M51 Whirlpool Galaxy last night. Now how to process.....?

[irtuk]

Hey folks.

I managed to get the attached file stacked in DSS last night from 86 60s subs at ISO800,  DSS picked about 60 or so leaving me with the image file that I have cropped to a manageable size.

For the post processing I am using photoshop 2121 trying to follow the guide from Trevor at AstroBackyard and slowly stretching the data with curve layers and correcting the levels but it's still a bit grainy. Where do we go from here? more integration? dedicated astro camera? different settings in DSS?

 

I am getting to about here with this data, and wondering what more experienced folks could do with the same set in photoshop? Obviously I am pretty happy with this, given where I was six months back struggling to find the moon and typing the wrong date format into the mount but if anyone has time and inclination could you reprocess the TIFF file and leave the layers in so I can see what's going on, see how aggressive stretches are and what other tools there are in the box other than curves and levels.

Ed.

 

cropped no process.tif Autosave.html

[Knight of Clear Skies]

You have some very good data there. Here's a quick version with just curve and level adjustment, no other processing.

You're doing a great job with the data collection and your stars look good, which are major hurdles to imaging. Something isn't right with your processing workflow, you are clipping the white-point and black-points and possibly introducing noise by boosting saturation.

 

[irtuk]

Brilliant thanks!

The problem with the processing workflow is that I don't know what I am doing! It's taken a fair while to get to this point, where I can actually gather the data fairly reliably but once in photoshop its a question of wiggling the sliders to work out what they do then almost randomly sliding them about!

[mikeyj1]

Hi Ed,

well that looks pretty similar to most early attempts at the Whirlpool, including mine   TBH you have done well to get the image from 60/60/800 settings, you should be chuffed.

It looks like you have cropped in quite along way, so the resolution will go down with that, a longer focal length is better for that.  DSLR's have quite big pixels normally, and a short focal length means less pixels covering the image.  However..you can do some things to help:

Go for 2 hrs integration time, and dither the images, which moves the camera a little so you cover more pixels and smooth the image a bit(although normally early on tracking is unguided so you get some natural dither..or trailing).  Software like APT lets you include some dither

Stars look nice and round, what was wrong with the ones thrown away?  maybe add some more in by adjusting the % used in DSS

what about Darks and Bias?  easy enough to do on a DSLR, and help alot

good luck with it, clear again tonight, so get some more data and process again..

Mike

PS: just seen knight of clear skies process...i hadn't downloaded the image file   looks very good, and less stretching definitely helps !

Edited April 6, 2021 by mikeyj1

[irtuk]

It does look like I have a good clear window tonight so I will be able to add another couple of hours of integration. I am using an Altair Starwave 102 F7 ED with a field flattener. Focus was  a bit of an issue, using FWHM in Backyard Nikon I  considered "in focus" to be at step 20514  whereas when I brought out the bahtinov mask 20119 was much closer. As it happens I didn't refocus yesterday but I will this evening.

[mikeyj1]

nice, i also have that scope and flattener  

[Knight of Clear Skies]

A quick process in PS, mostly using Noel's Actions. Looking more closely the stars are a little out of round but that could be fixed using the repair tool in StarTools.

[ollypenrice]

When stretching in curves I regularly monitor the brightness of the background sky and, when it gets to 23 per channel in Photoshop, I don't stretch it any further. There's no point because all you'll do is stretch the noise in the background and, having done so, clip it back to give you a value of 23 but with way more noise in it.

To continue stretching in search of faint signal just above the background value I pin the curve at 23, put a fixing point below that and then stretch just above the 23 point.

For a more general bit of advice I'd say experiment with the Ps tools by all means but always try to work out what it is that they are really doing. There are some really dreadful videos out there in which the imager is thrashing about with tools they don't understand and haven't thought through. Always try to think it through and you'll build up a sound technique.

Olly

Edited April 6, 2021 by ollypenrice
Typo

[irtuk]

I recently had a bit of a windfall so, I'm debating what best to upgrade. I think the camera is looking like the best place to invest. I am looking at the ZWO ASI1600MM pro Mono with filter sets but, maybe one-shot colour is the way to go. Folks say that they are not far behind the mono's in terms of performance, galaxies and nebulae are what I want to be looking at.

 

/edit/ 

went to check out Startools  and it looks sexy! going to have  a play.

 

Edited April 6, 2021 by irtuk

[Clarkey]

On 06/04/2021 at 12:52, irtuk said:

ASI1600MM pro Mono with filter sets but

I have the ASI 1600MM which I purchased last year with the full filter set. I have been impressed with it - but I was moving from a DSLR too so it was going to be a big improvement. I think some of the newer camera's have better sensors to the point it is a noticeable performance difference. I still think I would go with mono if I was to chose again - mainly for NB, although the gap between mono and colour is pretty small. There are the nights where I have got 3 of the four channels before the cloud has rolled in - this is when I wished for OSC! I have learnt to rotate my filters more for exactly this reason.

PS. Don't start a OSC / mono debate. It can get a bit heated🤣

[bottletopburly]

On 06/04/2021 at 12:52, irtuk said:

went to check out Startools 

Startools is excellent and if your struggling with photoshop or the like then is definitely worth trying , I personally didn’t get photoshop too complicated for me stretching levels and curves there no doubt it’s an excellent program but not for me , Startools will give you good results just take time to read settings for the stacker you use , and take calibration frames flats and bias and dither using a dslr 👍.