Re: [APML] Next TAK image - Barnards Dark Nebula

[Philip Perkins <philip@astrocruise.com>]

Monte,

http://www.astrocruise.com/misc/barnard1.jpg

Like the others, this is a superb shot.  In fact I cannot suggest a way in 
which it might be improved as single E200 shot. Like the others, it has 
also been scanned rather poorly.  The red channel has been set far too high 
- 24 points too high (on the histogram scale).  This is not subjective - it 
can be seen by inspecting the histogram (check the individual channels) and 
by measuring the black level (select the eyedropper tool - 5x5 - click the 
info panel and run the tool over an even neutral dark part of the 
image).  The RGB levels should read approximately the same.  The excessive 
red can be seen from this measurement.  But it can also be seen visually - 
you'll notice that image has a monochromatic "muddy brown" colour.  Very 
little colour is visible (apart from red) because the red channel is 
swamping the other subtle colours.  This can be "fixed up" to an extent 
after the scan, but the result will always be superior if it is possible to 
have the black level set correctly when the image is originally scanned.

--Philip

At 14:25 21/07/02 +1000, you wrote:
>Another 60 mins shot E200 push 1 stop in the process. The Tak hot spot is 
>a bit more apparent in this one but I am happy with the image. I think it 
>could be scanned better. I haven't altered the file before posting. Feel 
>free to have a fiddle with it.
>
><http://www.tradepart.com/techinfo/barnards.jpg>http://www.tradepart.com/techinfo/barnards.jpg
>
>Regards
>
>Monte


Philip Perkins - philip@astrocruise.com
Wiltshire UK & Luberon France
Astrocruise - http://www.astrocruise.com


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