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Posts Made By: Greg Shaffer

November 23, 2009 12:37 PM Forum: Eyepieces

21mm Ethos

Posted By Greg Shaffer

Saw an announcement from Anacortes that they are about 3 weeks out and the price is going to be $850......I am wondering about that price and if it is correct.

Saw where Astronomics made the same annoucement but at a price of $805.....

Makes me think one or the other transposed a couple numbers smile

December 15, 2009 07:57 AM Forum: Reflectors

New to me OTA - Questions

Posted By Greg Shaffer

Drove about 2 hrs Sunday to meet the seller and picked up a Parallax 10" F5 Newt with an Ed Stevens primary. I heard good things about his work, supposedly if you ordered one of the smaller Zambuto mirrors 14" and smaller that Ed was who did the figuring. It came with a really nice printed booklet with all the mirror test results and charts in it. Sadly my ignorence of such things leaves me wondering what I am looking at.....Could use some help interpreting what I am looking at.

RTA: .14 (not familar with this term but the booklet calls it "Relative Transverse Aberation")

Strehl Ratio: .999 (I know this is good but I also know there are several methods used to arrive at this with some being more accurate than others. It does describe it as "the wavefront for the entire mirror is averaged using the amplitude error for all of the zones")

Peak to valley wave: Less than 1/20

There are a couple of other specs that I dont grasp either.

P-V Wavefront 1/.. : 75.75

Wavefront RMS 1/.. : 223.46

Of course the weather wont permit me to physically evaluate it as usual when I get a new scope so here I am trying to educate myself on what I am looking at smile

January 3, 2010 06:04 PM Forum: Reflectors

My Christmas to myself :)

Posted By Greg Shaffer

Both the OTA and the mount.....Just got the mount home tonight. Only thing not here yet is the 12x80 finder. Hoping for 1st light tomorrow night.


January 28, 2010 11:52 AM Forum: Equipment Talk

10 amp Power Supply

Posted By Greg Shaffer

Someone posted a link a while back to a Pyramid 13.8v 10 amp regulated power supply with cig lighter and wire post ouputs off amazon.com for $49.95 w/free shipping. I believe it might have been Floyd....anywho whomever it was....Thanks!

http://www.amazon.com/Pyramid-PS15KX-13-8-Volt-Cigarette-Lighter/dp/B0002BA57A

Mine arrived today and works great.....


February 4, 2010 07:46 AM Forum: Astro-Physics

older vs newer 2.7" focusers

Posted By Greg Shaffer

Planning to use an AP 2.7" focuser on an 8" refractor project. I see some folks have upgraded to the newer greaseless version. However I have also been told there is no difference between the two other than one has grease and the other doesnt. This leads me to question why someone would pay nearly $400 for a new one when all they needed to do was clean the grease out smile I suspect the seller is either mis-informed or just wants to sell his greased version lol.....

Can someone confirm the differences if any?

Thanks
Greg

February 5, 2010 10:47 AM Forum: Eyepieces

Ep's for yard cannons.....

Posted By Greg Shaffer

Just getting started putting together an 8" f/15 build. This will be my 1st refractor over f/9 so I have no experience with choosing EP's for long focal length refractors.

Looking for advice/recommendations for quality EP's primarily for planetary use with an f/15....I currently have a set of Pentax XW's for my use and a set of Hyperions for everyone elses use smile Both of which work wonderfully in my shorter F/L stuff but I doubt they are ideal for f/15 based on what I have read. While I am sure the Zeis sets are wonderful I am not looking to spend THAT kind of money lol....Personally I prefer putting my funds in quality rather than a name AND quality.

From what I have gathered while both the XW's and the hyperions will work they may not be the best match for a f/15?

Any and all advice appreciated.....

Greg


February 9, 2010 04:07 PM Forum: Telescope Making

wealth of info for the techie astrogeeks :)

Posted By Greg Shaffer

Ran across this site by accident and the more I looked the more I had to concentrate....lots to grasp about all manner of technical information on design, theory, implementation when it comes to all types of telescopes.

Many of you may have seen this before.....maybe not. I found it facinating.

http://www.telescope-optics.net/index.htm#TABLE_OF_CONTENTS

February 26, 2010 10:10 AM Forum: Telescope Making

Tube counterweight set

Posted By Greg Shaffer

Currently starting a 8" f/15 OTA build and am looking for a source for a counterweight setup for balancing adjustments when switching from binoviewing to single EP. Have seen several different ones on various long refractors but have not seen them advertised for sale anywhere.....can someone point me in the right direction? While I am sure I could rig one I am not a fan of re-inventing the wheel if someone has already done so smile

March 4, 2010 06:33 AM Forum: Equipment Talk

Re: 2 inch ap diagonal vs tv diagonal

Posted By Greg Shaffer

I have both and rank them both the same in performance to my eye.....

IMO one would have to have nearly perfect seeing and be using them for planetary observations to have a chance at discerning any visual difference between 1/10th wave and 1/20 wave in a diagonal.

Pretty much the same thing applies to comparing a 1/4 wave (diffraction limited) to a 1/10 wave primary.....it takes pretty good seeing and a discerning observer to detect the difference.


March 18, 2010 08:48 AM Forum: Home Observatories

A sad situation for a friend

Posted By Greg Shaffer

A friend (made via AM) was given a 10 foot fiberglass dome that was originally made by Virgo Astronomics (now defunct). The original concept was a round building in which the entire building turned.....Not an appealing design IMO. He didnt want a round building that turned and neither would I.....So he modified the design to be a normal rotating dome on a square building.

Getting to the point.....His home owners association waited until he was 90% completed with the project to rule that he couldnt have it. As I understand it he fought it but couldnt win. He contacted me and asked if I wanted to come get it for the price of taking it apart and hauling it out.....While I am glad to get it and very appreciative of the offer I cant help but feel for his plight.

Never had to deal with a homeowners association myself but I would have thought there would be some legal and monitary options available to him given the sequence of events.....He is understandably upset and hates to even think about it but before we do this I would like to know if anyone has had a similar situation and if there is something they know he might use to fight with or at least recover some or all his investment.....

I can see denying the application before the thing is built if the rules allow for denial but to then come back when its 90% done and say wait.....you cant have it. Sounds like they (the association) should be liable.

Thoughts?

Thanks
Greg