Lentar 90-230mm objectives
Here are a pair of Lentar 90-230mm objectives removed from damaged lenses... back side view of the one on the left, front side on the right. They're used as close up lenses reverse mounted onto the front of several of my prime lenses. The front filter ring size is 58mm, so I use a double-male macro-reverse mounting ring having that size on one side, and my prime lens's size on the other. The bright mark on the rim of the lens on the left was made by the small retaining screw that locks the objective into the barrel of the assembled lens. Before this screw can be removed, a small drop of WD40 must be applied to soften/dissolve the "goop" applied to the threads at the factory to prevent loosening. WD40 is stuff that can creep into places it ought not to, so buy something called a WD40 "no-mess pen", which looks just like a felt tip marker, but contains no ink... just WD40. A quick dab... wait 5 minutes, and remove the screw. The cell is stuck on firmly, but by using two pieces of rubber "waffle" shelf liner to provide a firm grip, it can be unscrewed.
These objectives come in two varieties... one kind having the lens held in place by a slotted retaining ring normally removed by a lens spanner. The other type has a slot-less retaining ring that is handled using a rubber "friction" tool. The only time I ever actually remove glass is to clean internal surfaces if necessary, which doesn't happen very often.
Once removed from the rest of the lens, you'll find that the inside of the back end of the cell may, or may not be threaded. The cell on the left has had an empty 52mm filter ring pressed into it. This allows stacking another reversed objective onto it, which doubles the magnification and halves the working distance, but doesn't affecting the exposure at all.
I've discovered that a number of 90-230mm objectives from various brands of lenses are identical. Lentar, Mamiya, and Soligor all look like they used cells made by the same manufacturer, and come apart from the body of the lens in exactly the same manner. Other brands have the objective cell configured differently... with the lens difficult to remove, being part of a barrel containing a very greasy helicoid. The three brands mentioned above are the easiest to work with. The objective comes away in a single neat, clean piece that's ready to use as-is.
DSC-6216
Lentar 90-230mm objectives
Here are a pair of Lentar 90-230mm objectives removed from damaged lenses... back side view of the one on the left, front side on the right. They're used as close up lenses reverse mounted onto the front of several of my prime lenses. The front filter ring size is 58mm, so I use a double-male macro-reverse mounting ring having that size on one side, and my prime lens's size on the other. The bright mark on the rim of the lens on the left was made by the small retaining screw that locks the objective into the barrel of the assembled lens. Before this screw can be removed, a small drop of WD40 must be applied to soften/dissolve the "goop" applied to the threads at the factory to prevent loosening. WD40 is stuff that can creep into places it ought not to, so buy something called a WD40 "no-mess pen", which looks just like a felt tip marker, but contains no ink... just WD40. A quick dab... wait 5 minutes, and remove the screw. The cell is stuck on firmly, but by using two pieces of rubber "waffle" shelf liner to provide a firm grip, it can be unscrewed.
These objectives come in two varieties... one kind having the lens held in place by a slotted retaining ring normally removed by a lens spanner. The other type has a slot-less retaining ring that is handled using a rubber "friction" tool. The only time I ever actually remove glass is to clean internal surfaces if necessary, which doesn't happen very often.
Once removed from the rest of the lens, you'll find that the inside of the back end of the cell may, or may not be threaded. The cell on the left has had an empty 52mm filter ring pressed into it. This allows stacking another reversed objective onto it, which doubles the magnification and halves the working distance, but doesn't affecting the exposure at all.
I've discovered that a number of 90-230mm objectives from various brands of lenses are identical. Lentar, Mamiya, and Soligor all look like they used cells made by the same manufacturer, and come apart from the body of the lens in exactly the same manner. Other brands have the objective cell configured differently... with the lens difficult to remove, being part of a barrel containing a very greasy helicoid. The three brands mentioned above are the easiest to work with. The objective comes away in a single neat, clean piece that's ready to use as-is.
DSC-6216