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Chris7521
17-Apr-2017, 22:34
Recently purchased a Dallmeyer 4D patent serial #42***. I know they are listed as a 17" f6 lens but when I measure to the waterhouse slot@ infinity I get 15" or 381mm and the waterhouse stop internal opening is 63.5mm. That would be a 381mm f6 lens right? or am I doing something wrong? I just got around to rigging up a shutter so I haven't shot anything with it yet. I was going to make a couple of waterhouse stops when I see this?? Did they make multiple focal lengths of this lens? I had heard they did this with other lenses. Thanks for any info!

Steven Tribe
18-Apr-2017, 00:42
I have checked 3 catalogues between 1891 and 1934. All give the focal length as 17" / 431mm.

But, to my surprise, the 1934 catalogue has an additional model called the 3D bis - this has a focal length of 14.75" covering full plate only, like the 3D. Could this be your "4D" ? Will check further.

Steven Tribe
18-Apr-2017, 01:29
I have looked at an earlier catalogue. This gives the "back focus" - that is, focus distance from the rear of the lens. It gives the 4D as having a 13" back focus.

Probably the best check is to measure the diameter of the front lens, which is given as 2 7/8".

Chris7521
18-Apr-2017, 01:53
I have looked at an earlier catalogue. This gives the "back focus" - that is, focus distance from the rear of the lens. It gives the 4D as having a 13" back focus.

Probably the best check is to measure the diameter of the front lens, which is given as 2 7/8".The diameter is close to that, and with that back focus info it sounds about right I guess. Probably opening up a can of worms here but, am I measuring the f-stop correctly, by the the opening of the waterhouse slot? ( focal length divided by diameter) Thanks for your help!

goamules
18-Apr-2017, 05:57
Yes, to the slot. But also you measure the apparent aperture (the circle of light you can see) looking in the front glass. Not the glass itself.

Chris7521
18-Apr-2017, 09:02
Thanks!

Steven Tribe
19-Apr-2017, 01:43
Here is the table of Dallmeyer Patent Portrait lenses from the UK Kodak sales book from 1934. Sorry about the reversed image! No matter how I edit, it always gets turned upsidedown when I upload.

It shows an extended range of models compared with the turn of the century. I have no idea how these "extra" versions were engraved, as I have never seen any on the market!

It is possible that the 4D has been changed at some time and that the original 4D was the same lens as the later 3B bis lens. Full plate photography was still the dominant format in the UK for many years and a later "longer" 4D was introduced to cover the ""new" 10x8" format!

Chris7521
19-Apr-2017, 20:02
Here is the table of Dallmeyer Patent Portrait lenses from the UK Kodak sales book from 1934. Sorry about the reversed image! No matter how I edit, it always gets turned upsidedown when I upload.

It shows an extended range of models compared with the turn of the century. I have no idea how these "extra" versions were engraved, as I have never seen any on the market!

It is possible that the 4D has been changed at some time and that the original 4D was the same lens as the later 3B bis lens. Full plate photography was still the dominant format in the UK for many years and a later "longer" 4D was introduced to cover the ""new" 10x8" format!Thanks for posting that! This lens defiantly covers more than 8x10 with room for movements.
I did measure the apparent aperture the way I read and it measures the same as the actual opening so I come up with 6.8 for 17" lens. It does measure 13"@ the rear at infinity. Still a little confused but I'm keeping the lens and just see what happens with exposure as if it is a f6.
:)164036

Chris7521
19-Apr-2017, 22:49
Well I forgot I had 15" projector lens so I compared the view... This 4D is a 15" lens! So, all my measuring the first go around were right. Oh well, one should not believe everything they see and read regarding focal lengths with these dallmeyer's. If a seller says one thing because they see it written, it is worth getting some guarantee of this fact. It's ok for me I guess but, I should not have assumed what I was getting. It does cover 8x10 and then some but, it is a little shorter than I wanted

carylee2002
5-May-2017, 10:31
I watched this video. Learned a lot from it.

https://youtu.be/wsm6zFnnhvU