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Ahgii

M13-First time doing long exposure astrophotography

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Hi all!

Few days ago i tried imaging a deep sky object for the first time, so i tried m13 as an easy first target, I used took 7  lights, out of witch i selected 3 for stacking, and used 5 darks. DSS only selected 1 frame out of the 3 and stacked that. The result wasn't that good but then again....it's the first time i'm doing this. Settings were iso 6400, 15 second exposure, auto WB. I have also been having this problem, when my telescope slews to a target, it's always to the left of the frame and that was a bummer since i had to crop my picture. Please give me your advice and feedback, Clear skies!

 

M13 6-11-2018.jpg

Edited by Ahgii
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Just now, Forunke said:

Did you try the SkyAlign feature?

If you use it on Stars near your target it should increase the accuracy 

I used auto 2 star with vega and arcturus.

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Hmm... I rarely used any handcontroller but maybe try to recenter it yourself.

If your target is rather bright you should be able to set the ISO to max and see your target in live view. Then adjust with the controller.

The Skywatcher handcontroller had a way to manually update the position of objects. I don't quite remember the procedure though.

It was something like, goto an object, recenter it then either press esc once then again and hold it or hold esc, then press it again.

It then would ask if the coordinates should be updated. 

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Oh yeah the sync feature, i should use that too, but i have to take my camera off the telescope and look trough the eyepiece if it's a relatively faint object like M13.

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8 hours ago, Ahgii said:

I used took 7  lights, out of witch i selected 3 for stacking, and used 5 darks. DSS only selected 1 frame out of the 3 and stacked that.

Nice first catch.

If DSS only selected one image, it didn't do any real stacking. What we're seeing is actually the one image that you and DSS considered best.

My advice: put all 7 images in DSS and let it stack all 7. You will se a decrease in noise.

Which telescope/lens did you use for this target? Even at 15 seconds you have some trailing. You could try reducing the exposure time even more and stack LOTS of frames. You'll be amazed at how this will improve the final image.

Good luck, and have fun

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54 minutes ago, wimvb said:

Nice first catch.

If DSS only selected one image, it didn't do any real stacking. What we're seeing is actually the one image that you and DSS considered best.

My advice: put all 7 images in DSS and let it stack all 7. You will se a decrease in noise.

Which telescope/lens did you use for this target? Even at 15 seconds you have some trailing. You could try reducing the exposure time even more and stack LOTS of frames. You'll be amazed at how this will improve the final image.

Good luck, and have fun

I used the nexstar 8SE with the stock alt-az mount. I heard you could get up to 30 seconds without trailing with good alignment. But with a globular cluster you can notice trailing much more than you could with a normal DSO. What other easy targets would you suggest for me in this time of year. I would really like to image a nebula of some sort.

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(Emission) nebulae require two things: 1. a camera that can register Ha signal; either a modded dslr or a dedicated astro camera. And 2. a tracking eq mount or at least a barn door tracker, if you use a dslr with a wide angle lens.

Nebulae are much dimmer than stars, and most dslrs have a low response in their wavelength range. So you need to expose your subs as long as possible. With short exposures you won't reveal any more than the brightest parts of some. Clusters are possible, as are bright planetary nebulae, such as M27 and M57. There are quite a few globular and open clusters in good view at this time of year. Locate them on a star chart or a stellarium program. If you want to test your equipment on an emission nebula, the heart neb in cassiopeia and the Cygnus wall in the North America nebula in Cygnus are among the brightest. Capture them with a fast camera lens attached to your tracking mount. But don't expect too much. There is a non eq thread in the (beginners) imaging section that has a lot of useful information.

Good luck.

Ps

If you don't have it already: pick up a copy of the book "making every photon count" by Steve Richards (@steppenwolf on this forum). It's available from our sponsor.

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I used to use a DSLR with the 8se.

If you are getting trailing at 15s, cut down to 10s. Even allowing for download time, you should get at least 4/min.

So set it to take 120 subs which will only take about half an hour. Then put them all into DSS and let it select and stack the best 75%. This will give you an image with 60x the integrated time of the one above and the difference will amaze you.

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On 13/06/2018 at 09:10, wimvb said:

(Emission) nebulae require two things: 1. a camera that can register Ha signal; either a modded dslr or a dedicated astro camera. And 2. a tracking eq mount or at least a barn door tracker, if you use a dslr with a wide angle lens.

Nebulae are much dimmer than stars, and most dslrs have a low response in their wavelength range. So you need to expose your subs as long as possible. With short exposures you won't reveal any more than the brightest parts of some. Clusters are possible, as are bright planetary nebulae, such as M27 and M57. There are quite a few globular and open clusters in good view at this time of year. Locate them on a star chart or a stellarium program. If you want to test your equipment on an emission nebula, the heart neb in cassiopeia and the Cygnus wall in the North America nebula in Cygnus are among the brightest. Capture them with a fast camera lens attached to your tracking mount. But don't expect too much. There is a non eq thread in the (beginners) imaging section that has a lot of useful information.

Good luck.

Ps

If you don't have it already: pick up a copy of the book "making every photon count" by Steve Richards (@steppenwolf on this forum). It's available from our sponsor.

Well normal unmodified cameras still pick up Ha Wavelenghth, but not as much as a modded camera, I use my camera for normal photography as well, won't a Hydrogen-Alpha Filter have the same effect as a modded camera?

Edited by Ahgii

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1 hour ago, Ahgii said:

won't a Hydrogen-Alpha Filter have the same effect as a modded camera?

No, since the built in filter partially blocks Ha. With Ha filter you have one which decreases Ha (built in) and one which isolates it. If you remove the built in filter, you'll be better off. You use a(n) Ha filter not to get more Ha, but to get less everything else. Filters don't amplify signal, they can only block (unwanted) signal.

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