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Posts Made By: Alan French

January 6, 2006 10:00 PM Forum: Equipment Talk

DEW question

Posted By Alan French
Please tell us a bit more about your Newt. What is the tube made of? Is it lined with anything? How far does the tube extend past the secondary? Is it the secondary that dews up, or does the primary also dew over.

Thanks.

Clear skies, Alan

January 7, 2006 02:42 AM Forum: Equipment Talk

DEW question

Posted By Alan French
It is hard to come up with a universal solution to the dew problem. Some places have very few nights where dew is an issue. In other places, dew is almost always a concern (or, for some of us, frost can be an issue for part of the year).

At the Winter Star Party it is almost always windy and dew is not a problem, but one year it was pretty nasty. Texas Star Party tends to be windy and dry, but I've seen nasty dew there too. The Conjunction is held in a valley not far from the Connecticut River, and dew is almost always a concern.

The best approach, IMHO, is to be prepared for severe dew.

Clear skies, Alan

January 7, 2006 04:15 AM Forum: Equipment Talk

Trading an AP155 for an AP160..why?

Posted By Alan French
Scott Schneeweis said:

I periodically notice individuals who are "trading up" their 155's EDF/EDFS for the new 160...is there that much of an appreciable performance gain (only a 5 mm increase in aperature!) that motivates people to move to the 160?


Some folks just like to have the "latest and greatest." I don't think it is any more complicated than that. Some folks just have to have a new car every year or two, whether they need it or not.

Clear skies, Alan

January 8, 2006 12:09 AM Forum: Star Parties

Any star parties in Ohio?

Posted By Alan French
Mark Rice said:

Looks like I'll be living in the Columbus area for the next few years. Are there any Buckeye star parties?

Hidden Hollow, although the web page still has a link for 2005....

http://www.wro.org/index.html

January 21, 2006 03:05 PM Forum: Refractors

Herron Optical telescope/objective help needed

Posted By Alan French
Gary,

I don't think you will gain a great deal by having the second lens coated, and getting a lens coated always entails some risk. You have a rather unique lens, and if something happened to the one lens in shipping or in coating you'd just have an interesting conversation piece.

I suggest trying the lens under the night sky as it is. If it performs well, and ghosting is indeed not a problem, I'd table the idea of sending out one element for coating.

Clear skies, Alan

January 28, 2006 09:54 PM Forum: Equipment Talk

Apodizing Screen Revisited

Posted By Alan French

With what telescope?

Thanks.

Clear skies, Alan

January 29, 2006 03:37 PM Forum: Reflectors

Dew at WSP

Posted By Alan French
On many nights at WSP, it is too darn windy for dew, but there have been some dewy nights. One year - I think it was three WSPs ago - we had a couple of nights of nasty dew, and 12 volt hair driers and anti-dew devices were very "hot" items at the vendor's tents. I'd be prepared.

Clear skies, Alan

January 31, 2006 12:09 AM Forum: Equipment Talk

Celestron XLT Coatings

Posted By Alan French
Joe Morey said:

Hi,

Does anyone on this forum think that the Celestron XLT coatings wash out planetary images? :S I have a friend who owned a Nexstar 11" XLT who claims that this is the case, and I think it would be very interesting to hear your experiences between the Celestron XLT, Starbrite coatings, and the Meade UHTC coatings if possible. Thanks much for your time.

Clear skies (someday),

Joe

Joe,

Nonsense. Coatings simply increase light tranmission. They are not going to give you a "washed" out image. It sounds like poor contrast, perhaps due to a large central obstruction and optics that are barely or not quite diffraction limited.

The companies need something to brag about, so they emphasize what are really minor differences between their coatings and the other guy. My guess is that they are all pretty similar.

Clear skies, Alan

February 1, 2006 12:46 AM Forum: Refractors

How can you reduce the focal lengthof a refractor?

Posted By Alan French
george moissant said:

Got some f8 and 9's but I want to put them into a shorter tube, how can it be done?, thanks, George

George,

Fold them with some flats, or make a shorter tube with a drawtube.

Clear skies, Alan

February 4, 2006 03:30 PM Forum: Solar System Observing

Faint Star near Callisto

Posted By Alan French
Bill Possel said:

We had poor seeing and some clouds but I still went out to look at Jupiter. Did anyone else notice a faint star very close to Callisto?

Thanks
Bill

Date, time, location? With that information folks can check field stars with their planetarium programs.

Clear skies, Alan

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