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Posts Made By: dan hilts

October 16, 2006 03:59 PM Forum: Refractors

Re: 5" Achro Optical Test

Posted By dan hilts

Hi Steve,

Vega is a pretty tough test subject. It can be pretty difficult to accurately asses the rings with an achro due to the out of focus secondary colour. If you have a dark green or dark yellow filter you may want to try it again with a not so bright star. Pick something well above the horizon, mag 2-3 and make sure seeing is steady.

clear skies,
dan


October 21, 2006 04:39 PM Forum: Equipment Talk

Barlows to take a filter?

Posted By dan hilts

Hi all,

I have several 1.25" barlows and a GSO 2". I have been trying to add a filter to the optical path but so far, only my Rini 3X is threaded for filters but it is one of the long barlows and doesn't fit well into a diagonal.

I noticed that Orion states that their shorty barlow has a barrel threaded for filters. It doesn't show in the photo on the website so I assume it is inside the barrel. Can any one confirm this?

clear skies,
dan

January 29, 2007 07:32 PM Forum: Telescope Making

Re: bubble cavity between mirror blank and tool

Posted By dan hilts

You want to work COC, not the W stroke.

IF you dug a real hole hogging out to depth, then you will need to obtain contact with 80 grit; 120 will take a very long time to get there, especially on an F4 or faster. Go back to the 80 grit, work centre over centre, 1/3 stroke until contact is obtained. You can return to work MOT or TOT as required to control the sag once you obtain a spherical curve.

hope this helps,
dan

March 21, 2007 02:00 PM Forum: Star Parties

CSSP

Posted By dan hilts

Any news on the status of the proposed wind farm near CSSP?

clear dark skies,
dan

http://www.astromart.com/forums/viewpost.asp?forum_post_id=480108&poll_id=&news_id=&page=

April 18, 2007 03:25 PM Forum: Astro Binoculars

Four-element objective lens?

Posted By dan hilts

Celestron advertises this for some of their Skymaster binos. I've seen it in the 25X100 ads.

"Four-element objective lens for ultra sharp focus across the field of view"

So what's it all about? Did they count the prisms as objective elements or did they count left and right together? Or did they really use four elements in each objective?

dan

July 18, 2007 07:26 AM Forum: Beginning Astronomy?

Tour Guide

Posted By dan hilts

Here's a link to a site I stumbled on while searching for info on the teapot.

This site has a very easy to follow tour of the skies for each season. It is meant as a guide for tour leaders but will serve well for those who are on their own. I think it has a good blend of simplicity and subject depth which is often difficult to find.

We live in pretty good times. There are a lot of clubs that have made a wealth of information and experience available on the internet. Most have done it using volunteers and they do it only because of their passion for the hobby.

http://www.smokymtnastro.org/Seasons/Stargazing.htm

clear skies,
dan


September 18, 2007 12:12 PM Forum: ASTRONOMY

Another observatory closes

Posted By dan hilts

Light pollution has taken its toll. The University of Toronto has announced the closing of the David Dunlap Observatory. Originally this observatory was on a farm site 25Km north of the city limits. It is now encircled by the city known as the GTA- Greater Toronto Area.

When opened in 1935 this observatory housed the second largest scope in the world (1.88 meter) The mirror was cast by Corning and I believe was the first ever to use a pyrex type of glass.

press release:

http://www.news.utoronto.ca/bin6/070910-3374.asp

observatory web site:

http://www.astro.utoronto.ca/DDO/public/about_DDO.html

I had the oportunity to tour this facility last spring. I am glad I did.

dan

November 11, 2007 11:15 AM Forum: Eyepieces

24mm Hyperion, first light.

Posted By dan hilts

I received my new 24mm Hyperion last week. Last night was the first chance I have had to use it. I planned on using my 120mm/F12.5 achromat refractor.

First light was on M57 only because it was nicely positioned and was going to be lost in some sky glow as the night went on. Unfortunaely, just prior to this I had been looking at comet 17P through an 18" Obsession using a 24mm Pan. My little scope doesn't compare and I was under-whelmed. However, the view in the 24mm Hyperion was very nice, crisp to the edges, (at F12.5 it had to be), and once my eyes adjusted I had a vey good view of the ring in the nebula and the surrounding star field.

Second light was on the comet. Great view of the halo nearly filling the FOV. A couple of bright little pin point stars shining through the glow of the comet and just a hint of the core could be seen. Lots of faint stars in the background. The extra field over a plossl was a treat and framed the comet very nicely.

I like the 68 degree field. I have some 60 degree eyepieces which show the field stop and I like it when this is out the view. The hyperion does this nicely.

I tried the 24mm in a couple of different barlows just to see how it worked out and there were no issues. With an Antares 2" 1.6X, the effective eyepiece is 15mm or 100X in my scope. I usually use a 15mm Russian Erfle for this power but the Hyperion has a bigger field and was crisp across the view. I ran a few bright stars out to the edge and was able to detect some lateral colour but only at the extreme outer portions. Unfortunately, Mars was still very low in the sky and the best I could do was to detect that there were some dark surface features without definition. I ran it out to the edges and there was no excess color or flaring in the image. Better skies were needed for higher definition.

I checked out the Auriga star clusters as well as M35 using the unbarlowed 24mm. This was the first time I had ever noticed the faint little NGC cluster that is a companion to M35. The increased FOV over a Plossl allowed both clusters to be seen in the same view. This was a nice surprise as I knew the NGC cluster existed but had never really identified it as an individual object.

Before the night was out I did have an opportunity to try the Hyperion in an 18" Obsession and compare it to a 24mm Panaoptic. The target was the double cluster, high in the sky and easily detectable to the naked eye. Those who have made this comparison before and have suggested that the Hyperion was a little soft at the edges were being very gentle with their comments. The Panoptic showed a very crisp view right out to the edges. The field in the Hyperion was the same size and just as bright but the outer portions were very soft. Only the central 30% was what I would call crisp and eveything else was very soft turning to downright blurry in the outer portions of the field. The difference between the Pan and the Hyperion was very obvious and even a novice would have noticed. I would be very disappointed if I had purchased the 24mm Hyperion to use in a fast Newt. I might add that I also own a 19mm Siebert ultra that I have also tried in this same scope and it was very good, right to the edge. (That eyepiece has impressed everyone who has tried it).

In conclusion, I am somewhat happy with my purchase. The 24mm Hyperion works beautifully in my refractor which is my main use scope. Furthermore, it mates well with my existing collection of barlows. I would be happier if the Hyperion was more usuable in a fast scope as I have plans for a bigger aperature DOB. If those plans ever come to fruition, I am sure I will want the quality of the Panoptic. Meanwhile, The hyperion will work for me as it would for anyone with a SCT or refractor at the slower focal ratios. I have not tried the shorter focal length Hyperions but because these have a built in barlow, they may handle fast scopes better as these eyepieces are effectively working at the F ratio coming out of the built in barlow lens. I will have to research some more reviews before I add any more Hyperions to my collection.

clear skies,
dan


February 26, 2008 03:58 AM Forum: Eyepieces

Re: Outer Edge smoothness

Posted By dan hilts

It may just be some lint or dust that has stuck at the field stop in the eyepiece. You can correct this easily enough by wiping the edge of the field stop with a lens cloth folded to make it small enough to fit. Take a good look at the field stop edge before you clean it and see it it changes afterwards. You could also try to vacuum this space if you have a small probe.

good luck,
dan

June 13, 2008 07:28 PM Forum: Deep Sky Observing

Seahorse?

Posted By dan hilts

I was scanning the area around M57 and Beta Lyra at 25X when I came across this star field. It struck me as a perfect little seahorse. You can find it at RA 18hr46min and DE +32*17' or on a map by looking for NGC6700. Does anyone recognize it?

clear skies are nice,
dan