Posts Made By: Rod Mollise

Andrew Box said:

Hey, what's a decent dual axis mount that could be autoguided that isn't too expensive or could be found used? GM-8 is just too expensive, although I know they're very good quality. Just wanting to get some ideas.

What's reasonable? Here are three choices ranging from about 1500 to about 800:

Orion/Synta Atlas EQG

Orion/Synta HEQ5 Sirius

Celestron CG5

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Charles Geiger said:

Both of these mounts look beautiful and must be of the highest quality. Since they both carry about the same load, why would one pay about $2,000 to $2,500 more for a comparably equipped Paramount? And do these companies ever put these mounts on sale?

IMHO you simply cannot go wrong with either. As a matter of fact, these are the two mounts on my list for whenever me and Miss D. finally get out of the Historic District and I can finally build that observatory. Since I'll be leaving the mount in the observatory all the time and controlling it from inside the house--that's the plan for now, anyway--I'm leaning slightly to the Paramount.

If I wanted a mount that was transportable, it would be the 1200. Its more "normal" paradigm of...punch objects into the HC or send the scope on go-tos from a PC attached to the HC is more attractive to me in a poratable setup than the more "computer-centric" Paramount. OTOH, plenty of folks cart their Paramounts around. Ahh...the pain of choosing!

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Philip Blanda said:

Does anyone have a handy table or specific info on the actual focal lengths of SCT (specifically a C9.25) in different configurations? I'm specifically interested in the focal length of a C9.25 when a toucam is attached straight through. Since this setup makes little sense except in a specific cicumstance, a CCD camera attached with no filters is a good stand-in. This is to help someone out.

Thanks,

Philip

The article cited is excellent, but if you want a simple answer...very close to f/10. The scopes generally work at their quoted f/ls with the camera attached directly "via a standard t adaptor." Your setup is close to that.

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Bill Madewell said:

I my walkabout research, I have need info for one thing or another. My problem is, and I hope someone can answer , I am looking for a powerstorage system too run a laptop, red lights, ccd cameras , dew zappers and so on..
Bill

Hi:

These (jump start) batteries are fine for running a go-to scope OR dew heaters. They are insufficient for CCD cams, PCs, etc.

What do I suggest? For the laptop, start out with a DC to DC converter. IOW, a powersuppy for your laptop that allows you to run it off 12vdc. You could use a power inverter, but that is inefficient and will make your battery poop-out in a hurry.

Now, as for the battery to power all that stuff, forget a Celestron/Orion/Jumpstarter...not nearly enough amp hours. Instead of 17ah, to run all that equipment you'll want more like 50 or 75 or more.

What I use is what we down here call a "trolling motor battery" (aka deep cycle marine battery). These are inexpensive (about 50 bucks for 50ah). You'll need a decent charger too, but these are also cheap.

As for charging, here's what I do for the jumpstarters: I charge a battery that has been used for 12 hours. If it has not been used over the course of a month, I charge it for 12 hours anyway. I've done this with the battery I use for my Nexstar 11, and it's still working after nearly five years.

Marine batteries? I charge 'em with a computerized charger I got at WalMart...charges till they are charged. I do charge the marine batteries once a month too.

Greg Nowell said:


My question is: We always want to COOL a primary mirror or refractor objective to get optimal performance. But we prefer under many conditions a WARM eyepiece. Is there any reason to think that a warm eyepiece delivers a compromised image vs. a cold one? My guess is, that with the lens groups sealed and the short distances involved, it wouldn't matter, but I've never seen it discussed.

I suppose at another level it's academic. Even if there is a compromised performance, it's better to have a warm eyepiece that isn't frosted or covered with dew than one that is unusable.

regards
Greg N

There are no optical issues involved with warming an eyepiece. "Cooling" one would have one result--fogging and dew. As for primary mirrors, we don't want to cool them either...they'll dew up too. We want them close to ambient temperature...that's the ticket.

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Rex Cox said:

Can anyone recommend a good focuser to replace the one that comes with the Orion XT8? I don't want something extravagant, like a Feathertouch. Heck, that would cost as much or more than the scope did new. I want something that doesn't cost a great deal, but performs better than the stock focuser--soemthing that doesn't have so much slop, has better eyepiece fit, and better control movement.

I bought this scope from a co-worker this week, and I'll probably give it to my nephew.

A decent and inexpensive option is the RCF focuser from JMI. You can even buy it as a kit. There's one on my daughter, Elizabeth's, Parks 6-inch f/8 and it has always worked quite well considering the reasonable price.

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Ty Chamberlain said:

I am picking up a used LX200 this weekend. Anything in particular Ined to be looking for?

Also, what should I plan on budgeting for down the road? Anyone?

Well, the main thing you should be aware of is that these scopes are gettin' up there in years. One may, believe it or not, be as old as 15, now.

The main things I'd look for other than general condition?

Get one of the models that works on 18vdc (identifiable by the power supply/coverter).

Try to get one that was made in the last year or so of the run. No earlier than about 2001. Most of these had ball bearings rather than nylon bearings on the dec axis.

Don't pay too much. Again, these are OLD telescopes with complicated electronics onboard. If one is working well, chances are it will continue to work well, but any type of electronic gear does have a finite lifespan, and it may not be pleasant or inexpensive to get one repaired at this time.

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If I understand what you are doing, yes, that sounds workable. I'm not really sure why you are going to this much trouble, however...

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Chuck Kreiter said:

I've been using telescopes since 1983 starting with my Edmund Scientific 3" reflector scope. I'm currently using a 8" Orion Dob. I'm finally ready to plunk down some serious cash to pick up a scope that can find itself, track and find objects, etc. Star hopping is fun, but I'm all for automation.

I've looked at various posts and brands and really like the Meade Schmidt-Cassegrain and Ritchey-Chrétien scopes. I like the 12" mirrors as they seem still portable, but powerful.

Looking at the specs, I think the LX200R is the scope for me, but would appreciate any feedback the experts here might have on why the LX90 or RCX400 might be a better choice for me.

TIA

First off, the RCXes are not available right now. Meade promises they will be back after some engineering changes. You might talk to Herb and see if he has one or can get you one...but I doubt it. Also, forget the 12 RCX unless you can mount it permanently IMHO. This is a BIG scope. I've used the 10, and that one is, I guar-ron-tee, the size of a "normal" 12-inch SCT.

You might also ask yourself why you need a fork mount 12-inch. "Even" an R or an LX90 is a big thing to haul around and set up if you don't put it in an observatory. I would NEVER consider a larger-than-ten fork unless I could either mount it permanently or condiditions were such that I could wheel it out on wheelie bars. If you want a bigger than 10, my adivce is "OTA + GEM."

I assume you are a visual observer...if you are an imager, remember, that 12 brings a lot of focal length to the table, and that may be good OR NOT SO GOOD depending on the kind of work you do (I still stick to my C8 for deep sky imaging. Period.).

As to which fork mount? Get the R. The fork on the LX90 is too small for that beast IMHO.

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Greg Nowell said:

I read a rather disconcernting essay today on Yahoo! Refractors, by a noted authority on eyepieces, that rather explicitly wishes owners of SCTs to be, well, dead. I find this to be perhaps the most regrettable turn in the ongoing dialogues over equipment types. I thought it fitting to put the quote on to an overlay of an outstanding image taken by an SCT. This is strictly clip and paste stuff.

regards
Greg N

As I've said elsewhere, this dude MAY (or may not) be an expert on eyepieces. He don't know SQUAT about SCTs.

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