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focus issue on 24 mm f/3.8


jimleicam3

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Just got the new 24 mm, f/3.8, and quickly went on vacation with my wife and the lens! When focusing way off in the distance and the focus ring is all the way to stop, infinity is out of focus. However, if I move the focus ring back just a hair, infinity is spot on focus. Is this normal? Otherwise, the lens seems great. Thanks, and I think the rain has stopped and my wife has poured two glasses of wine!!

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Just got the new 24 mm, f/3.8, and quickly went on vacation with my wife and the lens! When focusing way off in the distance and the focus ring is all the way to stop, infinity is out of focus. However, if I move the focus ring back just a hair, infinity is spot on focus. Is this normal? Otherwise, the lens seems great. Thanks, and I think the rain has stopped and my wife has poured two glasses of wine!!

 

How many glasses of wine have you had so far?... :)

 

What do you mean by "way off in the distance"?... You really need to focus on something a few kilometers (+5) away to be at "Infinity"... A good way to try the infinity focus is to focus on the moon once the clouds clear...

 

Also - Where are you on vacation?

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The distance for infinity was a tree more than 500 yards away, I focused on the top of a tree, so I could adjust back and forth. At the "all the way stop point" I see two tree tops, just a hair back, I only see one tree top. Both are still at the infinity icon, just a short distance from each other. Thanks for all your help! The nice thing about the new 24 mm f/3.8 in black, to my wife, it looks the same as my 35 mm, f/2, thus I has still only have purchased one Leica lens!! I know that this sounds very sexist, and I am sorry, but now my question is: does the 50 Lux in black, look like a 35 Cron??? Is that another glass of wine???

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All of my Leica lenses, with the exception of my 50 'cron, reach infinity focus (both in RF and in real images) before the lens stop. Some by a hair and others more so (2-3mm). In other words they overshoot "infinity" so I need to pull back a bit and look at the RF instead of whacking them all to the stop point for distance shots.

 

I actually had my 28 Elmarit Asph fixed in Solms as the focus calibration was off. It was rear-focusing but I also mentioned to them that it was overshooting "infinity" according to the RF. They fixed the calibration issue but left the rest as-is, which doesn't bother me. The important thing is that the RFs match what is truly in focus (my RFs agree with their standard in Solms - i.e., they set it to their standard M8 which is in agreement with mine).

 

As long as your RF agrees with the images you needn't worry.

 

Cheers,

Jason

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You really need to focus on something a few kilometers (+5) away to be at "Infinity"... A good way to try the infinity focus is to focus on the moon once the clouds clear...

 

though it's good to test infinity at distances that far away infinity actually starts at about 1000 times the focal length. in that case that would be 24 meters!

so there shouldn't be any difference between 50 meters (2000 times - just to be sure) and a few kilometers.

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Just got the new 24 mm, f/3.8, and quickly went on vacation with my wife and the lens! When focusing way off in the distance and the focus ring is all the way to stop, infinity is out of focus. However, if I move the focus ring back just a hair, infinity is spot on focus. Is this normal? Otherwise, the lens seems great. Thanks, and I think the rain has stopped and my wife has poured two glasses of wine!!

 

What Khiromu said.

At the moment it isnt clear that you are describing that the lens is out.

It sounds as though you mean the rangefinder is not patching at infinity?

In which case it could be the lens or the body, but with the amount of trouble people are having I figure it is more likely to be the body.

I think there is a fair amount of unwarranted 'trashing of lenses' on the forum, not this thread specifically but generally, without people clearly establishing what can cause out of focus, apparent backfocus, lens/rangefinder couplings. Stuff just gets basketed under lens troubles.

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What Khiromu said.

At the moment it isnt clear that you are describing that the lens is out.

It sounds as though you mean the rangefinder is not patching at infinity?

In which case it could be the lens or the body, but with the amount of trouble people are having I figure it is more likely to be the body.

I think there is a fair amount of unwarranted 'trashing of lenses' on the forum, not this thread specifically but generally, without people clearly establishing what can cause out of focus, apparent backfocus, lens/rangefinder couplings. Stuff just gets basketed under lens troubles.

 

And given the copious amount of wine consumption we have many variables that can affect your focus issues... :rolleyes:

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500yds is not far enough. when i test focus using distant objects from my roof, i get infinity with objects 2-3km away, but not the sort of distance you used. close, but not inifinity.

 

The '1000 times focal length' formula is perfect for checking infinity on an SLR. A Leica rangefinder's accuracy at infinity is not lens-dependent; the rangefinder cam does not know which lens is mounted..... The finder frame mechanism does but, that does not affect focusing accuracy.

 

I assume that the OP has more than one lens - if the 24mm is the only one where the RF image does not line up at infinity, there may be a problem with the lens. If the other lens has the same issue, than both lenses may need adjustment (unlikely) or the camera's rangefinder is out.

 

As suggested in an earlier post - try focusing at a truly distant object, at least 1km away. The moon is an ideal object for checking infinity, weather permitting of course....

 

Best,

 

Jan

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The '1000 times focal length' formula is perfect for checking infinity on an SLR. A Leica rangefinder's accuracy at infinity is not lens-dependent; the rangefinder cam does not know which lens is mounted..... The finder frame mechanism does but, that does not affect focusing accuracy.

 

that is not true. the rangefinder cam is only passive and the lens dictates it what to show (how to move) at any given distance.

and any wideangel-lens will reach infinity earlier (and that's of course visible in the rangefinder) than a normal-angel- or a telephoto-lens.

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that is not true. the rangefinder cam is only passive and the lens dictates it what to show (how to move) at any given distance.

and any wideangel-lens will reach infinity earlier (and that's of course visible in the rangefinder) than a normal-angel- or a telephoto-lens.

 

I have to respectfully disagree. The OP's lens seems to have a problem at infinity. When you set any Leica lens to infinity, the rangefinder patch should be at infinity as well. And it does not matter which lens is mounted, because the rangefinder's base length and magnification does not change when you mount different lenses.

 

And it is the rangefinder's base length and magnification which determines its accuracy. The geometry of the focusing cam only becomes important when you start focusing closer - it adjusts for the descrepancy between the in-out movement of the lens unit as oposed to the linearity of the rangefinder cam. Only on 50mm lenses does the lens unit move the same distance as does the focusing cam. This is how it has been since the introduction of the first rangefinder coupled Leica, the model II in 1932..:)

 

Best,

 

Jan

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