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To get the star in the centre of M57 is meant to be a heck of an achievement, but you did it first time! Well done! Unguided too, but then I guess your exposures were only 15 seconds - what's the f-ratio of the 8" Starfinder? I had to go to 30s to a minute on my 6" f/9.5 refractor to get the sort of brightness you achieved, but I had nowhere near the focus or tracking you managed.

:Thumbsup:

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It's an F/6. The image needed quite a bit of alignment in meade image processing to get them aligned. While taking the exposures you could see M57 moving in the live image. After taking the L & R frames I had to reposition the scope to take the G & B frames or else it would have run into the tripod leg. I could make out M57 in exposures as low as 2.8 seconds, but it was dim and image was noisy. It helped in centering not having to wait 15 seconds each time I had to move the scope. For focusing I used a hartmann mask on vega before doing a precise goto. I also used the zoom feature in envisage 7 to zoom into the star to see the image in finer detail. I think I may have tweaked the focusing a bit when I was on M57.

I didn't use any dark frames during processing of the LRGB images. Dark frames were used for the first image combined by Envisage. Here is a single L frame....

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Doug

Sometimes I wonder......."Why is this frisbiee getting bigger" ...... Then it hits me!


Orion EON 72mm
Meade 8" starfinder
Meade ETX 90 OTA
CG-5 Advanced GT Mount
DSI Pro III
Orion SSAG
Stellarvue F50
Baader LRGB and Ha filters

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Good job Doug

Here is a link to a tutorial on how to do LRGB in Photoshop

http://www.waid-observatory.com/article-LRGB.html

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Thank you!! For the compliment and the link. I went out and imaged M57 again tonight. This time I got the mount almost, if not, precisely aligned. The ring stayed pretty much centered for the entire time. Which was about 45 min for L and R frames. Then the scope hit the mount and I had to reposition it. This gave me a chance to check the focus with the red filter. I then proceded to take more red frames followed by Green until it went behind a tree. Tomorrow night I will go back out and finish the green and blue images. I have 95 L frames from tonight for a total of 23m 45s. With the mount aligned better I was getting more quality frames then the last time.

Doug

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Doug

Sometimes I wonder......."Why is this frisbiee getting bigger" ...... Then it hits me!


Orion EON 72mm
Meade 8" starfinder
Meade ETX 90 OTA
CG-5 Advanced GT Mount
DSI Pro III
Orion SSAG
Stellarvue F50
Baader LRGB and Ha filters

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Hi Doug,

Very nice first images... Where in Jersey are you?

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Thanks! I'm in West Milford, NJ. A stones throw from the NY/NJ Border.

Doug

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Doug

Sometimes I wonder......."Why is this frisbiee getting bigger" ...... Then it hits me!


Orion EON 72mm
Meade 8" starfinder
Meade ETX 90 OTA
CG-5 Advanced GT Mount
DSI Pro III
Orion SSAG
Stellarvue F50
Baader LRGB and Ha filters

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To get the star in the centre of M57 is meant to be a heck of an achievement, but you did it first time! Well done! Unguided too, but then I guess your exposures were only 15 seconds - what's the f-ratio of the 8" Starfinder? I had to go to 30s to a minute on my 6" f/9.5 refractor to get the sort of brightness you achieved, but I had nowhere near the focus or tracking you managed.

:Thumbsup:

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The focal ratio won't determine the faintness of the star that can be imaged. Aperture alone determines how deep the scope will go for a given exposure when you are talking about point sources. It gets a little more complicated with extended objects, but even then aperture is much more important than focal ratio in terms of imaging faint details.

In any case, I suspect the reason Doug had such good luck with such short exposures getting so much faint detail is a combination of:

• Good focus
• Good tracking
• Fairly large aperture

. If Doug hadn't been able to put these three things together you probably wouldn't have been able to see the 11th magnitude white dwarf with just 15s subexposures.

Congratulations, Doug! Those results are all dramatically better than anything I got in my first few months of imaging.

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- Jared Willson

• Fluorostar FLT-110 w/ TEC optics
• Vixen VC200L
• Astro-Physics Mach1 GTO
• Stellarvue SV80S
• Takahashi Teegul SP Mount
• STL-11000

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