Focusing problems

[parigby]

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I have acquired a 50mm collapsable f2.8 Elmar, which is in absolute mint condition. Upon receipt l noticed that with my M8, as expected, the focusing was a bit off, so therefore sent the lens away for adjustment, specifying the camera to which the lens would be matched.

 

Upon it's return, focus was spot on for about a dozen shots, and then went off.

 

I returned it and asked that it be corrected, and upon it's return exactly the same as above happened again.

 

To give you an indication of the extent of the problem the distance to the test object is 7 feet ( sorry l'm in old measurements, but the lens barrel reads in feet ) but to achieve pin sharp focus the lens has to be set to a notch below 3 feet.

 

Has anyone any idea what the real problem could be, and suggested course of action.

 

philip

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Philip - just to eliminate the obvious: I presume that you locked the lens into its extended position?

[parigby]

I did indeed Phiipp.

[jc_braconi]

I suppose you sent the M8 with the lens ...

[parigby]

I asked the repairer if this was necessary, but they said no, in that they would use a M8 they had to test the adjusted lens on.

[jc_braconi]

I asked the repairer if this was necessary, but they said no, in that they would use a M8 they had to test the adjusted lens on.

The adjustment is made on the camera... usually

I am curious to know what they can do on the lens ...realy

 

here are the points to adjust on the M8

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Edited October 15, 2012 by jc_braconi

[250swb]

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Why would you adjust the camera to suit one lens, it will throw out of focus all other lenses used on the same camera?

 

A body should be adjusted to it's correct specification, and a lens should be separately adjusted to it's correct specification, and when the two come together that should be enough.

 

Steve

[parigby]

I have to admit Steve, that's kind of what my thinking had always been, hence why l had no objection to the proposal from the repairer.

 

But being no expert, l'm always happy to be pointed in the right direction.

 

philip

[jc_braconi]

I have to admit Steve, that's kind of what my thinking had always been, hence why l had no objection to the proposal from the repairer.

 

But being no expert, l'm always happy to be pointed in the right direction.

 

philip

And so you will be back again to him ?

[parigby]

OK, JCBraconi, let's try and approach it from a different direction.

 

The 50mm Elmar does not focus spot on with the M8 - your suggestion is that the adjustment should be done in camera.

 

My 1947 35mm Summaron is pin sharp with the M8 as it stands.

 

If the M8 is adjusted to work with the 50mm, will this not mean that whilst the 50mm becomes pin sharp, the 35mm goes off ?

 

I am no expert by any stretch of the imagination, but logic seems to suggest that adjusting the camera to perform with one lens, will throw it out in relation to others that are pin sharp.

 

I await to be corrected.

 

philip

[luigi bertolotti]

The real oddity is that, from you have said :

 

- Lens (Elmar 50) came back from the lab : focus OK

- Use it a little (a dozen of pics)----> focus goes SIGNIFICANTLY off (7 ft<---> 3 ft !)

 

- Did this happen slowly or abruptly ? And... the 35mm is and was ALWAYS ok, at ANY distance ? Have you another (longer) lens more critical to focus than the Summaron 35 f 3,5 ?

[parigby]

Hi Luigi,

 

The lens went off over a period of maybe three or, at most, four shots.

 

I have a 75mm Summarit, which focuses spot on. In addition a 1980 f2 50mm Summicron, which again is spot on.

 

You can see why l am somewhat reluctant to go down the route of adjusting the camera.

 

philip

[jc_braconi]

Hi Luigi,

 

The lens went off over a period of maybe three or, at most, four shots.

 

I have a 75mm Summarit, which focuses spot on. In addition a 1980 f2 50mm Summicron, which again is spot on.

 

You can see why l am somewhat reluctant to go down the route of adjusting the camera.

 

philip

Better to sell this lens, (if You have already a Summicron)....may be

[250swb]

My suggestion would be to make sure that as you change aperture the ring isn't dragging or turning the lens barrel. This could cause it to unlock or change focus, then lock again when you change it back to another setting, particularly if you are doing it by feel rather than looking at it as you change settings. The thing to do with an Elmar of any type, just to be sure, is to set your aperture then focus last of all.

 

Steve

[luigi bertolotti]

My suggestion would be to make sure that as you change aperture the ring isn't dragging or turning the lens barrel. This could cause it to unlock or change focus, then lock again when you change it back to another setting, particularly if you are doing it by feel rather than looking at it as you change settings. The thing to do with an Elmar of any type, just to be sure, is to set your aperture then focus last of all.

 

Steve

It is a 2,8 model... this ought not to happen with it...

[gyoung]

The twist lock on the extending barrel is stiffer on my 3.5, which has been little used, than on my well used 2.8. It is possible to start unlocking the head when changing the aperture, but you can feel it happening and make sure all is well before focussing.

 

Gerry

[250swb]

It is a 2,8 model... this ought not to happen with it...

 

Of course it can happen. Unless you only ever have the lens locked at infinity turning the aperture ring can turn the lens barrel, which then changes the focus of the lens. It can also occur if you accidentally touch the front lens ring while changing aperture. The point being that photographers get into habit's with lenses where it doesn't matter, perhaps focusing first then adjusting the exposure settings, or adjusting the exposure settings without re-checking the focus. On a rigid Summicron it makes no difference either way. But with a collapsible Elmar either a dragging aperture ring (could be new tightness or old dirt), or hitting the end stops at f/2.8 or f/16 can change the focus. The solution that many people come up with is to put a finger on the focusing tab as you count the aperture clicks while still looking through the viewfinder, this locks the focus. The other alternative is simply to set exposure first then focus.

 

Steve

Edited October 18, 2012 by 250swb

[luigi bertolotti]

Of course it can happen. Unless you only ever have the lens locked at infinity turning the aperture ring can turn the lens barrel, which then changes the focus of the lens. It can also occur if you accidentally touch the front lens ring while changing aperture. The point being that photographers get into habit's with lenses where it doesn't matter, perhaps focusing first then adjusting the exposure settings, or adjusting the exposure settings without re-checking the focus. On a rigid Summicron it makes no difference either way. But with a collapsible Elmar either a dragging aperture ring (could be new tightness or old dirt), or hitting the end stops at f/2.8 or f/16 can change the focus. The solution that many people come up with is to put a finger on the focusing tab as you count the aperture clicks while still looking through the viewfinder, this locks the focus. The other alternative is simply to set exposure first then focus.

 

Steve

 

You're right... but (having used many times collapsible lenses (*) ) I think that one cannot incur in the (frankly, trivial) error of moving the stop ring of, say, an Elmar 2,8, NOT "feeling" that all the lens barrel is moving, so defocusing the system... I hope that parigby the OP has taken care of this detail when reported his findings...

 

(*) In this context, I indeed did experience a certain slight difference between the 3,5 and 2,8 Elmars... with the 3,5 is almost practically impossible to change the f stop with the lens focused/unlocked... with the 2,8 you can someway do... with a little "hand-gymnick"... (keep the front element "firm" while adjusting the stop ring... it can work... even with the old collapsible Elmar 90...)

Edited October 18, 2012 by luigi bertolotti

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[tobey bilek]

I was always thrilled when I found a mint old piece. Problem is they remained mint because they did not work well.

 

Clean the camera roller and lens contact to be sure there is no debris.

 

Set the aperture before focusing as this lens will rotate when adjusting aperture.

 

Make sure the infinity focus is the same in all three possible locking positions.

 

Then give the repairer a third try and ask if there is some reason why the adjustment does not hold.

 

Try a different repair person such as Leica . They repaired a M3 for me after repeated failures with other sources. Explain the problem to them as to how it will not stay adjusted on the first trip in. The fact it will not stay adjusted indicated something is not locking down, or missing or broken, All repair people are not created equal.

 

If all this fails, you have a nice museum piece as you have exceeded any seller warrantee if there was one.

[250swb]

You're right... but (having used many times collapsible lenses (*) ) I think that one cannot incur in the (frankly, trivial) error of moving the stop ring of, say, an Elmar 2,8, NOT "feeling" that all the lens barrel is moving, so defocusing the system...

 

Even on a well serviced 2.8 Elmar the aperture ring has click stops that are far more pronounced and stiffer than on a later Elmar M. On an Elmar M there is far less chance of altering focus accidentally. It may be possible is to ask the camera technician to loosen up the aperture ring, possibly not something he has ever been asked before as many people would ask for an aperture ring to be made more positive and 'clickier'.

 

Steve