USER OPINIONS PAGE
This is a "User Opinions" page where YOU can express YOUR opinions. Contributions are welcome of course.
Subject: Catalog specs... Sent: Thursday, March 23, 2000 03:17:51 From: User100995@aol.com In early January I noted that Meade had incorrectly misrepresented the Secondary Mirror Obstruction as "(dia.;%)". The on-line catalog and printed catalogs state that this number is 9.6% for the 90 ETX and 125 ETX. Actually 9.6% would be correct if it was a % of area. I mentioned this to you in an e-mail and you stated you had been unaware of this misstatement in Meade catalogs. I had talked to a Meade tech rep about it and he said he could not comment, only John Piper could. I wrote a letter to John Piper concerning this in January but he did not reply. I told you what I had done and you asked that I let you know his response. Perhaps you could get a response from him. Here is the text of the letter: Dear Mr. Piper: I have been a satisfied owner of Meade products over the years. I have owned two 2080 SCTs and, more recently, the ten inch Starfinder dobsonian. I have been looking closely at the ETX 125. However, this exercise has brought something to my attention that concerns me. In the specs for the ETX 125 on your website there is a category "Secondary mirror obstruction (diam.;%)". It lists this figure as 9.6% for the ETX 125. But, in fact, 9.6% is the AREA of the central obstruction compared to the AREA of clear aperture, NOT the diameter. Checking through my Meade catalogs I note that this figure is always defined as (diam.;%) for all Meade cassegrain products, rather than the correct definition of AREA. This may lead the prospective customer who does not check the math to a false conclusion: that the ratio of the diameter of the central obstruction to the diameter of the clear aperture is far less than it actually is. Since the ratio of diameter to clear aperture is considered a reliable indicator of contrast and that an optical system with a ratio of less than 25% is very good and less than 15% to be excellent, Meade's figures are very misleading on their spec charts. There is no generally accepted "benchmark" for the ratio of obstruction "area" to clear aperture "area". Are you aware of this misstatement in your catalogs and website? As a regular Meade customer over the years, I would appreciate an answer. Thank you, Sincerely, James Phelps" Mike, can you get an answer from Meade? Jim PhelpsMike here: The "obstruction" size has been a topic of much discussion on my ETX site and elsewhere. There appear to be no incorrect answers; just depends upon how you measure things.
First of all, maybe you didn't get my main point about what Meade has printed in their catalogs. My main point with the Meade website/catalogs was not that there might be disagreements on how one measures things, but that Meade prints that 9.6% is a percent of the Diameter (this is how they have it "(diam.;%)"). Since the flared baffle on the ETX measures 52mm which results in 39.5% diameter obstruction. So, the first thing Meade doesn't do is accurately state the obstruction. Meade prints that the obstruction is 27.9mm, but it conveniently leaves out the baffling which is certainly an integral part of the obstruction. Then it calls it a percent of diameter, when in reality it is , without the baffling, a percent of area. Two different concepts altogether when discussing the nature of circles. So, my main point to Meade is that they have incorrectly printed the facts. What they have printed is just plain false. Even if they didn't think the baffling was part of the obstruction, then the % diameter of the secondary mirror to clear aperture would be 31%. Can you find out why they falsely print otherwise? Can you understand that if they instead printed that the 9.6% was listed as "(Area;%)" instead of "(Diam.;%)" it would be more acurate?
End of today's update
Subject: ETX-90EC after one year Sent: Monday, March 6, 2000 20:27:12 From: firstname.lastname@example.org (Todd Larson) It has been about a year since I last contributed to this site, so I thought I would mention a few things that might be of interest to other ETX users. I have been using an ETX-90EC for over one year. Because I am an ETX owner, I read this site often and can appreciate the different viewpoints concerning the ETX scopes. I don't need to delve into the long list of design problems associated with this scope. Anyone who is an owner, or has been checking this site for more than a few months, is already aware of them. But you might ask what do I think of this scope that I have been playing with for 13 months? Here is my opinion. The first ETX-90EC I received from Astronomics had an intermittent drive problem with the declination axis. Sometimes when powering up, the declination axis would slew for 15 degrees and stop. Since then I have noted several other users describing the same symptom. I waited a few more weeks for the replacement ETX from Astronomics. Actually I was glad that I had to wait for the next batch, hoping that Meade would have discovered and solved some of the early engineering and production problems. I wasn't thrilled with the second scope, but at least it worked. I decided I could live with the second scope, figuring that I could easily end up with an even worse sample for my third attempt. So how does the second scope perform? The optics are good, no surprises there. The electronics in the mount and the AutoStar are fairly good. The software is usable. I am still using version 1.0c and I will continue to do so until Meade comes out with a release that actually fixes more things than it breaks. It doesn't appear that version 2.0h will win me over. And, surprising as it is, the GOTO actually does work. If only the ETX had a decent mount, the GOTO would work MUCH better. Meade is still going in circles in an attempt to overcome, through software, the ever changing backlash in this mount (Meade recommends you retrain the drive every few months). The mount and motor drives are just awful. Toy-like is the best description. High power image vibration is bad. I have already had the declination axis apart once and will soon take both axes apart to try to minimize the ever worsening backlash and sticky motion. If you want to look at something scary, just disassemble that mount, or at least look at the 'tune up' guide at the Scopetronics site. I went on record here, one year ago, stating that I would have GLADLY paid $200 more for a well designed, solid mount. Can you say NexStar 5? Of course, even the NexStar mount has backlash. But it is apparently much more consistent, and the drive doesn't even have to be trained. Slap an AutoStar on a NexStar and then you might have something. Oh, well. Some of you might be wondering why I didn't buy an LX200. I would have, but the LX200 series is at least 7 years old. And with the recent rumors of big price cuts on the LX200 series, it appears that Meade may soon be releasing a replacement series for the LX200. Why buy an LX200 when it might be obsolete in 6 months? I hope they do it right and design a technologically advanced version of the LX200. Please Meade, don't come out with a cheap, low quality replacement for the LX200. You will truly be shooting yourself in the foot. And for those of you asking about CCD imaging (not digital cameras) on the ETX, don't waste your time and money. I do not know what Meade has in mind for that second Aux connector on the ETX control panel. But if they are thinking of CCD autoguiding (as some have suggested), I can't even imagine an autoguider that could tame the slop in that mount. Maybe an ETX-200EC with a rock solid mount and precision motor drive? Complete with PEC and Autoguiding? Then you could talk CCD imaging. OK... enough of this. I'm going outside to play with my ETX-90EC while we are still in this fantastic warm spell. Snow is forecast later in the week. Clear skies, Todd Larson
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