Posts Made By: Darren Drake

I recently was surprised to see a Meade 60mm F/5.8 short tube with 2 1.25 inch eyepieces, a barlow (plastic) and a 45 degree prism with a small tripod and carrying case. The tube has the standard 1/4 - 20 threads for tripods. All of this for only $50. I couldn't resist and have found that the optics aren't that bad but are not coated. A star test shows just a little spherical aberration and slight astigmatism but overall not bad especially for the $50. Color is also not that bad. This can make a good finder or auxilary scope as it is quite lightweight. Saturn showed the slightest hint of the Casini division using a good diagonal and planetary eyepiece. Overall I think this is an interesting find.

I have a friend who is fairlry new to the hobby who has a 12 inch Meade GPS and plans on keeping it stored outside under a waterprof tarp. Is this ok or can the elements do any damage over time?

Can the high end apo spotting scopes such as the Ziess 77mm Televid and others really compete with the astronomical scopes such as the Televues? The price tags are high but they can never exceed about 80X with the eyepieces they come with. I guesss what I'd really like to know is could the optics be pushed to high mags and produce images that would compete with high end apos such as TV or AP?

Ok I've been reading the previous thread on this topic. I have been doing fairly extensive indoor star testing (it's to cold and snowy for the real thing) and have found the following with my 80 ED. There is virtually no false color visible. Only when I use low power with a very bright artificial star do I begin to see the slightest and most insignificant bluish halo. This is for all intensive porposes a true apo.
Sherical correction does show some undercorrection. It's a little more than I'd like to see but still not all that bad. It's maybe 1/5 wave or so if I had to estimate. Comparisons with an ST90 and a minus violet filter reveal when put through the same test about 1/8 wave spherical undercorrection but a very slight about 1/6 wave miscollimation (after recollimating from much worse originally)error. The amount of light taken out of the airy disk with the 80 ED is slightly more than with the 90 if it were perfectly collimated and maybe about the same with the very slight miscollimation. This is an estimate only. The best way to really tell how much the spherical aberration effects the image is to compare airy disk patterns under the night sky with my 18 inch stopped down to the same 80mm using the same magnification. That may be a while after the snow we just got blasted with.
Another issue with this scope is that the balance point is to far forward. To alleviate this I simply removed the focuser and removed the upper screw from the adapter block and lossened the lower one and rotated the block 180 degrees. I then tightened the one remaining screw and found that it was tight enouph and didn't need to drill another hole. Probelm solved.

Can it be changed by slightly altering the spacer thicknesses between the two elements? If I have an undercorrected refractor would increasing the ulta thin spacer thicknesses correct or potentially worsen the correction? What about thinning the thickness?
Thanks

I saw a commercial about someting called Liquid lense. It supposedly removes scratches from glasses lenses. Is this for real? Has anyone looked into this? I'm quite sceptical.

Well the weather has been so lousy here lately that all I have to look at with my Orion 80ED is an artificial star. The problem is that it is only about 20 feet away. I know that this introduces spherical aberration but I'm uncertain weather it is undercorrection or overcorrection that is introduced. Does anyone out there actually know how much SA is introduced with an 80mm f/7.5 scope at that distance? Thanks

What is this Liquid Lense stuff all about? It claims it can effortlessly remove scratches from glasses.
Here's a link
http://www.liquidlense.shoppingcartsplus.com/page/page/843825.htm

I came along this article but can't find anything else yet. It should be interesting to try to see this visually.
http://news.bbc.co.uk/1/hi/sci/tech/3479615.stm

I came along this article but can't find anything else yet. It should be interesting to try to see this visually.
http://news.bbc.co.uk/1/hi/sci/tech/3479615.stm