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dagor 7"


andrew_frith

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I have both the front and rear cell for a 7" goerz double-anastigmat

(seriesIII no.2)....i dont have the barrel for it..just the cells.

the lens threads are 45mm, any ideas on what kind of shutter i might

look out for to put these in? does anyone else have this lens?

wondering how theirs is mounted?

thanks -andrew

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A 45.75mm-threaded shutter is probably what the Grimes site lists as a "#2" shutter, but a number of different shutters have apparently had the designation of "#2". (If it's really 45.00mm, maybe you have something else.) You can get more information at <http://www.skgrimes.com/compur/index.htm>

 

Spacing the lens groups will probably be critically important for good performance, so this may not be a do-it-yourself project. If you're determined to use this lens, think about getting an expert to mount it (like the Grimes outfit if you're in the U.S.). Will be expensive.

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Andrew-

 

I have that exact lens, a Series III No. 2 Focus 7 Inch Goerz Dagor. the first Dagor I ever bought. Uncoated optics but still and excellent lens. The one I bought had been remounted in a Copal #1 shutter. The serial number 170XXX dates it at about 1902 to 1905. The coverage on these tiny lenses is amazing when they are stopped down. Take this information regarding coverage as a starting point for your own investigating. This is what I've gleaned from Goerz literature on the 7 inch Dagor: Covers 56 degrees at f/6.8,(covers 5 x 7)... Covers 70 degrees at f/16, covers (6 1/2 x 8 1/2)... Covers 87 degrees at f/32 covers (8 x 10)... Covers 90 degrees at f/45 (may cover better than 8 x 10 up to 10 x 12???). If the glass is in good shape and you like the look of vintage optics it would be worth remounting.

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I've got two Dagors in shutters, one is the 150mm and one is the 7". They're both in old Rapax shutters, different sizes.

 

The 7" one looks to me like it has special adapter rings that thread into the shutter. It's not a typical Rapax shutter mounting, that's for sure.

 

Do you have the barrel for the elements? If so that can give you info about the spacing. The outer element rims should end up the same distance apart when mounted on the shutter as on the barrel. If you were lucky enough to find a shutter into which these elements would just go with no problem, and this distance were the same, then the chances are that the spacing of each element from the diaphragm would be okay. (Of course it would be best to be able to check this out.) On a symmetrical lens like this one, each element should be the same distance from the diaphragm.

 

I'm not confident that my 7" Dagor's specs are going to necessarily match yours; there's a good chance mine is a bit later production than yours is.

 

If you can't find a shutter that fits right off, maybe you should send it off to Grimes, if you can afford it. If not, if the lens is in the barrel, just use a lenscap for a shutter! If no barrel, then maybe just put the elements in a safe place and look for a 7" Dagor already in the shutter. They come up from time to time, and I've noticed lately that they've come down considerably in price, especially the older uncoated ones -- which are almost certainly every bit as good as the later ones.

 

One more caution: If you find a shutter that looks like a good candidate, DO try and actually screw the elements into that shutter, make sure everything fits, before you buy it -- even if that shutter had a 7" Dagor in it before! Up until about the 1950s there were no universal standards for threading and shutter sizes.

 

I recently had a 7" Dagor -- about the same vintage as yours -- in a Volute shutter and the elements wouldn't thread into the Rapax shutter -- different threading. I also have two identical Conley wide angle lenses, one in a Regno shutter and one in an Autex, about the same vintage as your Dagor. The elements look identical, but the threads are a different pitch! So they're not interchangeable from one shutter to the other.

 

Good luck! And let us know what happens. If you can get it all working, you've got a great lens.

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  • 3 weeks later...
Andrew, I have no information about the shutter you'll need, but may be a hint about spacing: In his "Leitfaden der praktischen Optik" ( sorry,I do not have the year of publication, but it should have been around 1910 ) A. Gleichen wrote, "Blendenabstand" ( the distance between rear lens apex and diaphragm ) for a Dagor Serie III 1:6.8 F=100mm should be "4.583 mm" on each side . As 7" translates into 180mm you only have to multiply this distance by factor 1.8, resulting in 8,25 mm ( or 16,5 mm between the rear lens surfaces of both cells). Source: Eder, Handbuch der Photographie, 3.Edition. But as you know, lens versions differ vastly even when carrying identical names and patent numbers. In patent D.R.P. 77437 (1893) the designer of the Dagor, A.v.Hoegh ,prescribed a spacing of 1,3mm for a single 100mm cell. If your cells were of that version, spacing would be much tighter - about 4 mm (if one assumes that your single Dagor cells have a focal length of ca. 300-320mm).
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  • 2 years later...
  • 11 years later...
I realize this is an old thread, but I have an early 7" Dagor front cell with a rear thread of about 36mm. It's in an old compound shutter. I have several Dagors and it's difficult to find any two early compound shutters with the same thread size.. Thankfully, shutter sizes were eventually standardized.
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