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

[Dan Vint <dvint@xxxxxxxx>]

> 
> 
> >   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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