I got out to the AAQ dark site near Boonah last night for the first time in over a year. I'd forgotten how much work it was to pack everything in the car and then set up at a new location. I finally got imaging two hours after arriving and managed to capture almost three hours on this target before it was time to head home. I adjusted the colimation this time and think I've got the spacing for the paracorr about right.
Comments welcome...
Last edited by peter_4059; 13-06-2010 at 05:43 PM.
Got to be happy with that one Peter, well worth the trip.
Hard to tell with the jpeg, but are there some lighter artifacts in the left top and bottom corners? I'm not overly familiar with the target, but just something that attracted my eye!
Thanks Darren. These could be artifacts - still trying to work out flats with this camera however it's hard to say as there is so much going on around this object.
I got very ambitious today and took a full size copy of this to the printer. I was surprised at how different it comes out of the printer to how it looks on the screen. Where can I find some tips on getting an image ready for the printer to give it the best chance of looking good?
As Dave Bowman should have said, "My God, its full of round perfectly focused stars from corner to corner".
Well worth the visit to the dark side., Luke
Really excellent shot and worthy of your new camera.
Greg, can you provide any pointers on how to get the flats right? The flats I used for this were 20x1.5 seconds. I used Nebulosity to capture and based on the pixel stats over the entire image the pixel levels range from 6780 to 14432 (mean 10892). I thought the flat should be exposed at about 30% and 60% of the maximum?
Cheers David. I think I've finally got the spacing right and the colimation was having an impact. I've been playing some more in PS - here's my latest repro
This is one very nice image Peter.... A shame about the vignetting/gradient/flats artifact in the corners but everything else in the image is really well done. How did you manage to highlight the reflection nebula and get the beautiful 3D effect. It almost looks like a bubble about to burst.
Even with the corners it is a great image. I would think it is a problem with your flats as I have had similar and found flats captured with an average of 23000 produced the best results for me. They have to be the hardest thing to get correct and all you can do is experiment. I actually sat one night and captured 10 different sets of flats after an imaging run one night and just processed the image 10 times then used the set which came out the best. Took a while but it did give me somewhere to start next time and I found they ended up being my flats setting for all future images with my QHY8 and Pro.
This is the post and comments made at the time: http://www.iceinspace.com.au/forum/s...ad.php?t=56267
Thanks for the comments. To be honest I don't think I could replicate what I've done (lots of tweaking!). Thanks for the tips re flats - they are quick to gather so I'll try some longer exposures next time. It is good to have a target level to shoot for so I appreciate you sharing your experience.
Cheers David. I think I've finally got the spacing right and the colimation was having an impact. I've been playing some more in PS - here's my latest repro
That is sublimely beautiful Peter! Long live the Newtonian !!
You've probably done this but just in case - if you have changed the spacing of the Paracorr since taking the flats you will need to redo them. Also, it depends on your camera, but I believe the recommendation is to take longer exposures for flats to avoid shutter artefacts (of course you would need to filter the light or otherwise).
Yes - these flats were from last night straight after taking the lights so the spacing was the same. I have the dimmer on my light box at minimum so it looks light I need some extra resistance to allow longer exposures for my flats from what people are saying. Off to Jaycar tomorrow.....
Thanks for the link to the thread on Flats. I'm looking for a bit of clarification on the measurements referred to in the thread. Are people referring to the mean or maximum pixel value? Ie you suggest 22k ADU - is this the maximum or mean pixel value in the flat? What software are you using to measure this? Nebulosity has a pixel stats window that gives min, mean and maximum pixel values - will this work?
Did you end up plotting the exposure vs pixel value curve for the QHY8pro? Mine still looks pretty linear up to 26180 maximum pixel value - might have to try some longer exposures.
Peter
Quote:
Originally Posted by Hagar
I would think it is a problem with your flats as I have had similar and found flats captured with an average of 23000 produced the best results for me. They have to be the hardest thing to get correct and all you can do is experiment. I actually sat one night and captured 10 different sets of flats after an imaging run one night and just processed the image 10 times then used the set which came out the best. Took a while but it did give me somewhere to start next time and I found they ended up being my flats setting for all future images with my QHY8 and Pro.
This is the post and comments made at the time: http://www.iceinspace.com.au/forum/s...ad.php?t=56267
