Need some help with a Dallmeyer 3B

[nkrustev]

Hi guys,
I recently bought a Dallmeyer 3B. I am going to be using it on my Cambo 8x10 for portraits.
I have not taken any pictures with it yet but I noticed something weird. I cannot focus it at infinity. Even with the standards closest to each other and the bellows compressed all the way the lens is not close enough to the gg to focus at infinity.
Can anyone who has it tell me what is the distance between the lens plate and the gg when it is focused at infinity.

Also is there a way to know when it was produced by the serial number.
Any other interesting info about the lens is also welcome.
Thank you in advance for your help.

http://photo-zona.net/images/user43270/album18102/large/1299909567_dkzm2260_dallmeyer_3b.jpg

[Richard Rankin]

If you look at the 1904 ad shown at this site http://www.antiquecameras.net/softfocuslenses.html, it says the 3B is 11 1/2" equivalent focus. So, when you rack the bellows out so that the aperture knob is at 11 1/2" from the ground glass, you should have an object at infinity in focus. That same ad explains how to use the soft focus feature.

This link also has some info about using the lens. Note that this blog says the focal length is around 8", but that is probably measured from the rear of the lens to the ground glass at infinity. http://blogs.salon.com/0004217/2005/07/18.html

Richard

[Steven Tribe]

This is the 20th C late version with 2 patents shown

[eddie]

11 1/2 inches to the iris for infinity focus. does it focus anywhere at any time?

please show us detailed and clear photos of the rear of the lens, from several angles. there should be two sets of glass in the rear. you should be able to unscrew them from each other. there should be a cemented pair in the front. can you see balsam separation? this helps to identify if they are both present and actually cemented. i have had several petzvals that were not cemented in the front. some i was able to re cement others were never right....like someone changes the elements in the past.

does your "turn for soft focus" work? does it move anything when turned?

once you ensure that all the glass is correctly configured that will help in your search.

eddie

[Geoffrey_5995]

Have you checked to see that there are two glasses in the back and one in the front. The element in the front should two glasses that are cemented together. Hope this helps.

Geoffrey

[nkrustev]

Thank you guys for writing.
All the glass that you describe is here. No separation visible anywhere. Two glasses in the back and one in the front. It all unscrews very cleanly. I can as well "turn for soft focus" in the direction of the arrow and the whole barrel unscrews nicely.
I can focus on closer objects without a problem. Very bright and nice in the gg.
My main problem is it seems the focal length is not 11 1/2 inches but less. When I compress the front and back standards all the way the distance between the aperture lever and the ground glass is a little less than 10 inches and even then it is not focused at infinity (needs just a little more but the cambo will not go any further).
Is it possible the focal length to be less than 11 inches? Something like 9 inches?

[Jason Greenberg Motamedi]

Focal length should be measured from the nodal point not the lensboard. On a regular (non-telephoto) this is approximately the same location as the iris. On your lens this is probably about 3" from the flange. So yes, it will looks like you have about a focal length shorter than 11," but in fact you don't.

[Geoffrey_5995]

You need the focus from the back of the lens, the back focus, to focus at infinity. As Jason says the equiv. focus is to the nodal point where the iris is which is 11 1/2 inches. So to hit infinity you will need to get the back of the lens to approx. 8 1/2 inches away from the ground glass for infinity. As for the Cambo which is not cooperating, I think it is possible to rotate the front and rear standards 180 degrees so that they get closer to each other. You'll need to remove the bellows to do this and then reattach the bellows once the standards have been rotated. This is easy with a Cambo since the camera is modular and breaks down easily. Hope this helps

Geoffrey

[nkrustev]

Ok, I turned the front standard (thank you Geoffrey) and managed to compress it enough to focus it at infinity. The distance between the aperture lever and the ground glass is 10 inches. Do you think that is normal?
In the mean time I also managed to polish the lens a little bit.
here is the result.

http://photo-zona.net/images/user43270/album18102/large/1300084179_egfy6578_dallmeyer_3b_after.jpg

[eddie]

wow. looks like it has been to the beauty parlor since march 12.....

if it is working use it. mine all have measured 11 1/2 inches to the iris/ water house slot from the gg.

[Geoffrey_5995]

Glad I can help. Now that I'm thinking about it, Dallmeyer changed the formula, and to some extent the focal lengths, of their Patent Portrait lenses. Your lens is a late one and they reformulated the elements so that the lens would have a flatter field. I also know that there were a couple of focal lengths of the 3B, 11 1/2" at f3 being the most common. But I have had a shorter one at 10 1/2" and it was not as late as yours. I remember seeing the the literature denoting the different focal length but don't remember where. I have a bunch of original catalogs and a bunch of Dallmeyer catalogs but would need to dig then out to confirm. In any case, it is clear that Dallmeyer was constantly reformulating their lenses so it is not a surprise that your lens does not fit with the commonly held understanding of these lenses. There is still a great deal to learn.

Geoff

[nkrustev]

Thanks again Geoff.
That is very interesting to know.
If you ever in the future are looking through the literature you have and come across information about shorter focal lengths 3Bs please snap it and post it in this thread.
Have a wonderful day.

[nkrustev]

Just an update.
I had a chance to compare it to another 3B (thank you seven) and as I thought there is a slight difference in the focal length. Mine is a little more than an inch shorter (about 10inches).
We compared all the elements and the rear two were identical. The difference was in the front element. It focused a light source on the floor at a different distance.
Can anyone confirm there were 3Bs with a different focal length?

[Steven Tribe]

Dallmeyer advertising and catalogues don't mention the focal lengths of the B series that often - in contrast to the B and D series. If no answer appears within a couple of days, I'll contact Seán to see if he knows the serial number the change was introduced.

[CCHarrison]

I am going to estimate 1920 on this lens based on serial number.

See the ad below for an ad from 1912 and one from 1913 which explains the new patent mount.

Also see the B series Patent Portrait specs from 1931 Dallmeyer catalogue from cameraeccentric.com

Dan

[Pete Roody]

I also have a 3B with a focal length approximately 10". I don't have it handy to give you the serial number but I think it was a 1920's version.