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Review of TMB optical Monocentric eyepieces
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#43
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Review of TMB optical Monocentric eyepieces
Leonard wrote:
Hello Group , In the August issue of Sky and Telescope Mr Gary Seronik does a review of the TMB Optical monocentric eyepiece and in my reading of it comes to the conclusion that there is very little difference (or none)in contrast and light scatter between the mono. and two well known Plossls and a symmetrical . Three high quality eyepieces to be sure but I would have thought more of a difference would be seen between them and the mono. Mr Seronik did what appears to be a very complete review . It comes as no surprise that in an F4.5 newtonian off-axis performance was less than excellent with the mono. What do you all think about this review after such glowing reviews from other people over the last few months ? Leonard ----------------------------------- This apparantly from Tom Back last week on The TMB Yahoo group. Hopefully, this will explain what happened ? :-) --------------------------- --- In , "tmboptical" TMBoptical@a... wrote: I don't take this matter lightly, in fact as time passes, and I reread the review, I only feel incredibly let down. In a previous post, I said how potentially damaging this S&T review could be for TMB Optical, not just from the standpoint of the Super Monos. cut I called S&T late today, to talk to the head Senior Editor Dennis di Cicco, where the test reports get their final go-ahead. He was not available, so they wanted me to talk to the reviewer Gary Seronik. And guess what? The test eyepieces were in my hands (UPS express just handed them to me) and I tested all four on my double pass autocollimator, using my reference Strehl .997 TMB 100mm f/8 objective. Gary seem happy to hear from me, but it soon turned into a shouting match. But when I brought up the fact that I just tested the eyepieces, did things ever change. Of the four TMB Super Mono eyepieces (as you know, I did not test these, they were taken from a large stack of untested units, figuring what could be more honest from a manufacturer than to do that -- not hand pick a set like I'm sure so many do. Markus assured me that the second run was flawless -- it certainly was not. The 9mm, and 8mm showed gross astigmatism, the 7mm less, and the 5mm none! And guess what eyepiece Gary didn't use, or used very little, the 5mm. He tested defective eyepieces, and this is a fact. Not only are the three astigmatic, but because of that, they also do not perform on-axis as well as a TMB Mono that is free from all defects, because of glass and/or the optical centering of the three glass elements. Talk about bad luck! cut Thomas Back __________________________________________________ ______________________ |
#44
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Review of TMB optical Monocentric eyepieces
Hi, I think maybe Mr Seronik may have erroneouly used a term
claiming that the TMB Monos displayed Astigmatism. More likely, it was Coma that was displayed at the periphery of view, and not Astigmatism. With a slower F-Ratio Instrument, I would assume Coma would not be an issue with these. Mark t (Ratboy99) wrote in message ... I have four of the TMB Super Monos (2-16's and 2-14's) and I haven't been able to detect any astigmatism in them at all. That's using my F8 Tak FS-152 and a Binovuew w/ 2x barlow. Nice eyepieces actually... rat ~( ); email: remove 'et' from .com(et) in above email address |
#45
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Review of TMB optical Monocentric eyepieces
Hi, I think maybe Mr Seronik may have erroneouly used a term
claiming that the TMB Monos displayed Astigmatism. More likely, it was Coma that was displayed at the periphery of view, and not Astigmatism. With a slower F-Ratio Instrument, I would assume Coma would not be an issue with these. Mark t (Ratboy99) wrote in message ... I have four of the TMB Super Monos (2-16's and 2-14's) and I haven't been able to detect any astigmatism in them at all. That's using my F8 Tak FS-152 and a Binovuew w/ 2x barlow. Nice eyepieces actually... rat ~( ); email: remove 'et' from .com(et) in above email address |
#46
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Review of TMB optical Monocentric eyepieces
lightshow wrote:
This apparantly from Tom Back last week on The TMB Yahoo group. Hopefully, this will explain what happened ? :-) Yes, indeed--if true, it explains quite a bit. That's rather unfortunate for Tom and his company. Brian Tung The Astronomy Corner at http://astro.isi.edu/ Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/ The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/ My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt |
#47
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Review of TMB optical Monocentric eyepieces
lightshow wrote:
This apparantly from Tom Back last week on The TMB Yahoo group. Hopefully, this will explain what happened ? :-) Yes, indeed--if true, it explains quite a bit. That's rather unfortunate for Tom and his company. Brian Tung The Astronomy Corner at http://astro.isi.edu/ Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/ The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/ My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt |
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Review of TMB optical Monocentric eyepieces
Tom T. wrote:
I was loaned a couple for review - No astigmatism in the ones I saw, but they do have a curved field that becomes fairly noticable on fast scopes. Since fast scopes often have significantly curved fields themselves, are you certain you are seeing the field curvature of the eyepiece, instead of the field curvature of the objective? After all, the field curvature of the eyepiece shouldn't change from telescope to telescope, it seems to me. Brian Tung The Astronomy Corner at http://astro.isi.edu/ Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/ The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/ My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt |
#49
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Review of TMB optical Monocentric eyepieces
Tom T. wrote:
I was loaned a couple for review - No astigmatism in the ones I saw, but they do have a curved field that becomes fairly noticable on fast scopes. Since fast scopes often have significantly curved fields themselves, are you certain you are seeing the field curvature of the eyepiece, instead of the field curvature of the objective? After all, the field curvature of the eyepiece shouldn't change from telescope to telescope, it seems to me. Brian Tung The Astronomy Corner at http://astro.isi.edu/ Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/ The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/ My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt |
#50
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Review of TMB optical Monocentric eyepieces
On Fri, 25 Jun 2004 15:51:47 +0000 (UTC), (Brian Tung)
wrote: Tom T. wrote: I was loaned a couple for review - No astigmatism in the ones I saw, but they do have a curved field that becomes fairly noticable on fast scopes. Since fast scopes often have significantly curved fields themselves, are you certain you are seeing the field curvature of the eyepiece, instead of the field curvature of the objective? After all, the field curvature of the eyepiece shouldn't change from telescope to telescope, it seems to me. Brian Tung The Astronomy Corner at http://astro.isi.edu/ Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/ The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/ My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt A good point - The nagler and speers waler zooms, multiple types of orthos and plossls, as well as several other types of eyepieces pretty much all showed flatter fields (to the same off axial degree) than the monos on the same scope(s). Tom T. |
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