Filroden

13 minutes ago, The Admiral said:

Hmm, I can't do anything with this image, I don't know where to start with the gradients. This is a straight auto dev on the fts. Wipe doesn't seem to do a good job.

Ian

I cropped first to remove the vignetting and then removed the remaining background which was then much easier.

Here's that image with mine rotated and resized to approximately match and one with it superimposed. In my original attempt I think I could just make out the outer boundary of the nebula against the background. I think another couple of hours of data might make it a lot clearer.

I definitely need more processing practice. I really struggled with this one as the nebulosity was so feint. Here's my quick effort in PixInisght. I cropped the image to reduce the processing time.

Steps I ran included background removal, background neutralisation, colour calibration, noise reduction on background, deconvolution, a masked stretch to protect the stars, curves transformation, small histogram transformation and colour saturation.

4 minutes ago, Nigel G said:

Exposure times, now I've been told and read in books that ( example ) 120 x 30sec exposures is equal to say 6 x 10min exposures and that you need 2 hours of data for dso's. 

After 9 months of experimenting I have decided this is not strictly true. I believe longer exposures are much better than shorter for finding detail and light gathering but more frames is better for noise elimination .

I have taken images of Andromeda with as little as 15 minutes of data up to  2 hours of data with not much difference in the final images. The longer the exposure times the more detail captured regardless of total time.

My latest image, ngc 6543 , firstly I stacked about 45 minutes  of 30 to 45 second exposures,  second time around I stacked 2 hours 20 minutes of 30 to 45 second exposures,  both with darks and bias. Both lack the emissions of the cats eye, the second image has a touch more detail but was far better to work with in StarTools due to much less noise.  The cats eye is a difficult dso to capture and I'm not disappointed with the result although it lacks most of the nebula.

I think my test images of ngc 7000 showed the power of the longer exp times. Our greatest barrier is the exposure time limits of the Alt-Az mount.

Having said that there are plenty of dso's as we have seen in this thread where short exposures are all you need,  it's the fainter objects that require the long exp.

I have posted both images of ngc 6543 so they can be compared.   

First the 45 minute,  second the 2h 20 minutes. 

There are 2 other dso's within the image which are more apparent in the second image also there is a wiff more emissions  .  The second being far easier to process with far less noise reduction needed, I think due to there being 238 frames. Although noise is present in no 2 thats because I'm trying to extract emissions. 

I'm sure someone else with better processing skills could get more out of it if I knew how to upload a fits image. 

With 2 hours of 600s I believe the nebula would be greatly improved,  I might be wrong.

Cheers 

Nige.

 

Interesting findings. I'd always thought that so long as you could exceed read noise then total exposure time was all that mattered (other than more subs for DSLRs is better to help reduce/remove banding).

if you can upload and share the fits file in something like OneDrive or Dropbox I can give it a go in PixInsight.

7 hours ago, jimbo747 said:

I can see at least 3 cat faces in that image, possibly as many as 6.

If you can see cats and this is the Soul Nebula then surely there must be nine in there? Happy hunting the other three

1 hour ago, The Admiral said:

Baby or Elvis? Not until you mentioned it!

And now I can't decide if it's an upturned baby or a side view of ET.

12 minutes ago, Herzy said:

You could probably get an old cardboard box and flatten it out and tape it with a small frame to the fence to keep the scope hidden from the streetlight. The light is most likely spilling into your frames and causing nasty gradients. 

This will be especially apparent if the seeing isn't great (i.e. A lot of dust and fog in the air) the light will start light up the surrounding air near it and you will be within that area. 

 

I think I've been lucky so far. The fence screens it completely already and the Dynamic Background Extractor finds no gradient. You're right though, poorer seem might diffuse the light and interfere more. I may need to increase the fence height with a temporary screen. 

Thankfully all the lights in the neighbourhood are LED and screened to only point down. I think that's why I'm seeing such dark skies. From the top floor (above the lights) I get some amazing views.

6 minutes ago, Nigel G said:

Was the image white balanced , I'm wondering if I used the correct opening tab in StarTools. 

It was debayered but I'd not applied white balance. This was straight from the integration. I'd normally remove any gradient then neutralise the background and run colour calibration as my first steps. I don't know what that would be in StarTools terms. 

Another great effort. Thank you for taking the time to process it. I'm glad you had some fun with it.

I've had a second try, this time managing to use Deconvolution - probably the hardest module I've found in Pixinsight so far. I've also reduces the stars and toned back the red. I'm not sure this is better as I've completely killed the background but I can see more of the fainter nebula.

BTW, does anyone else think this nebula looks like a) a baby with its head at the lower end of the photo or b) Elvis, with his quiff to the top?

For interest, I've also included two pictures of my current set up position (one with and without flash). I'm having to use the fence to block the light right next to the garden. There is one at the end of the garden too. Pretty amazing that night seem to affect my images with little discernible pollution and a rough measure of SQM at 20.4. If I also stand by the fence I can just trace the Milky Way overhead.

41 minutes ago, SteveNickolls said:

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

Thanks for trying it Steve. I'll see what more data I can collect and in the mean time I'm going to try deconvolution again with some better masks to see if I can sharpen it.

9 minutes ago, SteveNickolls said:

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

It will be good to see if StarTools can do anything more. I still haven't mastered deco nvolution so it will be interesting to see if it can sharpen the image. I'm not happy with my processing but I'm much happier with the raw data.

It goes to show more data makes a huge difference though it also makes alignment much harder as I'm having to collect data over a much longer window and crop back much further. In hindsight I should have rotated my camera by 45 degrees to give myself more field to play with. Tonight could be clear though windy so I might try to add more data. The moon will start to interfere soon and I'm worried in another month it will be too high and rotated too much.

Round 2 - I apologise this is badly processed but here's what an additional 80 minutes of data can do...

IC1848 - Soul Nebula

54º34’N 000º59’W

Equipment

Skywatcher Esprit 80

Celestron Evolution Alt/Az mount

Canon EOS 60d

Images

Lights        Quantity    Exposure    ISO    Notes

Lights              160               30s                  1600     10/09/2016 21:54 to 23:47, 63% Moon, SQM 20.4

                        60                 30s                  800       07/09/2016 23:03 to 23:44, 36% Moon, SQM 20.3

                       110 minutes total integration    

Bias                                                                            Superbias used

Darks             30                   60s                   1600     Scaled to 30s in Pixinsight

Flats              32                   1/32s                 1600

Here's a link to the raw fits file if you StarTools gurus want to see if it can pull out more detail: https://1drv.ms/u/s!AvTUh2l4A9nVgck6uy56qgCfDIcBzA

Next step top is to take about another 130 minutes and see what four hours will show.

3 minutes ago, SteveNickolls said:

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.

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.

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.

1 hour ago, SteveNickolls said:

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.

Really good to see it's possible to capture both nebula with an unmodded DSLR. You can definitely see both nebula in the image and it's nice to be able to capture both with the double cluster. My field of view barely covers the Soul Nebula and I'll have lost quite a lot of the Heart Nebula (once I finally get to look at those images). I did think to take a third sequence between the two nebula and try for my first mosaic but the clouds came over.

I'm on my third processing attempt. Although I got rid of my circular artefacts, there were two or three really bad marks across the integrated image. Given I'd rotated the image slightly when I cropped it to remove the stacking artefacts, they were not horizontal/vertical and they didn't cover the full width of the image - they almost looked like a bear had clawed them!. I'm running the data again with no calibration other than auto detection of hot/cold pixels to see if it's the bias, darks or flats causing me grief.

Well, I think I've no Heart but I might have a Soul. Just spent best part of the day integrating and re-integrating 60x30s shots of both Heart and Soul Nebula. In both cases I seemed to have a very circular artefact being introduced on integration. When I removed/neutralised the background and stretched the image it looked like someone had taken a circular grinder to the centre of the images! I've been pulling my hair out to figure what was wrong with my set up given the images appeared much sharper than the ones I took for the M31 image and I also reset my goto after every 10 shots (my tracking seems to degrade after about 10 minutes so I recenter every 5 minutes).

Well, it appears it was all down to one misclick in my settings. I'd noticed a function that looked like it was ideal for helping to de-rotate images and had clicked it. It certainly did something! If I only had a brain!

I've gone back to my original integration workflow and I'm just doing the final integration on the Soul Nebula. The initial integration, with a quick background neutralisation and stretch, seemed to show nebulosity. Hopefully I can have it processed tomorrow (removing the background is going to be tough because of the vast star field and sheer amount of nebulosity in that region). If successful, I'll then process the Heart Nebula.

I'm not expecting much as my camera isn't modded so I think it's only 25% sensitive to Ha and 30 minutes total integration time just isn't long enough. But it will be good to know if it's worth doing 4 hours on it.

Hi Nige

I definitely prefer the look of the 210mm compared to the 420mm even though its a fraction of the total integration time. I think you're right about the additional glass on the x2. 

Not to get too excited but the sky is an unusual colour (blue) and very empty. It's almost like I could be in for a clear night (at least until Midnight). Tempted to capture something new and try for either the Heart or Soul nebulae and really see how dark my skies are. It's premature but I've got the scope set up and bias/flats already being taken/calibrated. Wish me luck!

42 minutes ago, Herzy said:

Anyone else go out last night?

Yes. I had pretty clear skies. There was a ten minute spell with some very high clouds but otherwise it was clear until dawn when the rains arrived. Not looking good now for the rest of the week.

2 minutes ago, The Admiral said:

That's a nice image Ken, with plenty of colour around the periphery. Considering your total exposure must be around an hour, and with an 80mm 'scope, perhaps your skies are darker than you thought! How much 'yuk' was visible before subtracting the background?

Ian

The background was pretty flat. At ISO800 and 60s I think I was only getting to about 15% on the histogram. I did try 120s and that barely got me over 25% so it must be much darker than my previous house. 

Okay, after a long leave of absence moving house I finally found all my telescope boxes and got a clear night to test my new skies. After a very rough start (practically relearning how to set up and align the mount) and being unable to lock my focus (the knob fell off during transit and by the time I realised it was missing I'd already got everything set up and plugged in - so I took my chance and hoped the weight of the camera and any changing temperatures wouldn't affect it much).

My new skies look much more polluted - I live much closer to a very industrialised region. I also now have two very bright LED street lights just outside the garden so I had to place the mount right up against a fence to get some shadow. The good news is that it seems almost all the lights in my town are LED and very focused downwards meaning I think the sky is actually darker, even though I can see in full colour in the garden!

So here's my first effort of the season (stealing your idea of focusing on something big and bright)...

69 images of M31 ranging between 30s and 60s at ISO800 using the Evo mount, the 80mm refractor and the Canon 60D. I've probably over processed it in Pixinsight (something else I had to relearn from scratch). I was rather surprised I got the result I did. Most of the images showed some trailing, caused more by the mount losing position (I need to recenter my target every 5 to 10 minutes) rather than rotation.

Anyway, here's to more clear nights soon!

To get absolute responses yes, but to get comparative measures of cameras probably not. 

To test red response wouldn't it be simpler to attach a narrow band that only passes red and photograph a source of infrared such as an electric heating element whose power can be controlled? Then you're just comparing resulting amplitude of the capture in a fixed duration...

I'm partway through moving house so the scopes are all packed up. Typically tonight looks like it might me clear! Anyway, I doubt I'll be Imaging before July. 

Thats a nice M57 but is there a slight pink/red tint to it? Some of the stars look pink whereas they are probably closer to white? Nonetheless, amazing for 150s of data!

That reducer is giving you a similar field of view as my 80mm. Can't wait to see everyone's efforts on M33 in the coming months. 

3 hours ago, SteveNickolls said:

Hi folks, here is my latest offering taken on the evening of the 14th May 2016 of the Crescent Nebula NGC 6888 in Cygnus. The image was taken using a SkyWatcher Startravel 102mm f/4.9 refractor, Synscan Alt-Az mount and Canon 600D DSLR. Due to the position of the target I was able to employ 60 second exposures. I took 91 sixty second light frames at ISO 1600 and for the first time used stock dark frames (x50) and bias frames (x50). x50 flat frames were taken the following morning. The frames were stacked in DSS and further processed in StarTools. Of the 91 light frames taken DSS was happy to use x67 (just under 74%).

Hope you like the image.

NGC 6888 Crescent Nebula-

 

Beautiful image. Do you think the stock darks and bias had any effect?

I've been quiet for a few days. Although it's been clear here, the moon is getting too bright in the evenings and I've not had the stamina to wait until 2am for it to darken. Also, even though it's often looked clear, there has been a high haze that has reflected more light than usual.

I did take some subs but they were so bright from the moon plus normal background lights that I've not been able to integrate them with earlier subs. However, I did drag myself outside last night at about 2:30 and what a sight! I could almost make out the Milky Way (may have been imagining it but I thought it was there, overhead) and I could definitely make out mag 4.3 stars with direct vision. I was so tempted to set up and take some subs as the North America Nebula was at about 60deg altitude. Antares was quite high and another tempting target, though by 2:30 it was already behind the houses near me. I'm now wondering whether I need to set up and start imaging around 1:30. Though I suspect that now the moon will destroy any attempt other than globulars.