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NGC 7000 red only


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About this observation
Ray Emery
Time of observation
27/10/2019 - 18:59
NGC 7000 North America Nebula
Observing location
Brinkhill, Lincs
Canon 700D modified
Wratten 25 red filter
Genesis 500mm f5 refractor
8 x 10 mins & 5 x 15 mins exps @ ISO 1600
Like This Image
Humble stuff I'm afraid.
I bought an el cheapo Chinese (Wratten no. 25) 2-inch red filter.
The streaky stars in the lower part of the frame, esp. towards the lower right, are due to the cheap filter, I am almost sure.
The idea was to try to get improved images of h-alpha objects without shelling out for a very expensive h-alpha filter!
Now, I am aware that a DSLR is not the instrument of choice here, since I am only using 1/4 of the elements per pixel.
This image has of course been knurdled up in Photoshop on the machine.
No slings & arrows, please - it was just an experiment.
But I think the result ain’t too bad, and may be worth pursuing.
Quite a bit of flare around the brighter stars - I noticed this on Live View when focussing. May also be down to the filter?
No challenging moonlight of course - which is where a proper h-alpha filter would definitely score.


djswan2002's picture

I think this is really good, Ray. I was just looking at the transmission curve of the Wratten 25: it is a pretty steep cutoff lambda < 600nm. You've inspired me to have a go with my Hyperstar, with a 1.25" red filter just above the chip (I don't have a 2" one). I seem to recall my Baader red longpass actually cuts off more.....

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