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Field derotators
Thought I would just review the field rotator made by Meade.
First off this is for use on an alt az SCT. And it can be very expensive if you do not take into consideration that you should also buy an off axis guider at the same time. The OAG is needed because guiding through a guide scope in this mode will produce rather bad trailing. So Meade I believe should provide the OAG with the field derotator. Though this might be their marketing strategy "just buy the scope, then you will need this and this and this". Anyway I digress.
Now as for the performance, I have found that the criticism of the field derotator to be completely baseless. I have undertaken several large duration exposures and found that the derotator works perfectly to produce nice round stars. Meade's produced a nice piece of hardware. Its movement is not apparent at all and makes no noise whatsoever. It will also let you know when it considers that you are too high in the sky, although I found that it beeps when there is still plenty of room between the camera and the mount. Which brings me to a major disadvantage of the derotator. It cannot be used to photograph the zenith. You will come into contact with the mount and cause damage to your camera.
However that being said, its major advantage is that there is no messing with doing a polar aligment, which can take up valuable shooting time.
So the up shot is that for what it is intended, it is the perfect tool to compliment your astrophotography in the quick alt az mode. Cheaper than a wedge and good if you want to set up out bush and get into it quick
Paul
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