Re: [Leica] Re: APO for B & W??

["Tom Schofield" <tdschofield@email.msn.com>]

You've gone beyond the state  my  understanding.  I guess you'd have to
examine the transmittance curves for the filters.  While we are dreaming,
the only light source that is purely one specific frequency (Note invitation
of flaming by use of "only") is a laser.  Perhaps a laser light source
should be designed for B&W, with a matching lens corrected for that specific
wavelength.  Then

Tom


- ----- Original Message -----
From: "Doug Herr" <Dherr@energy.state.ca.us>
To: <leica-users@mejac.palo-alto.ca.us>
Sent: Tuesday, February 29, 2000 7:12 AM
Subject: Re: [Leica] Re: APO for B & W??


>
>
> Christer Almqvist wrote:
> >>>
> >Doug's response is consistent with my understanding.  Poor correction of
> >chromatic aberrations leads to color fringing.  It can be even worse in
B&W
> >than color because the white light coming through the negative contains
all
> >colors of the spectrum, whereas the color neg or slide filters some of
the
> >colors out, so the fringing is less noticeable.  On B&W the "color
fringing"
> >bears out as unsharpness or loss of acutance, rather than seeing the
colors
> >in the color firinging.
> >
> >Tom Schofield
> >
> Is this true for enlarger with multigrade filters above the negative?
> <<<
>
> Without having definitive information, I suspect the multigrade filter
will improve the performance of enlarger lenses that aren't well corrected
for chromatic errors, just because the filter will reduct the intensity of
many wavelengths.
>
> Doug Herr
> Sacramento
> http://ourworld.compuserve.com/homepages/telyt
>
>
>