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Posts Made By: Rod Kaufman

December 8, 2002 06:54 PM Forum: Equipment Talk

December 8, 2002 07:01 PM Forum: Equipment Talk

Celestron Ultimas

Posted By Rod Kaufman

I have the 15mm version of the celestron widefield series.A 16 mm version did not exist. The widefield versions were apparently the predecessors of the Axiom series of celestron eyepieces. I find the 15 mm widefield ultima to yield a bright and contrasty image but with coma at the edges.

March 5, 2003 10:03 PM Forum: Eyepieces

Orion Lanthanum Super Wides?

Posted By Rod Kaufman

I agree with Bob Hart on his assessment of the overall superiority of the Pentax eyepieces in the focal lengths in question. I find the Pentax units to be virtually distortion-free in my fast dobs with excellent contrast and superb light transmission. I have followed Bob Hart's advice throughout the years on various web sites and I find his information to be "on target".

March 17, 2003 09:54 PM Forum: Equipment Talk

Need advice on Coma Corrector

Posted By Rod Kaufman

I have a Televue 1.25" coma corrector and it is probably one of the few remaining 1.25" units as they are now made only in the two inch size. The unit functions somewhat similiar to a barlow lens and seems to work well with meade widefield eyepieces. Premium eyepieces, such as the pentax units and the speers-waler 10mm as well as those from televue can handle a short-focus scope to f-4 so if you upgrade to one of these eyepieces a coma-corrector may not be necessary. I have a Discovery 12.5" f-5 truss dob and an Astrosystems 16" f-4.5 dob and neither require a coma corrector with premium eyepieces.

March 25, 2003 08:53 PM Forum: Equipment Talk

To Plossl or to XL?

Posted By Rod Kaufman

Rob,
I have a Discovery 12.5 truss dob and an Astrosystems truss 16" dob.I believe the pentax units work quite well and my pentax 10.5 does not ghost on Jupiter in either scope. You may also wish to try the university optics orthos or the ultima plossls which have good contrast and little or no ghosting. I read posts from other amateurs claiming their Radians do ghost on bright planets.

March 26, 2003 08:14 PM Forum: Equipment Talk

To Plossl or to XL?

Posted By Rod Kaufman

Rob,
I have tried televue plossls in both of my dobs and I find them to be of high quality without significant ghosting issues. I am not sure of the reason for poor quality images in your scope unless seeing conditions in your area are poor or your optics are not collimated properly. I would recommend a laser collimator made by Howie Glatter. His laser costs about 100.00 for the 1.25" model but it is highly accurate and it will withstand being dropped on the ground without being de-collimated. I have found the lasers provided by Discovery to be un-collimated as have other amateurs. I returned one to Discovery and their replacement laser was even worse.

March 31, 2003 10:19 PM Forum: Equipment Talk

Which ep to purchase

Posted By Rod Kaufman

David,
Iam sorry to learn your widefield eyepieces from Adorama aren't working well for you. They are the same as the Orion expanse eyepieces but are sold under the pro-optic label. I have the 6mm version and it works quite well in my 16" Astrosytems truss dob. Other amateurs have rated it highly in excelsis.com where eyepieces and other equipment is evaluated.
The pentax eyepieces,although pricey,are virtually free from distortion and a 14mm unit should work well in your dob unless the optics are not collimated or some other problem exists in your scope. Less expensive eyepieces such as the widefield Russel 19mm may work well but the edges will be soft.(I just purchased and tried a 1.25 version of the Russel 19mm eyepiece in my scope and it works well for a erfle design). The celestron axiom eyepieces in 15mm or 19mm are relatively inexpensive but have good contrast and high light transmission but the edges will exhibit astigmatism in your scope.

April 2, 2003 06:46 AM Forum: Equipment Talk

Rod Kaufman

Posted By Rod Kaufman

David,
I think it would be preferable for you to link up with a local amateur group in your home town of Houston. This would save you the hassle of shipping the eyepieces and you could probably pop them in and out of a fast dob during a star party and see if the eyepieces are at fault. In addition, you could probably borrow a premium eyepiece from someone at a star party and try it your scope and then compare it with your own eyepieces. It sounds like your scope is collimated although I would recommend a laser in addition to a chesire eyepiece. Finally, use a good 7mm eyepiece and look at the in and out of focus images of polaris(since it hardly moves)and see if the diffraction patterns look similiar. If so, your optics are probably collimated and performing well. Give it a try.

April 13, 2003 05:29 PM Forum: Eyepieces

High power EP for Mars

Posted By Rod Kaufman

Jason,
Both televue plossls and university orthos are reviewed in an article on planetary eyepieces appearing in www.cloudynights.com. My experience with the 8mm televue is that it's a good eyepiece but eye relief is very tight. The university optics orthos have performed superbly on planets in my 16" f4.5 dob. I don't think you could go wrong with either televue or university but I would prefer the ortho design on the planets. I note that university now has an improved coating available on a somewhat higher priced version of their ortho design.You may want to try it and give us a report on your results.

April 23, 2003 05:06 PM Forum: Celestron

need help with celsetron advance astro master

Posted By Rod Kaufman

Chris,
Although I don't have an astromaster, I do have a minimax and a sky commander unit on my dobs and I have used my minimax on a 10" schmidt-cass. The warp factor of 2.9 is too high and indicates your alignment is off. It should be no higher than 1.5 and preferably under 1. Most encoders operate at 4000 tics or less so you might want to consult your owners manual to see if your encoder settings are possibly too high. Also, and this is important, make sure your optical-mechanical axis are in alignment. Finally, make certain your mount is level. If you stiil have problems,contact a tech at Celestron and ask for help.