Afocal Gassendi

[themos]

I hooked up the Canon compact on to the eyepiece (25mm Plossl) at the end of the 300P Skyliner Dob and zoomed up close. This was the best of 250-odd snaps. Camera set at f/8, 1/200 sec, ISO100, infinity focus.

[MikeD]

Nice detail.

mike.

[themos]

This was the next frame, showing what you typically get when the atmosphere is not co-operating. It's quite incredible really.

[MikeD]

This is where webcams and AVI's come into their own.

Mike.

[themos]

I have to say that it's a lot easier using the compact and the afocal method rather than prime focus and webcam. I need to convince myself again that the webcam produces better results for lunar features.

[MikeD]

The clincher for me is the fact that you can take 2000 shots with a webcam in just over three Min's and then weed out these few seconds of good seeing and stack just the good stuff.

Mike.

[themos]

Mike, I think your motorised mount takes away a lot of the pain of webcam imaging, as well. I am stuck with my Dob for now.

[MikeD]

Yes motors are a big help, but the lack of motors makes your afocal shot even more impressive.

Mike.

[themos]

Just putting these two side by side for pedagogical reasons...

[Sam]

It's quite amazing the difference - just shows what our atmosphere does.

[The Warthog]

Can I ask a couple of naive questions? Your 25mm ep would give you what? about 60x? So, how much of the frame are you showing here? My afocal shots tend to include the entire moon, so how do you concentrate on something as small as a single crater, even a big one?

[themos]

From memory, the 25mm gives me something between 1/2 and whole Moon in the eyepiece. I use the 4x zoom lens of the compact camera to magnify detail. I then cropped 352x352 pixels from the 6 megapixel image.

[The Warthog]

Ah! Thankyou. I don't have an optical zoom on my camera.

[lunator]

Themos

Nice afocal pic. Gassendi is a great target for afocal pics.

Cheers

Ian