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focal reducer

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HQA's picture
focal reducer

As part of the upgrade for OC61, we will be purchasing a QHY600 camera to replace the FLI PL09000.  This will give us about 2 magnitudes of improvement on the faint end.

The one problem is that the QHY600 yields a field of view of 14x9 arcmin, instead of the existing 14x14 arcmin.  It would be nice to increase the field of view.

The telescope is an old 61cm that was designed for photoelectric photometry, so is f/15.  What might be best is to use a focal reducer to get a larger FOV.  The design considerations:

- cover a 42mm corrected image circle

- flat field, coma free

- some reduction from f/15, maybe 0.5-0.7x?

- at least 55-60mm back focal distance

Does anyone know of a commercial focal reducer that meets these specs?  The corrected image circle is probably the highest priority; otherwise, why go to the big sensor?  I know of several for smaller chips, but not at this size (full 36x24mm film size).


spp's picture
Focal Reducer
focal reducer

Planewave makes several focal reducers for their optical design.  They may not be a perfect match to the classical Cassegrain that I am guessing OC61 is, but at f/15, the performance might be close enough to the flat field of the corrected Dall Kirkhams that it would still be a good fit.  There isn't a lot of detail on the Planewave reducers on their web page, but I'm sure they would be glad to help.


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