Plaubel Heli Orthar n4 f6.3

[alexvaras]

Hi all,

Anybody has any info of this lens? Focal length? It covers 4x5, but higher?

Thank you in advance,
Alex

183643

[Dan Fromm]

Fabre (1906), pp. 57-8, on the f/5.2 Heli-Orthar. (my translation):


The Heli-Orthar of Plaubel, in Frankfort, is made up of two lenses well-corrected for all aberrations. The front cell is a dialyte type made up of two air-spaced singlets. The rear is made of four cemented elements, with an aperture of f/10 and fully covers the recommended plate size. The two cells are mounted very close together, so that the complete lens is very small although it has six air-glass interfaces. It doesn’t produce a central hot spot and gives brilliant images wide open, with the plate covered with good resolution. At f/12.5 the circle covered’s diameter is more than 1.5 the focal length. The front cell, maximum aperture f/15, and the rear, maximum aperture f/10, are excellent landscape lenses.

Fabre lists numbers 1 – 7, focal lengths from 85 to 200 mm, maximum apertures from f/5.2 – f/6. Clearly not exactly the OP’s lens. All focal lengths from #3 (118 mm) cover at least 4x5 wide open.

The VM says the lens was made at f/5.2 and f/6.3 and that the f/6.3ers, not mentioned by Fabre, cover 90 degrees.

See the list for a link to Fabre.

[alexvaras]

So basically I can get 3x1 depending the combination described I get different focal lengths with different apertures.
When I cleaned yes, front is two lenses and back one very thick.

I found the Fabre suplement 1906, thank you!