Re: slide vs neg (lp/mm)

[P3D Grant Campos <gc6094@xxxxxxxxxxxxxxxxxx>]

> 
> Resolving power in lp/mm (I do wonder if there is a typo in this chart;
> the accompanying text discussion did seem 100% consistent with the
> numeric data.)
> 
> Film             lp/mm
> ----             -----
> K25               100
> Ek100HC           100
> Velvia            160
> Fuji 100 RDP      125
> 
> 
> (continued next post)
> 
> Paul Talbot

While reading the article on the Realist Custom which is in the May/June 92
Stereo World, Vol 19 #2 (which was so graciously loaned to me by Ron Babb), 
and some past posts from the archives I noted that some times the units are 
given in lines pairs per millimeter, lp/mm, and other times in lines per 
millimeter, lpm.  The Realist Custom rare earth lenses boast a lpm of 300.  
Is that lp/mm as above or is that equivalent to 150 lp/mm?  
Also, someone in the archives said that the lens should have twice the 
resolution of the film.  If the Custom is truly 300 lp/m then you would have 
to use Velvia to get the maximum benefit from the Custom lenses.  
This would go along with something Ron Zakowski, Mr. Realist Repair Man, said, 
"you have to use Kodachrome 25 before the differences between the Rare Earth 
lenses and the Regular Realist lenses (lpm 120) become appreciable".  
In other words it is not necessary to use these high resolution films in your 
regular Realist, because your lenses aren't sharp enough to take advantage of 
the extra resolving power.  So, if you have a regular Realist, Save your money 
and don't bother with high res professional film; use a regular ASA 100 slide 
film, like a Fuji Sensia or Kodak Elite II.

Grant


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