While I was out trying things and sorting out guiding, I noticed that in an exposure of any lenght or stack, my stars seem to have an almost egg shaped appearance. Guiding in Envisage seems ok and most X & Y references for guiding are generally around 0.3 to 0.7. In a preview image, the stars appear quite round and I check my collimation regularly with at least a Howie Glatter Laser Colimator. Is this related to the mount or drive system , or am I not seeing an out of focus situation.

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LXD55 SN10
LX90 8"
Orion 80 ST
Celestron 102
DSI & DSI PRO2
Atik Electric Filter Wheel
EQ6 Pro & EQMOD
Canon 40D
Lots of other Astro bits

It'll be easier to "guess" at what's wrong if you post a sample image with exposure/stacking details and the equipment used, (imaging cam/scope, guiding cam/scope, mount etc).

The original series DSIs tend to bloom in a vertical egg shaped pattern but that should only happen on the brightest star/stars in the image. If all the stars have the same shape it's probable there's a guiding issue or one or two bad frames got stacked in with the good ones.

If collimation is good poor focus should not cause egg shaped stars. The most likely culprit is the side to side drift caused by the mount's periodic error. XY numbers of .3 to .7 sound good but it depends on the relative focal lengths of the imaging and guiding scopes.

A lot of guys seem to get it to work but I was never able to get round stars with Envisage guiding. PHD/GPUSB is working much better for me.

...........Mike

http://autostarsuite.net/photos/mike7mak/

LX200gps 7" Mak
Takahashi FS78
DSIpro, DSIpro2
41deg 50' N
73deg 44' W

Here's an example of both the vertical blooming and side to side periodic error. :)

http://autostarsuite.net/photos/mike7mak/picture10535.aspx

...........Mike

http://autostarsuite.net/photos/mike7mak/

LX200gps 7" Mak
Takahashi FS78
DSIpro, DSIpro2
41deg 50' N
73deg 44' W

Howdy. Here is an example of what I was talking about. I guess the shaped stars are also blurring some of the detail of the object I was trying to image as well. Sorry, I didnt get the colour right, its my first image.(I couldnt work out how to get my image in here, so I hope the link works)

http://autostarsuite.net/photos/thedecepticon/images/16281/original.aspx

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LXD55 SN10
LX90 8"
Orion 80 ST
Celestron 102
DSI & DSI PRO2
Atik Electric Filter Wheel
EQ6 Pro & EQMOD
Canon 40D
Lots of other Astro bits

Ok well, my guess is you may have a couple of bad frames in the stack. But image analysis isn't my strong suit. Did you preview all the individual frames before stacking them? That's where I'd start.

Here's another try at posting the link...

http://autostarsuite.net/photos/thedecepticon/images/16281/original.aspx

...a cut and paste of the url got me to the pic but for some reason it didn't show as a link in your post. Hopefully someone else will have a more enlightened opinion of exactly what's going on with those egg shaped stars.

...........Mike

http://autostarsuite.net/photos/mike7mak/

LX200gps 7" Mak
Takahashi FS78
DSIpro, DSIpro2
41deg 50' N
73deg 44' W

No, I didnt check each frame, I let Envisage handle it all. I still havent emptied my folder so I can go back and check them out.
Thanks Heaps, Mike!

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LXD55 SN10
LX90 8"
Orion 80 ST
Celestron 102
DSI & DSI PRO2
Atik Electric Filter Wheel
EQ6 Pro & EQMOD
Canon 40D
Lots of other Astro bits

I have had a look through the folder of images, and it seems to be that the luminance images all have funny shaped stars, so I guess that would be "bad frames". The RGB images all have stars that are much better shaped & when I stacked them up in Photoshop(apart from colour & no dark frame), the image looks a lot better. What does this indicate a bout my scope? Does it need a higher level of collimation or something?

http://autostarsuite.net/photos/thedecepticon/picture16327.aspx

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LXD55 SN10
LX90 8"
Orion 80 ST
Celestron 102
DSI & DSI PRO2
Atik Electric Filter Wheel
EQ6 Pro & EQMOD
Canon 40D
Lots of other Astro bits

Well that is quite a bit better. If all the lum frames were bad my first though is that perhaps you changed to the lum filter without refocusing. What is your filter arrangement? If lum is shot through only one (IR) filter and the colors are shot through two (r,g,or b + IR) then there's probably a big difference in focus. That's just a wild guess. I think your gonna need to shoot some more images and pay close attention to what's going on as the images come in.

...........Mike

http://autostarsuite.net/photos/mike7mak/

LX200gps 7" Mak
Takahashi FS78
DSIpro, DSIpro2
41deg 50' N
73deg 44' W

Mmmmmm......I shoot luminance first, then refocus for the colour filters. The lum filter is on the DSI Pro 2 snout, with RGB in the slide. I'll get out at the next opportunity & see what I can find out, starting from scratch.

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LXD55 SN10
LX90 8"
Orion 80 ST
Celestron 102
DSI & DSI PRO2
Atik Electric Filter Wheel
EQ6 Pro & EQMOD
Canon 40D
Lots of other Astro bits

Would it be possible that as Im using a reflector I need to use a "parracor" filter? I hardly know what it does or where it goes, but I gather its to correct optical defects in the train somehow. If  Im using a filter(or two, as it were) and this helps correct the image, does this also point to the need for optical correction? Visually, when collimated, Im hard pressed to fault pretty much anything I see in the eyepeice! Anyone else have any ideas as this would be a great scope for close up work, being 10 in and f4.
Thanks!

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LXD55 SN10
LX90 8"
Orion 80 ST
Celestron 102
DSI & DSI PRO2
Atik Electric Filter Wheel
EQ6 Pro & EQMOD
Canon 40D
Lots of other Astro bits

You may have already answered but are you saving all un-combined? Based on your first image I expect not all of your Lum images are off. In "Save all uncombined" you can sort thru them and discard the bad ones.

JimT

I think that judging by what I was able to do with my image of Centaurus A, it really is bad frames and poor seeing. Also, just looking at all the uncombined subs, it may also be aberration in my tube, which is not cooled with a fan. I just cant quite bring myself to pull the mirror cell out and cut holes in the tube, it really is a great scope, but I guess the job is looming closer as Ive heard and read great results about artificial cooling for reflectors and I spose I stand on the cusp of neccessity!!
Thanks for everyones help, this is a really great site.

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LXD55 SN10
LX90 8"
Orion 80 ST
Celestron 102
DSI & DSI PRO2
Atik Electric Filter Wheel
EQ6 Pro & EQMOD
Canon 40D
Lots of other Astro bits

Howdy! I have noticed alot of my images turning out with these funny shaped stars. Ive tried to use a refractor, however, it seems as though they are still mis-shapen, just a lot smaller and harder to detect. It has been suggested that this is caused by too greater of a correction in declination. Could this be the case? I always seem to have round stars on live view when focussing and setting up, it seems to happen more when taking a longer exposure? Also, strangely, & I could be mistaken, it seems to be worse on one side of my image than the other? Any other ideas anyone, I really need to nail this!?
Thanks!

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LXD55 SN10
LX90 8"
Orion 80 ST
Celestron 102
DSI & DSI PRO2
Atik Electric Filter Wheel
EQ6 Pro & EQMOD
Canon 40D
Lots of other Astro bits

If you could post an example, we would be happy to take a look. Be sure to give us the specifics of telescope, mount, and optical train (including any reducers & their spacing).

Chuck

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Chuck Reese
CDIP Certified: Nebula, Galaxy, Solar System, Stars & Clusters Imager
CDIP Mentor: Nebulae & Solar System Categories
For information on the Certified DSI Imager Program, see:
http://autostarsuite.net/forums/1427/ShowForum.aspx

Hi Chuck.
 Setup is an LXD55 SN10 scope and mount. Guide scope is an Orion 80ST. Images shot at prime focus with a DSI Pro 2 mated to an Atik EFW with all 4 Meade filters in the filter wheel & an Astonomik IR in the shutter/adapter plate. Problem occurs also with the original Meade filter bar and cage. No field flatteners or correctors of any sort used.
Basic scope setup
http://autostarsuite.net/photos/thedecepticon/picture16234.aspx
SN10 images
http://autostarsuite.net/photos/thedecepticon/picture16281.aspx
http://autostarsuite.net/photos/thedecepticon/picture16859.aspx
http://autostarsuite.net/photos/thedecepticon/picture16999.aspx
Test Image using LXD55 mount and a cheap Celestron 102mm scope
http://autostarsuite.net/photos/thedecepticon/picture17000.aspx
I still think that the problem is starting to show up in the refractor image, just not as bad due to smaller image scale.The reason I dont image through the Celestron is it has VERY bad blue rings around bright stars.
I know some of the problems with the 10in are going to be atmospheric abberetion, but any suggestions welcomed.
Thanks.
PS: dont know why the links wont work, sorry!?!

---

LXD55 SN10
LX90 8"
Orion 80 ST
Celestron 102
DSI & DSI PRO2
Atik Electric Filter Wheel
EQ6 Pro & EQMOD
Canon 40D
Lots of other Astro bits