My long focal length setup is used principally for galaxies, globular clusters and planetary nebulae. Sometimes I will use it for smaller diffuse nebulae like M20.
I image with the C9.25 reduced 0.63 for a focal length of about 1500mm, and with the Canon 350D this gives an image scale of roughly 0.9arcsec/pixel.
This C9.25 seems to have very good to excellent optics as it produces very sharp images when I do my job right.
I have changed from a dual saddle setup to a straight piggyback setup in an attempt to remove some differential flexure I have been fighting in all my setups, not just the long focal length setup. I have the same field movement with the 130/780 and ED80 as well. It has been proportional to the focal length
May 22, 2008
© Hunter Wilson
