Prototype of a zoom lens for 4x5!

[Birna Rørslett]

at 105mm and f5.6 you only need 18.75mm lens diameter in theory ;-)

As witnessed by the large-format 105 mm mounted in the small Copal 0 shutter. However, it should be emphasised these are wide-angle designs. They typically have a pronounced 'wasp waist' shape dictated by large front and rear elements and a relatively speaking tiny central shutter unit.

[Akira]

as I see it the front standart is 4*5 inch, the bellows between first and second standart expands from 4*5 to 5*7 or 8*10 which is also the format of the third standart. He also seems to have another bellows as Compendium to protect the front lens from stray light and there is a supporting rail connecting both tripods. It took him very long to install all this, while I was already taking pictures

Frank, thank you for sharing your solid observation.  That makes sense.

at 105mm and f5.6 you only need 18.75mm lens diameter in theory ;-)

Klaus, you are right.  But I would think that the front elements of the fast standard zooms tend to be much larger than the theoretical size.  35-70mm/f3.5 or f2.8 zooms come to my mind.  An f5.6 standard zoom for 4x5 should be very fast.

That said, I will look into the front element when I have another chance to visit the museum.