ðòïåëôù 


  áòèé÷ 


Apache-Talk @lexa.ru 

Inet-Admins @info.east.ru 

Filmscanners @halftone.co.uk 

Security-alerts @yandex-team.ru 

nginx-ru @sysoev.ru 

  óôáôøé 


  ðåòóïîáìøîïå 


  ðòïçòáííù 



ðéûéôå
ðéóøíá












     áòèé÷ :: Filmscanners
Filmscanners mailing list archive (filmscanners@halftone.co.uk)

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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



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





 




Copyright © Lexa Software, 1996-2009.