What can you tell me about this lens?

[campy]

This is another lens from my friends grandfather. I have found some info and it appears to be a double Protor with one side a 29cm and the other a 35cm, but would like to know if it would work on a RB Graflex 5x7 or RB 4x5 Graflex and is it considered a good lens. Any info would be appreciated.
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[brouwerkent]

This is a dandy lens. Value of these on Ebay is stupid high. Your lens is a triple convertible. Used alone, front and back elements are useable...or combined the focal length will be different. Note the f stop is in mm...you will need to do a bit of math to figure the different stops for each focal length.

Phil

[Kevin Crisp]

Triple convertible Protar. Single cells are 290mm and 350mm, combined (put the 35cm lens in the front) just over a 180mm lens. Is rated to cover 5X7. You will find that with both front and back in use it is quite sharp and contrasty. Single cells have focus shift (refocus after stopping down) and you probably aren't going to be making enlargements since in my experience the edges aren't going to be that sharp, but maybe yours is better than the ones I've tried. I had better luck with the licensed B&L versions when using single cells.

Yes, you need to make a table of fstops to mm stops but this is a one time exercise and not that hard.

[Keith Fleming]

I have that set from an earlier vintage, and mine are mounted in an Alphax shutter. Individual cells work best in the rear of the shutter or barrel, and I recommend either a medium yellow filter or orange filter out in front if you want max sharpness. S. K. Grimes made me a custom adapter that fit in front of the shutter and accepted the filter. Kevin Crisp made some good points above about using the individual cells, and I think it would be best to use the individual cells on 4X5 or smaller. Refocusing after stopping down quickly becomes routine.