Rom | Tapas in the sun1d ago

I need help to work out the aperture settings for a vintage lens, believed to be approx 1915. The lens is marked:

H Duplouich, Paris, Rectilicne Extra Rapid

That is all: no max aperture and no focal length (my guess for the latter is 100mm).

The aperture scale runs from 2 to 22 with equidistant segments. 2 is the smallest aperture, 22 is WIDE OPEN, so it is not related to an f-stop scale. I think it is the aperture diameter in mm.

An idea how to work out f-stops?

#vintagelens #vintagecamera

Show threadLeanne J1d ago
@tapasinthesun any experience with older cameras like this @Documentally ?
Show threadDocumentally
@LDJ @tapasinthesun I think you’re right in regards to aperture measurement and if you are sure it’s a 100mm lens then wide open at 22mm will be f4.5. And if 22 mm = f4.5, 20 mm = f5, 15 = f6.7 and so on. Each F-stop should change by a factor of √2 ≈ 1.414
But I would definitely run a test for film through it first. Logging alongside a light meter :-)
Apr 6 at 7:55amIceCubesApp
Show threadRom | Tapas in the sun1d ago

@Documentally Thank you for the info. It is much appreciated!

I will try to confirm the focal length and the aperture diameter numbers as best I can. Then do the maths and carry out film testing. I will post the results here, possibly even do a blog post. But it may take a while…
@LDJ

Show threadDocumentally1d ago
@tapasinthesun @LDJ cool. Look forward to it. There’s nothing like resurrecting old glass. :-)