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Re: filmscanners: filmscanners: Scanner resolution (was: BWP seeks scanner)



Thanks for that thought, Brian. IMHO, some people (including me) are blaming 
their scanners for something their zoom lenses are doing! ;-)

It's interesting to note that digital cameras are offering "Digital Zoom," 
when what they are really offering is electronic zooming-in of pixels. This 
is the exact equivalent of making close-up crops of an existing picture--and 
if you don't have high resolution in the first place, you won't have it in 
the second place, either. All but some *very* expensive zoom lenses have 
traded on that appearance for quite a few years. The pure fact of the matter 
is that zoom lenses are not equal to telephoto lenses. Never have been, 
never will be. It's another of those compromises we make, to "get the 
picture." :-)

Best regards--LRA


>From: "B.Rumary" <brian.rumary@virgin.net>
>Reply-To: filmscanners@halftone.co.uk
>To: filmscanners@halftone.co.uk
>Subject: Re: filmscanners: filmscanners: Scanner resolution (was: BWP seeks 
>scanner)
>Date: Wed, 20 Jun 2001 15:46:44 +0100
>
>In <3B2F017D.9010003@ampsc.com>, Arthur Entlich wrote:
>
> > In general, some of the older fixed focus lenses proved to have better
> > glass, and if they are well multicoated they can be great.
> >
> > One of my best lenses is a Nikkor 135 2.8 tele.  It is a Q series, which
> > was a quality multicoated glass.
> >
>The main problem is that most SLR cameras these days come with zoom lenses
>as standard. Designing zooms always involves more compromises than fixed
>lenses, as you have to allow for the changing light paths as the elements
>move when zooming. Until computers where used for the design work zooms
>tended to be of poor quality or very expensive, because of the vast amount
>of calculations needed. Computers enabled designers to do these
>calculations in a fraction of the time, so zooms became better and cheaper.
>However there are still trade-offs involved.
>
>There are also many more glass elements in a zoom, and the internal
>mechanics are much more complicated. A good fixed lens will usually have
>6-7 pieces of glass in it, and simple mechanisms for focusing. A zoom can
>often have 14 or more glass elements in it, in several different groups,
>and these groups have to move backwards and forwards at different rates
>when zooming or focusing. It is a wonder that they can get them to work
>successfully at all, especially at the prices now charged.
>
>Brian Rumary, England
>
>http://freespace.virgin.net/brian.rumary/homepage.htm
>
>

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