My first DSO image

[Hackleby]

Hi All,

I managed to finally get some clear sky over the weekend and tried my hand at some photography.  Due to the heavy LP and moon I found that I couldn't see my targets as  has been the norm since getting my scope.  So I relied on the mount finding what I wanted to look at and tried to capture images of them.  Targets were M51,M101 & M82 and I took 50 subs of 20s, run through DSS and had a stumble around in CoralDraw.  To my amazement I actually managed to capture images of all three so I know their up there

I think I must be doing something wrong though as I have masses of noise radiating out from the centre of my photos. The image of M101 is very faint and I couldn't process it well enough to see it without looking almost sideways on to the laptop.  Trying to tweak it up was hampered by this noise that radiated from centre of image. I have since noted that I hadn't applied noise reduction on my camera and am hoping this is the problem.  Any advice would be most welcomed by this newbie who is now well hooked.

[Thalestris24]

Hi

Looks like you have some vignetting. You need to take some flats and stack them with your darks and lights. Otherwise they look quite good!

Um, it's useful to include your setup in your sig - scope, camera etc etc. Also useful to know exposure times and number of subs.

Hth

Louise

[Owmuchonomy]

Hmmm, as Louise says give us an idea of your kit and maybe we can give you some pointers. Great that you are giving it a try and sharing.

Chris

Sent from my iPhone using Tapatalk

[Hackleby]

Cheers for that Louise, I give it a try, next chance I get.

Not been able to add my setup as have been denied option to change sig until I hit 10 posts.  Not to far off now but I have the following

Sky Watcher Explorer 200P, NEQ6 pro, EQ5, Canon 1100d.

[Thalestris24]

Cheers for that Louise, I give it a try, next chance I get.

Not been able to add my setup as have been denied option to change sig until I hit 10 posts.  Not to far off now but I have the following

Sky Watcher Explorer 200P, NEQ6 pro, EQ5, Canon 1100d.

Hi

Yeah, you will definitely get vignetting with the 1100d - well I used to! You can take flats by pointing the scope at a even source of illumination. I use a monitor screen with Notepad opened It's important that the optical train hasn't changed since taking the lights so the camera has to be exactly as it was. It's usually recommended that you take darks and flats just after imaging unless you have everything set up more or less permanently and undisturbed. If you've taken the camera off the scope then you can't now take flats to go with your above images. However, you can still rescue them with StarTools. Possibly with other software but StarTools is the only one I have and know! It has a 'wipe' function which lets you remove gradients, like vignetting and light pollution (lp).

Hth

Louise

[Thalestris24]

ps don't use the noise reduction on the camera and always shoot in raw mode (or raw + jpg, if you like). You need the raw files for stacking and processing to maintain as much dynamic range as possible.

[Hackleby]

Awesome, just been searching for best ways to take flats and an open note page on a lappy came up like you suggest so think I'll run with that one to start with as I don't posses a white T shirt and never will.  Interesting that you advise not to use noise reduction, is that due to the required processing time between subs or does it not offer any benefit.  Was taking both RAW and jpeg but as jpegs are not being used I've decided to drop them to save some space on card.  Got my 10 posts up now so have added signature.  Thank you again for your advice.

Clint

[Thalestris24]

Hi

You can use the long exposure noise reduction - I believe it takes two exposures, 1 light and 1 dark of the same exposure time, and subtracts the dark from the light. The trouble is that you have to wait for two exposures which wastes imaging time. Most people take their darks separately when they've finished imaging.  With darks it's only important that they are the same length and same sensor temperature, more or less. Jpegs can be useful if you want a quick look, but aren't necessary. If possible, the best thing is to computer control everything - camera and mount. It makes life an awful lot easier if you have that facility. There are several really good packages which can be used to control the camera. I use a free one called APT (Astrophotography tool) which supports Ascom compliant ccd cameras also . APT gives you a liveview, image review, downloads images so you don't use the camera card, helps with focussing, allows you to setup exposure plans etc. Sooner or later you'll probably want to set up a guiding system and computer control is needed for that. Meanwhile, with accurate polar alignment you should be able to get subs of 60s or longer. But honestly, once you get the bug, 60s just isn't enough anymore!

Good luck

Louise

[wxsatuser]

It is possible to take the darks inadvance and they don't need to be the same temperature and length, as long as

your stacking software can scale the darks.

When you get to the stage of long exposures it's best to have ready made darks.

For short exposures just reel off the darks and bias at the end of the session.

[Pete Presland]

congratulations on your 1st DSO images, they have come out pretty well. Mike is correct re the calibration frames, last thing you want to do on those rare clear nights is waste time taking darks. you are effectively halving the amount of subs you can take.

[Hackleby]

Great idea Mike, I will look to put a library of darks together.  Seems I have a lot to learn but thanks to you guys and girls I should be getting improved results by next session

Thanks heaps.