Protarlinse VII R.18cm

[alexvaras]

Hi all,

Anyone could help me to age this lens and how to use it correctly (coverage, minimum aperture)?
It has the same lens rear and front.

183686

Thank you in advance,
Alex

[Myriophyllum]

Hi all,

Anyone could help me to age this lens and how to use it correctly (coverage, minimum aperture)?
It has the same lens rear and front.

183686

Thank you in advance,
Alex

Hi Alex,

gratulations, you could get a legendary lens! 8 elements in 2 groups!
With both elements you have a 1:6.3/105mm lens. It covers 7 x 10 cm wide open and 10 x 13 cm stopped down - so fine for 6x9 cm or as a wide angle for 4x5".
With both elements take the f-scale marked 10,5cm...
About age others may know better (pre 1925? just a guess).

Best wishes
Jens

[Steven Tribe]

Good lens and the original shutter with F values for using both lenses, or just the rear lens with the longer focal length.
It would have been used on a 6x9cm quality camera made by ICA Germany. Single lens use would be OK for 4x5", but I doubt you would find the faster use of both lenses together satisfactory.

The front lens was made in 1912. The rear lens will have another serial number on it, but is probably made the same week in 1912.

[alexvaras]

Thank you for the information.
What would be the aperture for a single lens? 12?
How this mm rule bellow the aperture can be read?

[Steven Tribe]

All Protar VII lenses are f12.5. Combined series VII lenses (called VIIa) have slightly different F values from f6.3 .It depends on the degree of difference in the focal lengths of the two combined lenses.

Some makers of convertible lenses used the iris diameter in mms, rather than actual f values. Apart from escaping from the f scale wars/competition, there is sense in having a little table which gives the required "mm" to achieve the right f value for a specific focal length combination (single or a pair).

I have assumed that the rear lens is an 18cm, but Zeiss made a whole range of focal lengths which supported a particular sized shutter. So the mm scale is an insurance that the adventurous photography who added extra series VII to his kit could easily workout the correct aperture.

[alexvaras]

Yes, rear lense is 18cm as well.
Thank you all for the information.

[David Lindquist]

That's a very nice clean looking example of a Zeiss Protar from the early 20th century. I'd expect the serial number of the rear lens to be consecutive with the front as it is also 18cm, is it 186906? You might look again at what is engraved on the bezel, I think what you describe as "R." is "F=" , as in focal length equals 18cm. The typeface Zeiss used back then was rather heavy on the serifs. Zeiss catalogues found here: http://www.cameraeccentric.com have some useful information on the Protars including the "Diameter of circle covered at small stops". I thought these catalogues might also include tables giving f stop equivalents in millimeters but they don't seem to. I have that information somewhere and will dig it out.
David

[David Lindquist]

This is from some tables I printed out back in 2008, they accompanied the description of a Protar set that was on ebay. I think I've seen these tables (or the equivalent) somewhere on the internet. Anyway for the 18cm f/12.5 Protarlinse VII:

f/12.5 = 15mm
f/16 = 11mm
f/22 = 8.0mm
f/32 = 5.5mm
f/45 = 4.0mm
David

[alexvaras]

That's a very nice clean looking example of a Zeiss Protar from the early 20th century. I'd expect the serial number of the rear lens to be consecutive with the front as it is also 18cm, is it 186906? You might look again at what is engraved on the bezel, I think what you describe as "R." is "F=" , as in focal length equals 18cm. The typeface Zeiss used back then was rather heavy on the serifs. Zeiss catalogues found here: http://www.cameraeccentric.com have some useful information on the Protars including the "Diameter of circle covered at small stops". I thought these catalogues might also include tables giving f stop equivalents in millimeters but they don't seem to. I have that information somewhere and will dig it out.
David
You nailed David, 186906 it is and yes, checked with a loupe and changed the topic F=18.
Thank you!