Re: [photo-3d] transparencies vs. prints

["Don Lopp" <dlopp@xxxxxxxxxxxxxxx>]

I  believe that stereo is much better seen in a viewer than when seen via
projection-especially as reguards to resolution. In my better viewers I can
see up to 40 lines per mm whereas in the viewer included with expo 2000 I
could barely see 28 lines per mm and I have never seen better than 28 lines
per mm when 35 mm is projected and would be greatly surprised to find a MF
projector doing even 28 lines per mm though I have never seen MF stereo
projected so I do not realy know . The 35 mm stereo I have seen projected
was using a lenticular screen which greatly inhibits resolution in
conjunction with the mediocre reolution of most projection lenses. I fully
realise that impact is the object of projection and that there would never
be enough time to put each slide in optimum focus plu in most cases only a
few viewers would be in a favorable position to see a sharply projected
slide.  I have high hopes that Buffao will prove me wrong but I would not
bet on it , but I can dream ? DON
----- Original Message -----
From: "John A. Rupkalvis" <stereoscope@xxxxxxxxxxxxx>
To: <photo-3d@xxxxxxxxxxxxxxx>
Sent: Friday, February 02, 2001 6:48 PM
Subject: Re: [photo-3d] transparencies vs. prints


> What is your meaning of "M F stereo"?  When I first read this, I
interpreted
> it as meaning medium format.  But, you must mean something else, since
> medium format stereo can be viewed as either prints or transparencies
> (depending on your choice of film and type of viewer), or even projected.
I
> project my 6 x 9 (120 film) transparency pairs using a pair of lantern
slide
> projectors.   The detail and other attributes are absolutely superb, even
on
> a very large screen (this film size has a larger area than even Imax
> images).
>
> Your resolution observations appear very close to what I have observed.
In
> general, all things being equal, transparencies have the potential for
being
> superior to prints in both resolution and tonal scale.
>
> Someone stated that negative film has a greater tonal range than
> transparency film, and this seemingly contradictory statement is correct.
> The problem is, that prints made from these negatives have a much narrower
> range.  That is why you do not have to be as accurate in exposure with
> negative film.  Transparency exposure errors of plus or minus one-half
stop
> can be easily seen by most people as less than optimum in quality.  With
> negative film, the same tolerance occurs only on the underexposure side,
but
> up to two full stops overexposure can be corrected for in printing with
> little image degradation.
>
> This is extremely important for stereoscopic images, as both shadow detail
> and highlight detail contribute greatly to the impression of depth.
>
> Color dyes tend to diffuse in paper prints much more than on film base.
> Also, transillumination will allow both greater detail (resolution) and
> wider tonal scale than reflected illumination, for both black-and-white
and
> color images.  To get an idea of this, take a transparency, and set it on
a
> sheet of white paper.  Illuminate it with reflected light.  Compare what
you
> see with what you see when the same transparency is viewed with the light
> source behind (going through it).
>
> For a real interesting test, shoot negative film in your stereo camera.
> Have both prints and slides made from the same negative pair.  View the
> results in a slide viewer and a print viewer.
>
> JR
>
>
> ----- Original Message -----
> From: "Don Lopp" <dlopp@xxxxxxxxxxxxxxx>
> To: <photo-3d@xxxxxxxxxxxxxxx>
> Sent: Friday, February 02, 2001 5:42 PM
> Subject: Re: [photo-3d] transparencies vs. prints
>
>
> > As reguards to the resolution qualities of prints as compared with
slides
> we
> > ran a test in a photo-physics class at the U of W in 1948 where the
class
> > looked at resolution charts in the form of contact prints and slides. On
> > average , the best we could do was - prints- 7 lines per mm with out
> > magnification and 14 lines per mm with magnification. With slides,
> depending
> > on how much magnification , Kodachrome 10 , we could see up to 48  lines
> per
> > mm-a few claimed to be able to see 56  lines per mm but these claims
were
> > not seen by anyone when using a decent microscope. This helps me back my
> > prejudice against M F stereo which to me is both a clumsey and akward
way
> to
> > view stereo in my opinion not mentioning the lowering tonal qualities
etc.
> > DON.
> > ----- Original Message -----
> > From: "Dan Vint" <dvint@xxxxxxxx>
> > To: <photo-3d@xxxxxxxxxxxxxxx>
> > Sent: Friday, February 02, 2001 8:50 AM
> > Subject: Re: [photo-3d] transparencies vs. prints
> >
> >
> > > >
> > > >
> > > > >   From: "Ferguson Studio" <larry@xxxxxxxxxxxxxxxxxx>
> > > > ...
> > > > >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
> > > >
> > > > You know, we've discussed this in the past privately, and we either
> > > > disagree or we are misunderstanding each other.  My experience with
> > > > practical photography is as yet limited, especially with prints, so
my
> > > > feeling on this is based on something more like intuition.
> > > >
> > > > The way I understand it, compared to prints, slides give you more
> tonal
> > > > impact, more dynamic range when you actually view them.  The OUTPUT
> has
> > > > greater range.  When brightly illuminated, the perceived brightest
> spot
> > is
> > >
> > > Yes this is the difference between a projected/illumintaed source and
a
> > > reflective print.
> > >
> > > > lots and lots brighter than the darkest shadow, and the slide will
> show
> > > > detail in both these brightest and darkest areas if exposed
carefully.
> > > > Prints made from negatives do not, cannot give you this very wide
> range
> > in
> > > > tonal output!  They can only reflect light diffusely, and this alone
> > will
> > > > reduce the perceived range.  Prints also cannot perfectly absorb all
> > light
> > > > (such as a very dark coal black), but then neither can slides.
> > >
> > > Take a look at a book on the zone system started with Ansel Adams.
Slide
> > > film typically is a 3 (usal) to maybe 5 zone range that you have to
> > carefully
> > > place to get a good slide, I beleive print films are like 5 to 7 in
this
> > 10
> > > point scale. It is easier to get more information in a print film and
> work
> > > with that so you have a more complete tonal range in the picture. In a
> > slide
> > > you either blow out the highlights or loose the shadow detail in a
> slide.
> > >
> > > >
> > > > Another way I look at it is that the negative generally is never
fully
> > > > transparent.  Completely unexposed, the negative still has some
> density,
> > > > which looks to be around 10%.  Exposed to the max, it is fairly
> opaque.
> > > > But this range on the negative film is less than what the slide will
> > show:
> > > > from nearly perfectly transparent to quite opaque.  (But here I am
> > > > guessing.  Emulsion gurus please correct me!)
> > > >
> > > > The very widest range of tones (reality) is compressed onto the
tonal
> > range
> > > > of the slide, which will range from transparent (brightest) to
fairly
> > > > opaque (darkest).
> > >
> > > But it is how much is compressed into the highlight and the shadow.
> Print
> > film
> > > is more forgiving because you don't have to get the filtration and
color
> > balance
> > > 100% on with color print because you can adjust this in the print
> process.
> > Take
> > > your twined rig and load a roll of print and a roll of slide film and
> shot
> > > duplicate images of a wide range of lighting situations. Get out of
the
> > studio
> > > and into some high contrast situation. Then look at the details in the
> > negative
> > > vs the slides and you'll be surprised how much you actually loose.
> > >
> > > You also mention sharpness, for that you would have to look at the
> > combination
> > > of negative and the paper surfaced used. Your basic gloss no texture
> > surface is
> > > the sharpest way to go there. For direct measurement I have no test on
> > this one.
> > > I suppose you could actaully take one of these lens test patterns that
> > would
> > > show you the resolving power of your lens as well as the film being
> used.
> > >
> > > ..dan
> > >
> > >
> > > >
> > > > Larry, you say:
> > > >
> > > > >...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.
> > > >
> > > > Quite frankly this goes against everything I can see with my own
eyes,
> > > > against what I tried to explain above.  I don't know what you mean
> with
> > > > that statement.
> > > >
> > > > I do understand that negative emulsions have more _latitude_.  This
> does
> > > > follow logically with the notion that transparency film has greater
> > > > _dynamic range_.  Latitude and dynamic range are opposites.
Latitude
> is
> > > > ability to capture a broad range of tonality, and dynamic range is
the
> > > > ability to reproduce the broad range faithfully (i.e. uncompressed).
> > > >
> > > > Imagine the INPUT tonality as a bell curve of values (like the
levels
> > > > dialog in Photoshop shows it) that has to fit in a receptacle of a
> > certain
> > > > width.
> > > >
> > > > Negative film is a relatively wide receptacle, and it can accomodate
> the
> > > > bell curve of your values even if the curve falls a bit off center
as
> > you
> > > > put it down in the receptacle (the equivalent of under/over
exposing).
> > > > That's wide latitude.
> > > >
> > > > Transparency film is a relatively narrow receptacle, only a smidgen
> > wider
> > > > than the bell curve of tonality you will set down in it.  If you
don't
> > get
> > > > your bell curve set down just right (i.e. good exposure) then part
of
> > the
> > > > curve will spill over one end of the receptacle and be lost (i.e.
loss
> > of
> > > > detail in an overexposed or underexposed region).
> > > >
> > > > Perhaps what you mean with "seven stops tonality range" is this
width
> of
> > > > the negative film "receptacle?"  because it is wider, because of the
> > > > increased latitude, the film can actually capture detail in a
broader
> > range
> > > > of exposure.
> > > >
> > > > But when you consider the "output", the negative film is compressing
> > this
> > > > broader range of tonality onto its own actual, physically more
limited
> > > > range of density.  Then the final output, the print, shows a
> > substantially
> > > > compressed range of tonality, from a diffuse white to a muted black.
> > > >
> > > > What makes the transparency so great for viewing is that the range
of
> > > > tonality in the scene is not compressed so much.  Exposed well, and
> > viewed
> > > > with lots of light, the transparency will show the scene much as it
> was
> > > > originally, with minimal "compression" of the lightest and darkest
> > areas.
> > > >
> > > > (I recently read something closely related to all of this: all other
> > things
> > > > being equal, that negative films are much better for digital
scanning.
> > > > This is because scanners do not have such a great dynamic range.
Most
> > > > scanners cannot handle the dynamic range of a transparency - it is
too
> > > > much.  Better to scan a negative, where the tonality is relatively
> > > > compressed.)
> > > >
> > > > >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!
> > > >
> > > > This sounds wrong, theoretically.  Do you mean that the emulsions in
> > larger
> > > > formats are not as high resolution (I can't believe that), or that
the
> > > > optics for larger formats do not create images of as high a
> resolution?
> > (I
> > > > don't believe that, either)  Certainly I am unaware of the practical
> > limits
> > > > of the larger formats.
> > > >
> > > > I did just shoot my first session with Medium Format, side by side
> with
> > a
> > > > 35mm twin rig.  The MF transparencies make my 35mm originals look
like
> > poor
> > > > quality dupes!  But more to the point, down around the resolution of
> the
> > > > grain, the MF transparencies do not look any softer than the 35mm
> > > > transparency.
> > > >
> > > > >By the way, how was the shooting with the twin-rig Hasselblad setup
> > with
> > > > >Betty?  When are we going to actually see a Boris print stereoview?
> > > >
> > > > Well, ever since I met you Larry, you have raised the bar for me
very
> > high
> > > > indeed.  So it may take a while yet, before I feel that my stereo
> cards
> > are
> > > > going to be up to snuff (i.e. as good as yours).  You might have to
> give
> > me
> > > > a few more weeks ;-)
> > > >
> > > > Boris
> > > >
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