Lens Question - Rapid Rectilinear 18x22 Series A No. 10

[gphoto]

So I just found this lens at an antique shop and can't find much information about it. The focal length is approximately 40", maybe a bit more.

Just wondering whether someone has any more info on it, I would assume that the 18x22 indicates the coverage?

Thanks for any help.
168330

[AlexGard]

If my JC Sommerville RR lens with "16x20" engraved upon it is anything to go by (it does indeed cover 16x20) then I assume you are probably right in your assumption seeing as 18x22 was/is a standard plate size. . I really like my RR and wish i had a shorter focal length one for my 12x20 (bellows aren't long enough :( )

Mine is an f/8. Which i think is pretty standard.
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[Steven Tribe]

Yes, that is the coverage for the lens. RR makers were conservative about coverage, so expect it to cover the next size up with smaller apertures, that is 20x24". I forget who Manhatten Optical became later.

[Louis Pacilla]

I forget who Manhatten Optical became later.

Korona/Gundlach.

[Jim Fitzgerald]

I guess I need to check more of the antique stores in my area

[gphoto]

Thank you for the answers. I am curious as to why the lens is marked F.28 which would appear to be the focal point but the actual tested focal length seems to be more like 40 inches. From what I understand the angle of coverage for the rapid rectilinear lens is around 45 to 50°, which would suggest that the coverage would be pretty massive with a 40inch draw. Something g like 49x448?

[Steven Tribe]

I have the Dallmeyer data for the equivalent RR in front of me. I assume yours is the usual F8 variety, too.

He has one that covers 22x20 and the focal length is given as 30" (At infinity, remember!).

[Louis Pacilla]

Here's a cut from the Manhattan Optical Co Catalog 1899 before Gundlach/Korona bought them out. This is the "official" FL for the #10 27 1/2" FL and f8 at full opening.