observing from bed

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nigeljoslin
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Joined: Sat Jan 26, 2008 4:03 pm
Location: Galloway, SW Scotland
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Re: observing from bed

Post by nigeljoslin »

Hello Brian, it is quite strong, yes. I bought a Sirius Optics Minus Violet filter for planets and the moon with similar results to your filter. Not that I generally use it for planets and the moon because my 14 inch reflector is far superior.

I find the telescope superb for low magnification sky-sweeping though, don't you? Lovely wide-field Milky Way views, and the advantage that clusters and brighter nebulae can very quickly be found at its lowest 18x. The optics seem very sharp; I've used it for outreach at Galloway Forest dark sites and people have commented on its sharpness. Not a planetary instrument though!
Skywatcher 350P f4.65, Skywatcher StarTravel 102 f5, Adler Optik 9x63 binoculars
brian livesey
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Joined: Mon Jan 09, 2006 11:05 am
Location: Lancashire
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Re: observing from bed

Post by brian livesey »

Yes Nigel, a 4-inch/f.5 refractor makes a good richest field 'scope. Ideal for the Orion Nebula the Perseus double-cluster and M31 in Andromeda, etc. :D
brian
brian livesey
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Joined: Mon Jan 09, 2006 11:05 am
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Re: observing from bed

Post by brian livesey »

Just to say Nigel, that you could go down a couple more notches in magnification on the 4-incher. From the sources I've read, the lowest magnification with a scope is 4D. That's to say four times the diameter of the aperture in inches. This would be 16X for a 4-incher.
brian
nigeljoslin
Posts: 681
Joined: Sat Jan 26, 2008 4:03 pm
Location: Galloway, SW Scotland
Contact:

Re: observing from bed

Post by nigeljoslin »

Thanks Brian. Yes, that is one good thing about a refractor, no central obstruction to show up at high exit pupils. Unlike with an f4.65 reflector, where 25mm is the longest focal length eyepiece I can get away with on bright targets. In fact, an image of the secondary shows up on Mars at this magnification when it is not that far out of focus. I could just about manage to push it with my Skywatcher EF 27mm eyepiece, but the outer third (at least) of the FOV falls apart coma/astigmatism-wise at anything below f5.

The 27mm gives me a nice 18x in the refractor, but I do tend to use my Celestron ExCel LX 25mm now, which gives me 20x but with a 60 degree FOV rather than the 53 degree FOV of the Skywatcher eyepiece...and of course, slightly more contrast, although I suppose that would be negligible at such low magnifications.

However, cloud is reigning just now. But at least not raining!
Skywatcher 350P f4.65, Skywatcher StarTravel 102 f5, Adler Optik 9x63 binoculars
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