Re: [photo-3d] On achromatic stereoscopes....& Trans vs. Negs...

[Paul Talbot <list_post@xxxxxxxxx>]

Ferguson Studio wrote:

> Why not try out one of the viewers that Harry Richards is selling.  A very
> nice polished Lucite model that will fit into your pocket.  Everyone who has
> one swears by them and everyone who doesn't have one wishes they did !  They
> run $35 and $55 which is a 1/4 of what you will pay for a Telebinocular.

It sounds like Boris needs a viewer that will eliminate chromatic
aberration.  (So does almost everyone!)  Harry has been offering
some interesting card viewers, but I have not seen "achromatic"
in any of the descriptions.  While good glass lenses can provide
a much improved view as compared to lower quality viewing devices,
single element lenses cannot compete with good achromatic lenses.
You'll pay more up front for achromatic quality, but it's an
investment well worth making for your primary stereocard viewer.
Good quality glass lens viewers serve a useful purpose for secondary
viewers, gifts, sharing with a group, etc.  But if you are serious
about the images you make or collect, you owe it to yourself to have
at least one achromatic viewer.

> On another note, the perception that Transparencies are sharper or have a
> longer tonality scale is a myth.  You must factor in size of the original
> and degree of enlargement for sharpness and if you would just use a
> densitometer you would see that the tonal scale of a good transparency is
> about three f/stops whereas the tonality scale of a good BW print is about
> seven.

I believe that if you compare COLOR prints to color transparencies, you
will find the color transparency wins.  The pecking order is probably
something like:
  - B&W negatives
  - Color negatives
  -------------------- (above are not directly viewable as a final image)
  - B&W prints
  - Color transparencies
  - Color prints

(I'm guessing on where to place color negatives relative to B&W prints,
as I haven't seen data on point.)

> Large 4x5" transparencies are in fact less sharp than small 35mm
> trans and resolve fewer lines on resolution charts but their bigger size
> makes them appear sharper because they require less degree of enlargement to
> make bigger prints so when you enlarge them they are sharper!

Isn't final image all that really matters (as your story of why you love
your bigger stereocamera demonstrates)?

Paul Talbot