"Shim" wrote in message
...
I've been using an LX90 and DSI for imaging, and I've decided to get a
focal
reducer to increase the FOV. I've had a look at the Meade options, and
there
is one specific for CCD imaging, and others that are more general
purpose.
Does anyone have any experience of the CCD specific one, or any comments
on
the other Meade (or other brands) that I should consider?
There is nothing specifically 'CCD' about the 'CCD specific' reducer, it
is just that the area it can cover at the focal plane is small (making it
not useable for film), and the focal length is such, that you cannot
really get an eyepiece close enough to the reducer to work (certainly not
with a diagonal).
Given the relatively small size of the DSI CCD, relative to the focal
length of your scope, the *.33 reducer (this is the one that refers to
being CCD specific), is pretty much ideal. You need to work out how to
mount the camera, to that the CCD itself,is about 59mm, from the centre of
the reducer. This will then give the *.33 factor, and the unit will give
the nicest images, spaced like this, or very slightly closer together
(which will give a little less reduction). Your final focal ratio, should
then be perhaps F/3.4 to F/3.5. Your camera will then cover an area of:

(510*9.6)*206/(200*3.5) arc seconds
= 1440 arc seconds.

This is about 24 arc minutes across the CCD.
There are several other reducers that will also work, but this unit is
likely to be a good workable match for your camera.

Best Wishes