Ray,
The RCC1 was designed by Dave Rowe (not Jim Rowe)
He did indeed design the optical configuration for a number of CDK's including
those made by Planewave, Hubble optics, The Alt-Az initiative
and also one or two custom jobs, all them ex-gratis to my understanding.
As for the RCC1, it does not introduce spherical aberration to the wavefront
when used in conjunction with a paraboloid. It has something in the order of
100mm back focal length so it has significant advantages with respect to the
equipment you can fit in the imaging train.
As for the bad write up on IIS... all I can say is that the RCC1 design is
quite a bit better than the MPCC1, so if results were obtained that didn't
reflect this, then the problem is most likely the result of incorrect mechanical
assembly either due to spacing of the focal plane, or customs have
inspected it by pulling it apart and putting it back together ass-about.
Also... it is not necessary to preserve diffraction limited performance for
an imaging telescope unless you are talking about long focal ratios designed to
operate at the diffraction limit, such as the HST F/D=24.
It is only at that level of over-sampling at the focal plane that you will
notice 1/2 wave of SA or the effects of a 50% central obstruction.
There is a reason why planetary imagers use powermates.
At F5 or so, you can get away with a level of aberration that you simply wouldn't tolerate for a visual instrument.
best
~c
Quote:
Originally Posted by Shiraz
RCC1 is the Rowe coma corrector – it got a bad writeup on IIS and does not seem to be sold here in Aus. However, it is designed by Jim Rowe who I think also designed the CDK series of scopes, so it is probably pretty good – no spec available though, so will need to test to make sure it does not introduce SA (like the MPCC, which probably adds about 0.7wave SA). SA would completely negate my underlying assumptions and my coma corrector will need to maintain diffraction limited performance over much of the relatively small field
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