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My first DSO image M31

Spikey

By Spikey
in Imaging - Deep Sky

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Spikey

Spikey

Posted
Posted

Ok I finally managed to get out with the scope and attempt my first DSO image. It was a night of firsts !

With the weather recently in the UK this is my first outing with my partial new imaging setup. Took me about 3 hours to get setup with setting the mount up,EQMOD, polar aligning and syncing with CdC but I'll be quicker next time (I hope).

Anyway, managed to grab 15 x 120 sec unguided on M31 with my Canon 400d and took about 8 darks of the same length. Just had my first baptism by fire of processing, dusting off Photoshop 7 that I've had for years and only ever used for red eye removal (might try it on myself this morning!) ;)

Processing is hard, and I have a LOT to learn about the whole imaging sequence of events. I used no method to process because I haven't got a clue what I'm doing; just a quick levels and looking at the curves by eye.

The results are below and I would welcome comments on how I can improve.

Making every photon count helped me a lot so thank you Steve for putting in the effort - I'm now off to re-read it !

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mark7331

mark7331

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That's a brilliant start Spikey. The time to set up does come down a bit - I've got it to about an hour now. I've put markers on the mount & saddle plate so I can put things back exactly where I had them to reduce balancing time etc. I think a routine comes to you after you've put it up a few times (if the clouds let you).

The image is great and there is more data in there. You've suffered from a bit of vignetting which shows up when you stretch a bit more but you can easily reduce this with flats. I didn't start taking them until a few months ago and I wish I had much sooner. They're really easy to do and the difference is amazing.

Are you planning to fire up the guider soon? I have the ST80 & QHY5 too and have found they work really well.

Mark

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Spikey

Spikey

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Thanks for the further comments and thanks Peter for having a further play with the image.

Mark, You are right I haven't done any flats yet so I'm going to have a read up on how to go about them, what method do you use?

Yes I will be autoguiding soon, I've got a dual mount side by side that I need to set up and balance. I'm going to mount the ST80 with one ring so I can move (twist) it if necessary although to be honest the FOV is so wide I may never need to.

I have also ordered one of the SW 2" LP filters to try out as I have a lot of bright lights to the east.

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mark7331

mark7331

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Spikey, I used to mount my old guider in adjustable rings but it introduced flexure and I could never get very good guiding even though I could pick out lots of stars. I have the ST80 in fixed rings and I haven't needed to adjust for a guide star at all where as I usually had to with the old narrower/slower scope. Also, if it helps, I can post my PHD guider settings (calibration etc) for when you start guiding as it took me ages to get the rightish numbers!

To take flats I made a circular mask that fits over the end of the OTA (I used some of the packaging that came with the OTA to keep it secure). I've taped a few sheets of high quality artists tracing paper over the circular packing. Then either before or after the imaging run but always after I've focused , I get (now don't laugh ;) ) my little boys 'Ben 10' bedside lamp, sit it under the scope and point the scope down at it. Then I take some exposures, after cooling the camera to say zero, and adjust the exposure length to get about 1/2 to 2/3 maxiumum signal and knock of roughly 30 (for each filter). When processing I simply take away a bias master (made from 50 ish zero length subs at the same temperature) from the flats as they're usually very short exposures.

I'd be interested to know how effective the LP filter is. I've used a UHC-S L-booster which I felt worked really well visually.

Cheers

Mark

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Coco

Coco

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Outstanding first result... Much..Much better than my my 1,2,3rd attempt!

My advise would be mark your mount with a laundry marker and it'll seem like seconds rather than minutes to balance up you gear. mark your favourite spot with a semi permanent mark where your tripod legs are going to stand...

The ST80 will rarely not find a guide star with a QHY5 or similar, bolt it against your imaging scope, if you dont flexure will come into play but you'll blame your self for not guiding properly, you'll always think your doing something else wrong.

You have the equipment to produce outstanding award winning images.. and your off to a fantastic start.. ;)

P.S M31 believe it or not is a very difficult target to get right... try IC 1396 or NGC 7000 both massive targets and will show nebulosity even without a modded camera..

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mark7331

mark7331

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Mark I would love to see your PHD settings, it's one of the reasons I haven't set it up yet as I didn't want to do that as well.

Here you go. PHD version is 1.13.0. I have to play with aggression and min motion according to seeing but these have allowed me 10 minute subs so hopefully it's a good place to start from. ;)

I get roughly 11-14 steps in both EW and NS calibration but you may need to tweak the calibration step value for your mount.

Sometimes, when starting NS calibration, PHD can wait a while to clear the DEC backlash but it gets there. Other times it zips along but that may be because of the way I've slewed to the target (i.e. last move was North rather than South so the backlash has been taken out).

Hope it helps

Mark

post-20393-133877642739_thumb.jpg

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