I have sold the DCA(Zoom). When I used it, I used two adaptal rings* to lengthen it. I usually used a Nikon P5100 along with the DCA.
With the measure taken, I was able to get vignet free images for the zoom range from 28mm to the telephotographic end of this superb camera.
The way I controlled the length of the depth of the two adaptal rings was to incorporate the thread that held the glass of a lens filter in position into screw furrows of one of the adaptal rings. If I want to shorten the depth of the two adaptal rings, I screw in; if otherwise, then I screw out.
The ring-like thread will be held in position when you screw in to have the adaptal ring pressing against the thread. The shortcoming of such a makeshift measure is that there is only a short distance for the thread to move in and out, so the depth you can play around with is pretty limited.
But, in digiscoping, a few millimeters of manuvering distance is often good enough to have the vignetting problem resolved significantly.
I have seen Master Chan's product. It is a very good device to resolve the problems arising from the short height of the DCA(Zoom). Thanks Chak Wing for sharing what he has designed with us here.
Regards,
Peter
Postscripts
* Here, the adaptal ring refers to the one that either steps up or steps down a filter to make it screwable onto a lens. An example is the one that converts a 62mm filter to be a 52mm.
[ Last edited by lwingkay at 14/07/2011 16:20 ]
