Diffraction grating?Posted By tim winship |
I'd start looking in the Edmund Scientifics web site, and their optics site.
Posts Made By: tim winship
December 12, 2002 06:06 PM
Forum:
Equipment Talk
January 21, 2003 05:46 PM
Forum:
Equipment Talk
Star collimation question.Posted By tim winship |
I'm no collimation expert, but when you collimated with the Cheshire and laser did you have the tube pointing nearly straight up, as you did when using the "star overhead?" I wonder if the mirror (or maybe some other component) is moving a bit as you change tube orientation.
January 27, 2003 12:09 PM
Forum:
Equipment Talk
Meade ETX90 Solar FilterPosted By tim winship |
Oddly enough, while solar viewing (yes, sometimes using my C90) I often have trouble getting my eyepoint just right. For me, this can lead to the kind of problem you describe--only seeing glare from the disc, and not the disc itself. Sometimes it helps me to remove the eyepiece from the diagonal (leave the solar filter in!) and just find the flash of unfocused sunlight on the diagonal's mirror. This lets me know I'm aimed reasonably well. If I now replace the eyepiece (using low-powered ones as you have been using) I'll generally find the sun within the view somewhere.
March 3, 2003 11:53 AM
Forum:
Equipment Talk
sct mirror shift and collimationPosted By tim winship |
I asked the same question last summer. Never did get a real straightforward answer, but the overall gist was "not enough to worry about." True? Well, it's on my test program for this spring.
March 12, 2003 05:05 PM
Forum:
Equipment Talk
MV1 Minus Violet Filter - worth it? Love astromartPosted By tim winship |
I can only vouch for its use with a C102 which does throw up some violet. It takes the fringing out very nicely on planets and, to my eye, noticeably sharpens up detail on Jupiter and especially the Moon! It gives a gold-bronze color cast to these object which some observers find objectionable--I don't. They make another filter which minimizes the color change but, as I understand, is not quite as efficient at violet filtration. I think I paid $65 for it (from Anacortes)--money well spent, in my opinion.
September 22, 2003 02:16 PM
Forum:
Equipment Talk
Stolen Telescopes!!Posted By tim winship |
Gail, it would be wise to keep in touch with whatever pawnshop squads your local police departments have. A few years ago several of my scopes were stolen by "amateur" thieves who had no idea what they were taking, except they looked valuable. Unable to sell the scopes to their regular fences, they had the brilliant idea of going to the local pawnshop, where an alert clerk called the cops--amazingly, I got my scopes back! I really don't know how many "pro" thieves there are out there, but scopes can be hard to get rid of among the drug crowd.
April 15, 2004 11:18 AM
Forum:
Equipment Talk
correct time sitePosted By tim winship |
What about time as indicated on a handheld GPS unit? I recall reading somewhere that GPS satellites transmit a time synch signal every 7(?) minutes or so. such that a GPS left on for around ten minutes would have updated its own clock to the GPS standard. On a few occasions when I have compared GPS time to a clock recently updated by one of the methods described previously the results were pretty good. It bothers me, however, that the time indicated on my two identical GPS receivers (Magellan 330) seemingly always disagrees by a couple of seconds. GPS experts?
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