Quote Originally Posted by 250swb View Post
The 'standard' focal length on almost any traditional folding 6x9 camera is 105mm. So a 180mm lens would be a medium verging on long telephoto equivalent if you accept the 105mm standard lens analogy. So for instance a 90mm (Angulon perhaps) would therefore be a slightly wider than standard lens, perhaps (off the top of my head) a 40mm equivalent in 35mm terms.

Funny you should say that. Nominal 6x9 is more or less 56 x 81, whence its normal focal length is 100 mm. Slightly longer tessar types were used on 6x9 folders to improve image quality in the corners a little. 35 mm still is 24 x 36, whence its normal focal length is 43 mm. That 35 mm cameras are usually supplied with 50 mm lenses is due to an historical accident.

The two formats have the same aspect ratio, so comparisons between them are easily made. A 90 mm on a 2x3 (nominal 6x9 is actually 2.25" x3.25", usually called 2x3; 6x9 is a lousy metric approximation) is sees the same view as a (90/100)*43 = 39 on 35 mm still. A 180 on 2x3 sees the same view as 1.8 * 43 = 77 on 35 mm still. Short verging on medium tele, I'd say.