Moon - and the law of diminishing returns

[Omaroo]

After taking a few single-frame shots through the C8 tonight, I found that I was again having trouble focusing the camera properly. Not that focus was bad, but it wasn't absolutely perfect. The seeing isn't brilliant tonight so that is exacerbating the problem.

I though I'd do it a bit smarter and take a collage - so that each frame covers quite a small portion of the moon. The theory is that the features would look larger through the barlow, and I'd be able to attain focus more easily without slipping out either side of it. Problem 1 is that as soon as you stick a barlow on - you get less light, so at ISO200 the frames turned out quite dim - and lost a lot of colour information. Not to worry - I'll boost the ISO setting next time, but I'm happy with mono tonight.

I ended up with fourteen 6MP frames and brought these into CS3 as a PhotoMerge. It did so and I ended up with a file that was just under 230Mb in size and 9,000 x 7,000 pixels in dimension.

The theory was that if I merged correctly I'd be able to apply a highpass sharpen action to tidy it up at this size, and then downsize the file to 1620-odd pixels wide, giving me sharp focus at that size.

Well - not quite. The barlow coupled with average seeing saw to it that I couldn't get great focus anyway.

It's not a bad image at this size, but not great. Roll on winter time in Cooma where the air is STILL and COLD :)

Fun anyway...

Edit:
28th Feb - reprocessed a little...

[RB]

Wow fourteen frames, not bad Chris.
Nicely assembled and nice image scale.
At this sort of scale it's difficult to focus well.

I noticed there's a lot of random 'spots' spread across the frames.
Not sure what caused them.
You may need to give the barlow a bit of a clean or a blast of air.

Yes bring on winter !
:thumbsup:

[Omaroo]

Thanjs Andrew :)

Yeah - The spots arrived courtesy of the image size reduction somehow - they weren't there on the version prior to the reduction. I should have gone through and cleaned them up. Something's always going to happen when you downsize an image that sites at 200+ Mb down to 200k i guess. :(

Maybe, due to the scale, I've discovered US & Russian landing craft??? ;)

[toc]

What camera are you using? I found that using a camera with live view (Canon 40D) pretty much solved my focus issues.

[Omaroo]

Unfortunately, live view has only recently been made available on the latest release cameras, and I've had mine for nearly a year now. At the time I got mine it was a present from my wife, so I was lucky to get a DSLR at all.

I currently run a Nikon D40, but plan to eventually upgrade to a Nikon D300 - or D3 if I flog something else to help. That should solve ALL my issues...including terrestrial where I can make proper use of my 12 Nikkor Ai full-frame lenses again. :)

[toc]

Live view is an absolute god send...This was my second effort soon after getting the 40D...

http://www.pbase.com/timothyo/image/87538422/original.jpg

This is actually a stitch of two separate shots, both at prime focus on the C8.

[Omaroo]

Now try it as I did. Put a 2x barlow in your C8 and take 14 panels. The seeing is what gets you - not the lack of being able to focus the camera.

[toc]

Forgive me - but Im not sure I understand why you doing that though. The end result does not seem anywhere near as good as just doing a few frames.:shrug:

Or are you doing this to capture a really massive image?

Edit: Ok, I re-read your original post :-) - I see what you are trying to do and why. I have also experimented with using a Barlow, and even eyepiece projection with moon shots, but my mount is just not stable enough, and does not track that well. Ive always found I got better results by either upping the ISO (Ive even gotten good results by using ISO 1600) or simply taking LOTS of shots and picking the best image from the lot.

I appreciate the work you have put into the image...

[Omaroo]

Reprocessed a little in the original post (#1). Better focus was achieved, believe it or not, by letting SC3 auto-adjust colour! Weird!