Emil Busch Petzval Lens Info

**pierre506** · 14-Jul-2017, 16:50

Click image for larger version.

Name: FB_IMG_1500067829686.jpg
Views: 60
Size: 110.1 KB
ID: 167261

Saw it on Facebook

**Steven Tribe** · 15-Jul-2017, 00:26

A lovely use of Google to find original correspondence from someone who actually visited the Exhibition where the 10" Petzval was on display!

**anachromatic** · 15-Jul-2017, 11:32

This one, really big, at the Deutsches Museum...

An original catalog from 1859.

**Steven Tribe** · 15-Jul-2017, 15:01

Useful!
Obviously, Prussia had problems with making the join correctly in big dimension brass tubing.

Any confirmation of the meaning of '' and ''' shorthand in Prussian Imperial Measurements?

I note they confirm the Petzval modification - " now with no focus difference ".

**anton orlov** · 15-Jul-2017, 15:12

OK, so I put my lens on a camera today. Indeed it is 20in FL (at infinity from aperture point) and so the f5 mark on that Studio shutter is correct.

One surprise to me was that moving the lenses apart makes the focal length SHORTER rather than longer, which is what I was expecting. I moved the front lens out by about 3in and the focal length became 19in, so not much change.

The lens is nutty sharp, so I'm stoked.

Anachrmoatic - thanks so much for that brochure listing, but indeed - what does ''' indicate? That's not inches is it? Mine's still not in there - I mean my glass is 10cm (maybe 10.5) and FL of 20in is 50cm...

**anachromatic** · 15-Jul-2017, 16:18

Originally Posted by anton orlov

OK, so I put my lens on a camera today. Indeed it is 20in FL (at infinity from aperture point) and so the f5 mark on that Studio shutter is correct.

One surprise to me was that moving the lenses apart makes the focal length SHORTER rather than longer, which is what I was expecting. I moved the front lens out by about 3in and the focal length became 19in, so not much change.

The lens is nutty sharp, so I'm stoked.

Anachrmoatic - thanks so much for that brochure listing, but indeed - what does ''' indicate? That's not inches is it? Mine's still not in there - I mean my glass is 10cm (maybe 10.5) and FL of 20in is 50cm...

I'm not sure about what does '''indicates, but I'm 100% sure are not inches. It's the usual way to indicate lens aperture in many german catalogs from the 19th. century. I will try to find more info about, but I think are german or austrian "lines". In a similar way that the movement diameter is expressed in the watch industry.

**anachromatic** · 18-Jul-2017, 16:08

I was crossing with other german catalogs and a big Busch lens and I think that the triple apostrophe(''')are old german lines.
One old german "linie" is same than 1/12 inch or 2,116mm.
My lens is marked 60'''(60 linie), and his front glass diameter is around 127mm.
60 linie are 127mm. The focal length from the rear glass(as was common in the 19th century)is around 440mm.
All this data match with the 60'''/17'' lens, that can be seen in this 1862 catalog.

Emil Busch catalog of 1862.

Catalog detail.

**Steven Tribe** · 19-Jul-2017, 03:31

Well done!

I did a bit of research on the linie (''') Some years ago. and found that the linie was slightly different in the various mini nations of Germany. That problem was solved by Bismarck ( and Napoleon!).

The conversion of Anton's lens into old Prussian measurements gives a lens diameter of 48''' which is one of the "standard" lens sizes in the old tables. But it is a lot slower than these series.

**anton orlov** · 3-Mar-2018, 14:18

Fantastic info Anachromatic! Thanks so much! Very much looking forward to soon testing this lens too - fitting a spring back onto the swinging-style Century 11x14 and then it'll be ON!