Posts Made By: Rod Kaufman

Chas,
I have the Discovery 12.5" truss dob and a variety of eyepieces to go with it. If planetary viewing is important to you, the UO orthoscopics are superb and relatively inexpensive. If you are after both the planets and DSOs, you can try the antares ultima plossls which are the same as the orion ultrascopics but cost less--check-out their prices at astronomics, meridian and e-scopes. If you need eye relief, consider the celestron xcels at adorama. Also, if you like the plossls that come with your scope, you can get more at owl services at a variety of focal lengths at three for $69.00. I think these may be better than the plossls that come with your scope and have a wider field.

Cameron,
The only eyepieces you have listed that will be sharp to the edge in your F-5 scope will be the panoptics based upon my experience with some of the eyepieces on your list and reviews on the others.

Stephen,
I don't have any direct experience with the eyepieces in the focal lengths you have mentioned nor have I read any reviews of them. A difference of a few mm may not seem like much but it makes a direct comparison imprecise. I have compared a 10.5mm pentax XL with a 10mm XW and I had the impression of slightly greater lightthroughput in the XW versus the XL but another observer thought they were identical. Either way, it's somewhat remarkable as the new XWs have more elements in most of the focal lengths versus the XLs. You can also reference a cloudy nights review of the XWs versus XLs as a pay per view lab report. Hope this helps.

Darian,
You may want to give some consideration to a 7.5mm speers-waler eyepiece. The eye-relief and edge correction is quite reasonable with it's 82 degree AFOV although I am unsure of the f-ratio of your scope. There have been some reports of soft edges in the epic/celestron variants but a longer f-ratio would probably help.

Floyd,
I would have thought the comparo between the pentax XW and the UO ortho/Orion ultrascopic would have been closer except for the greater AFOV and eye relief of the pentax. I compared my 10mm speers-waler with the pentax 10mm WX on Jupiter at Pinos on Friday in my 12.5" dob, just before I sold the dob. My subjective impression was a greater amount of contrast with the pentax XW and I didn't see the lateral color another reviewer had seen in the pentax XW. I am already on my second box of eyepieces so don't post on how great the pentax units are lest I buy another. On the other hand, if I don't buy more accessories, I will just blow the money from the dob sale on another scope!

Ron,
I viewed the ring nebula through one of these eyepieces a few years ago but I don't know if it was a later generation eyepiece or not.
The scope was a 25" dob and the eyepiece delivered the image with an artificial green cast and the amount of scintillation was marked. The image looked like an old-time silent movie flickering through a projector.It did deliver detail;I could see filamentous structure in the ring but I disliked the artificial appearance of the image.

I found the Sky and Telescope article on TMB monos to be interesting and informative. Standards of performance stressed scatter/contrast and resolution. The difference in contrast between the TMBs and other eyepieces was described as "subtle" and the author noted,"This is a far cry from some reports I had read on the Internet that proclaimed that the TMB's contrast "blew away" other eyepieces". The author also states, "can I conclude the TMBs are in fact superior planetary eyepieces? I never saw a difference that was pronounced enough that I would be comfortable making that statement without qualification".
One important point not mentioned in this article is cost-effectiveness. If, as the author states, TMBs are at least as good as the other eyepieces tested(but not significantly superior as vendor hype has suggested) why pay over $200.00 for an 8mm TMB versus $89.00 for a 8mm Televue plossl which provides a much larger AFOV without astigmatism?

I will second Floyd's vote on some poor eyepieces from Russel. The 18mm widefield has virtually no eye relief which was advertised by Russel as having much more. The 19mm is better in this regard but both of these designs suffer in a fast dob.
I've used the 7mm Seibert in my fast dob with success on the planets but I can't comment on the longer focal length models. I also agree with Floyd regarding the dim,poorly performing 7mm type 1 nagler, My Seibert 7mm outperformed it on DSOs!

I would encourage everyone to read the new cloudy nights article on the reviews of the TMB super monos. The specific issues I found to be of interest involved quality control problems in the super mono line as well as in other types of eyepieces. The reported inability of production eyepieces to meet specifications in some cases is of concern to me especially when you read statements from a vendor to the effect of,"superior quality control is assured".
I would also encourage readers to consider the discussion thread on the cloudy nights forum regarding this particular article.The author of the controversial CN review article on planetary eyepieces offers his opinions and impressions of the TMB monos compared to other types of eyepieces.
I believe the current CN article offers a balanced and objective analysis of the strengths and weaknesses of the reviews that have been written to date. I hope it will lead to a higher degree of rigor for the methodology utilized to evaluate and assess the performance of planetary eyepieces in the the future.

John,
I've not compared the two but I am pleased with the on-axis sharpness of the TAL 24mm in my 16" F4.5 dob. I've compared it with my 24mm axiom eyepiece which is quite sharp on axis and I can't see an appreciable difference. I don't find the off-axis aberrations of the TAL 24mm as distrubing as the axiom 24mm which has the characteristic edge astigmatism of the axiom line on fast scopes.
The TAL edge aberrations are subdued with the use of my GSO 2" barlow and you might consider using the combo if you have a fast scope.
I would also add that to appreciate the resolving power of longer focal length eyepieces such as the TAL 24mm, one benefits from eith a longer focal length scope or a larger aperature fast scope. Even though my 16" operates at 4.5 the focal length is sufficient to exploit the resolving power of the longer focal length eyepieces and unless one experiences the difference between smaller aperature fast scopes and larger aperature units, the difference is not realized by many observers. Even a 12.5" f5 appears to resolve sigificantly less with a longer focal length eyepiece than say a 16 f4.5 scope. I utilize the longer focal length eyepieces if seeing conditions are poor and I can still resolve planetary detail I wouldn't have even attempted in a lesser scope such as a 12.5" f5 unit.