Leica Summicron 35mm asph II not perfect at infinity

[andgrimaldi]

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Hello everyone, I bought this lens, and I’m notice that when put the lens at infinity (at the end of scale) the pic is not perfect sharp in the center but at the corners of the frame is perfect!, when I put the lens not at the infinity, but a 1mm first the infinity the pic is perfect in the center but not perfect at the corners.

the difference is very minimal! But there is!

is this normal??

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[farnz]

It's curvature of field (so yes, it's normal).  It will be more pronounced at larger apertures and probably not visible by, say, f/8.

Pete.

Edited March 7, 2021 by farnz

[andgrimaldi]

Thanks a lot for your feedback, in fact, I see this also at f8 but as said the thing is really minimal important for me is sure that this fenomeno is normal! Because the lens is new and very expansive! Thanks again

[jdlaing]

It’s normal.

[Kwesi]

3 hours ago, andgrimaldi said:

Hello everyone, I bought this lens, and I’m notice that when put the lens at infinity (at the end of scale) the pic is not perfect sharp in the center but at the corners of the frame is perfect!, when I put the lens not at the infinity, but a 1mm first the infinity the pic is perfect in the center but not perfect at the corners.

the difference is very minimal! But there is!

is this normal??

It doesn't sound normal. Thought lenses are generally sharper in the center than at the edge.

if you live close to a Leica dealer, I would suggest checking your lens against one in the store. 

Do your other lens(es) behave like the 35?

[andgrimaldi]

I have only this lens unfortunately 

[Casey Jefferson]

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I have V1, I realized this when I got the lens, same behaviour where I need to back off just slightly before infinity to get a sharp center. It's however lined up nicely with rangefinder calibration, means the RF also won't align the patch when put the lens at infinity hard stop. My guess that the lens calibrated with focus shift or field curvature in mind.

Recently tried another lens and seem the lens focused perfectly, so definitely not the RF calibration.

As long as your RF agree with your lens, and you get sharp focus every time (which mine did), I wouldn't worry.

[andgrimaldi]

Thanks a lot, when I see with my eye on the window of telemetro, at the infinity (end of scale) the image is perfectly aligned! I try with the live view of my 246 and I noticed that at the end of scale of the lens, the image in the center is not perfectly sharp in the center but when I go back about 1mm from the end of scale the focus peaking is very red!!!!! Perfect!!! I another words for to have a perfect focus at the infinity in the center I go back a very very little (1mm) from the symbol of infinity, in this case the center is perfect and the corners are a little soft with f8 dyaphram you can see this 

[Casey Jefferson]

Not sure what else I can offer other than suggesting you to go to Leica dealer to try another same lens and see if it does it. All the best!

[farnz]

It's not a good idea to judge 'sharpness' with focus peaking because there are too many variables.  If you can, print the picture out as large as you can and judge from that.

If the point of focus in your rangefinder window and on LiveView (or EVF) don't match then it's likely that your rangefinder needs adjusting.

Pete.