Heliar question

[swmcl]

Hi,

Could someone please help me out.

I would like to find out the mounting thread diameter of 300mm heliars (normal and universal) in mm please. Is the diameter of the heliars different to that of the Velostigmat of the same focal length? If so why? (f 4.5 varieties)

I'm assuming lenses that aren't mounted in shutters!

I don't know but sometimes Google searches are fruitless. Maybe I need to learn some special search techniques or something.

Cheers,

[Ole Tjugen]

The Heliar 300mm f:4.5 fits the same shutter as a Xenar 300mm f:4.5 - a Compound V 12/2.

For the thread dimensions, see the link in my signature.

The Velostigmat is of US manufacture, and intended for US made shutters, so the threads are different.

[imagedowser]

The mounting threads on my 360 Univ Heliar are 103mm and it is on a 6x6 board, the flange is 130mm outside diam, opening req is 114mm for flange, if you have it...

[Steven Tribe]

The mounting threads of a 30cm Universal Heliar are 91.35mm (measured at "hill tops"!).
Flange thread dimension is 89.80.
Cell thread sizes for shutters have no meaning for the Universal, of course.

[Stephane]

The flange for the normal and universal 300/4.5 heliar is the same (I have both).

[swmcl]

Many thanks.

The actual dimensions of things is not easily found unless specifically requested sometimes. The search terms are too vague - even for an advanced search! Most posts laud the characteristics of such lenses and do not speak of their dimensions as such.

Am I right in thinking that the optical design of lenses affects to some extent the size of the front and rear thread sizes? for example, the heliar is a relatively narrow angle of view compared to a say an angulon or something. Because of this, when you have two lenses of the same focal length and aperture rating the actual glass size can be significantly different. I think of the 90mm SA and it looks quite strange in that it has a very large glass and yet necks down through the -relatively small - shutter. The older lenses seem to be more barrel-like and don't neck down anywhere near as much.

I wonder if a modern heliar design with the latest glasses and tools available would need to have all that glass assuming the same aperture and focal length?

Thanks again.

[Steven Tribe]

You are right - but using less glass is a problem with a moveable triplet in the Universal design. I suppose dialyt soft lens like the Graf Variable could have had a "waist" - but loosing speed, of course.

[imagedowser]

Sorry, thought you asked abt 360mm .. my mistake.