Home made 200mm Astrograph - Second Light

[David Fitz-Henr]

I've had a second round of imaging (and enhanced the colour in M8 as per previous recommendations). I've also pushed the envelope with respect to the sub frames exposure lengths (they're all unguided using my Paramount). You can detect some slight egg-shaped stars when you blow the image up :

- M8 (Lagoon) 6 subs at 6 minutes each. I had intended taking some more tonight, but there was too much cloud of the artificial kind (bush burnoffs all around Sydney creating masses of smoke). I've processed the image with more attention to colour this time. I hope it looks OK here - it looked good on my notebook, but some of the colours look over-saturated on my main PC (I think due to a lower contrast monitor - there's yet another expense I guess, to replace my old monitor!).

- NGC 253 (edgewise spiral) 8 subs at 6 minutes each.

- NGC 6744 (barred spiral) 6 subs at 8 minutes each - stars are definitely egg shaped here. I may be expecting too much here from the mount, although I think it was at a relatively low elevation which would be more subject to variation in tracking.

[multiweb]

Very nice David. Three very tidy shots. :thumbsup: I didn't think you'd be affected at Bowen mountain with all the smoke. I couldn't make it to Crago tonight so I did a bit from home and it was bit smokey here too.

[Hagar]

Nice images David. Looks like the scope will be a keeper for sure. Just a quick note. You seem to have clipped the black point quite heavilly in the M8 image. May be worth having another crack at that one to reveal a lot more of the outer area.

Well done.

[gregbradley]

Pretty round stars for unguided.

Autoguiding is the way to go if you can.

Also it would've been better to stick with one object if possible and
max out the exposure time as noise is still the dominate factor in these
images making it difficult to bring out the object clearly.

It looks like your scope is going to be a winner.

Greg.

[Moon]

David
Thanks for posting this and congratulations on getting to this point with your scope. I'd love to hear more about your scope, observatory and mount. How long have you had the paramount?
James

[leon]

David you have done well indeed nice going.

Leon

[David Fitz-Henr]

Thanks Marc, Doug, Greg, James and Leon for the encouraging words.



Yes, they were doing burnoffs somewhere close to Bowen Mt - thick smoke clouds were covering half the sky in the evening, and posibly helped set off a nasty attack of hayfever. Oh well, will try again next weekend !



Good advice - I have tried reprocessing the image with that in mind - see attached. I think I originally adjusted the black point too far to get a dark background, but of course the whole area is bathed in nebulosity.



Yes, I plan on getting CCD camera / autoguider eventually - just spreading the costs out a bit to keep the "Domestic Expenditure Committee" onside !
Yes, a good idea - I wanted more time but M8 was too low. Next weekend I will concentrate on one object. Also, I had the ISO setting at 200 - I will change to 400 or 800 and see how that goes. I think that the lower ISO setting may have compressed the dynamic range at the low end.



I'm happy to tell all ! I've had the Paramount for 3 years, but it sat in the box for 2 years while I built the observatory and completed the 200mm Newtonian. You can se some images of the observatory in the "Adventures" section on "marc4darkskies" pbase site (http://www.pbase.com/gailmarc/gallery/bellsobservatory) - mine is the roll-off roof observatory. I was worried that it hadn't been properly tested in the warranty period, but it appears the tracking is excellent (with ProTrack). Before my imaging session, I spent 1.5 hours creating a TPoint model (mapping known stars and selecting mathematical terms in the TPoint software) that is used for accurate GOTO pointing as well as tracking adjustments using ProTrack. This only has to be done once unless a change is made to the scope alignment / position. I did one test where I slewed to Antares (with meridian flip) and it landed within an arc minute of the cross hairs in the eyepiece. I framed all the objects in this post by just clicking the object and slewing to it in TheSky6 - no further positioning was done.
I built the scope tube out of fibreglass (sandwich panel construction) - you can see some pics during the construction at this thread - http://www.iceinspace.com.au/forum/showthread.php?t=23188 . I also made the mirror cell out of fibreglass, and bought the main mirror from Bintel (cheapie f6 from China) and I use a Paracorr.

If you want to know more details about anything just ask - maybe send a private email if you want ?

[marc4darkskies]

Going great guns there mate! Colour is much improved over first light. I agree with Greg - as tempting as it might be to blitz the sky, sticking to one subject will pay big dividends.

Cheers, Marcus

PS: Get yourself a PBase subscription :D

[Octane]

David,

I'm envious of your observatory and handy skills!

You've done wonderfully with the reprocess of M8.

May I suggest sticking to ISO-400, rather than ISO-800? You'll find the images will turn out a whole lot cleaner. :thumbsup:

Definitely looking forward to more images from your gear setup!

Regards,
Humayun