If your digicam cannot accept a threaded filter you may be able to use a “clamp-on” adapter.
Scopetronix sells such an adapter system, which they call an “EZ-Pix
Digital Camera Holder” Click on the thumbnail on the left, for a larger picture of the Scopetronix adapter. Note that Orion also sells a similar adapter.
This adapter mounts on the scope’s eyepiece and provides a mounting bar to which you can fasten the digicam using its tripod mounting hole. It allows you to position the digicam’s lens directly over the eyepiece. Click on the thumbnail on the right for a larger picture of the Scopetronix adapter holding a Kodak DC280 digicam.
There are a number of issues you need to be aware of with this system:
1. The eyepiece you plan to use cannot be more than about one and 5/16 inches in diameter at its top, or the ScopeTronix adapter’s mounting
clamp won’t fit on it. The 26mm Plossl eyepiece that Celestron provided with the U2K works fine, but eyepieces designed to provide a “wide-angle” field of view are typically too large to accept this adapter’s clamp.
2. The digicam must be reasonably shallow, or look like a point-and-shoot camera. Another way of
saying this is that there can’t be a distance of more than about 4” between the digicam’s tripod mounting hole and the front of its lens when the lens is fully extended. On the photos above, you
can see that this is a limitation of the length of the slotted mounting bar that the digicam attaches to. Most consumer digicams are OK, but those that are long and skinny like some of the Sonys, rather
than wide and flat, may not work.
3. If the distance from the center of the lens on your digicam to the base of the digicam is less than 1
.75” you need to also get the “Spacer” ScopeTronix sells for their adapter. The spacer is being used in the above photos with the Kodak DC280 - it’s the large silver cylinder between the base of the camera
and the slotted mounting bar.
The biggest problem I had with this ScopeTronix adapter is this: optical alignment of the
digicam’s lens with the scope’s eyepiece is critical to avoid vignetting and to achieve focus, and is impossible to achieve (in my experience) with this adapter. The problem here is that the ScopeTronix
adapter lines the eyepiece clamp with rubber, to avoid damage to the eyepiece. Whereas this does protect the eyepiece, the rubber liner has enough play in it to allow the entire camera system to tilt
when the scope is aimed in any direction other than horizontal. This destroys the optical alignment of the system - the CCD chip in the digicam cannot remain parallel with the plane of the eyepiece, which
means you can’t achieve good focus and you can’t eliminate vignetting. (This isn’t a problem if the scope is horizontal, but you may have noticed that the moon or the sun tend to be high in the sky when
you normally observe them.) This is totally exasperating and is avoided by those digicam adapters that mount the digicam directly on the eyepiece. (End of rant <grin>)
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