Needle Galaxy NGC 4565 - Beginner looking for advice

[russp]

NGC4565 - 14 10minute colour exposures with flats and bias (No darks used) - 127mm APO Triplet Refractor with x0.8Reducer, AZEQ6-GT, Atik314L+, SGP for capture, PixInsight for stacking and processing. Still very much a beginner at this so would be grateful for any tips/help on what can be improved and more importantly how. Taken Monday 7th March from rural village back garden in South Oxfordshire.

[RSM]

Did you use dithering between individual subs. I'm guessing that at 10 min exposures, you are using a guiding system which could also drive the dithering too. I use a Lacerta auto guider which dithers for me, I choose a 14 pixel dither which really cuts down the noise and allows me to stretch more in Pixinsight. I use bias and darks in my calibration before stacking and rely on DBE to remove vignettes in place of flats.

the other advice I would give is get as many subs as you can and use only the best. For some of my recent images I've used up to 100x3 minute subs, that's 5 hours total exposure time after I've discarded any with star trails or camera wobble.

By the way I love the image russp. The detail on the dust band edge on is fantastic, must have a go at this from my backyard in Surrey sometime soon. I was concentrating on M51 at the same time on Monday.

Richard.

[russp]

9 minutes ago, RSM said:

Did you use dithering between individual subs. I'm guessing that at 10 min exposures, you are using a guiding system which could also drive the dithering too. I use a Lacerta auto guider which dithers for me, I choose a 14 pixel dither which really cuts down the noise and allows me to stretch more in Pixinsight. I use bias and darks in my calibration before stacking and rely on DBE to remove vignettes in place of flats.

the other advice I would give is get as many subs as you can and use only the best. For some of my recent images I've used up to 100x3 minute subs, that's 5 hours total exposure time after I've discarded any with star trails or camera wobble.

By the way I love the image russp. The detail on the dust band edge on is fantastic, must have a go at this from my backyard in Surrey sometime soon. I was concentrating on M51 at the same time on Monday.

Richard.

Thank you, Yes - enabled dithering for the first time (no idea how many pixels - just selected high setting!) - guiding with PHD2, also not using darks was an experiment based on advice on techniques elsewhere to use a superbias but everything I read seems to stress the importance of flats - I think my CCD is low enough noise that it doesn't need darks but I do have the same image processed with darks that I need to finish off to see the difference. Would have had more subs if the guiding hadn't failed after I left it running and went to bed!!  The mount is rock solid and I rarely have to discard for anything other than clouds or guide failures (one went by the wayside in this) but I did weight the exposures using the subframe selector script. 

[laudropb]

I think it is a very nice attempt, but I am no expert.

[Barry-Wilson]

This is a very good start - nicely framed, good focus, flat background.  There appears to be some artefact in the background toward the upper left and this maybe an effect from your flat field.

I think you simply need to collect more data which will help build on detail, SNR and enhance the lovely colour that your data is showing.

[russp]

Thanks Barry - the artifact is a blur in my optical train - needs a good clean and the flats didn't quite get it all out. That will be sorted before the next session.

 

[morimarty]

I agree with the guys above, thats a superb image for a relatively new imager. You say 14x10minute colour exposures, So I assume this is just RGB? my advice would be to get some luminance subs to add to the RGB you already have.

[russp]

It's a one shot colour camera Martyn ... thanks though.

 

[kendg]

Very nicely done.

[russp]

Thankyou Ken