Quote:
Originally Posted by sally1jack
i know Peter has tested f3.3 mirrors at you place with good outcomes
phil
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Hi Phil
Its not about ladder free viewing. The dome slit at Sydney observatory would probably be chest height at the base so a Dob would be vignetted by the slit at lower altitudes. A 20" F3.3 would have you seated or knealing at 45 degree elevation- not suitable to standing crowds.
I assumed by Ultra fast you meant F2.8 to F3 . I haven't tested any F3.3 mirrors. We tested a 22" F3.6 that had been made by another vendor and refigured.
Contact me PM if you need any more info.