Vivitar 1.5X-21 Teleconverter for OM

Does anyone have experience with this teleconverter? I am

interested in using it with a 300mm f/4.5. I am sure it is not as

good as the Zuiko 1.4X, but it is much cheeper. I know you

generally get what you pay for, but I don't anticipate using it

extensively. If it is junk, I won't use it at all and it would be a

waste of money. Also, people have commented that the 300mm is soft

and I have found my to be rather sharp (much, much sharper than

200mm f/4 or 65-200). What does the -21 mean. Is this a 7 element

or 4 element?

Any information would be appreciated.

Dean

Any 1.5x teleconverter is almost certainly a 4 element type. And many Vivitars are/were matched to specific Vivitar lenses and may not perform optimally with other lenses.

An exception is the Vivitar 2x macro focusing teleconverter. Seven elements and an excellent performer and value. It's compatible with many types of lenses. I generally used mine with a fast normal lens to make a reasonably fast 100mm macro lens.