Quote:
Originally Posted by Paul Haese
Alright I am going to say it. - Having this scope at your home in a light polluted sky is a crime against astronomy Peter. It clearly produces sharp detail but the light pollution is messing with producing nice colour.
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Frank and fearless.
See below
Quote:
Originally Posted by Andy01
Nice image Peter - havn't seen that guy before - well done! |
Ta Andy.
Quote:
Originally Posted by traveller
right, time for me to go to spec savers!
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Crimes against Astronomy?
Actually...apart from the fact there seem to be no rural plots less than $300k to be had within a couple hours of Sydney...there is method to my criminality
Being an urban imager is all about maximising signal, and minimising noise. Hence perversely, large apertures do better (Max signal). Other things I do the get, let's call it MAXSIG, are:
1) High quality mount. The less guiding that needs be made, the more the signal fills the same pixels
2)Adaptive Optics whenever possible...which is just an extension of point 1
3)Use a really rigid mount and protect it from any wind buffeting...i.e. stick it in a dome
4)Well engineered OTA. Sag due gravity that causes any collimation error, or thermal expansion causing focus shift, or camera tilt simply doesn't help.
5)Have an OCD about secondary optics (primary mirrors can be left for some time)e.g. ultra-clean Correctors, filters, CCD windows. Scattering reduces signal.
6) Use a field flattener/corrector to concentrate the signal at the edge of frame
Reducing noise is also important, things I do to get MINNOISE are:
7) Use a CCD with low read noise and deep cooling. DSLR's don't cut it in the 'burbs.
8) Run the CCD as cold as possible (I typically use -30C)
9)Take many sub frames. with 20-30 subs there are many software tools that can perform magic on your data
10)Take many and accurate Darks
11) Take many and accurate Flats (sky flats are best).
12) Don't image on nights of tragic seeing . If you must, do ultra wide field or use a camera lens both will be almost immune.
13) Protect the scope from local lights. Any scattering..like that from my neighbours DMZ security lights...can have fatal sub exposure results. i.e. stick it in a dome.
14) Use a long focal length....or to put it another way. ...less sky glow per pixel.
In my example of NGC613, yes, colours could be more saturated, but then is simply due the fact (due crappy weather) I could only get 4 subs of red and blue, and two of green.
I expect with 20-30 in each channel , order will be restored to the Force.
