Posts Made By: Greg Nowell

Since some of our best minds hang out here I thought I would solicit diagnostic opinions on this optical oddity which has been reported on two Bosma Maks.

MOUNTS are divided into alt-az and equatorial, but all of them use piers and tripods.

With finders and diagonals getting their own categories, I've often wondered about piers and tripods....

Greg N

MOUNTS are divided into alt-az and equatorial, but all of them use piers and tripods.

With finders and diagonals getting their own categories, I've often wondered about piers and tripods....

Greg N

Ads don't seem to be moving as quickly as in days of yore.

I have no problem paying for $15 a year but I worry that the fee has chased away newcomers to other sites.
They don't ever get to see what they're missing.

I have a modest proposal: Once a year, say in May, have a one month free trial. If free trial members don't pay up they don't stay on. It might lure some people in to see what they are missing. Or maybe just a 30 day free trial membership. Many businesses do it.

Greg N

I set up my GT 130 the other night and noticed that stars were flared in an odd shape that I've never seen, elongated roughly like the bug nebula with the flaring on one axis on both sides of the stars.

My first impulse was to panic but remembering other situations where panic was not productive I decided to ignore the problem. First off, I was seeing it in a low power eyepiece, and my own astigmatism is an issue. Second, I had just set up, and I thought well, thermal issues do their own thing, and then they go away. Third, after years with doublets, this is my first triplet apo, and my first oil-spaced optic. So I can't be sure how cranky it can get, although I have had the 130 out many times and never seen this before.

It *has* been exceptionally warm here in upstate NY. I can't rule out that the scope was warmer than ambient, though it was shirt-sleeve weather.

Anyhow I just concentrated on building the model for my computer and then started looking at stuff, and forgot to worry about anything. I figured if the effect persisted I would send it back to AP.

At some point the problem went away. I had a gorgeous view of 30 & 31 Cygni with STFA 50, which makes for a blue/gold double every bit as good as Albireo, and a white star thrown in to the mix. There was no flaring by the time I got to it.

At some point I noticed that there was some play in the AP Maxbright diagonal, apparently when I last cleaned it I had not tightened up the back screws all the way so the back plate was a little loose. In optical terms a 32nd of an inch of play is humongo so I was wondering whether my issue might have been the diagonal and the angle at which I was viewing when I noticed the problem. I noticed the diagonal issue about two hours into a six hour night, got out the allen wrenches and fixed it.

So I'm trying to figure out which was the most *likely* source of the flaring effect, the triplet and its cooling, or varying angles on an improperly secured diagonal. It seems kind of stupid not to have all four screws snugged but I think the issue is that I have the habit of cross tightening screws (putting them in loosely at first and then snugging when all are in) and I may have gotten distracted after they were all in and not finished the job. In the beginning of the evening I go all sky (and lower to the horizon) for building a pointing model whereas in observing I tend to stay higher for optimum transparency and seeing. So I might have noticed a loose diagonal back plate effect when model building (maximum likelihood of diagonal mirror shift) and then not seen it as I started observing higher (the diagonal settling straight back), and then the problem vanished because I tightened the screws. (I'm not keen on trying to duplicate the flaring effect by loosening the Maxbright back plate again and testing the hypothesis)

OR, very hot tube....

Greg N

Here's what makes me sad.

The discussion fora pretty much died after the annual charge was initiated (I am *not* opposed to paying, and kicked in $ before the annual charge).

But we lost something there. Almost everyone moved on to CN. As CN got bigger and more diversified, it sucked a lot of the participation out of the Yahoo groups too. I'm not sure that's a bad thing. There were getting to be too many Yahoo groups.

I wish there would be some brainstorming about how to bring people in, if only into the forums. It's difficult to get newcomers to understand that it's in their best interests to participate in a market that's got an excellent regulatory system going. I like the forums here because they are more rough and tumble, no automatic bleeping of profanity or political views. But mostly it seems people come here for the business of buying and selling, not so much chat any more.


Greg N

Whatever you do, DON'T get a Pentax 10.5 XL. These are extremely expensive eyepieces. They are typically found on the 'mart for $190 to $210. Mine, however, cost $3,000 (well, mid to high 2's, I guess I bought some used).

See you think you just want a nice 10mm, and then you begin to get the Pentax feel, and then you think, well maybe I'll swap out my 8mm whatever for a 7mm XL, and then you think, well maybe I should try and XW, and then you think, well jeeze the 10XW is pretty good, maybe the XW30 is good too, and then....you look in your box and it's all Pentax, and you're out $3k.

So DON'T buy Pentax!

regards
Greg N

Yeah and if you get even a touch of paint from somewhere on your acetone paper it will smear the paint on to the lens. Acetone is for supremely difficult situations only.

I have tried many alternatives and currently am happiest with Purosol.

regards
Greg N

Look I have acetone, I use acetone sometimes. But it attacks not just plastic but also paint. It also has the unusual characteristic of being so hydrophilic that it will suck air out of the atmosphere as you are using it, so if you are in a humid area (like where I live) don't be surprised to see water streaks after using acetone.

My preferred cleaning solution these days is Purosol. It is actually easier to use (no water streaks) and requires less carefulness around furniture etc. It's also not flammable. Acetone in my usage is reserved for special cases.

regards
Greg N

You can use a Losmandy counterweight but that's a different recipe. --Greg N