A Dumb Question?

[cmdrzed]

I have noticed that the aperture scale on many lenses is not complete. For instance, the Zeiss ZM 50 has scale marks for f/22 to f/4 even though the lens is an f/2. Where are the marks for f/2 and f/2.8? The Leica 50 Summicron lacks the f/2.8 and f/5.6 marks but it is obvious where to guess if one is scale focusing. Is there a reason that some of the Zeiss lenses only go to f/4 and how does one "guess" where f/2 and f/2.8 are located? I know this might be a stupid question but I was curious.

 

[ferider]

Not a dumb question.

On these lenses the focus throw is so short that the marking for any aperture smaller than the marked minimum could not be accurately used.

On older, long throw lenses the markings go lower. For example early Summicrons (see below).

My Nikkor 50/1.4 LTM lens has markings for 1.4, and the throw is so long that it's actually usable.

I like long throw lenses partly for that reason.

Hope this helps,

Roland.