- Joined
- Jul 8, 2008
- Messages
- 19
- Format
- Large Format
You can get some information on how the lens is constructed by counting reflections. Close the diaphragm all the way so you can check the front and rear groups separately. That way you don't have to look through all the lens groups at once. Look at the reflections of a small light bulb in the front lens group. Bright reflections are where glass meets air. Very dim reflections are where two elements are cemented together. Count the bright and dim reflections. Then do the same with the rear lens group. Here are some examples:
Two bright reflections - single lens element
Two bright and one dim reflection - a cemented doublet
Two bright and two dim reflections - a cemented triplet
Two bright and three dim reflections - a cemented quadruplet
Four bright reflections - two single elements, air spaced
Four bright and one dim reflection - a single element, an airspace, and a cemented doublet.
There are more combinations, but this is a start. Let us know what you find.
If it's a cemented doublet in each cell it's not a Doppelprotar - that takes at least three elements in each cell.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?