[EMAIL PROTECTED] wrote:
>
> Hi Thomas,
>
> When looking at specifications of the D30 (and other cameras), I
> was struck by the flexibility of the digital format:
>
> 1) Dynamic range could be increased over the native sensor range
> by compositing bracketed exposures. Michael Reichmann describes
> a related method using contrast masknig.
Of course everything can be done, but it means work. And of course
this can also be done with film, it just means more work. A neg
usually holds much more information (dynamic range) than a scanner
(or photographic paper) can use.
>
> 2) Noise can be reduced by dark frame subtraction (that the D30
> does automatically for slow exposures), but can also by averaging
> multiple frames. E.g. by averaging 8 frames, noise can be reduced
> 3 stops.
Dark frame subtraction doesn't reduce noise, it reduces the effects
of different sensitivity of the single pixels. Averaging 8 frames
does reduce noise (at least in theory) by 3 stops or sqrt(8). But you
*need* to shoot from a tripod and you *need* a stationary subject.
If you can meet both conditions, this will work. It would of course
as well work with film to improve the image, but this is another story.
>
> 3) The native sensor resolution can be increased by compositing
> or stitching several high resolution images of a narrower field
> of view. The field of view can even be made 360 degrees or wider
> by use of appropriate software.
>
Again, it is cumbersome to do. I prefer to use a single 20mm shot
instead of stitching 4 images to give a similar angle of view.
Shooting that single shot is just much faster and easier and
doesn't need a special setup. You can even do it handheld.
> 4) One other advantage of digital that I did not see mentioned
> is how lens spectral transmission characteristics take on lesser
> importance. White balance not only removes colour cast from
> lighting, but also from lens optics and coatings.
Yes, this is kind of an advantage, as long as you don't scan your
film.
>
> 5) Along the same thinking, linear distortion properties (barrel
> and pincushion) can be post-processed away. A perfect rectilinear
> picture every time, even from the bottom of a wine bottle :-)
> (or a circular fisheye for that matter).
>
Again, this applies to every digital image, no matter how you
arrived at it. You just have to calculate the correction for
all your lenses once and you're done. Well, maybe you need several
corrections for different focusing distances and focal lengths
with some lenses.
> 6) And there are unexplored OPTICAL features that would only
> be possible with the digital format. Imagine:
> ELECTRONIC TILT function. If the sensor is SCANNED from top
> to bottom as the lens focus is adjusted from near to far, it is
> possible to have a tilted plane of focus. No digital camera
> currently does this, but it is possible (but very tedious) to
> do manually. Imagine making EVERY EF lens a tilt lens :-)
>
Sounds interesting. Although there might be some complications
with scenes that aren't as simple as a "flat" landscape.
Thomas Bantel
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