Robert:
First, the ST10 is not a typical CCD
camera, nor are its images typical
in resolution. For every ST10, there are
probably 50 ST7's and ST8's out
there. So, for the few 2184 x 1472 images
out there, there are lots and
lots of images at 765 x 510 and 1530 x 1020.
With film, actual resolution
captured, grain of the film, and grain of
the paper determines how well an image will
tolerate enlargement.
Digital images are different from
photographic enlargement, however.
Your unbinned ST10 image gives you
sufficient resolution at 8"x10" for
the 175 screen Sean Walker claims. Barely.
No cropping. Anything else
requires that you increase the resolution in
the image, be that with
something like Fractal Graphics or the
bicubic interpolation in
PhotoShop. I'm sure you know, that there's
no free lunch when you do
that. You introduce noise and soften the
image. You can sharpen the
enlargement, and then you introduce more
noise.
ST8 and ST7 images, which are far
more common and typical, need
considerable digital enlargement to get to
180 screen for an 8x10 image.
The unbinned ST8 has sufficient information
for just 125 screen at 8x10.
The unbinned ST7 can't even muster up 65
dpi, less than the resolution
of the typical monitor when you try to print
them as an 8x10 picture.
No matter how you slice it, your
ST10 provides 3.2 million pixels of
information. Run of the mill magazines use
175 or 180 screen. That's not
what most people would consider photo
quality. Even high quality
magazines, like National Geographic and
Audobon, are not satisfied with
175 screen. They use 300 or 240. That leaves
a 3 mega-pixel image enough
print resolution for a 4"x6".
Period.
Now, you can get some lovely CCD
images with an ST10. Same with an ST7
and ST8 (if you don’t push the digital
enlargement too far). That's
owing to the small pixel size of the CCD
imager in the ST10. At 6.8
microns each, your pixels are capable of
resolving more detail than the
9 micron pixels in the ST7. So, not only do
you have more pixels to
capture an image, each pixel is tinier.
That's exactly like using a
finer grain film.
I agree, you can digitally enlarge
an ST10 image more than an ST7 or ST8
image before you notice noise. If you think
I argued otherwise, you
misunderstood my point.
I am not deprecating CCD images in
any way. I have been using a digital
SLR for a couple of years for nature
photography, landscapes, and street
photography. I loved my D30. I adore my D60.
I even use an STV and a
three-color wheel for imaging upon occasion.
So, don't read my comments
as a knock on CCD imaging. That's not the
case.
What I am saying is that it is still
common for magazine publishers to
refuse digital images AND while that is
partly a prejudice based on
outdated perceptions, there is still some
merit in that position. If you
want photo quality images and you want
headroom for cropping, digital
SLRs are just now getting to that point for
8x10, 11x14, and comparable
size images.
3.2 million pixels needs
considerable digital enlargement to go beyond
4x6 and print at near photo quality. When
digital images are pushed that
far, the noise and loss of sharpness is
noticeable, and you don't need a
loupe to see it.
As to you comments about film v.
CCD, that's a red herring I'll decline
to chase.
Cheers,
Mitch
-----Original Message-----
From: owner-astro-photo@seds.org [mailto:owner-astro-photo@seds.org]
On
Behalf Of Robert Gendler
Sent: Sunday, October 27, 2002 6:56 PM
To: astro-photo@seds.org
Subject: Re: [APML] Matt's S&T Cover
Mitch,
Look at the November 2001 S&T cover and
you will see
a CCD image (mine, NGC 6888), taken with an
ST10. The
resolution is fine and the image fills the
entire cover. Matter of fact
I would like to see a comparable film image
of the same object at the
same size. I've said this before but it
doesn't seem to register. Its
not
the number of pixels in an image but the
actual resolution captured
which determines how it will tolerate enlargement.
I think Matts
statement
reflects more his negative experience with
CCD which was due to
technical
issues.
Rob Gendler
Email: robgendler@att.net
Web site: http://www.robgendlerastropics.com/
----- Original Message -----
From: "Glenn E. Mitchell II"
<mitchell@dot-com-group.com>
To: <astro-photo@seds.org>
Sent: Sunday, October 27, 2002 6:32 PM
Subject: RE: [APML] Matt's S&T Cover
> S&T is far from unique in
their preference for film compared to
digital
> images. Especially for a full-size
cover shot.
>
> Lots of magazines will not even
consider digital images. I run into
this
> with nature photography all the time.
Some of it is prejudice, which
is
> beginning to erode. Part of it is a
desire for images that can be
> cropped, still screen at 300 or 240
dpi, and be larger than a 4"x5".
>
> For a cover shot, you need something
like a 300 or 240 screen at
8"x10".
> The typical CCD image doesn't approach
300 resolution much beyond
about
> 2"x3". Especially if the
image was binned.
>
> S&T has been willing to display CCD
images inside the magazine, with
> appropriate sizes of a few square
inches. It looks like they use 180
> screen for those images, which provides
reasonable quality.
>
> Mitch
>
> Glenn E. Mitchell II, Ph.D. (aka Mitch)
> 10" f/10 Meade LX-200 GPS (Big
Blue) s/n 01088
> Supercharged at ASO by Dr. Clay
Sherrod, # 2314-2010
> N 30° 30' 49.2" / W 084° 20'
13.8"
>
>
>