicking the aperture ring, though I am not sure if this would help, as it is it isn't hard.
any ideas?

cheers, andreas


PostPosted: Sun May 18, 2014 11:46 am    Post subject: Reply with quote

Andreas,

You're doing right, setting the focus first, and then the aperture.
One possibility for fixing is to replace the small spring of the steel ball which clicks the f-stop position for another with more compression resistance.

Best,

Renato


PostPosted: Sun May 18, 2014 12:52 pm    Post subject: Reply with quote

I can sometimes get a few fingers on the barrel to steady it as I'm changing the aperture. Failing that it has a distance scale?


PostPosted: Sun May 18, 2014 1:06 pm    Post subject: Reply with quote

thank you for your answers

Just found out that the Canon LTM 3.5/100 behaves the same, possibly it is typical for some Canon LTM tele lenses and I wonder which others exactly do.

Renato I believe either you or I must misunderstand: my thinking is that replacing the aperture ring with one that has more resistance would only aggrevate the problem, no? I should try the opposite though, try to de-click.

tromboads I am afraid that steadying the focus ring with other fingers while changing the aperture, as you suggest, is the only viable solution. Have not tried to rely on the distance scale, anyway either I don't like. Unfortunately for me this issue is a reason to not use them Sad


PostPosted: Sun May 18, 2014 2:19 pm    Post subject: Reply with quote

Andreas,

I jetted an eye over a lens as yours in the net, it seems like the 3.5/135mm M42 in terms of construction. I had 5 or 6 of these lenses already.
The focus helicoid is positioned over the focus ring, so i think there is some dirt which are making possible both parts to touch one to other. Cleaning internally can solve the problem, it would be my first try.

Cheers,

Renato


PostPosted: Sun May 18, 2014 3:09 pm    Post subject: Reply with quote

Hi Renato,

oh wow, thank you so much for your effort! it's these two lenses:
http://www.canon.com/camera-museum/lens/s/data/100-1000/s_100_35v3.html
http://www.canon.com/camera-museum/lens/s/data/100-1000/s_135_35v3.html

your suggestion is very good! a few other Canon LTM lenses that also have the aperture ring in front don't behave like this. Trying to decrease the friction between the internal aperture ring assembly and the sourrounding focus barrel must be the way to go! will give it a try.

I am a bit doubtful that I an do it though, still wonder if this might be normal, or at least very common behaviour of these lenses. In case I can fix it I shall report back,

thank you again, cheers, andreas


PostPosted: Sun May 18, 2014 4:08 pm    Post subject: Reply with quote

Andreas,

Youŕe welcome, give us feedback of it,

Cheers,

Renato


PostPosted: Tue May 20, 2014 3:11 pm    Post subject: Reply with quote

RSalles wrote:
Andreas,

Youŕe welcome, give us feedback of it,

Cheers,

Renato


+1: my rf nikkor 35/2.5 has the same "issue": everything feels fine with my lens, but if you find a way around this it would be great.


PostPosted: Wed May 21, 2014 12:20 pm    Post subject: Reply with quote

RSalles wrote:
Andreas,

Youŕe welcome, give us feedback of it,

Cheers,

Renato


the problem is solved for the 3.5/135. That was very easy to do, now there is very little resistance between the aperture clicks, changing aperture doesn't move the focus ring any more and it's easily 'reversible'.
no success yet with the 3.5/100. I'd have to disassemble the lens further which I have not yet dared. If anyone reading this knows how to disassemble the 3.5/100 LTM Canon please help me or if you know of one please point me to a site that gives instructions.

Aanything wrote:
RSalles wrote:
Andreas,

Youŕe welcome, give us feedback of it,

Cheers,

Renato


+1: my rf nikkor 35/2.5 has the same "issue": everything feels fine with my lens, but if you find a way around this it would be great.


I am afraid that most likely the solution I found for the Canon LTM 3.5/135 won't help in the case of the Nikkor, that each lens has, if one at all, it's own solution. But if interested I shall take and post a few photos to explain soon.

It is very interesting to know that this Nikkor has the same 'issue'. I have been bidding on this lens now and then. As mentioned this behaviour is a reason why I wouldn't use a lens much, for now I won't bid on this famed Nikkor again.

Generally I would be very interested to find out which lenses do, or are in danger to behave like this. Better I open a thread asking this question, wonder if better at rangefinder forums or here. If anyone reading this knows of a lens that has this 'issue' please be so kind and report!

cheers, andreas


PostPosted: Wed May 21, 2014 1:08 pm    Post subject: Reply with quote

Andreas,

Glad to know it, what did you do to fix the issue with the 3.5/135?

Renato


PostPosted: Thu May 22, 2014 12:36 pm    Post subject: Reply with quote

RSalles wrote:
Andreas,

Glad to know it, what did you do to fix the issue with the 3.5/135?

Renato


Renato here you go:

the lens:


one can simply screw it apart in the middle, the upper part contains the entire optical block inkl. aperture, the part remaining consists of helicoid and mount only:


the 'click mechanism' is readily revealed and quite curious:


here in detail, to 'fix' it I didn't even unscrew that assembly but simply bent that part that holds the rounded pin that snaps into the grooves a bit upwards

just enough so that the aperture still 'clicks' but loose enough so it doesn't turn the focus ring

the 3.5/100 seems to be made similar at first sight, but the upper part that unscrews only holds the front block, aperture assembly and rear block remain inside the barrel:


turning the aperture ring is turning the full housing / assembly of the aperture, that is all seen below the rim where the arrows meet


there is an 'open ring' inserted in that space between barrel and aperture assembly, but cleaning it, even leaving it off and putting a bit of grease in the gap doesn't loose up the aperture assembly well enough for not moving the focus ring when turning


cheers, andreas


PostPosted: Thu May 22, 2014 1:36 pm    Post subject: Reply with quote

Ok, thanks Andreas, for the 100mm the disassembling procedure must go further to arrive to the same point as the preceding lens.
Good luck, and if you arrive to do it, keep us informed,

Cheers,

Renato


PostPosted: Thu May 22, 2014 1:44 pm    Post subject: Reply with quote

RSalles wrote:
Ok, thanks Andreas, for the 100mm the disassembling procedure must go further to arrive to the same point as the preceding lens.
Good luck, and if you arrive to do it, keep us informed,

Cheers,

Renato


hihi, right..just how to? Smile


PostPosted: Mon Jun 16, 2014 7:08 am    Post subject: Reply with quote

Is it being used on a rangefinder camera? If yes, there is no need to change anything on the lens. Just set the aperture, focus and trip the shutter.


PostPosted: Mon Jun 16, 2014 10:09 am    Post subject: Reply with quote

zanxion72 wrote:
Is it being used on a rangefinder camera? If yes, there is no need to change anything on the lens. Just set the aperture, focus and trip the shutter.


I use it on either on Ricoh GXR M or NEX5N. As mentioned I am used to focus the lens wide open, imo allows for more prcise focusing. In case of the 3.5/100 it will be better to set aperture first.


PostPosted: Mon Jun 16, 2014 10:17 am    Post subject: Reply with quote

Thanks for sharing, I got the same lens and the same problem Smile


PostPosted: Mon Jun 16, 2014 10:55 am    Post subject: Reply with quote

Jesito wrote:
Thanks for sharing, I got the same lens and the same problem Smile


interestingly, as Nordentro commented in another thread, the V2 of this lens, the silver / black one, doesn't have this problem: http://forum.mflenses.com/7-canon-rangefinder-lenses-t66636,start,15.html


PostPosted: Thu Feb 12, 2015 12:15 am    Post subject: Reply with quote

kuuan wrote:
RSalles wrote:
Andreas,

Glad to know it, what did you do to fix the issue with the 3.5/135?

Renato


Renato here you go:

the lens:


one can simply screw it apart in the middle, the upper part contains the entire optical block inkl. aperture, the part remaining consists of helicoid and mount only:


the 'click mechanism' is readily revealed and quite curious:


here in detail, to 'fix' it I didn't even unscrew that assembly but simply bent that part that holds the rounded pin that snaps into the grooves a bit upwards

just enough so that the aperture still 'clicks' but loose enough so it doesn't turn the focus ring

the 3.5/100 seems to be made similar at first sight, but the upper part that unscrews only holds the front block, aperture assembly and rear block remain inside the barrel:


turning the aperture ring is turning the full housing / assembly of the aperture, that is all seen below the rim where the arrows meet


there is an 'open ring' inserted in that space between barrel and aperture assembly, but cleaning it, even leaving it off and putting a bit of grease in the gap doesn't loose up the aperture assembly well enough for not moving the focus ring when turning


cheers, andreas


I have the same problem with the 135 f3.5 and would like to see the photos if you still have them.
Phil