Re: [APML] OT: Nikon D2H Astrophotography Tests

["Robert Gendler" <robgendler@worldnet.att.net>]

Jerry,
Below is a paraphrase by Terry Platt explaining his one shot color camera.
I believe it applies to most one shot color digital cameras on the market.

"Most digital cameras use a CCD with a built-in Bayer matrix of red, green
and blue filters, directly deposited onto the CCD surface. The matrix is
decoded
to red, green, blue and luminance data by the software and gives a
resolution
which depends on the decoding algorithms. The optimum processing gives a
luminance resolution of about 70% of the pixel resolution, so resolution is
down, but not dramatically so.
Colour matrix CCDs are a compromise between resolution and simplicity, but
make colour imaging a good deal easier and quicker. Virtually all digital
still cameras use the same principle."

Rob Gendler
Email: robgendler@att.net
Web site: http://www.robgendlerastropics.com/
----- Original Message -----
From: "Jerry Lodriguss" <jerry@astropix.com>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Sunday, January 04, 2004 3:02 PM
Subject: Re: [APML] OT: Nikon D2H Astrophotography Tests


>
> >
> >Nice review. That must have been alot of work.
>
> Hi Rob,
>
> A little bit more work because I had to manually trip each exposure and
> they were only a couple of minutes each. Not like just opening a 60 minute
> exposure on film and then taking it easy for an hour. <G>
>
>
>
> >Because of the way these cameras acquire color ( not all the pixels
> >are used at once) they will not have the same resolution as the
monochrome
> >astronomical CCD cameras.
>
> I'm not quite sure what you mean when you say not all the pixels are used
> at once, this is not my understanding of how the Bayer pattern cameras
work.
>
> I've read that the resolution is the same for the luminance data, where
> each pixel is used, but that the color data is what is sacrificed, and
even
> then, it's a pretty clever algorithm that is used to reconstruct the
color.
> Of course, there is no arguing that these consumer digital cameras are
> vastly inferior to a dedicated cooled CCD astro camera in a lot of other
ways.
>
> On the other hand, they do have their advantages, such as price and sensor
> size/pixel density.
>
>
>
>
> >Also the blue halos and distortion of the stars
> >are more likely due to the performance of the 400MM F2.8 lens. These
lenses
> >are not apochromatic or even close.
>
>
> Yes, I tend to agree with that.   On the other hand, this performance is
so
> bad, I really have to wonder if something is wrong with the lens, or if
> something else is going on (perhaps bad focus too).
>
>
>
> >CCD's will bring out all these optical
> >flaws.With film the optical flaws of these lenses are masked by the
> >overall low
> >resolution
> >of the image.
>
> Now I don't think that is true. I've seen this exact same kind of poor
lens
> performance with a 300/2.8 ED Nikkor on shots taken on E200 film.
>
> Both the 300 and 400 are the latest Nikon models too.  I didn't think it
> was possible for my opinion of Nikon to get any worse, but even despite
the
> promise of the D2H, it has.
>
> Jerry
>
>
>
>
> Photoshop for Astrophotographers - http://www.astropix.com/PFA/PFA.HTM
>
>
>
>
>
>
>
>
>
>
>
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