Vignetting
The easiest way to judge light fall off and/or vignetting is to mount
the lens on a body, set the speed to bulb, the aperture to any setting other
than "A", open the back and fire the shutter. Look through the lens and see
if you can see the filter or lens barrel and notice at which aperture the
diaphragm block either of them out. This should be your minimum aperture
that assures full illumination of the frame. If the filter remains visible
with stopping down, consider getting an adaptor ring to step up to the next
size.
BTW, I never use filters except a polariser, filters for B&W and UV and
colour correction for slides. A filter, unless it is part of the optical
design (as in some of Pentax's wides and fish eyes) will degrade the image.
Bob
----- Original Message -----
From: "Steve Larson" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, August 15, 2001 11:42 PM
Subject: Re: what UV filter for FA 24-90?
> Hi Frank, I doubt it will vignette, but it can`t hurt to test it. Stop the
lens
> down all the way with the filter on, look at a bright light and see if you
can
> see the filter edges, and sneak up on the edge of the filter with a finger
> to see how much room you have. It`s not a perfect test because the
> viewfinder doesn`t show 100%, but it`ll get you in the ballpark. Since
> the "slim" filters are relatively new they command a high price.
> Steve Larson
> Redondo Beach, California
> ----- Original Message -----
> From: "Frank Wajer" <[EMAIL PROTECTED]>
> To: "pdml" <[EMAIL PROTECTED]>
> Sent: Wednesday, August 15, 2001 6:26 AM
> Subject: what UV filter for FA 24-90?
>
>
> > Hi,
> >
> > I'm nearly convinced to get the new FA 24-90 zoomlens. One question
> > remains.
> > What UV filter to protect the lens would be ideal?
> >
> > The shop advised a B&W slim MRC UV, they are Dfl. 196,- ieek, thats
about
> > $80.
> > I already have an SMC 67mm UV filter on my A 35-105 f/3.5,
> > but am afraid it will vignet at 24mm end.
> >
> >
> > bye,
> >
> > Frank
> > -
> > 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 .
> >
> >
>
> -
> This message is from the Pentax-Discuss Mail List. To unsubscribe,
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