Mystery Brass Lens Identification

[Ezo]

Hello, I hope I'm not breaking any rules here by asking for help with this. I recently picked up this old brass lens of Yahoo Auctions for just about nothing with the intention of cleaning it up and tossing it on my Speed Graphic. I can't find any identifying marks, and it doesn't match any lenses I've seen. It looks like a rapid rectilinear design, but it's definitely not a Dallmeyer based on the design details. I haven't had a chance to really check focal length yet, but using the "compare the came object looking through two lenses method" I suspect it's about 300mm? I'm new to LF so I don't know a lot. Wondering if anyone has seen the same design elsewhere. Thank you!

[Steven Tribe]

Looks like a standard RR/Aplanat F 7.7. - 8.0. Only distinguishing feature is the indent in the barrel to house the tab on the Waterhouse stop.
The round lens board was quite a common feature of non-taking camera-type optical devices - but was also used by some “normal” camera makers. If it is French, then there may be Indian ink/pencil marks on lens edges.

[Ezo]

Oh, that's not an indent, the waterhouse stop tabs were all just bent at some point. I've been trying to figure out a way to get the elements out, but the retaining ring on them is stuck fast so I've kinda given up. Thank you so much for the information! Based on my estimation of 300mm focal length(which is most likely off), and the size of the largest waterhouse stop, I think you may be right about f8. I'm curious though, what is a "non-taking camera-type optical device?"

[Steven Tribe]

Cameras made for graphic arts, horizontal enlargers and various multi purpose set-ups see figures below.

[Ezo]

Oh that's interesting, I didn't think about that. That would also explain why it has waterhouse stops. Hopefully it takes some fun photos! Thanks again!