Keyhole from Cape Town

[skwinty]

Hi All
A shot of the carina nebula from the other night.
Full moon and lots of light pollution.
15 by 5 sec subs with 12" and 40DH.
Thanks for looking and any comments

[[1ponders]]

Pretty good for a 75 sec shot Steve. Fairly noisey though. Any reason why you are only using 5 sec subs? Longer subs will help marvelously with the noise. Did you add or average the combination of the subs? Any dark frames?

[skwinty]

Hi Paul
I kept the exposure times to 5 sec as
1. Not accurately polar aligned.
2. Not guided
3. Lots of light pollution and full moon.
4. No noise reduction, flats or darks.

Guess I am trying to set a baseline reference and then applying the correct procedures so that I can appreciate the difference.
Also, because I am new to this, I suppose I am also impatient and want to see immediate results.:thumbsup:

[Zuts]

Hi Steve,

That is a good result for 5 sec subs. I am only a beginner myself but i will offer a few comments.



(0) Focus doesnt look too bad, that is hard to acheive.
(1) You need to be polar aligned. You really do. Your EQ6 if it is polar aligned and PEC trained should be able to go at least 30 sec to 1 minute. On a bright object like Eta you would be wrapped by your results if say you did 15 by 45 sec subs. It is a real pain polar aligning but after a few months it will become second nature.
(2) Even if you had the worst EQ6 made, with good polar alignment and PEC you shouldnt need guiding upto 30 seconds. I know you have a heavy scope and your mount is maxed out but guiding would allow you to go far longer. Get a 70mm Saxon achro short tube and a meade LPI. This will be hard to use but it would come in at under 750 grams and may give you great results.
(3) I image in central Sydney 3 km from the center of a city of 5 million people. I could go at least 2 minutes with my DSLR without filters, so 5 seconds is far to low. Pick objects closer to the zenith. Also if you cant guide and want to practice pick objects closer to the SCP.
(4) The canon probably doesnt need darks upto around 20 to 30 seconds. After that even the best DSLR will have thousands of hot pixels after a few minutes on a hot night, so darks are a must over around 20 seconds.

Anyway, you must be wrapped getting a recognizeable image of the keyhole so congratulations and keep at it :)

Paul

[skwinty]

Hi Paul
Thanks for the encouragement.
Will be imaging again this coming weekend and will try longer exposures.
Wish my reticule eyepiece was here already. Its still in Oz. Damn.
Ps. for the other Paul.
I think I summed the 15 images. Cant remember as I tried sum, average and median. Will have to consult my notes. Only other processing was linear brightness scaling.:)