help identifying a lens

[Blueberrydesk]

I picked this up a while ago for 4x5, and I got it fairly cheap (I think it was $40) but I have no idea what it is. The focal length appears to be about a 90mm, with just the rear element as a 8 in focal length and just the front as a 14in or so. These numbers are really just estimated guesses from popping it on the front of my 8x10 and eyeballing the extension.

But I'd really love to know what this lens is and what to expect from it. I'm going to shoot with it this weekend but anything I can know ahead of time would be great.

Thanks for any help you can give me.

[Blueberrydesk]

Forgot to add, the shutter says "Kodak Ball Bearing Shutter" and seems to fire accurately. i.e. the 1/50th is faster than the 1/25th.

[wclavey]

I have a shutter and lens that look identical to this. My lens is marked "RAPID RECTILINEAR - BAUSCH & LOMB OPTICAL CO" and it has about a 135mm focal length, to the best that I can determine. The markings are faint around the outside of the front cell, so you have to look close to read it.

The f/stops are the old American system, so I believe that the f/4 marked on the lens is actually about an f/8 or so...here is a link to a thread that gives the exact conversion between the old American system and the current f/stops.

http://www.apug.org/forums/archive/i...hp/t-6838.html

I tested all the shutter speeds on mine and they were all off... 1/25 = 1/29, 1/50 = 1/34, and 1/100 = 1/47. I understand that over time, all the ball bearing shutters tend to migrate to about 1/33 at all the speeds, although I have seen some reports of people with more accurate ones. My shutter and lens came off of a Kodak 3A and it should cover 4x5.

[wclavey]

I forgot to add, I use this lens on both my 4x5 and my Bronica S2A (attached to an old body cap). The pictures are interesting. I like the looks of them, but I haven't found the right subject for them... sometimes they just look like soft images and other times they look very interesting. I need to play with it more.

[Blueberrydesk]

Thanks wclavey! I don't know how I missed it, but on the outside of my front lens cell there is (very faint) lettering that says the same on this lens; Rapid Rectilinear, Baush and Lomb optical etc. Thanks for the info, I'll do some testing today.
Paul

[Richard Rankin]

The way I remember the conversion between f systems is to just remember that f16 = f16 in both. So, looking at your lens and working back, you can see usf16 = f16, usf8 = f11 and usf4 = f8.

Cheers,
Richard

[Gene McCluney]

Larger format (view camera) sized Rapid Rectilinears are often quite sharp, particularly with b/w film, however it seems some of these smaller Rapid Rectilinears used with old folding roll film cameras, such as the one depicted in your photos can often be softer. I have no idea why.

[Blueberrydesk]

Thanks Richard and Gene. I did a little more research on this site and found this topic:

http://www.largeformatphotography.in...id+rectilinear

where DannL mentions that just using the front element gives a roughly 300mm that will cover 8x10. I put the lens on my 2D 8x10 last night and removed the rear element, and it decidedly does look like it covers at a focus of around ten feet (tested it in my brother's living room) but I have not shot with it yet. I think I'm going to shoot Old Main here in State College with it just to check out the results.

Thanks again for all the help! I guess I just gotta ask the lens how good a performer it is.

[Jim Jones]

You may get less curvature in the image plane by using the elements behind the shutter. Since Rapid Rectilinears weren't designed as double or triple convertable lenses, performance might not be great. A rough and quick way to check focal lengths is to measure the distance from lens to the image of the sun or a bright street light. This is easier than using a ground glass.

[Blueberrydesk]

Thanks for the suggestions, Jim. I think I may like it better with more curvature, though. I haven't shot with it yet, I postponed shooting until tomorrow so I could watch LOTR, but what I'm hoping for in the way of final images is a sharp center with, well, with oof extending to the edges. I've got in mind a shot for one of the university buildings here that would look great like that. We'll see, though. Thanks again.
Paul