Please help with data for Dallmeyer 3A

[lenser]

I'm getting ready to make some Waterhouse stops for my Dallmeyer 3A. Even after searching here quite thoroughly, and Google efforts as well, I don't find the information about the actual focal length and wide open f stop. (Probably my search techniques, but frustrating none the less.)

Can anyone here please help with that data so I can calculate the needed stopo sizes for the Waterhouse stops?

Many thanks in advance.

Tim

[pierre506]

It's the best way that someone could provide the scanned pix with ruler of his Dallmeyer waterhouses.
The most common Dallmeyers are 2B， 3A，3B，3C ，3D...

[Mark Woods]

Focus on something distant (infinity), then measure from the center of the lens group to the film plane. That is the focal length. The actual stops are a fraction of the focal length. F/16 is 1/16th of the focal length. You can measure the opening of the lens (ideally in the middle of the lens) and that fraction of the focal length is the maximum speed of the lens.

God luck.

[lenser]

Thanks, Mark. That's most helpful and with that I came up with a roughly 16" focal length and with a 4" diameter, a maximum aperture of f2.5 (if I calculated correctly). Could anyone please confirm those figures?

[goamules]

Look on the collodion.com forum, I think Joe has templates he's made for the 3A stops. http://www.collodion.com/forum_posts.asp?TID=1979
And I think Eddie had stops manufactured, out of steel, for sale for a while. Keep looking, it's out there.

[lenser]

Thanks, Garrett. I just signed up so I have to wait for approval to access. I'll do that shortly and hopefully find what I need.

Again....Thanks!

Tim

[Mark Woods]

Looks good. Keep us posted about what you're up too. You can make your own waterhouse stops. You could even make them out of cardboard. I've done that for lens mattes in an adapted matte box.

[lenser]

Thanks, Mark. I actually have a few extra 4x5 dark slides that I'm planning on using. A great friend has a water jet cutter and will do all the shaping for me so they should turn out perfectly.

[Mark Woods]

That's great. Enjoy the journey!

[Steven Tribe]

The speed sequence for Dallmeyers is CBAD.
16" is correct, 4" is correct - this gives F4.
There may be slight differences between the versions due to necessary room for itis internal iris mounts. But a Waterhouse stop version will be F4.

Note that Dallmeyer made waterhouse stop sets that covered various model (including Petzvals and RR's). So a set that fits your 3A may not be marked correctly for your model (or did they use a code like a casket set?). Eddie, in his manufacture of stops for Dallmeyers, found that there is not a universal fit for all versions (rear and front turn) of the same lens.


CCHarrison has a good summary of the models in the Soft lenses part 1.