Re: [APML]: Latest Tony Hallas Images - Art or Science

[Andy Wallace <andywallace@home.com>]

The Astro-Photography Mailing List
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Philipp--these "manipulated" images may be fairly accurate in a
sense--if we could get close enough to, say, M-42 for our eyes to
register the various colors, the much greater ability of our eyes over
any emulsion to deal with widely varying levels of brightness might give
us a very similar image to that produced by the beautiful M-42 image
produced by Tony and Daphne which I agree utilizes a "black" art.

Andy

Philipp Salzgeber wrote:
> 
> The Astro-Photography Mailing List
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> 
> In my opinion astrophotography is a (mostly black) art, and I suppose most
> of us do it for fun, but while an image looks good, it can also have
> scientific value too!
> 
> For my taste (sic!!) the M42 picture looks slightly bizarre, BUT look at
> that faint wisps of nebulosity all over the field! It is quite an
> achievement to display this great contrast range in one image!!!
> 
> This image, while not displaying  the brightness scientifically correct,
> gives you an impression of the arrangement of the Hydrogen cloud. I get the
> impression of looking into a bowl blown into the cloud by the young stars of
> the Trapezium. So (if my interpretation is correct) this image is also of
> scientific value, because it shows the extent of the cloud and its
> interaction with the stars around and in it.
> 
> I think, especially the image of M42 is not only unsharp masked, but also a
> composite image. The brightness range between the center of M42 and the
> nebulosity that connects the M42 complex with the emission nebula behind the
> Horsehead is way too great to be registered in one exposure. David Malin has
> also made an image showing the faint nebulosity, but M42 and M43 (?) are
> completely overexposed. And, according to my experiments, if only one
> exposure had been used, I expect the faint nebulosity to be more noisy
> (grainy). ...correct me if I am wrong.
> 
> I have been playing around with unsharp masking a little and one of the two
> articles that will appear on my website soon, will be about the unsharp
> masking method not as an algorithm, but as a photoshop action, which
> automates the process to a certain extent.
> 
> Philipp
> 
> philipp.salzgeber@vienna.at