Please define focus shift

[bourne]

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I have the latest version of the 35 Summicron ASH (non-APO) and notice no focus shift at all.  Is that generally the experience with this particular lens?  I find it sharp and just a delight to shoot with!

[Luke_Miller]

2 hours ago, bourne said:

I have the latest version of the 35 Summicron ASH (non-APO) and notice no focus shift at all.  Is that generally the experience with this particular lens?  I find it sharp and just a delight to shoot with!

I have the same lens and enjoy it as well.  It does have focus shift.  I know that from Sean Reid's ReidReviews tests of it, but not from my personal experience.  Sean's test methodology involves a series of images of his test board each taken one stop apart. He does not refocus between images.  He takes several image series with each lens and then uses the series in his review that produced the sharpest image at maximum aperture.  With the current 35 Summicron each shot gets progressively  less sharp as it is stopped down due to focus shift until eventually the increasing DOF starts to restore sharpness.  If you were looking for a 35mm lens you would be put off the Summicron after reading his review.  Fortunately I already had mine and knew it was a fine lens regardless of how it fared in his test methodology.  I also shoot with the Voigtlander 50mm Nokton f1.1 (not the new f1.0 version) which has significant focus shift easily seen in my own testing.  But in actual use does not seem to be an issue.  

My takeaway - focus shift is real and exists in some lenses. But unless you are a lens tester you may not care about it. 🙂

[bourne]

Thanks for your response. Have you found an “ideal” aperature with this lens that helps enhance sharpness?

[Jeff S]

I no longer subscribe to Sean Reid, but his v1 35 Summicron ASPH exhibited focus shift at f/2.8- f/4.  I carefully tested mine many years ago and found the same behavior.  In practice, however, it’s easily accommodated, and not an issue my prints.  No viewer has ever commented on “sharpness;” it’s either a worthy pic/print or not.

Jeff

[Luke_Miller]

6 minutes ago, bourne said:

Thanks for your response. Have you found an “ideal” aperature with this lens that helps enhance sharpness?

Generally I select aperture based on my depth of field requirement. I have no hesitation shooting the 35 Summicron wide open if needed in low light. I find it a great lens for "people shots" where bitingly sharp is not desirable.

[bourne]

Mine own experience is that wide open the lens is very sharp and 5.6/8 also really sharp.  As was stated above....there is more to a photo then sharpness!

[bourne]

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Thanks for your response. Have you found an “ideal” aperature with this lens that helps enhance sharpness?

[bourne]

Thanks for your response. Have you found an “ideal” aperature with this lens that helps enhance sharpness?