Quote:
Originally Posted by Shiraz
the assumptions make it a bit ropey to backcast like that Lee, particularly in extricating seeing from the effects of guiding RMS. The actual seeing is likely to be in between what the spreadsheet gives with your measured RMS and with zero RMS, but there is no way of being any more precise, so it is what it is and that is still useful information.
you are fortunate to have seeing that good, but it is not unheard of in Australia - just not available in all locations http://articles.adsabs.harvard.edu//...00101.000.html
pretty good here tonight as well - between gusts it is well under 2 arcsec  .
yeah, you need a bigger scope ..... and a bigger mount and ....... |
Thanks Ray
I should probably correct myself in that I routinely get 1.8" (sometimes better, but rarely) for part of the night, definitely not all night. As the target drops in the sky and I shoot through more atmosphere the FWHM goes up.
If I was to get a bigger scope I'd be looking at an 8" RC or Edge, both of which are smaller and lighter than the Esprit. But getting one would only be sensible if the resolution gain I'd get from the greater aperture wasn't offset by less great optics.
Quote:
Originally Posted by Slawomir
Speaking of bigger mounts, I'm not sure if it is always plausible to assume that bigger aperture, even from the same manufacturer, will necessarily yield tighter stars given the same level of guiding is maintained with a heavier telescope. It is curious that for example Orion Optics states that for their fast Newtonians 12inch will yield the smallest spot size on and off axis, while their smallest 8" as well as their largest 16" Newtonians both have the largest spot sizes. Or is spot size unrelated to the FWHM we can expect in our images?
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I don't know much of anything about spot size, or optics in general. Doesn't seem to be published for the Esprit either. I think I've seen Colin posting recently about the ideal spot size for a given camera, but I'm not sure of the details. Colin, can you (or someone else) elaborate on this?