Re: [APML] Matt's S&T Cover

[Jerry Lodriguss <jml@astropix.com>]

>I just wanted to set a few things straight, The S&T cover is printed with 
>a 150 line screen, although we follow the 1.5x rule, images for the cover 
>have to have a minimum resolution of 250 dpi.


Rob, Craig,

The ST10 is a 2184 x 1472 pixel array. That produces a 3.07mb file for only 
one color channel.  A color image with the same number of pixels is 9.2mb.

If Rob's file was 3.2mb then this does not fit your above stated rule.

8.5 x 11 inches at 250 ppi is a 16.8mb file.

So what's the secret?

Did you use bicubic, fractals or wavelets? <G>

Jerry









>  The images for the interior of the magazine are printed with a 133 line 
> screen which allows a minimum resolution of 200 dpi(which I only let pass 
> if the image is printing small).
>2184x1472 at 250dpi only results in an image of about 6"x9" which isn't 
>even close to filling a cover and your right, we usually do crop in.That's 
>the biggest limitation for using a CCD image on the cover, because the 
>image is physically smaller than 35mm film it's not always possible to get 
>it to the size needed, it can be done but it's not always easy.
>Now if SBIG starts using Kodak's new 14 megapixel CCD that has the same 
>dimensions as 35mm film we might have a whole different story!
>
>Craig Michael Utter
>
>"Glenn E. Mitchell II" wrote:
>>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>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/>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"
>> >
>> >
>> >


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