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35mm Lux focus


mmk60

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Folks

 

I am having a focus issue with my 35mm Lux on a M8 - back focus and focus shift.

 

I have sent my 35mm Lux to Leica USA twice with no success. The lens just came back from its 2nd "adjustment". Leica USA states in the enclosed letter that ti has been set to factory tolerance.

 

I just did a quick test at the minimum focus distance. The focus is spot on at F1.4 but as I stop down, the focus still shifts like crazy.

 

I have heard that the issue is more typical with the M8 than film Ms. I have not tested it on my M6 but I am wondering if you, film shooters, have the same issue with the 35mm Lux.

 

duh.. I miss my 35mm cron that I sold to get the 35mm Lux. It did not have the focus issue on my M8....

 

Thanks in advance

 

mashu

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Backfocus is adjusted at the rangefinder or the lens depending on which one is causing the problem. If your M8 focuses fast lenses such as the noctilux or 75mm lux wide open ok then the backfocus most likely is the lens. Focus shift is a different issue and has been determined in previous threads as being a design issue of this lens.

 

Don't forget that to make the focus shift effect minimized, the wide open focus point should be adjusted to be right at the front end on the DOF region. Then as the lens is closed down it should step back a little at a time but still pretty much covered by DOF. The worst case is if at wide open, your focus point is already at the back end of the DOF region, it will move out of the DOF as you stop down.

 

You can always send the lens to DAG for adjustment, if you determine it's not the M8 adjustment. If it is the M8, it's very easy 3 minute adjust to move the focus point using the allen wrench.

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Backfocus is adjusted at the rangefinder or the lens depending on which one is causing the problem. If your M8 focuses fast lenses such as the noctilux or 75mm lux wide open ok then the backfocus most likely is the lens. Focus shift is a different issue and has been determined in previous threads as being a design issue of this lens.

 

Don't forget that to make the focus shift effect minimized, the wide open focus point should be adjusted to be right at the front end on the DOF region. Then as the lens is closed down it should step back a little at a time but still pretty much covered by DOF. The worst case is if at wide open, your focus point is already at the back end of the DOF region, it will move out of the DOF as you stop down.

 

You can always send the lens to DAG for adjustment, if you determine it's not the M8 adjustment. If it is the M8, it's very easy 3 minute adjust to move the focus point using the allen wrench.

 

Thank you for your input! I should send my lens to DAG for adjustment. What you said makes good sense to maximize the usability of the lens.

 

My other lenses, 50 lux and 75 summarit, are almost spot on, including my own focus error so I believe that it is the lens.

 

Cheers

 

mashu

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