On 12 Dec 2001 17:18:24 -0800, Paul Rubin wrote:

>I'm wondering what those wideangle converters that you screw into the
>front of a lens do the effective f/stop. Normally they're used with
>video lenses but I've seen them for photographc lenses too. I know
>that a 2x teleconverter loses two stops of speed, so a 50/2.0 becomes
>a 100/4, etc.
>
>Does an 0.7x wideangle converter *gain* a stop of speed? Does a
>50/1.4 lens with an 0.7x converter become a 35/1.0? Anyone try this?
>
>I currently have a crappy 0.5x converter that gives ok results with
>a video camera but soft images with a 2mp digicam. However, there
>are some much higher quality converters available and I'm thinking
>I might like to try one on a 35mm SLR lens.

Results on 35mm lenses are, well, virtually always *quite*
soft (the medium is *much* higher in resolution than video,
and the optics-quality is more important) - and there will
be no speed change with the front-mounted converter, unlike
with rear-mounted converters...