Mystery lens

[fsphotography]

Any one know of this lens? Early brass construction with waterhouse stops,inscribed"made by A.Krufs in Hamburg for Y.Spencer in Glasgow; No,2362". Appears to be of a three element ,or three pairs of elements construction. The two outside elements[or pairs] are separated by an element[or pair]in about the centre. Focul length is about 280mm and covers 10x8 with lots of movement. Overall hieght is 55mm ,front element is 37mm,centre element is 25mm and rear element is46mm. Sorry no pictures at the moment. I hope someone can help. Regards, Frank.

[CCHarrison]

John Spencer (and later his son John Jr. ) were long time sellers of photo equipment. Spencer goes way back as early as the 1850's.... 1858 ad attached.

I see lots of references to a Dr Hugo Krufs of Hamburg (1880-1910 period), but very few from "A. Krufs" who I assume is related - likely son or father to Hugo...

A photo of your lens would help a good deal.

Hope this helps
Dan

[Sevo]

Capital A and H are hard to distinguish if you aren't familiar with the "gothic" German typefaces fashionable in the 19th century - given that there also seems to be a misreading of ü for u, I am quite convinced that that will have been a lens made or more likely formulated (he seems to have been a researcher and co-authored books on optics) by Hugo Krüfs...

[CCHarrison]

Sevo,

I thought the same intially, but there are references to thermometers being made by A Krufs and it looks like there is a distinct "A". See http://www.liveauctioneers.com/item/2377212

Best
Dan

[Sevo]

Barometers are within the 19th century scope of scientific glassware, and so are lenses. That may be the guy - or his father. I found further references to Hugo Krüfs, and it looks as if we both were right - in another publication he is listed as Professor A.H.Krüfs, owner of the Optical Institute A. Krüfs in Hamburg. He co-authored books on the optical properties of glass and on quartz dispersion - pretty damn close to be explicitly named as a lens designer...

[Ole Tjugen]

Only one question left then - is it Krüfs or Krüſs?

Thiele lists two lenses made by H. Krüss, and nothing from Krufs or Krüfs...

Update: I think I found it! http://www.kruess.com/laboratory/about/company-history/

[Sevo]

Ah, excellent point! Even the German library electronic catalogue got that wrong in scanning...

[Steven Tribe]

My first thought was the fs used (even to-day) as a symbol for double ss in German - but I assumed that the early posters had already checked that!
A variation of the Rofs/Ross confusion!

[fsphotography]

Thank you guys, you have solved the riddle of the name. It is now apparant that the name is A.Kruss ,with an umlat over the u. Not A. Krufs(with umlat)as i read it. Following your lead i stumbled onto a wikipedia site that shows a microscope inscribed in the exact same manner as my lens. Correct,SS not FS, well done. You are a bright bunch,thank you very much. I will try to provide you with a pic of the lens over this weekend. With a bit of luck we may be able to together find out what the design,exact focul length and speed is. I own quite a few vintage brass lenses,but this is the only one with an element in the middle of the front and rear lenses. Has anyone seen this before? Its common in more modern lenses. Thank you for your interest. Frank.

[Ole Tjugen]

Hartmut Thiele's "Deutsche Photooptik von A - Z" lists only two lenses by Krüss, and both are Petzvals. Yours sounds much more like a triplet I believe.

[fsphotography]

Ole, the front element ,i have found, is a cemented doublet. The centre element is also a cemented doublet,as i can see the balsom just starting to fail at the very edge, all around. I cannot tell what the rear element construction is. I made a test negative with this lens and was amazed at how very,very,sharp it is. Useing the prescibed formula and measurement, i have worked out that wide open its at F7. Does " Deutche Photooptik " describe the two A.Kruss lenses that they listed. Regards, Frank.