Focus Shift on 50 Summilux (Current Version)

[kdriceman]

Advertisement (gone after registration)

I believe this lens is giving me some focus shift. It is dead-on wide open when focusing in the 1-3 meter range, but I have noticed when I focus wide open at 4 meters + the lens back-focuses slightly. Although I have had this lens for a year or so, I have not noticed focus shift, but I have rarely used it wide open at a distance of more than a couple meters. I have a 50mm Sonnar f/1.5 which does the same thing, but I know this is a known characteristic of the Zeiss lens. On the 50 Summilux, is this something that can be adjusted out or is it a characteristic of the lens? Thanks in advance.

[Advertisement]

The Leica Q3 is available for pre-order at B&H Photo Video and Adorama

[thighslapper]

I'm not sure you are describing focus shift in the normal sense of the word.....

 

This lens has a floating element and I believe the lens needs adjusting during manufacture to be in focus at near, mid and infinity.... and this is not easy

 

It also shows up any problems with rangefinder adjustment when used wide open which may not be apparent with other lenses.

 

I think you will need to do some more critical tests to work out where the issue lies.

 

From previous posts it is quite likley it is the lens that needs adjustment.

 

When rangefinder and lens are adjusted correctly you should find this lens performs impeccably at all distances and apertures....

[jaapv]

Focus shift is the change in the plane of focus when you stop the lens down - what you are describing is a lens that needs to be calibrated. Not unusual on this lens.

[pico]

Why do I never have such focusing problems?

Is it because I use old lenses?

 

I suspect operator error is responsible in a majority of such complaints.

[kdriceman]

Why do I never have such focusing problems?

Is it because I use old lenses?

 

I suspect operator error is responsible in a majority of such complaints.

 

Well Pico, operator error is a possibility and it is a problem for me in many a poor photos, but in this case I think I have eliminated all those variables... Which is why I'm asking. Plus, I've been doing this the better part of 35 years. The eyesight isn't what it used to be, but I can still tell when my focus point isn't sharp but the foliage behind it is. Still, it's a good point, you can be sure that I will have another operator give it a look before I fork over a couple hundred to Leica NJ.

[IWC Doppel]

Have you measured using a tripod and scale so you can measure how close you are with say 10 manual focusses at each position ?

 

I use a steel tape measure held at 45 degrees and focus on say the 1m/1ft mark or similar then evaluate and adjust for the line of measurement you are interested in (multiply by 0.7) as the measurement is along the hypotenuse. So the actual focus shift is this length you can see on the tape x Cos45

 

You will soon see how they lens performs, at 1M and 4m (Which should be very similar from y understanding)

 

Focus shift is where you adjust the aperture with no other adjustments and the focus moves in front or behind.

[kdriceman]

Advertisement (gone after registration)

Have you measured using a tripod and scale so you can measure how close you are with say 10 manual focusses at each position ?

 

I use a steel tape measure held at 45 degrees and focus on say the 1m/1ft mark or similar then evaluate and adjust for the line of measurement you are interested in (multiply by 0.7) as the measurement is along the hypotenuse. So the actual focus shift is this length you can see on the tape x Cos45

 

You will soon see how they lens performs, at 1M and 4m (Which should be very similar from y understanding)

 

Focus shift is where you adjust the aperture with no other adjustments and the focus moves in front or behind.

 

Yes, thanks. This is exactly what I do to check my lenses (and camera). I think this is a calibration issue as Jaap suggested.