Re: [Leica] Re: Film vs Lens Resolutuon - facts wanted

[Duncan Young <dunk@mincom.com>]

On Mon, 9 Feb 1998, Erwin Puts wrote:

  <snip>

> The recent add by Zeiss in PopPhoto claims a resolution of 300 l/mm for its
> MacroPlanar 2,8/60. This claim I find on the high side. Leica lenses easily
> handle 150 - 250 l/mm (areal resolution!!!!). But that is not the question.
> Looked at the MTF curves the important figure is the contrast transfer at
> 80 l/mm. Most lenses have really trouble getting this relatively low value
> on the film with a good contrast.
> So here you have it; on the face value most modern films will 'handle'
> around 125 - 150 l/mm. Most lenses can on one count easily top these
> figures and chalk up values of 150 and 300 l/m, depending on the
> measurement method. This comparison gives the plus to lenses.
> 
> But lenses also are really in trouble to get 80 l/mm. In this comaprison
> the film easily wins. If you go for high contrast transfer for both system
> components (film and lens); the film can handle 40 to 80 l/mm and the lens
> can handle 20 to 40 lines (or to be a bit tolerant 80 l/mm). In this
> comparison both components are about equal. The best lenses just outperform
> most films and the best films just outperform most lenses.
> Are we lucky that with Leica lenses we can have the best of both worlds.

Just to make things worse, I was reading an artical about the problems of light
scatter on/in the film.  Given the same "resolution", a smaller aperature will
give a better lpmm on the film.  Though your lens may give its best performance
at f4, f8 will probably give you better resolution on the film.

Then again we can start on film flattening devices etc, etc.

The lpmm of film is, I belive, performed using contact printing methods.

    Duncan ( just adding annother level of complexity to the equation )