Herzy

2 hours ago, The Admiral said:

Trouble is, a 4 hour or 9 hour stint using an Alt-Az mount does create other problems!

Ian

Why would it? Sorry, I don't know too much about altaz.

6 hours ago, SteveNickolls said:

The recent clear dark night skies have allowed me to image M31 and M33 using the combination of Synscan SkyWatcher Alt-Az mount, 102mm Startravel refractor and Canon 600D DSLR. This season I have been trying out ISO 800 after finding ISO 1600 was producing images which on the camera histogram were well to the right hand side. I've also been using stock dark and bias frames. I realise I can't control the temperature of the camera chip but the dark frames do help with bad pixels. I am going to try using the kappa-sigma clipping in DSS as it's meant to be an alternative to using dark frames for removing rogue pixels.

The following two images were both taken using 60 second exposures since both objects were well placed in the East for field rotation mitigation purposes.

M31

x50 light frames, x50 dark frames, x60 flat frames and x50 bias frames. Stacked in DSS and subsequently processed using StarTools. Taken 29th August 2016.

M33

Again x50 light frames, x50 dark frames, x60 flat frames and x50 bias frames. Stacked in DSS and subsequently processed using StarTools. Taken 30.8.2016.

DSS was happy to accept 72% of the M31 exposures and 75% of the M33 ones. At sixty seconds I'm averaging 76% acceptable frames from all my exposures up until now.

This season I've obtained a Canon 75-300mm USM III lens to have some fun taking wide-ish piggyback shots using the Synscan Alt-Az mount and below is my first attempt at M31 in wide view taken on the 26th August this year. Taken with a camera lens setting of 200mm f/5.6.

The image is made from x50 sixty second light frames at ISO 800, x50 dark frames, x60 flat frames and x50 bias frames. Stacked in DSS and subsequently processed using StarTools. DSS was happy with all the light frames taken.

Cheers,
Steve

You really need more integration. Integration is key. Especially on M33, where the spiral arms aren't very well defined in your image and there isn't much detail to be had. That is because the noise is just too strong relative to signal. You need at least 4x the integration to improve the sharpness by 2x and reveal details half as bright (due to diminishing returns) and that is well worth the effort. You would be surprised how much detail you could pull out of a 4hr stack vs a 1hr stack. I was certainly surprised with the results of M16 (1hr vs 9hrs). It was a HUGE difference.

Also, your color balance is a little off. Not sure what is causing that.

At the end of this day, the images are great. They would impress almost anyone you showed. Good job!

9 minutes ago, Stub Mandrel said:

I did a comparison using kappa sigma and adaptive average and the kappa sigma appeared to have least noise.

I found leaving out darks made noise worse but 'your mileage may vary'.

That's because averaging does far less work. Assuming your dithering property, any correlated noise or walking noise will be removed from a reject/sigma algorithm.

7 hours ago, Nigel G said:

A possible target for the test could be M17 Omega nebula, around the same altitude as Saturn in the southern sky atm.

I took this during the full moon last night and it was close to the target, because of the moon I could only get 15s exposure at 400 iso and only 30 minutes worth before the faint clouds started to arrive. 

Nige.

I haven't been out either because the moon is wrecking my view of the Eagle Nebula which I have an ongoing project on. You mentioned earlier how you feel you've reached the limit of your mount/scope so I'll chip in on that. Longer exposures and more of them will help... ALWAYS. Due to diminishing returns 4 hours will produce 2x less noise then 1 hour. 4 hours is a long time but it is worth it. If you put in that kind-of time you will get amazing images fast. Another problem you might be facing is that your imaging targets that are really faint. Your skies seem to be better then mine so I can't really comment on this with much accuracy but at my house I can't image the NA nebula because it is too faint. My 90 second subs are simply too short to distinguish nebulosity from noise. No matter how many subs I take it won't matter because I'm still not capturing any nebulosity. You might have something similar going on when you go after the faint nebulas. Just my $0.02.

Hayden

I know this thread is supporting alt/az mounts and all but if you want to really get into serious imaging with a guider to image some of the best objects available an EQ mount will be needed. If you are going to go down that route you want to get a good one because your mount is the most important part. That can be VERY expensive. So just as a reminder this should be on your list. With an alt/az mount guiding is not really needed because of the rotation. An APO refractor will definitely help short-term but if you want to long-term improve to your astrophotography skills an EQ mount is the way to go. 

So that's long-term. If you want to best improve your results here and now a nice APO refractor would be good. An achromat refractor will be pretty good but eventually the CA will start to annoy you.

Hayden

5 hours ago, Nigel G said:

Hey guys.

Sorry for not contributing,  my mother has been taken into hospital,  I will catch up on posts later on. But for now I have a mother who needs her son.

Nige.

Oh, thats awful! I hope she is okay!

1 hour ago, Nigel G said:

Thanks for your replies, I'm learning ☺

I'm thinking the 130p-ds, do you think I would be wise to get a coma corrector and can I use a coma corrector with a dslr? 

Will a coma corrector be of benefit when using an alt az mount .

So many questions,  maybe not the right place to post but as it's for use on the alt az mount imaging dso's this seems the right place, 

Nige.

A coma corrector will work regardless of the mount. It just fixes the elongated stars. I don't have one atm because I'm not really annoyed by the strangely shaped stars but most people use one. As for if you should go with a 130p-ds, that is a very nice scope for astrophotography but eventually your going to want an APO refractor. So I would suggest you upgrade to the 130p-ds now and then save up for an APO because they are very good for astrophotography.

17 minutes ago, Nigel G said:

I'm afraid I don't know anything about flattners or where to put them or CA, need to research a bit.

 

Field flatteners go in your scope's focuser and fix the oblong stars in the corners/edges of images. CA is something specific to achromatic refractors. It's strange color fringing around bright objects that is especially distracting in astroimages. APO refractors were designed to remove this problem by focusing all wavelengths of light in the same place though a series of lenses. Newtonians don't have CA because they don't use lenses.

There is a quick rundown, hope it helps!

Man I wish I had your optical tube, Nigel! I can't fit NGC 7000 in the FOV of my scope.  I'm heading to an observatory for some dark skies and my EQ mount is too heavy/bulky to bring so I will be imaging with my SLT mount. In the next week Ill have an image of the Lagoon Nebula. 

Let me get this straight - If I take a 30 second exposure at ISO 3200, my histogram peaks 30% from the left side. However, if I take a 75 second exposure at ISO 800 I get the same result. Which is better? 

One more question: I'm limited to 30 second exposures right now because I don't have an intervalometer to insure that I get the correct exposure length. Would it be beneficial to increase the ISO to increase the brightness of what i'm imaging?

10 minutes ago, Nigel G said:

I'm going to try an experiment today, what do you think the result will be

I'm going to take the 3 best 90second exposures and copy them several times to get about 60 frames, I will have to rename them all different I think. Then stack them.

Will it work ?

Nige.

That won't do much. Stacking is able to remove noise because noise is random, so over the period of many pictures it can figure out what's random and what isn't. If you stacked the same picture 100x the randomness of the noise wouldn't be there. 

17 minutes ago, SteveNickolls said:

I feel like a criminal after last night's Alt-Az imaging session. OK, I'll come clean and tell the whole story.

You have to remember everything was running well; I'd planned to set up extra early and like Ken on SGL had advised, I did the dark frames first. Alignment went swimmingly, first Vega then Regulus, return back to Vega and wait until any mount movement ceased. Vega remained bang in the centre of the eyepiece and none of the usual minor adjustments were needed. Tonight was going to be a steal.

Focusing too with the Bhatinov Mask went without a hitch. If I'm being really honest there was a little wind to spoil the mood and I had to wait a few minutes for the sky to darken once slewed to NGC 7000. At fifty seconds Live View was just a white-over but things got quickly better as the sun finally sank below the horizon.

Fifty frames later and how glad am I now that I decided to hedge my bets and next image M29. I wonder did I have an intuition?

Just before the witching hour I honestly thought I'd got away with it, no problems, no major hitches. I was soon packed away then gone like a thief in the night. The perfect imaging job.

Nemesis swiftly followed the hubris of the night before when, processing my images the next morning, a strange blob appeared on all the light frames. Oddly they were only on the first set of frames used for NGC 7000, M29 was fine. Whatever was the cause? The investigation didn't take long and I realised I hadn't got away with things at all, I'd been caught by Spider, man he'd been hiding in the dew shield all along! Here's the evidence-

It's a true story, honest. I'll post my M29 image soon :-)

Cheers,
Steve

 

Pesky little buggers! I had a big moth fly towards my phone, the only source of light out there. I frantically tried to hit it away and I knocked my scope out of alignment.

20 minutes ago, Nigel G said:

Steve & Ken. Great images, nice work. I love the nebula's always my favourite. 

I had a go at NGC 7000 last night, a beautiful mild and clear night, went to bed as the morning chorus started 4.20 am.

I tried some longer exposures as the mount was on top form last night. The first image is 85 x 45s plus 5 x 90s @1600 iso, I added 2 x 90s darks to 14 x 45s , the flats didn't work again, 50 bias.  The second image is 85 x 45s , darks and bias. DSS and StarTools. The first image with the 5 x 90s seems to be slightly better to me.

I am pleased with these, while taking the subs I could only make out a fairly small amount of emissions but there's plenty in there. I'm sure more could come from these.

Nige.

If I had taken an image as good as that I would print it and have it hung up! How good are your skies?

4 hours ago, happy-kat said:

Herzy you have bought an eq mount an advanced VX which has totally different capabilities to what can be managed with an altaz mount on this thread. Which mount are you using to image?

That's what I'm using. I was simply congratulating others for their amazing results and looking for targets to image.

1 hour ago, wxsatuser said:

Against other nebulae, it's quite bright, it's possible to get good detail in short subs, with the right gear.
To try and give you an idea here is a stack of just 7 x 30sec subs of this region.
The subs are from an unmodded Canon 6D with a 50mm lens.

Notice the NA nebula is much brighter than IC1396, lower left and quite a bit brighter than the Veil, middle right.

 

Jesus Christ that is a lot of stars... You must have much darker skies then me. Maybe it's just that yours is a relatively wide field of view, but I doubt that my images would look anything like that. (I have skies that are 6 on the bortle scale) That image is beautiful! I think I will give nebula this a go the next clear night I get.

6 hours ago, Filroden said:

I'm so tired after staying out until 1:00 and even then I almost stayed out longer. I'd just finished a sequence of subs and noticed both Saturn and Mars had cleared the tops of the local buildings. I was so tempted to set up the SCT and take some video but I know I had to be up by 6:00.

The evening started taking some test shots of M13 at different exposures and ISO settings to see how far I could push it. I could only get to 60 seconds but M13 was quite high (about 55 degrees above the horizon) so I moved to M56 which was only 20 degrees above the horizon. I did manage to get a single shot of 90 seconds though only at ISO 400 because of the light pollution. Given how many bad subs I got, and even the one "good" sub still showed rotation, I think 60 seconds is probably my limit and 45 seconds is a good working limit as that gives me almost 100% good subs.

Here's the single sub, processed in Lightroom.

I then stayed on M56 just to see what I could get and managed 31 x 45 subs at ISO 1600. Again, I've not bothered with any calibration files. I need to get back into that habit soon. Here's the finished M56 after processing in Photoshop and Lightroom.

Do you know what? I'm not entirely convinced I've got these the right way around! The second image is actually the single shot (the satellite trail gives it away)

I then moved onto NGC7000, the North America Nebula. I'd previously taken 30 subs the week before but I'd either lost focus or dew blurred the images. I did manage to stack them and I could make out the nebula but the light pollution at such a low altitude made it look terrible. Still, I wanted another try. Here's a new set of 43 x 45 second subs at ISO 1600. It's very noisy and I've had to hit the pollution with a fairly crude bat (dehaze in Lightroom). I am going to download a trial of the Gradiant Xterminator plug in for Photoshop to see if it will help me. At some stage I will have to invest in a Light Pollution filter.

In honour of Steve, I aimed for a Kenyan blend in my light pollution but in the end decided to cheat and make it a little more red. It's not a great image but I'm pleased I can see the nebula and hold out hope that when it rises higher I'll start to get better subs.

Is the North America nebula bright? I haven't tried it, but would I be able to get some good detail out of it in about 1.5 hours of data? That is especially beautiful... Amazing job! Also what is the focal length of your scope?

I never get time to image with school. I'm limited to imaging only on clear nights on weekends. With the weather over here that's like 1 clear night a month.

(removed: accidentally double-posted.)

51 minutes ago, The Admiral said:

As dusk approached last night I wondered if it would be worth imaging, as there was so much high cloud around. But by the time I and the twilight were ready it didn't look too bad so I thought I'd push on with Makarian's Chain. It meant placing my 'scope in a slightly different position in the garden so that I'd get long enough on it. All going smoothly, until near the end of my first batch of 60 x 30s subs when I realised that I had only roughly focused whilst aligning. Doh! A wasted 1/2 hour which meant a really late finish (for me). No stars in the FoV to focus on, so I slewed to Jupiter (clearly a Nige moment!) and focused on its moons, then back to Makarian. In the end I had 123 frames for DSS to munch on, of which it decided to stack 91, so in all about 45 minutes total exposure. Not long enough really, and it shows in the noise levels. All things considered, I'm quite please with the final result. NGC4477 looks a bit odd because it's in a stacking artefact and so doesn't benefit from all the subs during stacking, hence the noise. M84 is also a bit noisy, but the bottom RH corner generally shows rather more noise. I suspect the darks aren't doing much good there.

 

91 lights stacked in DSS, along with 51 darks, 51 bias, and 50 flats, processed in Star Tools, and polished in Lightroom. Fuji X-T1 at 1600ASA through an Altair 102mm f/7 Super ED, all mounted on a Nexstar 6/8SE mount, 4th May 2016.

Ian

 

Great picture I can't wait to see the image once you've got more data! This is my next target.

I'm in this situation right now. I have a T-ring and an adapter ring stuck together. I've scraped my hands to the point of bleeding twisting them. I've tried WD40, I've tried sticky gloves, and I've tried running hot water on it. Any ideas?

I fixed that! My DSLR was weighing down th back so it was giving bad star trails. I just attached a bag of flour to the front to balance it out. I don't always get good stars, but maybe 70% of my pictures work out well!

Believe it or not, I used after effects. You probably haven't heard of it because it's not an image editor, but a video editor. It's by the same company that makes photoshop so there are a lot of similarities between the two. I didn't use any dedicated astro-packages, but I tried my best to get rid of the light pollution!

I used a Nexstar SLT mount for this one. M42 is low in the sky so light pollution is awful. However I was able to capture some detail in it!

Beautiful results Steve... I wish I could do that!

Oh, lol i probably sound pretty stupid, I didn't know that abbreviation.