13 replies to this topic

[HoustonSky]

Hope I have the correct forum.

 

I attached my Nikon D300 to my Celestron 6SE to capture the Orion nebula as my first foray into astrophotography.  I used ISO 1600, shutter speed 30 seconds, captured 30 RAW images.  I knew it would be just a test for learning stacking and processing software.

 

After I loaded the lights, darks, flats, dark flats into SkyStacker, my light frames list between 0 and 9 stars, regardless of where I set the slider in SkyStacker.  It will only stack one of my light frames.  Is this the result of my ISO/shutter combination, or another obvious rookie error?  I can see stars in the image, although not exactly focused.

 

thanks for any suggestions.

[D_talley]

Post one of your photos here and we can take a look to see what DSS is complaining about. 

[HoustonSky]

I am using the Celestron corrector, so that helps field of view a bit.

 

I realize my focus needs work, and if the GoTo was not precise, I might just have Orion in the frame, but I still should see stars, right?

 

I had to crop severely and save as jpg to meet the max file size parameters.

 

Edited by HoustonSky, 24 March 2025 - 12:44 PM.

[StarBurger]

Probably DSS does not like those star shapes. It is very fussy. Looks like there is some tracking/guiding error causing the stretched stars. That's where I would look first. Perhaps reduce exp. to 10 secs to see if the star trails reduce and maybe DSS will find more stars..

It could also be that the  Celestron corrector is not at the correct spacing causing coma. Depends where the image is in the field. Was the nebula centered?

Is it guiding or just tracking you are using?

[HoustonSky]

Thanks for the help.  Clearly, focus needs to be improved.  I will work on that, as well as reducing exposure time.  
 

One oddity.  When I first did this on SkyStacker, my laptop was standalone.  I reconnected it to power and my larger monitor and just for grins, made a new try.  Although I needed to set the slider on the upper right at about 5%, suddenly it was finding thousands of stars upon registering and stacking.  Odd.  
 

I don’t think the nebula is even properly set in the image.  Is that it on the lower right?

 

oh well, I am gaining on this process and tonight looks like a beautiful, clear night with low humidity.  I will take better care with focus and centering, try a new exposure time and try again.  This experience helped me learn the basics of SkyStacker.

 

hopefully, next will be processing.  I currently have Star Tools, since it seems simpler and cheaper until I really understand the concept.

[cnbilbo]

10/10 Just for making the effort. Stick with it.
Your pic has trailing stars probably due to the long exposure. The nine stars detected are most likely hot pixels as they would remain stationary.
SCT's are not the ideal scope to start out with, Long focal lemgths demand a lot. Beg steal or borrow a small refractor, anything will do, Even a simple lens.
forget about stacking & darks/flats etc just try to get a recognisable focused image. 10/15 sec exposures at different ISO's to compare
You'll get a lot more help if you let us know which mount you are using. Post a pic of your setup.

I use my kit for observing just a couple of minutes in total, or even seconds.

One of my first shots with a cheap 72mm refactor was M42 for just 8 secs, Focused by eye

[steveincolo]

The 6SE is on an alt-az mount.  Alt-az mounts will show star trailing in longer exposures, as yours did at 30 seconds.  The maximum amount of exposure time depends on what part of the sky the scope is pointed to (and also what is acceptable error).  The gory details are all here, but as a rule of thumb I stick between 10-20 seconds on an alt-az mount. 

Edited by steveincolo, 24 March 2025 - 06:12 PM.

[HoustonSky]

Forgot to mention, I also use the Celestron wedge.  I think my biggest issue now, within the constraints of my equipment, is trying to focus and centering the object being imaged with the camera attached to the scope.  I am using BackyardNikon, which I like, but I haven’t figured put how to view the image to focus and center.  I have Liveview selected, but the image won’t display to allow focus.  I have the Bahtinov mask to help with focus, if I could just see the image.
 

I am running a new set tonight, at 20 sec exposure, which looks better, but I need to learn how to view the object on the camera to focus and make sure it is even in the frame.

 

As we all know, this is a fascinating hobby with TONS of stuff to learn to do it right.  Every week I gain another step in the process.  By the time I am 80 (76 now), I may get it right.  lol….

 

One of my life’s goals has been to succeed at Astronomy.  I’ll post an image when I get there.

[HoustonSky]

Great shot, Ranger!

[steveincolo]

Forgot to mention, I also use the Celestron wedge.  I think my biggest issue now, within the constraints of my equipment, is trying to focus and centering the object being imaged with the camera attached to the scope.  I am using BackyardNikon, which I like, but I haven’t figured put how to view the image to focus and center.  I have Liveview selected, but the image won’t display to allow focus.  I have the Bahtinov mask to help with focus, if I could just see the image.
 

I am running a new set tonight, at 20 sec exposure, which looks better, but I need to learn how to view the object on the camera to focus and make sure it is even in the frame.

 

As we all know, this is a fascinating hobby with TONS of stuff to learn to do it right.  Every week I gain another step in the process.  By the time I am 80 (76 now), I may get it right.  lol….

 

One of my life’s goals has been to succeed at Astronomy.  I’ll post an image when I get there.

How are you doing your polar alignment, then?  That’s a possible source of issues.

[HoustonSky]

Ranger:  I will try your ideas, using various ISO/exposure to see what I get.  I was thinking that it would take extensive processing to see a nebula, but it may be easier than I think.  

[HoustonSky]

I use CPWI and Starsense to align. Then do an ASPA in CPWI and adjust latitude and E/W with the wedge control knobs to center an object, usually Sirius for brightness.

At that point, I GoTo my object of interest. Should I be doing a second alignment after polar alignment is set?

[scanner97]

@OP...

 

From looking at some other posts, it sounds like ASPA should give you a good-enough PA.  I'm guessing, even with the wedge, the trailing is down to the mount.  You may just not be able to get 30 seconds unguided on that mount.  (M42 is near DEC=0 as well, so that doesn't help.)  Also not sure what kind of guiding you can get with it.  Someone with specific experience will need to comment.

 

Anyway, as suggested by others, try shorter subs until you get some w/o trailing.  M42 is very bright so it's totally doable.

 

The D300 is an old camera with lots of challenges for AP, but it's what you've got and it's enough to get started.  You won't need a lot of processing to see the nebula, but you'll have a chance to experiment a bit with processing to see how stuff works.  A good content creator for AP, especially with DSLRs, is Nico at Nebula Photos.  This is a playlist of "Start to Finish" videos, including a couple on M42 with DSLR.

 

And unlike daylight photography, don't think about adjusting ISO at this point.  800 or 1600 will work fine, regardles of your sub length.    You can pick one and stick with it.

 

Great start - keep going, and good luck!

Edited by scanner97, 25 March 2025 - 06:09 PM.

[HoustonSky]

Yeah, the D300 is like 2007…. Ancient.  Still a marvelous camera with all sorts of controls.  I did better with 20 sec exposures at 1600 ISO, so I will continue to experiment.  
 

i need to work more on actual centering of my target in the frame and taking single shots to focus.  There is a ton to learn.  Even the camera has a 100+ page manual to digest, let alone the basics and DSS.  
 

I appreciate all the suggestions here.  I realize that, as a newbie, these issues are simplistic to experienced users, but it is humbling to continue to get good help from you folks.