Re: Digital Camera Resolution WAS: Warning of major NHS IT overspend

[Brian Morrison <[EMAIL PROTECTED]>]

On Wed, 03 Nov 2004 10:23:28 +0000 in [EMAIL PROTECTED]
Brian Gladman <[EMAIL PROTECTED]> wrote:
 
> > About 15 years or so ago the typical resolution obtainable on film
> > of the period with standard camera lenses and independent
> > manufacturers' zoom lenses was between 100 and 150 line pairs per
> > mm. Some did a little better, but not a great deal. I don't expect
> > the state of the art for the consumer market has improved a lot in
> > that time.
> 
> While I agree that a few lenses could get above 100 line pairs per mm
> at small aperture in their centre of field, I measured my high quality
> fixed focal length lenses at full aperture and corner to corner and 
> never got close to an average of 100 line pairs per mm across their
> full field of view.  And the zoom lenses did a fair bit worse than the
> fixed focal length ones.

It's fair to say that there are often aberrations at the edges of the
frame, some lenses are noticeably better than others in this respect as
sometimes the optical centre of each element is not perfectly aligned
with the lens assembly axis. I think this was the most common problem in
the lens reviews I saw, but that's early 1980s so it may be that
tolerances have improved.

> 
> This was 20 years ago so I honestly don't know what line pairs per mm 
> modern zoom lenses can achieve.  Does anyone know if it is sensors or 
> lenses that limit the resolution of modern digital compact cameras?

I think that the limiting factor is always going to be the lenses as the
sensor technology is maturing more rapidly than the old-fashioned
business of grinding and polishing.

-- 

Brian Morrison

bdm at fenrir dot org dot uk

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