Voigtlander lens question?

[Jim Fitzgerald]

I picked up the rear half of a Voigtlander lens from someone on the LFF. It has cleaned up nicely. The glass is in good shape and it is about 95mm tall and the glass in the rear is about 66mm. It came with one waterhouse stop marked #30. I know Ole or Jim Galli has posted how to convert this to f- stops but I'm not having any luck figuring it out. The serial number is # 28144 with the number 4 above that. I believe the VM dates it to about 1844 and shows it to be a RR or Euroscop. Since it is only the rear element any ideas what I can expect in the way of image and coverage. It would be nice to find the other half, and so would finding a needle in a haystack! Thanks.

Jim

 

[jonw]

I don't know if I am doing it correctly or not, [if not, please someone pipe in and set me straight], but I hold my barrel lens up to light and focus an image on the wall. I then measure the distance from the in focus image to the estimated nodal point of the lens. I then take the measured distance and divide the diameter of the lens....thus I have estimated my Voightlander #5 which has a image focus of 24 inches and a three inch lens diameter as being f8.

BTW, can you get an image focused with your single lens? I do have a JH Dallmeyer Rapid Landscape No. 2 lens which was designed to have only has a single lens.

Jon

 

[Jim Fitzgerald]

Jon, I tried what you suggested. It throws a huge image at 46". I comes into focus nicely, only problem Is running out of bellows. My 11x14 is only going to have 36" as it stands right now. Guess I could make it longer or find the other half. Thanks.

Jim

 

[Ole]

The date can't be 1844, since that's well before the invention of the RR.

1885 is far more likely, and is what I find in my books (27450 in 1884, 39465 in 1890).

A Rapid Euryskop Ser. VI No. 4 of about this age would be a 500mm (20") f:7.75; this fits nicely with a 66mm lens diameter. When only the rear half is used the node will be somewhere behind the lens, as with just about all converted lenses. So my guess is that your half lens will function as a 1000mm f:15.5. That makes determining the f-stop of your waterhouse stop very easy: Measure the diameter of the hole (in mm), and divide 1000 by that diameter.

 

[Jim Fitzgerald]

The date can't be 1844, since that's well before the invention of the RR.

1885 is far more likely, and is what I find in my books (27450 in 1884, 39465 in 1890).

A Rapid Euryskop Ser. VI No. 4 of about this age would be a 500mm (20") f:7.75; this fits nicely with a 66mm lens diameter. When only the rear half is used the node will be somewhere behind the lens, as with just about all converted lenses. So my guess is that your half lens will function as a 1000mm f:15.5. That makes determining the f-stop of your waterhouse stop very easy: Measure the diameter of the hole (in mm), and divide 1000 by that diameter.

Ole, I'm so glad that you are on this forum. Your knowledge never ceases to amaze me. Well it looks as if this half of a lens will have to sit for a while until I find the other half or come up with some idea for the front. I don't have enough bellow for it. The Waterhouse stop it 32mm. So if I understand correctly 32/1000= .032. Would that be F-32? Any ideas for the front? Thanks.


Jim

 

[Steve Smith]

So if I understand correctly 32/1000= .032. Would that be F-32?

I think you got the correct answer by the wrong method!

1000/32 = 31.25 Close enough to f32.



Steve.

 

[jimgalli]

Jim, what you want to do with that is find a #1 or #2 dioptor (macro filter) that is also about 66mm and put it up front. You'll end up with a Verito like lens that will focus probably around 20"? Thats just a swag. It will bring it down to useable length and give you a unique signature. Have fun.

As to your other question, measure the aperture hole in mm. divide that into the distance in mm from waterhouse slot to ground glass when you're focused. ie. the hole is 30mm and you measure 660 mm bellows, you're at f22. 30mm hole, 330mm bellows, you're at f11 etc. etc.

 

[Jim Fitzgerald]

Jim, what you want to do with that is find a #1 or #2 dioptor (macro filter) that is also about 66mm and put it up front. You'll end up with a Verito like lens that will focus probably around 20"? Thats just a swag. It will bring it down to useable length and give you a unique signature. Have fun.

As to your other question, measure the aperture hole in mm. divide that into the distance in mm from waterhouse slot to ground glass when you're focused. ie. the hole is 30mm and you measure 660 mm bellows, you're at f22. 30mm hole, 330mm bellows, you're at f11 etc. etc.

Jim, that was the info I was looking for. How to make to be able to use it. It cleaned up pretty nice and I would like to see what it can do. As it stands it would need 46" of bellows now! 20" is not a problem. I will hunt for the diopter lenses.

Thanks for the info on the waterhouse stop measurements. By the way nice going on the Big B&L lens on e-bay last night looks like a nice one and you got it for a great price. All the best.


Jim