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Re: iSight Astronomy
by Simon at 09:33 01/03/06 (Blogs::Simon)
Yep, a single one extracted from 11,000+ frames from a 40MB .mov.

The eyepieces of the 'scope happen to be about the same diameter as an iSight body so I've bodged a sleeve to hold them close together (out of an empty spice container and a pair of jubilee clips).

This is called 'eyepiece projection'. If the iSight's lens was removable, then I could dispense with the 'scope eyepiece and do prime focus photography instead.

The bodge works OK with the 25mm eyepiece, because it has a long shank that the sleeve slips over quite nicely and the exit pupil is about 15mm diameter so it's easy to line up with the iSight's field of view.

However, the magnification of the 25mm is only x48 so the image itself is very small and only covers a dozen or so pixels on the CCD. OK for the moon, but pants for planetary work.

It was exceptionally good seeing last night, so I tried my 12.5mm and 6mm eyepieces for fun - even though they're shorter and the sleeve bodge is less precise and more wobbly. Their exit pupils are smaller by comparison - less than 10mm - so it's more difficult to get the eyepiece and the iSight axes co-linear.

The image was taken through the 6mm (x200) by starting a recording and then wiggling the bodge around until Saturn showed up on screen, at which point I tried to hold the whole thing as steady as possible to capture a few frames (most of the 40MB file is blank, or has a very blurry Saturn whizzing across from one side to the other).

Oh, and the equatorial drive on the scope is very sloppy and therefore useless - so I'm also pulling on the end of the tube to counter the Earth's rotation.

And it was bitterly cold. And I was being attacked by a herd of mad yaks.

I'm going to track down a Philips ToUCam 840K (sadly no longer made) because they're definitely more suited to this kind of work - very sensitive CCDs, their lens is removable and there are T-adaptors that screw in to allow you to do prime focus.

I did some image stacking of exposures of the Moon a while ago, which were OK but I really need to sort my equipment out if I'm going to have a proper stab at this.

--
simon

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iSight Astronomy There is an attachment here Simon - 28/02
    Re: iSight Astronomy Bruce Ure - 28/02
    Re: iSight Astronomy Gordon Hundley - 28/02
       Re: iSight Astronomy Simon - 1/03
          Re: iSight Astronomy Gordon Hundley - 2/03
             Re: iSight Astronomy Simon - 2/03
                Re: iSight Astronomy Simon - 2/03
                Re: iSight Astronomy Gordon Hundley - 2/03