First Try at Cygnus

[Stub Mandrel]

Having got all the bits together to be able to use an out-of-the-ark Canon D10 common sense suggested that I start with some wide field shots. I got up last night at about 12:45 and had less than an hour before cloud obscured everything. Cygnus seems to be a sort of satellite cross-roads - I saw loads!

I used my old but good f2 Zenith 50mm lens and took about 10 30-second subs of the Plough and Cygnus at ISO 800, f2 - ISO 3200 more or less bleached out. The plough shots showed more distortion than the cygnus ones, but cygnus was close to the area of high LP to the north east. May of the shots were spoiled by thin cloud, but the first two cygnus ones were more or less cloud  (and satellite trail) free, although they had a lot of LP in the bottom left quadrant. I took six dark frames but no flats or bias frames. No tracking.

I stacked just these two best images and uses photo-paint 10 to balance the colour and edited the curve for the red and yellow channels to try and get rid of the colour cast without desaturating all the lovely red and yellow stars.

A bit disappointed that, although there are loads of background stars, I had hoped to get a more obvious signs of the milky way/ great rift, but at least I am seeing stars... This is a jpeg version, heavily compressed, but gives you the idea. Clearly a long way to go, less cloud will certainly help.

I just found a few subs I took right at the beginning with less cloud - I had written these off as playing to get the focus right, but they may be better...

[xtreemchaos]

nice image mate,thanks for sharing.charl.

[Pete Presland]

Nice start 30 seconds seems a bit long to me for a 50mm focal length, the stars do look a little elongated.

Have you consider using perhaps a shorter focal length, maybe the stock 18mm that comes with a lot of cameras and capturing more of the sky?

[Stub Mandrel]

Nice start 30 seconds seems a bit long to me for a 50mm focal length, the stars do look a little elongated.

Have you consider using perhaps a shorter focal length, maybe the stock 18mm that comes with a lot of cameras and capturing more of the sky?

I agree, all the images show short trails. The advice I read was to use the 'standard lens' so I assumed 50mm (I grwoed up on 35mm film) although it seems with the 10D my 28mm will be equivalent to 1.6 * 28 = 44mm and might be a better 'standard lens', although its not as fast.

I've now got my EQ5 tripod (not mount) but when I get some clear skies I will try all different lenses and telescopes with unguided tracking. Advice seems to be you can go up to 3 minutes unguided if you are prepared to dump some frames. My RA takes over 10 minutes to do one rotation, but the periodic error appears to be concentrated in two places. If I can track these down and mark the gear wheel I can, perhaps, take slightly longer subs during the windows between the periods of noticeable drift. Guiding is on my (long)to-do list.

[Stub Mandrel]

Three of the first five trial images looked clearer than the later ones. I've put them through DSS and really bashed the image histogram about.

I  think I've picked up the Milky Way and some structure around the great rift as it seems to clearly defined to be cloud (and it isn't yellow-green), but i do suspect light pollution coming in from bottom left as well. Comments on this pic and any advice on processing this sort of image greatly appreciated.

[Pete Presland]

You certainly have picked some of the milky way, did you use any calibration frmaes?

[Stub Mandrel]

Five darks (there's only so long I want to spend in the front garden at 1:00am exploring the universe in my dressing gown - I'm not Arthur Dent) and about seven bias frames. The bias frames are jet black, but the darks have a good sprinkling of 'hot' pixels.

I went to find the 28mm and found it on the canon, so that's as wide as I can go (although its about a 75% crop to get rid of a light change of position, rotation between frames and a bit of tree :-)

If I want to get a decent slice of Milky Way it looks like a 0.45 fisheye adaptor ... that can wait!

[Pete Presland]

Next time i would skip the bias frames, i dont think you need them and try to get some flats. They would help with the uneven illumination in the image.

[Stub Mandrel]

I tried again last night, there was less cloud. I've also done some flats which show slight vignetting especially at the top two corners but very little in the way of dust bunnies.

I used ISO 3200 and stopped down two stops to get the same exposure.

I'm pretty sure the glow at bottom left is light pollution :-(  I took pictures in all sections of the sky I can see from the back garden last night, and the glow was in different parts of each image. Here's a heavily processed Cygnus which looks a bit better than the earlier try, but the LP is quite extreme - I would say I could see the 'pollution dome' quite clearly.

This off-centre hercules that shows a much more even glow across the lower edge.

But if I use a flat, I get this awful vignetting. My processed flat (from DSS) is extremely dark - I am sure that I must be doing it the wrong way :-(

I'm assuming that with DSS I (1) don't need to pre-process my RAW images and (2) can use just the master flat, dark and offset images it generates instead of adding all the separate images each time?