Moon through a big lens

Last Friday the sky was very clear so I had a go at shooting the moon. I used a Sigma 300-800mm lens set at 800mm, plus a 2x Extender.

This is the full frame, UNCROPPED:



And here's a close-up of the lower section.



I think I could probably process the close-up a bit better if I have another go at it. I'm struggling to find the right balance between noise reduction and sharpening. Suggestions welcome.

nice work

suggestions?, use a telescope and webcam, much easier ;-)

Not bad at all... you've got some CA around the rim, and it looks a little soft... could be all sorts.. possibly the TC and the lens at full stretch, could be conditions... That shows up in the closeup, but some nice details around Clavius non the less.

There doesn't seem to be any exif... what were the settings ?

jgs001 said:

Not bad at all... you've got some CA around the rim, and it looks a little soft... could be all sorts.. possibly the TC and the lens at full stretch, could be conditions... That shows up in the closeup, but some nice details around Clavius non the less.

Click to expand...

Cheers John.

I did find it quite hard and I'd appreciate tips on technique.

At 1600mm just touching the lens induced a LOT of vibration, and that made manual focussing very difficult. I was using LiveView x5 or x10 to focus, but the lens is so long that I couldn't conveniently reach the focus ring and see the display at the same time. So it was a case of reach forward and tweak the focus... wait for the vibrations to reduce ... check the display ... reach forward and tweak the focus ... wait for the vibrations to reduce ... now the moon has drifted out of the display ... reacquire the moon ... wait for the vibrations to reduce ... and so on. Very tedious. I suspect that I might have been able to get a slightly sharper focus if I'd taken more time over it, but I didn't have much time available so I made do with what I got here.

jgs001 said:

There doesn't seem to be any exif... what were the settings ?

Click to expand...

1600mm (800mm x2), ISO 200, 1/200th at f/16. Wide open would have been f/11 but I hoped that stopping down a bit might improve the sharpness.

Not really much I can suggest Stewart, it's a pain trying to focus on the moon at long focal lengths, unless you've got tracking ... and the wobbles are quite normal too. Might be worth trying without the TC and see how you get on... At least it will show if the issue is in focus or the TC (or at least it'll make it easier to reach the focuser. What I've found with my telescope, the focus point is identical whether I use with or without the TC, so it might be that you can focus without, then add it back in, and not change the focus position...

A telescope and webcam will produce better results, but then you're not using a single frame but shooting a video of 1000 frames and combining the top 30% odd of them into a single image (and making a mosaic of perhaps 30 or 40 of these frames), that makes a big difference when it comes to overcoming the atmospheric disturbances

jgs001 said:

Might be worth trying without the TC and see how you get on... At least it will show if the issue is in focus or the TC (or at least it'll make it easier to reach the focuser. What I've found with my telescope, the focus point is identical whether I use with or without the TC, so it might be that you can focus without, then add it back in, and not change the focus position...

Click to expand...

Hmm, interesting idea. Without the TC I can use AF too, which might help... certainly worth a try!

Great details. Well done.