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M33 & M45 19/12/14

Guest StevenWhatley

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Guest StevenWhatley

So I managed to get out into the garden finally to try the Canon 1100d Modded camera I brought.


As most of us that were out last night knows it was a tad tricky at times with the wind and guiding but I managed to get in


3 x 300sec ISO800 before it clouded over, I spent the earlier part of the night on M45 before I remembered that M33 was the original target I went out for :facepalm:


15878617959_440dfc5510_b.jpgM33-Triangulum Galaxy by stevenwhatley231284, on Flickr


M45 - I managed to get more subs then I stacked but clouds and wind ruined about 6x 300s   



3x 300 sec - iso800

2x 200 sec - iso800

2x 120 sec - iso800



2x 1-4000s



4x 300s -iso800


16062752791_dd70d64a90_b.jpgM42 - Peleiades by stevenwhatley231284, on Flickr

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Guest Phillyo

Hi Steven,


Lovely images there, liking the second process on M45. Have you used flat frames in your calibration? Seems to be a lot of vignetting there? Also, just a suggestion, as you're using a DSLR and I'm guessing it's not a modified/cooled one try taking about 500 bias frames and using a master bias instead of a dark for your calibration. Using a dark with a DSLR is often worse for introducing noise due to the temperature variations which you can't control.


Just a thought :)



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Guest StevenWhatley

Hi Phil,


Yes its a Modded 1100d from cheap astronomy with the Baader BCF filter.


Nope no flats in this..


I took a couple of Bias but only a couple still abit unsure of how many of each to do !!


Is there a general rule of thumb with how many lights flats darks ect ect



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Guest Phillyo

Flats need (should) be taken after each imaging session because if you move your camera on the scope then you need new flats to remove duts and dirt etc. If you don't move the camera then it's not such an issue. Take around 20 or so flats to make a master flat.


Darks, again I wouldn't bother taking darks with a DSLR because you can't control the temperature so you'll probably add more noise than remove it.


Bias frames, take as many as you can. With a DSLR that doesn't take long, you can fire off 500 or so at 1/4000th of a second in just a couple of minutes. Again, make a master bias from that.


The rule of thumb is that the more the better really. Within reason. Diminishing returns notwithstanding more is better. If you do want to take darks, that's up to you. Try to take around 50 darks at the same exposure and temp, if possible, that you took your images. This is another reason it's hard to take darks for a DSLR. With a cooled CCD you can set your temperature and take 50 or more at say 1min, then 50 at 5min, 10min, 20min and and 30min and you can do this over a few days when the weather is rubbish in a nice dark room/shed? You can then save them as master dark set ready for when you can image again knowing that you have a set at -10, or -20 etc ready for imaging :)





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