First Attempt - Need help!

[FlyDoc]

My first foray into astrophotography after reading the "No EQ" challenge! Total noob here so apology if I do sound like one!

Equipment - Celestron Astromaster 130, Star Discovery mount, Canon EOS 6D, Celestron 2x Barlow

All photos are single shot long exposure. 

Just need couple of advices: 

1) Stars at the periphery shaped like halos. What's name of this optical defect and is this something I can do to fix?

2) I don't seem to be able to get the outline shape of Horsehead Nebulae + nebulosity of Pleiades / Rosette for some reasons.  despite 30s exposure on ISO 25600(!). Do I need a filter or I need to stack multiple exposures. 

3) Is my tube needing collumination?

Thanks guys!

FlyDoc

 

The obligatory Orion Neb

Carina

Alnitak and Flame Neb (very subtle) but can't see Horsehead(??)

Pleiades

Rosette

Who else but the brightest star in the sky!

[wxsatuser]

Considering your setup a good first attempt.

The optical effect is Coma, I think the scope was slightly out of focus as well.
It can be cured with a coma corrector but I don't know if you can get one for your scope.
Some one else may know.

When stretched there is bad vignetting, the scope finds it hard to illuminate a full frame sensor.
Taking flats may cure some of this.

[newbie alert]

I'd say the halos are as suggested above, coma..as the stars in center are in focus but the fainter  ones on the edge have halos..

Sorry to say but to pull out nebulosity from Pleiades and feint ha signal from the rosette you will need longer exposures..

But great images for 30 sec subs

[PeterCPC]

As above. A modified camera would show more nebulosity.

Peter

[FlyDoc]

Thanks guys!

I did find focusing rather difficult as adjustments are very small. Do you guys use say the brightest star for the initial focusing adjustment? 

I guess my concern was that if a 30 sec sub at ISO 25600 did not show the nebulosity, would stacking of say 120 lights of 15 sec + ISO 6400 show it? 

And for Rosette, would a HA filter help?

Another interesting observation: the diffraction spikes  - which I like - only shows up when exposure time is longer. I thought they would've showed regardless of the amount of exposure - only fainter if it's short.

[catburglar]

You should also look to stack more images, and perhaps try knocking the iso setting back a bit to reduce the noise. I’ve attached one of my first captures. It’s with a camera lens rather than a scope, but it’s a stack of approx 60 x 30s subs, iso1600 at f5.6. There’s all sorts of problems with the image- focus, star trailing and some lens aberrations, but the horse head is (faintly) captured and I’m sure would do better with more captures. My focal length was shorter than yours, but photographically similar to your setup a f5 so I think you should keep going.

[RayD]

Yes I echo all the above.  

Coma corrector to sort out the aberrations (you will need to check if the right one is available for your 'scope as not all things are equal here).

30 seconds isn't a particularly long exposure in AP when imaging DSO's.  It should be fine for galaxies etc. but for nebulosity you may need a bit more.  For example, many of my images are 30 minutes, so that gives you an idea of how far you may need to go to get very faint stuff.  You won't do that successfully with your kit as you would need a better mount, guiding and a cooled camera but, as noted above, push the times up a bit if your tracking will allow, drop the ISO, and shoot lots and lots of subs.  Don't forget to look in to calibration frames (darks and flats) which will also help.

It is worth looking at getting this book by @steppenwolf which is a superb guide to help you on your way in AP as it can be very frustrating and expensive.

[Demonperformer]

Great start with single 30s subs. Can I suggest good things for early practice are open clusters. There are some nice ones aroundat this time of year (M41, M44) and when starting out, I found them easier to get reasonable results.

[happy-kat]

That's a nice camera makes me ask what lenses do you have?

Only camera lenses can work well for imaging and many DSO are huge and the barlow is adding demands onto your setup. I know why you are using a barlow but I think it is worth looking at what camera lenses you may have.

[SteveNickolls]

Hi FlyDoc and thanks for posting.

You have managed to capture some of the objects you were after and they are nicely centred. As others have mentioned you can see the coma from your optical set up and that your camera wasn't quite in focus. A Bhatinov Mask can be used to help focus, a very easy and quick process. Some DSO's are brighter than others, you will need to image for longer and stack multiple images to improve the signal to noise in the exposures. If you have appreciable light pollution it doesn't help the cause. Don't worry about Ha filters right now, learn use your gear and take each step at a time. Your ISO at 25,600 is way too high for what you were attempting, bring it down to perhaps 1600 or 800, each camera model has it's best setting. When taking multiple exposures save them as RAW files. There's a lot to comprehend but one step at a time :-)

I have a old Skywatcher Synscan alt-Az mount and within the constraints of the mount construction and field rotation managed 60 second exposures with virtually all being to keep. If you are going to get one book then, "Astro-photography on the Go-Using Short Exposures with Light Mounts" by Joseph Ashley is the one, it's available from our sponsor -https://www.firstlightoptics.com/books/astrophotography-on-the-go-book.html Joe BTW is a great, helpful guy and his book will set you up for Alt-Az work and using lightweight EQ mounts, I'd go so far as saying it's become THE Bible for Alt-Az work as it introduces and explains the important concepts involved by someone who has delved deeply into the hobby and who has tips to help you improve your mount's stability.

You will need to obtain software to stack and process your images, there is the free Deep Sky Stacker software and many processing softwares, some of which are free to trial. You will find one that suits you. I use StarTools which I have found a good processing tool and you find out that you never stop learning and improving technique. One blessing of astro-photography is that you can reprocess data as you become more confident and experienced in using the software. 

Keep up the good work and do keep on posting!

Cheers,
Steve

[catburglar]

45 minutes ago, happy-kat said:

That's a nice camera makes me ask what lenses do you have?

Only camera lenses can work well for imaging and many DSO are huge and the barlow is adding demands onto your setup. I know why you are using a barlow but I think it is worth looking at what camera lenses you may have.

+1 for camera a lenses. The image I posted above was a crop from the wider field view made with a canon 70-300mm lens @200mm at f/5.6 below.

If you do have some medium fl lenses and can find a way to mount the camera either piggy backed on your scope (or preferably direct to the mount without the scope to reduce the weight a bit) you should be able to get good results.

[FlyDoc]

Thanks everyone for the advice and encouragement. 

Guess I was a little bit too optimistic with what a $150 scope can do. 

Yes I do have a 70- 200mm F2.8 with 2x extender but I thought I will give the scope a try anyway. 

I will try stacking tonight and see how it goes!

FlyDoc 

[billyharris72]

Hi FlyDoc.

As others have already said, these are good for a first attempt. My recommendations (and they are only recommendations) would be:

1) For focussing, if your camera has live view, I find the best approach is to use it and zoom in a few steps. Then tweak the focus of a bright star to get it as small as possible. One approach, which might work (and might not, give it a try), is to decentre the star about 1/3 before you focus - aiming to sacrifice focus in the centre of the image very slightly in exchange for a wider usable field.

2) Drop the Barlow lens, and if you use a camera lens (good idea) don't touch the teleextender. For the kind of imaging you are trying with a non-EQ mount you need the optics to be fast. A 2x Barlow or extender means you need 4x the exposure time to get the same amount of photons per pixel. Better going for wider field with smaller image scale. 70mm at f2.8 could be good.

3) Drop your ISO down to about 1600. There is no need really to go higher as you can stretch the images in post processing.

4) Take multiple subs and stack them. This will allow you get brighter and deeper images with the short 30s subs you are using. Try stacking about 20 - 50 subs in Deep Sky Stacker or similar.

5) Definitely explore using dark and flat frames - they will make a significant difference.

And keep at it. Be good to see how you get on.

Billy.

[happy-kat]

To help with points made by Billy above

1 - or focus on a star where a third insects.

3 - let you histogram drive your iso selection, review your test shot and aim for the histogram peak to be clear of the left edge, most likely will be either 800 or 1600 iso.

[catburglar]

If that’s the Canon L series lens you should get some great images - and at f2.8 30seconds should be plenty long enough for each sub. As said above, get lots of subs and keep histogram away from the left edge so your signal is well above the noise level and not too far to the right otherwise you’ll lose details in the brighter bits. For the Orion Nebula you might want to try some 10second subs and some 20-30second subs. Stack each set separately in DSS and then combine as layers in Gimp or photoshop etc. So you can maintain detail in the trapezium region.

If you really want to use your scope, then you just need to come to terms with some of it’s limitations- don’t use the Barlow, keep the sub length relatively short and the sub count high.

Since you’ve got a full frame DSLR, it’s difficult to get sharp stars to the edges of such a big detector and I don’t think you’l get a coma corrector that will cover your chip because your limited by the 1.25inch focuser.

The cheapest way get sharp stars across the whole field I guess would be to get something like the Skywatcher 130pds and the coma corrector to go with it (there’s a separate thread on here showing what that scope can deliver). But I don’t think that makes sense if your planning on sticking to an AltAz imaging setup.

You’re off to a good start- just keep going.

[dph1nm]

On 06/02/2018 at 08:10, FlyDoc said:

I guess my concern was that if a 30 sec sub at ISO 25600 did not show the nebulosity, would stacking of say 120 lights of 15 sec + ISO 6400 show it? 

ISO has no effect on the amount of light your camera detects, so really high ISO like this has no advantage. So the question you should ask is whether 120x15sec will show more than 1x30s, to which the answer is most certainly yes!

NIgelM

[bobro]

The Astromaster 130 can be turned into a good imaging scope - but only for those who are happy with diy:

> First problem is it won't come to focus with a DSLR attached (using a Barlow isn't a good idea to achieve focus as it increases exposure by 4x and makes guiding more difficult). A diy solution is to cut about 35mm from the mirror end of the tube, allowing a DSLR to come to focus. It's only a thin metal tube so this is easy and cheap!

> Second problem is coma - an off the shelf 1.25" coma corrector isn't generally available, though making one isn't hard.

My main imaging scope is a Meade 130 (basically same as Astromaster 130) modified as above. If you don't want to shorten the tube as a minimum (think of imaging without a Barlow as a 'free' 4x increase in exposure time) then better to stick to imaging with a standard lens, or purchase a scope better suited to AP such as the 130PDS mentioned above.

The mount of course is another matter.....

Hope this helps with a way forward.

[Stub Mandrel]

30 seconds is plenty to get the Horsey with an ordinary camera.

I would suggest using a lower ISO, say 1600, and stretching more.

While you have coma, the complete circle stars are too extreme for this alone and it suggests either poor focus or the camera is tilted slightly, probably both.

You're on the right track!

 

 

[TareqPhoto]

If you have enough big budget then i will advice you to buy one of those astro cameras such as ZWO or QHY [not necessary an expensive one] and order SGPro license and call it a night, it will make the job much much easier really, i was giving up, but those cameras really opened doors for me, and then you can buy some cheap filters of Ha even at 1.25" to go with it and you will see a LOT [sorry, i mean you will imaging].

[FlyDoc]

2 hours ago, Stub Mandrel said:

the complete circle stars are too extreme for this alone and it suggests either poor focus or the camera is tilted slightly, probably both.

 

 

Thansk SM!

What do you mean by complete cir stars are too "extreme" ? And what is a "tilted camera"? 

[FlyDoc]

4 hours ago, bobro said:

The Astromaster 130 can be turned into a good imaging scope - but only for those who are happy with diy:

> First problem is it won't come to focus with a DSLR attached (using a Barlow isn't a good idea to achieve focus as it increases exposure by 4x and makes guiding more difficult). A diy solution is to cut about 35mm from the mirror end of the tube, allowing a DSLR to come to focus. It's only a thin metal tube so this is easy and cheap!

> Second problem is coma - an off the shelf 1.25" coma corrector isn't generally available, though making one isn't hard.

My main imaging scope is a Meade 130 (basically same as Astromaster 130) modified as above. If you don't want to shorten the tube as a minimum (think of imaging without a Barlow as a 'free' 4x increase in exposure time) then better to stick to imaging with a standard lens, or purchase a scope better suited to AP such as the 130PDS mentioned above.

The mount of course is another matter.....

Hope this helps with a way forward.

Stupid question : once I cut it, can I still do visual work with it?

I have a Canon 70-200mm f/2.8L and this Astromaster (650mm) Would you recommend getting something like this to complement the gear (my limitation is obviously the mount load limit of 5kg(!)

https://www.bintel.com.au/product/bintel-gso-rc6-f9-astrograph-metal-tube/

Thanks 

[Demonperformer]

Not a stupid question at all.

My understanding (I don't own one) is that it just moves the point of focus further out of the OTA. So, if your focusser does not extend that far, it will be a matter of buying an extension tube to enable it to do so.

[happy-kat]

You have a decent camera lens, take the telescope off and use your camera lens for your imaging adventure. Telescopes are bigger but that doesn't always mean better and aperture is needed for visual observing but that's not the case for imaging so much.

[Stub Mandrel]

8 hours ago, FlyDoc said:

Thansk SM!

What do you mean by complete cir stars are too "extreme" ? And what is a "tilted camera"? 

In the first image some stars are tilted circles rather than fuzzy dots. With  newtonian scope this is what they look like when out of focus.

If one side of the image is out of focus and the other isn't, then the camera may not be fixed so its pointed straight down the middle of the focuser.

[bobro]

8 hours ago, FlyDoc said:

Stupid question : once I cut it, can I still do visual work with it?

As @Demonperformer said, a simple eyepiece extender will allow visual by moving the eyepiece outwards. A Barlow with the lens removed can also be used.

8 hours ago, FlyDoc said:

I have a Canon 70-200mm f/2.8L and this Astromaster (650mm) Would you recommend getting something like this to complement the gear (my limitation is obviously the mount load limit of 5kg(!)

https://www.bintel.com.au/product/bintel-gso-rc6-f9-astrograph-metal-tube/

GSO make good scopes, but that one is slow (f#9 makes for long exposures) and has a long focal length (1370mm will show up any tracking errors). It is too heavy for your mount.

When starting with AP it is better to have a fast scope/lens (better light capture) and a shorter focal length (more forgiving with mount tracking).

It's easy to jump in and make the wrong decision when purchasing, that's why @happy-kat suggested using your camera on the mount with a lens. You will learn a lot with this setup and be in a better position to decide what to do next. Getting a good book such as 'Making Every Photon Count' will help with the basics.