Need info re: Protar V Lens Spacing

[Kevin Crisp]

I would be really grateful if somebody out there with a 6 1/2"X8 1/2" B&L Protar V in barrel (141 mm) and a caliper could tell me the proper spacing of the lens elements. Either measured as the overall width of the lens with both elements screwed in or just the width of the barrel with both elements unscrewed would do. If I can impose further and you can tell me how far back from the front of the barrel (front element removed) one finds the aperture blades that would also be useful. Disclaimer: I take no stand on midtone separation with different pyro formulas. Thanks in advance.

[Phil]

Kevin,

I have two of these lenses, so I measured both with a 'consumer quality' 1/128 inch caliper, so the resluts are not machine shop accurate, but the results are interesting.

First lens has a serial number stamped on the face of the front element - 757399 - length with both elements screwed in - 7/8 inch - barrel without elements - 9/16 inch.

Second lens has a serial number engraved along with the other markings 1207602 - length with both elements screwed in 109/128 inch - barrel without elements - 9/16 inch.

An eye check of the two lenses seems to validate the older lens has a heavier mount for the elements, but the barrels are the same.

The aperture looks to be 9/32 back from the front edge of the barrel.

Good luck with the lens mounting. It's a great lens for 8x10.

Phil