620 with 120 film

[Ernst Dinkla]

I'm a bit confused now. I removed the lens for internal cleaning. My understanding is a triplet is 3 elements. This lens has 4. The front group has 2 and the rear group has 2. In my book that equals 4.. So what gives? Everything I have read about this camera is it uses a triplet lens..

With 4 elements I would expect a Tessar design for a Kodak Anastigmat. That is 4 elements 3 groups, the cemented group at the back. Is that what you see? Two cemented groups is quite unusual for that kind of cameras.
http://en.wikipedia.org/wiki/Tessar

I have removed a Kodak Anastigmat Special 101mm 4.5 (Tessar type) from a Monitor 620 and put it on a Agfa Record (120) model. Still have to make trial images but I think it is much nicer that way than 620 conversions in whatever way. The lens performed well on the Monitor that I converted to 120 spools but even then the space to insert rolls was very tight. There were more issues with that camera.

Ernst Dinkla

 

[colyn]

With 4 elements I would expect a Tessar design for a Kodak Anastigmat. That is 4 elements 3 groups, the cemented group at the back. Is that what you see? Two cemented groups is quite unusual for that kind of cameras.
Ernst Dinkla

The front group has 2 separate elements as well as the rear. None are cemented..

 

[Ernst Dinkla]

The front group has 2 separate elements as well as the rear. None are cemented..

So in optical terms; 4 elements, 4 groups. Which usually points to a Dialyte type for Anastigmats. Or an Aviar type which looks similar but is more a triplet with the center element split in two. The separation between them should be less than in a Dialyte

http://forum.mflenses.com/viewtopic.php?t=6068&view=previous

To go from a Triplet to a 4 element, 4 groups design:

Front element replaced by a pair of lenses: Kern Kino-Objektiv.

Rear element replaced by a pair of lenses: Taylor-Hobson Speedic and Coric.

Middle element replaced by a pair of lenses: Taylor-Hobson Aviar. This makes the lens symmetrical and closer to the Double-Gauss type. In the Aviar the two negatives are placed very close to each side of the diaphragm, then the Dogmar type makes them pulled further apart.

Taylor Hobson origins are likely but the patents may have been expired by the time this camera was made.

Ernst Dinkla