Chuck, Thanks for that great report! I noticed Mars (only naked eye object visible) in the twilight at 5:30 this morning as I was putting on my shoes to go haul a load of hay for my horses (wishing I was at the eyepiece instead of getting ready to break my backside). :o) Is there a simple calculation or rule of thumb to determine what the diffraction limit is for a given telescope? Rich --- Chuck Hards <chuckhards@yahoo.com> wrote:
There is still surface detail to be seen despite the storm warnings. I used my 6" f/8 Newtonian, at powers of 280x-320x. Best view was at about 290x. Seeing was poor to fair, of the "slow" variety, with a bit of atmospheric dispersion thrown-in. Result was a clear view only every fifteen or twenty seconds for a moment. Best contrast of surface details was with a #56 light-green filter. "Melt line" clearly seen around the polar cap, which is huge. The area of Ausonia & Eridania appeared about as bright as the polar cap, indicating the possible presence of atmospheric dust. Gibbous phase obvious. As morning twilight advanced, the view went sour and the planet turned into an orange featureless ball by 5:15 am. A well-spent hour despite the indifferent seeing.
Here's an old trick: Any eyepiece-barlow combination can be used to make your own "zoom" eyepiece. Pulling the eyepiece back in the barlow barrel increases magnification slightly. You'll have to touch-up the focus as you vary the seperation, but it's a neat tool when working near the diffraction limit of your telescope. You can tweek the magnification to just exactly the right power. Push it until you reach the point of diminishing returns, then back-off just a tad. You can tweek it as conditions change. I use this technique a lot when observing planets.
I'm going back to bed.
C.
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