At 11:35 1/4/80 , Hank Hogan wrote:
>Dear Olympus doubler users -
>
>Have you experienced using doublers with wide angle lenses ?
>I put my 28mm on the Vivitar zoom extension doubler and wow the
>depth of field from the 28 mm is remains even though the focal length
>is now 56 mm !
> [snip]
Hank,
Did you take into account that a teleconverter also changes your
(effective) aperture? A 1.4X shifts aperture (stops down the amount of
light reaching the film) by one stop; the 2X you used by two stops.
Example: if a lens aperture ring is set to f/4, the effective aperture
with a 1.4X is f/5.6 and with a 2X is f/8.
There is no free lunch with DOF. Your 28mm with 2X TC acts just like a
56mm without one. Just remember that it also doubles the f-stop numbers as
marked on the aperture ring and the DOF will be the same as for a 56mm lens
at the effective aperture (the doubled numbers).
Regardless of how it works, if it works well for you keep doing it!
-- John
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