ZM Sonnar Focus Shift?

drjoke · 10-10-2007

Is the lens still optimized at 2.8 for newly released ones? I got mine about 2-3 months ago and through unscientific tests it seems to focus accurately at 1.5. I don't have a digital RF, so it's not so convenient for me. Does anyone else have experience?

mfogiel · 10-10-2007

Apparently Zeiss never stopped selling the F2.8 version. If you want it sharp wide open, then you have to send it to them for adjustment. Shoot a newspaper from close range, with the camera at 90° and on a tripod, and see if there is a shift and where the focal plane is.

jsuominen · 10-11-2007

Quote:

Originally Posted by mfogiel

Shoot a newspaper from close range, with the camera at 90° and on a tripod, and see if there is a shift and where the focal plane is.

Or you can download some focus test chart from Internet:
http://www.focustestchart.com/chart.html
http://regex.info/blog/photo-tech/focus-chart/
http://photo.net/learn/focustest/

I did the test with my vintage Sonnar and Nikkor 50mm lenses from 1950's here:
http://www.rangefinderforum.com/foru...5&postcount=14

And another vintage lens 'test' without chart:
http://www.rangefinderforum.com/foru...28&postcount=8

Roger Hicks · 10-14-2007

In Oberkochen this year (May) when I picked up a 50/1.5, I was told by Dr. Nasse that focus is now optimised for full aperture. He also said that for a rule of thumb, if you treat d-o-f as being all BEHIND the point of sharp focus, you will not go far wrong.

Several months later, using this rule of thumb, I have been very pleased and indeed the Sonnar is may favourite 50mm lens out of quite a choice. It's nothing like as sharp or evenly illuminated at full aperture as a Summicron but I love the signature of this lens. Then again I generally prefer 35mm lenses anyway...

Cheers,

Roger (www.rogerandfrances.com)

xayraa33 · 10-14-2007

is there any way of telling if the new lens one is buying is optimized for f1.5 focus at close range, other than testing it out?
no markings on the lens or by serial number?

Roger Hicks · 10-14-2007

xayraa33 -- is there any way of telling if the new lens one is buying is optimized for f1.5 focus at close range, other than testing it out?
no markings on the lens or by serial number?

Not that I know of, but next time I talk to Zeiss, I'll ask (I'm waiting for the near-legendary 85/2, which I have been promised this month, so I have an excuse to contact them).

Cheers,

Roger (www.rogerandfrances.com)

Update: I'm still waiting for a reply (and an 85/2)

Article now finished, including d-o-f tests at nearest focusing limit. Dr. Nasse's rule of thumb is slightly oversimplified (or I misunderstood him -- much likelier).

The d-o-f grows much faster behind the focused point, but also grpws in front od it. Using the brilliant schematic from Another Member (thanks, but I can't find the post), if a lens with no focus shift is

___[]____

then the Sonnar is more like

_[]______

than

[]_______

as you stop down, using [] as the focused point and ________ as depth of field

Cheers,

R.

kshapero · 10-14-2007

Quote:

Originally Posted by Roger Hicks

Not that I know of, but next time I talk to Zeiss, I'll ask (I'm waiting for the near-legendary 85/2, which I have been promised this month, so I have an excuse to contact them).

Cheers,

Roger (www.rogerandfrances.com)

cheers, Roger

xayraa33 · 10-14-2007

Quote:

Originally Posted by Roger Hicks

Not that I know of, but next time I talk to Zeiss, I'll ask (I'm waiting for the near-legendary 85/2, which I have been promised this month, so I have an excuse to contact them).

Cheers,

Roger (www.rogerandfrances.com)

Thanks Roger, a way of knowing which version of the lens there is in a dealer's stock would stimulate sales for Zeiss, for those who want a fully f1.5 optimized lens (or not) straight out of the box.
One can then shop with confidence.

visiondr · 10-14-2007

Quote:

Originally Posted by Roger Hicks

In Oberkochen this year (May) when I picked up a 50/1.5, I was told by Dr. Nasse that focus is now optimised for full aperture. He also said that for a rule of thumb, if you treat d-o-f as being all BEHIND the point of sharp focus, you will not go far wrong.

Roger,
Thank you for that info. I wonder if the DOF charts for this lens can be used as a method to determine how focus shift will affect the final image?

drjoke · 10-14-2007

I got my lens from a dealer who held no local stock and had to order from Zeiss directly (from Japan?). Then was I more likely to get one optimized at 1.5?

drjoke · 10-14-2007

Roger, can you please show us nice pics taken with your Sonnar at 1.5?

Thanks!!!

35mmdelux · 11-21-2007

Hi Roger - I was reviewing your book Rangefinder earlier this evening. Nice compilation and use of VC lenses. Would be nice if you wrote a book on lenses that fit the Leica and their performance [kind of small portable paperback].

Just a suggestion. Best Regards - Paul

Roger Hicks · 11-21-2007

Quote:

Originally Posted by 35mmdelux

Hi Roger - I was reviewing your book Rangefinder earlier this evening. Nice compilation and use of VC lenses. Would be nice if you wrote a book on lenses that fit the Leica and their performance [kind of small portable paperback].

Just a suggestion. Best Regards - Paul

Dear Paul,

Thanks for the kind words, and the suggestion, but alas, it's increasingly difficult to persuade a publisher to buy a book that doesn't have 'Photoshop' in the title. this is one reason why I am putting so ,much work into www.rogerandfrances.com (see also my reply below).

Cheers,

R.

Roger Hicks · 11-21-2007

Quote:

Originally Posted by drjoke

Roger, can you please show us nice pics taken with your Sonnar at 1.5?

Thanks!!!

As soon as I have finished this reply, I'll be back at work on a free article on the Sonnar for www.rogerandfrances.com, which should be up in a couple of weeks (I have to finish it and get it to California, after which the web-master will have to get it on the site). I'm starting a new series of free articles, 'First Look', which relate to equipment I've recently received and/or especially like.

They'll be less detailed than magazine tests (for which, after all, I get paid) but they'll also have more pics than most magazine tests. For example, the Summarit piece (all but finished) has well over 20 pics taken on the M8 with the 35, 50 and 90, and should go up at the same time.

They're a blatant 'hook' to try to get people onto the site and subscribe, because I don't take advertising, and frankly, the site doesn't make a lot of financial sense without more subscribers. But I live in hope!

Cheers,

Roger

Roger Hicks · 11-22-2007

See update in Post 6. It was supposed to be a new post but I screwed up.

Cheers,

R.

nzeeman · 11-22-2007

i an wondering - did anyone made a test between old sonnar, jupiter 3 and new sonnar. i saw many photos fromnew sonnar and i never noticed some real problem with that shift. i think that people on forums made that thing bigger than it is.

back alley · 11-22-2007

i think ferider may have done some testing along those lines.

Roger Hicks · 11-22-2007

Quote:

Originally Posted by nzeeman

i an wondering - did anyone made a test between old sonnar, jupiter 3 and new sonnar. i saw many photos fromnew sonnar and i never noticed some real problem with that shift. i think that people on forums made that thing bigger than it is.

Seconded. See revised post 6.

Cheers,

R.