Recently Alin Flaider wrote:
>
> The problem with the "macro" teleconverters is the additional 1/2-1
> stop of light loss, that reduces a f/2.8 lens to f/8 instead of f/5.6
> - as do "normal" 2X teleconverters. I suspect this is due to the
> additional extension required by the helicoid mechanism.
Hi Alin,
You are right. The light loss is due to the extension -- it simply moves
the lens further away from the film => the image circle increases => the
image brightness decreases.
However, a Macro converter set at 0 additional extension (if that is
possible) would only cost you the "normal" amount of light loss, so a
Macro converter is not an evil thing. In fact, it can be as good as a
standard teleconverter but with the additional advantage of a helicoid
ext. tube (with all positive and negative consequences).
Cheers,
Boz
-
This message is from the Pentax-Discuss Mail List. To unsubscribe,
go to http://www.pdml.net and follow the directions. Don't forget to
visit the Pentax Users' Gallery at http://pug.komkon.org .
