Schneider Componon-S 100mm f5.6, double iris

Hi,
I just got this enlarging lens. One ineresting "feature" is it seems
to have two sets of aperture blades, each set has 5 blades, but seems
only one set of blades can be useful, the other set will just
extend/retreat as I rotate the aperture ring, they never get into the
light path. Why such design?


Also, the lens mouting thread diameter is about 33mm, not the usual
39mm, I have the retaining ring, but seems I need an adapter ring to
mount this lens to my enlarger?

The serial number is 13 xxx xxx, so it was made in 81-83.


Thanks,
Suibuliu

In article ,
(Suibu Liu) wrote:

Hi,
I just got this enlarging lens. One ineresting "feature" is it seems
to have two sets of aperture blades, each set has 5 blades, but seems
only one set of blades can be useful, the other set will just
extend/retreat as I rotate the aperture ring, they never get into the
light path. Why such design?

It could be a preset detent. In other words, you determine the f-stop for
exposure, then open up for focusing and composing, then just press the
lever or turn the ring to the pre-set detent without having to look.

What you see is not really two sets of 5 blades, but 5 pairs of blades. The
two blades of each pair are joined at one end with a rivet and they are
installed in the lens in a scissor-like fashion. The one blade of the pair
has a sort of curved v-shape notch. This is the blade that you see
primarily. The other blade of the pair is curved and you can see these
blades as the aperture is almost wide open.

This is just one of a number of different blade designs Schneider uses in
their optics.

KHB Photografix
www.khbphotografix.com


"Suibu Liu" wrote in message
om...
Hi,
I just got this enlarging lens. One ineresting "feature" is it seems
to have two sets of aperture blades, each set has 5 blades, but seems
only one set of blades can be useful, the other set will just
extend/retreat as I rotate the aperture ring, they never get into the
light path. Why such design?


Also, the lens mouting thread diameter is about 33mm, not the usual
39mm, I have the retaining ring, but seems I need an adapter ring to
mount this lens to my enlarger?

The serial number is 13 xxx xxx, so it was made in 81-83.


Thanks,
Suibuliu