[LargeFormat] A simple Yellow Filter

[Les Newcomer]

Jay Allen wrote:
> 

> The Yellow filter --------
> 
> So they would use a yellow filter to make the lens sharp like an Apo
> lens.
> 
> And, just when you thought it was just to make the clouds show in a
> photograph.
> 
> Does any one know why -- the yellow filter makes the older lens extra
> sharp?
> 


Sure, some of the old lenses exhibited blue fringing, particularly the
convertables. add a yellow filter to eliminate the blue and you
eliminate the double image or halo and thus a sharper image, add to that
it decreased the blue for the blue sensitive film of the time and it
brought in the clouds to a certain degree.

Les