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Re: First light for a new AP 130 f6; TV 102

Started by RolandC, 04/14/2004 09:21AM
Posted 04/14/2004 09:21AM Opening Post
>>The AP had more false color on Mars, worst near the edge of the field where a violet streak was seen (but not on stars, anywhere). >>

Lateral color (off-axis color) is always caused by the eyepiece. It is not caused by the objective lens. Eyepieces will always show more aberrations off-axis the faster the scope. At F6, the aberrations are 2 times worse than at F8, and 4 times worse than at F10. You will see lateral color even in a Newtonian.

Roland Christen
Posted 04/14/2004 03:11PM #1
>You will see lateral color even in a Newtonian.

Indeed Roland! Last night, I was out watching Jupiter with my 8-inch Discovery PDHQ Dob and while trying to locate it with my 30mm Ultima plossl (40x) and with Jupiter positioned off-axis, I saw the purple halo! I couldn't believe my eyes until I took a look at the OTA again just to make sure it was a Dob I was looking thru ;-).

Having said this, after going to the 6mm TV Radian last night (200x), I noticed no off-axis color on Jupiter. I wonder why not.

Thanks,
Ron B[ee]