[DIY] 1939 Zeiss Tessar 8cm f/2.8 modified for DSLR use

Esox lucius · Expire: 2011-11-18

This is a long story and I am only at prototype stage, but I have managed to confirm that this crazy idea actually works. I will later post more photos and samples taken with the lens on my Nikon D3, I only need to make the PVC tube bellows mechanically better and cosmetically better looking.

WHERE IT ALL STARTED
In February 2008, I bought my 5th Zeiss Super Ikonta for 2$ + shipping on eBay. Serial dated is at made in 1939. There was no butchering done, the camera was already dead: bellows was broken, body mechanics unrepairable and parts had been sacrificed to fix other cameras. This is how it looked when I started with it

The only thing useable was the lens, shutter had dried out and did not work. Optics were hazy and had some cleaning marks on the front element, but no scratches. Shutter did not close properly and two of the aperture blades were misaligned. Focusing was not, it was cemented from dry lube. A quick inspection revealed that repairs were going to be time-consuming, so I left the lens on my shelf for 3 years.

DIY MODIFICATION OF LENS
Some time ago I read this blog post and thought that hell, if someone can make a lens from a crappy magnifying glass http://www.diyphotography.net/manual-lens-from-pvc-pipes then why not give a new life to a lens which I know performs very well. The lens is designed to cover the area of medium format film, so I knew that it would cover a 35mm full frame sensor as well. Medium format lenses are usually not as sharp as SLR lenses, but I wasn't interested in how many lines per mm it draws.

I wanted to manufacture an extension tube, which would attach to Nikon mount and provide tight fit with no light leaks or mechanical flaws that could damage my Nikon DSLR's mount. The idea of two PVC tubes inside each other gave me the spark, because that would allow me precision to calibrate infinity focus correctly. I do not need to slide the PVC tubes to focus, as the lens is equipped with a focusing mechanism of its own.

MODIFYING THE TESSAR 8cm f/2.8 LENS
First task was to remove the shutter blades, because I had no need for a shutter now that I had decided to fit the lens to my Nikon body.

disassembling the rear element to access the shutter blades (aperture assembly is to the left)

halfway done, one bent shutter blade already removed

the shutter blades have now been removed

Here I took my time to carefully clean the lens elements that I had disassembled. The haze and dust was quite easy to remove.

Next task was to fix the diaphragm, which had two misaligned leaves. This was a nerve-wrecking task and I was distracted so much that I forgot to take photos of this phase. Anyway, about 1 hour later I had managed to disassemble and clean the blades, then align and assemble the diaphragm mechanism. It now worked smoothly and closed nicely to form a round circle.

Next it was time to clean the front lens elements, and lube the dried out focusing mechanism.

After this it was time to re-assemble the lens & shutter unit for a family reunion (the 524/16 Ikonta I also own could not attend this time)

Lens in its final, modified for Nikon state Twisted Evil

Enough with the gear pics. Quick check how this lens performs on a Nikon D3. These are taken at ISO 400, with some bounce flash. First victim was my colleague

f/5.6 (on 120 film this Tessar 8cm f/2.8 is sharpest at f/11, but good already at f/5.6, improving at f/8 further)

100% crop of the above picture. For full size image, go to http://www.flickr.com/photos/mureena/5461067251/sizes/l/

lens wide open f/2.8

100% crop of the photo, confirming that on this one I missed focus and nailed the hair in stead of my colleague's eye. Out of camera results have a veil and low contrast that can be easily cured with post-processing, but I left these untouched. Not bad for a 72 year old lens at minimum focusing distance, wide open. Full size available here http://www.flickr.com/photos/mureena/5461069763/sizes/l/

Next I will finalize the prototype and make some mechanical changes that improve useability. Operation is very simple: focusing is from the lens focusing mechanism, and aperture is set from the lens ring. My Nikon body indicates focus lock, but metering is of course manual. The full frame viewfinder is very bright since the lens aperture is quite large. Stopping down to f/8 dims the viewfinder image of course. Flare resistance is likely non-existent, this is an uncoated lens. The Tessar also exists as a coated version, I have one which is the red T version but that one I won't butcher because it still works (though rangefinder is off target).

Later: More photos taken with this lens!

Geoff C. Bassett · Expire: 2012-06-18

This definitely makes me want to scavenge for destroyed Medium camera for some glass like this.

I cannot wait to see more samples, especially how it performs outdoors!

trifox · Expire: 2014-05-29

wow!

and congrats..

THe lens performs really well!! and what is also surprisingly good is the bokeh, of course!!

tf

Esox lucius · Expire: 2011-11-18

Thanks Stan!

Esox lucius · Expire: 2011-11-18

Update: The extension tube prototype #2 is now ready, and I just carefully need to trim it to achieve infity focus correctly.

Some careful shaving of the tube is needed before it is correct for infinity, but I am almost there (maybe 0.5mm more to reach infinity).

Note that the 32mm PVC tube screws to the lens, so fit is tight and exactly 90 degrees.

Here is the lens mounted on the D3

sample photo f/2.8 ISO 200 with flash

f/4 ISO 200 with flash

f/5.6 ISO 200 with flash

f/4 ISO 4000 no flash. Almost at infinity, need to carefully trim the extension tube a little more and then lens is correctly calibrated for infinity focus. After that, focusing will be done using the focusing mechanism of the lens itself.

trifox · Expire: 2014-05-29

Absolutely superb bokeh!!!

Vilhelm -- do you want me to make that tube with no glue? Wink

Let me know..

tf

leo_b · Joined: 16 Feb 2011 Posts: 53 Location: Germany

impressive what you made!

that makes me looking at my next flea market walk for such an old camera to build my own one.

cheers leo

Esox lucius · Expire: 2011-11-18

Thanks Leo! Yes, interesting project especially making it Smile

RioRico · Posted: Thu Feb 24, 2011 9:24 am Post subject:

Truly inspiring!

Inspiring me to frustrate myself, that is.

Way back at the dawn of history, about two years ago, I bought on eBay for US$7 (shipped) a CZJ Tessar 80/2.8 # 5328671 set in a shiny Prontor-SVS shutter. It had been removed from a camera unknown -- some Ikonta, was my guess.

I fitted an M42 ring to its back and mounted it on bellows. But if I retract the bellows towards infinity focus, protruding shutter levers jam against the bellows body. I haven't the skill to disassemble the shutter -- and I don't know that I really *want* to disassemble the shutter, since it still works. Maybe I'd be able to use it on a homebrew MF camera in the future. Yes, that could happen...

I should mention that the lens+shutter assembly has no focusing mechanism. If it could focus, I would just put it on M42 macro tubes. Except that the tubes jam against the aperture lever, leaving it immobilie. Bother.

I have fiddled with it (again) for the last hour but see no obvious solution. So I shall put this aside and return to my usual time-wasting. And maybe think of getting some PVC tubing and trying this project myself.