Hi Eric
EricRed wrote:I recently acquired a Schneider 50mm f/4 enlarge lens in the B00 iris mounts. I'd like to do this iris mount transplant with my Schneider 28mm f/4 to create a f2.0.
I've never dismantled a lens other than replacing a shutter on a view camera lens. I have the proper tools and I've watched a number of youTube videos on lens repair. The degree of difficulty seems to vary substantially from lens to lens. I have not found little on disassembling enlarger lenses. I would think the simpler design of an enlarger lenses would put it on the easier side.
Yes, Schneider Componons are modular, all the elements are contained in two cells. Other lenses use retainers to mount the elements in the housing, some of the Rodenstocks and others are like this. The 4/28 Rodenstock is not modular for example.
I'm looking for advice on swapping the iris mounts. After comparing the differences between the front elements of the two lenses, I realized I'm not completely sure I understand what parts I need to swap. Is the object to remove the front and rear lens assemblies and swap the entire barrels? The other possibility might be to open the lens, pull some assembly I don't know about which contains the iris and move that.
There are images on my site that show the 4/28 and 4/35 Componons disassembled but thanks to this message I discovered that my site is down, or at least the images are down.
I might have an image on my computer that I an upload now while I wait for help with my site.
I've found in both cases the rear elements easily unscrew from the barrels. I could see the back of the iris blades, like the back of a shutter.
The part I am less sure about is how to deal with the front lens elements. The fronts of the two lenses look quite different. On the 28mm there is a thin ring with spanner wrench slots and the ring with the lens information. Using a silicon rubber filter wrenches, I was able to rotate both of those ring together. Those parts appear to unscrew as a group along with the ring containing the filter thread. I'm thinking all those parts must be the front lens assembly. I didn't want parts pouring out, so I did not unscrew it all the way.
That is front a lens cell. It houses elements. Opening up a lens cell doesn't serve any purpose if you are trying to swap lens iris mounts.
The 50mm is a little different, but I've been able to unscrew what appears to be the equivalent elements. Images on Robert's site makes it appear that the two lens elements from the 28mm were just unscrewed from the the 28mm barrel and moved to the 50mm barrel. Is that all I need to do? Does it make any sense to put the 50mm lens assemblies onto the 28mm barrel understanding that the f-stops will screwed up.
If the two lenses are the same iris mount type of iris the cells are swappable.
You might have a mis-match or iris mount types but there is no way to tell unless I see the housings.
Maybe count the iris blades to check?
The image below is of the older round aperture iris mount. The cells from the 4/28 of the same type will thread right in and are a direct swap for the 4/50.
I'm going to try a different approach with the test updates that I posted today and post a highlight from the page updates.
