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Do you want a 10.5mm f2 prime?

Started Jul 22, 2015 | Polls thread
tpani
tpani Regular Member • Posts: 332
Re: Do you want a 10.5mm f2 prime?

Flange/registration distance with M43 is 20 mm. For the Nikon mount the distance is 46.5 mm. M43 sensor area is 17.3 x 13 mm, while Nikon FX has 36 x 24 mm. The one thing that is not roughly 50 per cent is the mount diameter. The wikipedia article on the Nikon F-mount says that the mount "external diameter" is 46.5 mm. I am not sure how to measure the corresponding for M43. I just checked the 9-18mm mount, which measures between 50mm (outer) and 40mm. Anyway, the M43 mount diamater seems (relatively) much bigger than the Nikon mount (not 50 per cent, but more like 80 per cent). But this is really the only thing that is not about 50 per cent.

The width of the mount, and the need to have many parts of the lens as thick as (and not 50 per cent only) for bigger lenses (so that things do not bend or break) explains why a 10 mm f/4 is not 44 grams, but 100 g, or possibly even more.

The basic procedure is: take any Nikon FX lens design, scale down _everything_ to 50 per cent. You get a M43 lens for a flange distance of 23.25 mm. Make the mount M43, and add 3.25 mm to the lens to make the flange distance effectively 20 mm. Same of course can be done with Canon EF mount lenses. Flange distance 44 mm. Sensor 36 x 24 mm. Same story.

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