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Posts Made By: Judson Mitchell

July 2, 2007 06:03 PM Forum: Equipment Talk

Re: where do the go-to's go to?

Posted By Judson Mitchell

I remember one member commenting that he would never again buy a scope if it couldn't be operated without power. It must be very frustrating to lose power after traveling several hours then setting up for what might be a weekend of observing. A friend once bought a Tasco at a Walmart sale. It would go-to, but the item it went to was never identifiable, nor was it pointing in the expected direction. It remains a standing joke as to what its intentions were.

July 3, 2007 05:09 PM Forum: Eyepieces

Eye Piece FOV-Do You Believe?

Posted By Judson Mitchell

Has anyone out there tried to measure the actual field of view of an EP in their scope? I continue to see EPs advertised with fields of view that do not coincide with measurements done on my 12" Dob (1500mm). These measurements were performed with steel tape at a distance and on specific star fields. What I have found is the TV EPs seem to coincide very closely with their claimed AFOVs.

One striking difference was the GSO 2" 42 mm Superview with a claimed AFOV of 65 degrees that provided only a 55 degree AFOV in my scope. I have measured FOV using a number of other EPs. EPs with values that didn't measure up were TMB Planetaries 7mm & 5mm (although the difference was not as dramatic as the Superview) and Siebert Star Splitters. In contrast, the 17mm and 13mm Hyperions and the 8mm Stratus appeared to provide a FOV greater than that advertised.

You may want to perform some simple tests on your EPs to see if you are getting the FOV that would be expected. Also,it would interest me to learn of causes that would effect a difference in the claimed AFOVs. Perhaps my method is flawed, however, TV did seem to measure up quite nicely.

July 17, 2007 08:40 AM Forum: Eyepieces

Do you Really need a 2" Filter?

Posted By Judson Mitchell

Considering the size of the cone of light coming into my 12" dob, is the full diameter of a 2" filter necessary? One would think that an adapter to accept a 1.25" filter would be all that is required. There are probably scenarios where this wouldn't work, but for my EPs, I wonder? Consider a 40mm Paragon with an F4.9 12" dob. Do I really need all that much filter?

By the way, I just got a 2" OIII filter.

July 23, 2007 06:27 AM Forum: After Dark

Meteor Showers

Posted By Judson Mitchell

Saturday night we observed 5 meteors in about an hour near midnight. They seemed to be radiating from the vicinity of Sadalmelik in Aquarius. I found a page that described this secondary radiant point for these meteors, but now cannot trace it down. Can someone lead me to a link. The frequency was quite high considering that of other meteor showers.

July 26, 2007 06:50 AM Forum: Eyepieces

Help Select Next EP!

Posted By Judson Mitchell

I have a gap between my 13mm Hyperion and 8mm Stratus which can only be filled by barlowing my 17mm Hyperion with a 1.5 2" Proxima. My preference would be to insert an EP in the slot and am considering T6 Naglers and Radians. My current scope is a 12" F4.9. Which focal lengths might you recommend and are there any other EPs out there in the comparable price range that I should take into account?

September 13, 2007 05:11 AM Forum: Eyepieces

Why Rectilinear Distortion?

Posted By Judson Mitchell

It is a little confusing to me why rectilinear distortion seems to have been a necessary evil in Tele Vue EPs. First, why was it accepted when it seems other designs have minimized it? Second, since I have not used such EPs in refractors or slow dobs, is it as pronounced in these scopes? There must be a benefit of RD, be it design cost, increased image quality toward the edges, or other.

Now, with the introduction of Ethos, RD seems to have been minimized. Any help in clarifying this will be appreciated.

October 10, 2007 05:45 AM Forum: Star Parties

Mid Atlantic Star Party?

Posted By Judson Mitchell

Any reports from the Mid Atlantic Star Party?

October 20, 2007 10:59 AM Forum: Equipment Talk

Stabilizer for Bino Parallelogram

Posted By Judson Mitchell

I may have pointed this out before, but it could be worth repeating. If you have or are considering building your own bino parallelogram, one problem can be balance or stabilization of the mount, especially with larger binos (+80mm). This can be solved by inserting a reverse thread rod from a wood clamp as shown in the photo. The threaded pins in the wood screw are inserted in the parallelogram rods. This assembly maintains the binos in their position even if the mount is not perfectly balanced. Granted, it will not be silky smooth, but it works.

I had noticed the balance of the mount changing as the angle of the binos changed due to the weight of the lenses. This is no longer a problem. You do have to twist the screws to adjust for vertical position.

October 30, 2007 06:41 AM Forum: After Dark

Comet Body Still Visible!

Posted By Judson Mitchell

Has anyone seen an attempt to explain why the comet body is still visible? Particularly since is has increased from about mag 16-17. One would thing that this may be evidence of its continual "degassing", which might suggest that as long as the core is visible, it will continue to contribute to the coma and the thing will grow. Others may suggest that this is only because the interior has been exposed due to stripping of dark surface material. But, its brightness is quite intriguing and requires some plausible explanation.

November 6, 2007 07:28 AM Forum: After Dark

17P/Holmes Acham's Razor

Posted By Judson Mitchell

I wish some erudite analysts would consider the (as the self appointed scientific apparaisers have poopooed) possibility of an impact for the explanation of 17P/Holmes outburst. The magnitude of this is such that the expansion in apparently all directions is approaching 100,000 miles per day. Also, consider where in the solar system it resides and the expansion occurred. Is it not in the Asteroid Belt? In fact we really do not know where all the "small" denizens of the AB are, or how many there are?

Now, for a mass that is reported to be a few miles in dimensions, the self contained ability to explode with the apparent magnitude we have observed seems quite unusual.

Will someone please provide a more plausible explanation why an impact is not the cause using something more than the supposition that it is "highly unlikely" since there is very little out there. First, how much is really "out there"?

Has anyone found an analysis that describes why the outburst due to impact is not a probably explanation? Just how would an impact manifest itself? What type of impact would cause the observed phenomena? Are we too scared (global warming) to propose or evaluate an unpopular hypothesis? I remember a training session where during a contrived quiz, one of the members burst out laughing "Stick them in your armpits?!" Well, everyone got the answer wrong. The question related to giving a little life to spent batteries.

Do we need some complex explanation that is not verifiable rather than to trust Acham and at least consider something more common like an impact? I suspect that various scenarios of impacts could be evaluated through computer modeling to either justify the possiblilty or demonstrate that impact is just not "possible".