SteveNickolls

48 minutes ago, Filroden said:

Isn't it great to always be able to go back to older data and reprocess it with newer tools/knowledge?

 

+1 to that. You can spend many a clouded out night usefully having another go :-)

Cheers,

Steve

Hi Nige,

Thanks for posting your 'before' and 'after' images. I'd definitely agree that on a larger screen the improvements in both second renditions is more obvious, both being much darker backgrounds and less noise.

Well done.

With our Alt-Az set ups we get to see the greater effects of light pollution and of imaging at lower altitudes through more atmosphere and the more so the fainter the object. I have come to consider that StarTools needs a certain quality of data to perform at all well, and for me the functioning of the COLOR module is the one most sensitive to poorer data.

Thanks again for posting.

Cheers,
Steve

36 minutes ago, Nigel G said:

Steve, that's a nice clean image, thanks for your good efforts,  there all better than mine, I have a lot to learn with StarTools,  I'm re stacking and saving as a tiff file to see what PS can do. The stacking alone without registering is taking just over 2 hours ?. 

Cheers 

Nige 

Thanks Nige, I've only recently started following some advice Ivo made on a forum about using the isolate option in the LIFE module, it really 'pushes back' the background. Some objects respond well to using mask and your data had just enough for StarTools to process the area immediately around the (masked) centre not as background and left it as a wispy area. As I mentioned before with more data this should become easier for you to pull out. You really should be pleased with what you have imaged. The great thing I find with imaging is you can go back at a future date and reprocess your data with your growing ability (whether StarTools or another software) and find what was hiding there all along for you :-) Good look using PS.

Cheers,
Steve

3 hours ago, Herzy said:

...I saw a thread on a different forum where they had nearly 100 hours (a hardcore imager) on this target worth of 30m subs. That should tell you just how faint this is. 

 

Wow, I could only dream of being able to spend so long on one target. They must have excellent conditions (lucky people).

Regards,
Steve

Nige,

I just had a further attempt in StarTools with your image-

Very delicate balance between the faint nebulosity and the noise. It will be fascinating to see what you get after even more exposures. I managed to play with the image in the LIFE module with a mask and isolate option. I used mask to cover just the centralpart of the PN and the little blue fleck at seven o'clock. There was just enough in the halo for StarTools not to 'push it back' into the background like the surrounding stars.

Good luck.
Steve

Here's a closer cropped processing in StarTools-

I'd be happy with this, after all it is a faint, small object Nige.

Cheers,
Steve

Hi Nige,

I've had an attempt with your Cats Eye Nebula using StarTools-

i'll try a closer cropped one next.

Cheers,
steve

Thanks Herzy for this explanation. There's still a lot of the brighter objects in the sky to image (thankfully) with 60 second exposures and as we don't here in the UK get many clear nights they should at least see me out (I mean to sound cheerful) :-)

Best Regards,
Steve

Hi Nige,

Thanks for posting this. I very much agree with your observation that the longer the individual exposures are, then other things being equal, the resulting image (S:N ratio) will be superior and is of course why people use EQ gear to get longer individual frames unfettered as they are by the effects of field rotation. With our Alt-Az equipment we are limited by the length of individual exposures possible by field rotation and the ability of our mounts to track and their (lack of) stability. Within this envelope (perhaps 60-70 seconds, sometimes much less) we hope to collect as many photons out of the decent % of frames from both the brightest through to the dimmest parts of a DSO and hope the signal can be pulled out of the noise enough. Local light pollution will add to the task. By repeating the exposures many times we hope to detect as much as we can the faintest part of the DSO which statistically will show up in lower numbers and in some exposures not at all if the object is very dim or the pollution very bad (that's my poor way of explaining the different ways signal and noise are treated mathematically). Joseph Ashley in, "Astro-photography on the Go" mentioned a survey of images posted an the Internet he made and concluded that 120 minutes of exposure was the right amount to get a decent image, so with Alt-Az gear that can amount to hundreds of light frames especially as not all frames are good enough for DSS to use in stacking. In practice I think the most frames I have ever taken on one object was 160.

Your images of NGC 6543 bear out the positive effect of taking more frames-reducing the noise more. As an aside I'm unsure right now about the pro's and con's of using dark frames at all. It's telling that you felt StarTools was happier processing the second batch of exposures with the greater number of exposures. As the object is a difficult (fainter) one you are adding to the difficulty of extracting a good image.

There is also some gain we can make by getting more adept with our processing software. Yesterday for example I reprocessed a cropped image of Kemble's Cascade taken originally in August and through better use of ST's got a much improved colour and dark background. However NGC 1502 (Mag 6.9) is much easier to image than your NGC 6543 (Mag 9.8) and in there hangs a tale.

Original-

Most recent reworking-

I'm really pleased you have posted this subject Nige for us to chew over :-)

Cheers,
Steve

With immediate light overspill like that Ken you are doing extremely well to take the images you do. I've just been watching one of the old Astro Imaging Channel sessions (on You Tube) about light pollution and the 'orange peel effect' noise we all see in images can be attributed to light pollution.

I think you have started the subject of a ramble on this thread Ken-that is what our imaging locations look like at night! Will post up when I get chance to take a night shot.

Can just make out the upturned baby and Elvis too in your image now you point it out.

Cheers,
Steve

34 minutes ago, Stub Mandrel said:

You ALT/AZ folks shouldn't think using an EQ mount is a bed of roses. Here's what happens if last night's PA is 12 hours out:

 

 

He, he we know EQ mounts aren't beds of roses :-) Good luck sorting out your mount problem though.

Best Wishes,
Steve

Hi Ken,

I've had a try with StarTools on your downloaded image. The COLOUR module did not like the data and would have washed the nebulosity firther away so I missed that step out. The background is becoming darker and some nebulosity is developing. If it had been a more regular shaped object using isolate/mask in the LIFE module can really bring out an object more. I hope you can get more data to get this to be a good success.

Cheers,
Steve

Yes, time is not our friend as it could place the nebulae too high to work with. Looking back on my records September tends to be a good month for clear skies, so fingers crossed. I'll have a look at your downloaded file now :-)

Cheers,
Steve

Well last night regardless of the Moon it turned out to be very clear here. I was surprised firstly that when I was imaging the Double Cluster in Perseus that the Live View on the camera showed a dark blue background, usually it's a various shade of 'light pollution orange-red'. This morning stacking the images the master image in DSS was a dark grey colour and not the usual mucky orange hue. I rather think last night the sky was largely free of moisture so the level of scattered light pollution was a lot less than normal. I took x60 fifty second images of the double cluster at ISO 800 and this morning took the flats and bias frames (both x50). Again I did not take any dark frames. I used the usual equipment, the Synscan Alt-Az mount, Startravel 102mm refractor and my Canon 600D DSLR with a lens at 300mm. StarTools was able to process the images very well and I had no trouble in the COLOUR module and got a nice dark background automatically. The image is reproduced below, in the bottom left corner is the open cluster NGC 957. I love the double cluster and will spend ages now looking at the patterns and colours of stars v Stellarium.

Cheers,
Steve

Hi Ken,

Thanks for posting this. I'm going to download the FITs file to see if I can process in StarTools later today.

Best Regards,
Steve

9 minutes ago, Filroden said:

My Heart Nebula was a bust. Like you say, I need far more photons for something this feint. I can't get above the noise with 30 minutes. It looks like another clear night tomorrow with little wind. I may see if I can get a couple of hours on the Soul Nebula though I'm tempted to park it as even if I got a couple of hours, by the time I crop the image, I don't think I can get it in a single shot. I'd need to do a mosaic which doubles the subs I will need

I'm thinking I might have to try something else tomorrow - probably adding more to my M31 image.

Don't be too upset over this Ken, it's sometimes difficult to know how some DSO's will appear on the restricted images we can make with alt-az gear. I'm often uncertain over the different brightness values stated for DSO's on sites. Often you just have to try imaging to see what you find. What's more of a disappointment in the UK is we get so few clear nights that spending two or three on one object when you could be imaging three others is a hard choice to make.

Here's hoping it will be clear tomorrow night as promised in the forecasts.

Cheers,
Steve

4 hours ago, Filroden said:

Not my finest work. I can't remove the lines that look like claw marks and I've given up processing it and just pushed it through a quick stretch in Photoshop. This is only 30 minutes of total image so I'm actually surprised to see anything. Going to see if the images of the Heart Nebula are any better.

 

 

I'd put them down to your relatively short total imaging time there Ken. I've been re-reading Joseph Ashley's book, "Astro-photography on the Go" this afternoon and he did a review of the images people had placed on the Internet that they were pleased with. He came to the conclusion that 120 minutes total exposure was the point to aim for which practically might mean multiple sessions. TBH I've never achieved that level of exposures but if the night is dark then of course the more photons collected the better and the easier subsequent processing becomes. Don't be downhearted if the image of the two nebulae needs more work as you could add more images another night.

Cheers,
Steve

8 hours ago, Nigel G said:

While I was processing M31 420mm I had hundreds of very luminous green dots in the image, which I have never seen before, each one about 3 or 4 pixels in size but covering the entire image, the only way to get rid of them was with the final noise reduction in StarTools,  I'm wondering if not using darks was the cause of it. 

The green dots looked exactly like the small specks you get when setting a star mask in ST. I have no idea where they came from though.

Strange. 

It's a long learning curve ☺☺

 

I hope you get to the cause of the green artifacts Nige. I haven't had anything like that all across the whole image but I have had green and red short tracks on a wide field image before where I hadn't employed any dark frames and did think that was the cause. Your mention of StarTools green specks, could they result from the use of the DECONVOLUTION module? I have noticed it sometimes leaves odd gaps of colour often only noticeable in a magnified view?

Anyway good luck sorting it out and do let everyone know what it is/how it can be resolved.

Cheers,
Steve

I have just obtained a ball joint to attach to the top of my telescope to allow me to accurately align the camera when doing piggyback work (I was having problems with the camera mis-aligning in altitude). Now the finder, eyepiece and Camera all point to the same spot, quite helpful really;-) :-) Despite looking top heavy the ball joint has worked very well with no movement even with the big 75-300mm lens attached or the camera falling off at higher altitudes. The joint is rated for supporting 8kg. 

Here's a wide view below (at a 75mm lens setting) of the area around the Double Cluster in Perseus, the Muscleman Cluster (Stock 2) is in the image. The image was taken on the 7th September using x50 forty second exposures at ISO 800 plus x50 flat and x50 bias frames. No dark frames were used in the processing. On the night of imaging there was a lot of moisture in the air and the usual light pollution. I was using my Canon 600D DSLR piggybacked on the Startravel refractor and Synscan Alt-Az mount. The images were stacked in DSS and images processed using StarTools. I have tried reducing the worst effects of the bad light polution by removing the luminosity from the red channel in ST's. This doesn't affect using the COLOUR module however.

Cheers,
Steve

Hi Nige,

Very well done with this sequence of M31 at different FL's, I do like them very much as a record and I'm not going to pick any one of them out as I feel each one gives a different perspective on the object. You have certainly got me itching to emulate what you have done :-) Here's for clear, dark skies to come.

Cheers,

Steve

Hi Ken, sorry to hear of your mishap but good to know you have resolved the problem. Look forward to seeing your images, particularly how much nebulosity your camera has picked up. Earlier in August I was trying out my 'new' 75-300mm lens on the Canon 600D and took some wise-ish angle shots including the area with the Heart and Soul Nebulae and Perseus Double cluster. The image below isn't great with much false colour but it was the sum of x80 45 second exposures at ISO 800, plus the usual dark, flat and bias frames (x50 each). There was a bright Moon up that night and moisture in the air but you can make out some shapes :-) On the right hand side you can see the Double cluster in Perseus. Having never seen the two nebulae before even this poor image felt an achievement. Good luck with your imaging.

Cheers,
Steve

38 minutes ago, Herzy said:

"...Anyone else go out last night?"

No, there were clouds scudding around and today the rain has started. The outlook for the coming week is very mixed. We might be lucky and have one clear night. Take opportunity of any clear sky you get :-)

Cheers,
Steve

4 hours ago, Stub Mandrel said:

I use Kappa Sigma and  darks

Thanks, must try that option also :-)

Cheers,

Steve

Yes, 

That's a lovely image of M31 Ken and one to try to emulate. I do like all the blue star forming areas around the galaxy edge. You must have quite dark skies you know :-)

Nige, you are building up a lovely collection of images at the different FL's :-)

Cheers,
Steve

10 minutes ago, happy-kat said:

I thought what about no dark frames but with bias and flats.

The second image looks better without the darks but it is not so clear cut with the first. Thanks for experimenting.

Hi,

Thanks for your view on the image :-) All images had flat and bias frames. The image of M33 was definitely the poorer and this would be down to it being lower in altitude and intrinsically being fainter. It would be interesting to muse the dark frames added more noise than they were meant to take away. StarTools doesn't like poor images hence the red background hue.

Cheers,

Steve