Jan

You hit the Nail dead on with each point:


Some further clarification; an achromatic objective in the 5" aperture
range and up, even with EXQUISITE optics, is going to show color at f/12,
and the further you go below f/12, no matter if the optics are essentially
PERFECT, there will be progressively more and more color, the shorter the
focal ratio...

If one's expectation is for high performance lunar/planetary images at
short focal ratios, that's an unrealistic expectation for an achromat.
With those expectations, one must be prepared to move into the apochromat
class...

Or be happy with what a quality achromat CAN deliver... Which is plenty,
given one's expectations are realistic. And what they DO deliver is why
D&G remains in business...

Refractor Acro's can and will for a long time to come be enjoyable
Scopes when one knows and acknowledges their limits. Darn shame some wish to
make something into something it isn't as it generally results in
disappointment..........

Crazy Ed