Hi,

I recently became the proud owner of a lens which is more than four times my age, a 1918 Ross xpres 7 1/4inch f/4.5. I expected that it might not have been in the best condition, from the photos on the 'bay, but I thought that a quick scrub would brighten it up. However, it seems that there is some significant corrosion to the brass, which affects the lens both cosmetically and also prevents it from being fully dissasembled.

I was able to remove the rear cemented group. Judging by the serial number (and so the age) I believe it should be the triplet version, however, I'm not sure about that. Cleaning the group proved difficult, there is a slight mistiness to the back surface of the lens. I've tired dish soap, isopropyl alcohol, and lens cleaning solution, which have all helped a little, but not removed the cloudiness. I wanted, also, to clean between the front two lenses, but I was unable to remove them from the housing. There is a small screw which was difficult (but possible) to turn, and did not come out. It seemed to have no effect, I thought that it might have been to keep the aperture in place, or else secure the some other part of the lens. I used my lens spanner on the front holes of the lens, which I thought should release the front lens. I was unable to release it, and scratched the front quite badly.

The internet suggests using vinegar and salt on corroded brass and scrubbing hard at it. But I'd only want to do something like that if I could remove all of the lens elements from the body. Does anyone have any tips for unlocking stuck brass threads? Do you think the small screw has anything to do with it? Should I just deal with it? I'd like to fully restore the lens, and repaint it, but I think that is outside of my ability, I didn't make much of an improvement by cleaning it alone. I also found some chips in the front element, and a flat area. I'm not sure what caused it, but I hope it wouldn't effect image quality too much.

I'm not sure what I should do with the lens. I believe the lens covers 1/4 plate and I have a 5x4 camera, so I might try using it on that. I also like the idea of trying to mount in for my DSLR, as its lack of a shutter wouldn't matter. I haven't found anyone posting example images from it, lots of people have said that the xpres lenses are excellent, and that the five element triplet is better than the later tessar style, but I don't really have any context for that. I expect that it would be resonably poorly corrected for colour, and might be optimised for the blue/near-UV because of the sensitivity of the plates used at the turn of the last century.

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Thanks for your time.