Information needed on lens

[campy51]

This is another lens from friends grandfather. I can't seem to find a lot of information or a value so any info I could get will be appreciated.

 

[MattKing]

There are two different lenses in your photos.

 

[campy51]

No it's one lens with two elements of different focal lengths.

 

[Dan Fromm]

http://www.largeformatphotography.i...p?129380-What-can-you-tell-me-about-this-lens

 

[shutterfinger]

The 35 cm serial number is mid range of the numbers listed for 1925; the serial number for the 29cm is between the end number listed for 1925 and the beginning number listed for 1926. There is a 18,000 gap in the 1925 to 1926 numbers. (from A lens Collectors Vade Mecium)
http://www.cameraeccentric.com/html/info/zeiss_1.html shows it as a Selected Convertible Set for 7 1/2 x 5 plate size.

 

[campy51]

http://www.largeformatphotography.i...p?129380-What-can-you-tell-me-about-this-lens

Yes I know. Different forum, different people with different opinions

 

[Dan Fromm]

Yes I know. Different forum, different people with different opinions

You don't want opinions, you want well-founded information.

 

[David Lindquist]

Some of this may be redundant and repeat some of the useful information also posted over on the large format forum. Anyway: This is a Zeiss Double Protar, the front cell of 35 cm and the back cell of 29 cm focal length combine to make an objective of 18.5 cm focal length, maximum aperture of f/7.2 (Sometimes this is rounded off to f/7). It looks like your aperture ring is graduated in f stops for the combined lens and is engraved with the combined focal length, 18.5 cm. Either cell can be used alone behind the diaphragm. Here the aperture ring's millimeter graduations are used to set the f stop. The maximum aperture of a single cell is f/12.5. See this:
http://www.rontalis.com/tech/protar/index.html

If you scroll down to the bottom of the page there are links to charts giving the millimeter settings for f stops for both the single cells and pairs of cells.
David

 

[campy51]

Anyone know what the thread size is? I thought about getting a focusing helicoid and trying it on a Sony A7II camera. It's not m42, that I know.

 

[AgX]

I am puzzled, within 11 years you were unable to find out yourself the thread size of that lens?

 

[campy51]

I am puzzled, within 11 years you were unable to find out yourself the thread size of that lens?

?????

 

[AgX]

It needs a caliper a thread profile gauge.

 

[campy51]

I'm confused about the 11 years comment.

 

[MattKing]

I'm confused about the 11 years comment.

My guess is that Dan (oops, actually AgX) read your join date on largeformatphotography.com as being the post date.

 

[AgX]

I have to beg your pardon, Campy.
Not Dan but me.
I'm not used to small or low-contrast figures anymore. I mixed up years at that other site.

(Thank you Sean for Apug being better readable.)

 

[E. von Hoegh]

Anyone know what the thread size is? I thought about getting a focusing helicoid and trying it on a Sony A7II camera. It's not m42, that I know.

You'll need to measure the threads for diameter and pitch, both will be metric; then have a machinist make an adapter. You will also meed an extension tube to place the diaphragm of the lens approximately 18.5 cm. from the film (sensor) plane. Or, you could just have a flange made and put it on a 4x5 or 5x7 view camera and use it as intended, it's a rather nice triple convertible.

 

[campy51]

You'll need to measure the threads for diameter and pitch, both will be metric; then have a machinist make an adapter. You will also meed an extension tube to place the diaphragm of the lens approximately 18.5 cm. from the film (sensor) plane. Or, you could just have a flange made and put it on a 4x5 or 5x7 view camera and use it as intended, it's a rather nice triple convertible.

What I wanted to try was putting it on a focusing helicoid and try it on a Sony mirrorless camera.

 

[Dan Fromm]

What I wanted to try was putting it on a focusing helicoid and try it on a Sony mirrorless camera.

Lessee now. You want to hang a 350 mm (one cell), 290 mm (the other cell) and a 180 mm lens (the whole thing) on a focusing helicoid in front of a Sony mirrorless camera.

An adapter to attach the rear of the barrel to the helicoid is simple. Send lens, helicoid and money to SKGrimes. If I were doing it, I'd use a helicoid with a standard SLR mount on the lens side and ask the machinists to make a barrel-to-T-mount adapter. Then get a T-mount to fit the helicoid.

But what are you going to do to get the extension needed? Your best bet is to get a monoral view camera with usefully more than 390 mm of extension, a flange to hold the lens to the board, and an adapter to hold the Sony mirrorless camera behind the view camera. The typical tiny camera bellows attachment won't give you nearly enough extension.

Mods, this thread is about d*igital. Shouldn't you delete it?

 

[campy51]

Mods, this thread is about d*igital. Shouldn't you delete it?

Let's all chant "digital format matters" If not in the U.S. you might not get it.

 

[AgX]

Mods, this thread is about d*igital. Shouldn't you delete it?

I don't see this.

This thread is about gaining information on a certain lens, that basically is of interest to the Apug-community.
What the OP has in mind with that lens should be of no interest, as long as any off-Apug issue is kept outside.

 

[Dan Fromm]

I don't see this.

This thread is about gaining information on a certain lens, that basically is of interest to the Apug-community.
What the OP has in mind with that lens should be of no interest, as long as any off-Apug issue is kept outside.

See post #17 above. He wants to use the lens on a Sony digicam.

 

[campy51]

Why do people care how I use a lens? All I am looking for is information on this particular lens. I have been told on other forums that here and the large format site is where to go for information on large format equipment.