Sonnar-Xenon Clone, J-8+Retina Xenon

[Brian]

Okay, I wanted to see if you could use the back portion of a Xenon 5cm F2 with the front portion of a Sonnar lens and see what you get. The Sonnar front end focal length is much longer than the Xenon's front portion, and same with the rear modules.

SO: when making the two come out close to 50mm, the stand-off distance is much greater and the back-focus is longer as well. I "eye-balled it" doing a two-point calibration with the I-26 module and a TTL viewer. It looked decent enough at 3m, 5m, 20m, and infinity.

Here's the lens, I'll try a couple of test shots and post in a week or two.

http://www.ziforums.com/attachment.php?attachmentid=81&d=1233505968

http://www.ziforums.com/attachment.php?attachmentid=80&d=1233505942



Look at that clearance for the rear element! I could use this lens on an SLR.

http://www.ziforums.com/attachment.php?attachmentid=79&d=1233505914

[Brian]

Just a quick test to show this thing actually forms an image. I held my Nikon D1 with 60/2.8 up to the through-the-lens viewer.

Digital camera is hand-held, TTL viewer is on a Tripod. So the image is projected onto ground glass, and I took a digital image of it. The hybrid lens is wide-open at F2.

http://www.ziforums.com/attachment.php?attachmentid=82&stc=1&d=1233530648

Test roll using a real camera goes in tomorrow. What's this prove? It proves that you can make a lens out of left over parts from Sonnars and Xenons. I still think the Simlar is a modified Xenon with the front doublet split into a triplet!

[raid]

Brian,
While you have threads documenting what you are doing with the lenses, once you put them away for storage, you may forget the details. I suggest that you write down all these details. It is very interesting investigation of lens design history by you. I have two J-3's that were inspected/corrected by you, and now I don't recall which one has the J-8 rear element! I should have written down which lens is which.

[Brian]

Raid- your Contax Mount 5cm F2 with the FingerNail polish for the Set Screw has the J-8 rear element. Plus- the front section is UNCOATED and the rear element is coated.

I forget if I used Blue or Red Fingernail polish. As you know, Nikki does one hand in each!

It's funny what the mind remembers. I wrote an assembly language program in the early 1980s for the Z80. Pulled it out, remembered how I did it, and rewrote it for the MIPS R3000. And another subroutine -written over 20 years ago- I could not find the source code, so I disassembled my own program to remember it.

Kind of like my lenses.

[raid]

Brian,

I also have a really good long term memory. At times, I surprise my students by remining them of small details that happened [by them] many years ago.

Yes, the rear element is coated for the J-8 element. You have to remind yourself of details for more than two lenses though.

[Trius]

The most important thing is .... what will you name it? Sonnon? Xonnar?

[Brian]

I'm waiting for the test roll to come back before naming this one.

I like Xena.

But I might end up "and I shall call you Squishee, come here little squishee" (from Finding Nemo)

[furcafe]

Xena is good, but since you live in Northern Virginia, my vote is for "Novanon" (since "Novar" has already been used by Schneider). Whatever you choose, it's hard to avoid having something that sounds like a pre******ion [that's presc/cription, not sure why it's automatically asterisked out] drug. :p

I'm waiting for the test roll to come back before naming this one.

I like Xena.

But I might end up "and I shall call you Squishee, come here little squishee" (from Finding Nemo)

[digitalintrigue]

Yes, if it has a name reminiscent of those conjured up by pharmaceutical companies, you'll have to list all of the side effects, too. :)

[Brian]

I'll be scanning the test results. Center sharp, blurry edges. I suspect the Xenon rear-module cannot correct the curvature of field of the front end. But it's really cool! A CPU would be cranking to duplicate the results in PHOTOSHOP.

Sometimes, Optical Processing is the fastest way to acheive certain results.

The "Astigmar" is Born.

[Brian]

Test Results Are Back!

http://www.ziforums.com/album.php?albumid=99

Looks like the actual focus at the center and RF agree at all distances- Good Things. The Focal Length is to the Leica Standard, and the lens is collimated in its I26 Mount.

The Xenon Rear end does not provide the corrections for the J-8 Sonnar Front! What does this mean? Well, you get some really cool special effects when mating optics at Random. What can I speculate about the Simlar?- I still think it's a Planar Formula Lens with the front group split into a triplet, and not a Sonnar/Planar Hybrid.

Wide-Open on the Bessa R2:
http://www.ziforums.com/picture.php?albumid=99&pictureid=825
Stopped Down to F4:

http://www.ziforums.com/picture.php?albumid=99&pictureid=826

Distance Shot at F2: We're NOT in Kansas Anymore, Baby!

http://www.ziforums.com/picture.php?albumid=99&pictureid=829

Also Stopped Down to F4:

http://www.ziforums.com/picture.php?albumid=99&pictureid=828

How's that for Bokeh!

[jmkelly]

Lots of uncorrected spherical coma! The shots look very "arty" to me - not that there's anything wrong with that ;).

[mellie]

Wow, love the nice dreamy effect:cool:

[Brian]

That's me... A Lens Hacking Artist. I'm thinking I need to shore up the fitting a bit with an internal strength member, and then find a good home for this lens...

[Brian]

One of my Flickr contacts saw the images with this lens, and really liked them.

It will find use on a Leica M8 and MP. I'm looking forward to seeing his work.