Re: Exact fl of lenses... 220 VR

[Bill Glickman <bglick@xxxxxxxx>]

Alan

      To give you an example, my 150 mm lens works at 146.3 at 1/125 shutter
speed... when I shoot it at 150mm instead of 146.3 mm , letters on buildings
will have blurry edges.  This is visible with a 4x loupe.  So a 10x
enlargement would look very poor in my opinion.  So I guess its all
according to what you are shooting to determine how bad the effect will be.
The further your fl is off from exact at a given ss, the worse it gets.

       To answer your question in a bit more practical way.... I have
recently produced some sharp images from the camera, but that is when I use
the exact fl that has been calibrated with a specific shutterspeed.  But
with the same lens at different ss, the image can get a bit soft, making
equal enlargements undesirable.  So its all a function of how close your fl
value is vs. the required value for that fl, and the speed of rotation .....
IMHO, that will dictate the image degradation.  A few times by chance I got
a sharp images...  But the odds of that occurring are low.... unfortunately.

Regards
Bill G




----- Original Message -----
From: "Alan Zinn" <azinn@xxxxxxxxxx>
To: <panorama-l@xxxxxxxxxxxxxxxxx>
Sent: Wednesday, June 14, 2000 9:58 AM
Subject: Re: Exact fl of lenses... 220 VR


> At 07:12 AM 6/14/2000 -0700, you wrote:
> >All this work just to figure out how to use a camera
> >that costs *that* much? Unbelievable. For that much
> >money, I'd expect to set it up and use it, or at
> >least, find complete instructions and charts included.
> >IMMHO!
> >
> >
> >>          So for me, its boiled down to an
> >> estimate....  Sure wish this was
> >> in the manual?  Bottom line, .05mm is a unrealistic
> >> goal, and even .1mm will
> >> only reproduce itself at the shutterspeed it was
> >> tested at.
> >>
> >>       Anyone have a different experience?
> >>
>
>
> Guys,
> Where do these fractional FL differences become a real-world problem?  Do
> you need a magnifier to see them in side by side evaluations with a fine
> optic on a stationary lens camera?  Or do they jump out at you like the
> difference between 35mm and 6 x 6?
>
> AZ
>
>
>
> Lookaround Panoramic Camera and Gallery:
> http://www.geocities.com/SoHo/Gallery/8874/
>
> Bob Talbot's Vagabond Camera web page
>  http://www.st-abbs.fsnet.co.uk/vagabond/
>
>
>
>