Optics Replacement with Meade's UHTC optics.
1990 vintage 10" Schimdt-Cassegrain OTA with Meade's new UHTC optics group.
Back in March of this year (2002), I took my scope out for a long overdue observing run. I had been doing a lot of astrophotography and figured that I should look through an eyepiece for a change. The night was a strange one, it was very transparent AND steady. In fact I would say that it was 2nd best night I can remember for seeing. It seemed to be a good night for tweaking the alignment of my old Meade 10" f/10 SCT OTA (1990 vintage). Once the collimation was tweaked I aimed it at Castor. Yes it split it, but there sure was a good deal of "mess" around the image and it wasn't wiggling! At that point, I decided to get my ETX 90 OTA and piggyback it on the 10". I used a 2x barlow in the ETX and moved my 10mm LV eyepiece between the two OTA's to compare the views at the same power. The difference was stunning! Now in fairness, the ETX's optics are perfect - period, but this was the first time I was able to compare the two scopes on a night with such good seeing. At that point I knew that I was sending my old 10" OTA to Meade for an optics replacement.
The next day I called Meade and made the arrangements to send my old OTA. I was going to wait 6 weeks before I shipped the scope so the work could be done while I was in Europe on a long overdue vacation. A little over a week after I made the arrangements word of the new UHTC coatings came out. Within weeks, reviews of the UHTC optics indicated that the new coatings were actually as good as Meade was claiming. As my vacation was approaching so I called Meade to get more shipping information and I also asked if I could get a UHTC optic set during the replacement.
To my surprise the answer was "Yes!" - it was possible to get those fancy new UHTC optics put in a older scope! So I sent my OTA to Meade near the end of April as planned. The trip to Europe was great and the day after I returned a giant box was sitting on my front porch. Meade had repacked the OTA for the return trip in a 10" LX200 shipping box. Needless to say, the packaging was very good and the OTA was in great shape. On the underbelly of the OTA was the nice little UHTC sticker (which is now covered by my Losmandy dovetail plate). One thing that stood out was that there was a brand new focuser knob on the OTA. After removing the cover and a quick inspection, I really felt that the optics actually looked like the figure was better and smoother. At first the corrector was not quite as transparent as I thought it would be, but it was worlds better then the old optics. Then I looked straight into the tube and the corrector simply disappeared! This was verified for me when I went to remove a small speck of dust that was on the corrector. When I tried to remove it I hit the front of the corrector! The speck was on the inside and I couldn't see the front surface of the corrector... Anyway, I bolted all of the accessories back on the tube and waited for a clear night...
The first clear night was May 14th. Cloud free - yes, Steady - No, and it wasn't very transparent either! In fact, seeing was the worst I have EVER seen! First light came in the form of Arcturus and my 50mm "Zeiss" super plossl. I centered the star and aligned the finders. The collimation was very good straight from the box - no tweaking required. The first impression was that in spite of the bad seeing, the image "snapped" into focus - something that I never experienced with the old optics. I next tried the 26mm Meade SP (96x). Same snap. I next moved to Mizar. Not only did the image snap, but I was amazed at how much brighter the image was then I remember! I was able to resolve many faint background stars in the image. These new optics really have greater light transmission then my old ones. I next tried my Vixen 10mm LV eyepiece (250x). The seeing was so bad using this eyepiece was useless! I waited for epsilon-Lyra to get high enough to see. At first the seeing was so poor that there was NO separation - only two elongated stars. The seeing never really got much better, but some separation was finally achieved after an hour or so when the stars fully cleared a lilac bush that was in the way. The seeing would only allow quick glimpse of a airy disk and diffraction rings but for the most part, it was the strangest "mush" I have ever tried to look through.
The second day revealed much better seeing and much better transparency. The seeing was still worse then average (maybe it was just "bad" as opposed to horrible) but at least I could begin to detect diffraction rings and could see an airy disk in among the wiggles...
There was some mirror shift and backlash, maybe 20% more then before the OTA was sent in. I also noticed more focus drift in the first seconds after achieving focus. The scope also seemed to loose (change) focus more then before when viewing different parts of the sky. My guess at that time was that the grease on the baffle tube *may* have be replaced or refreshed -or- the whole primary mirror assembly was replaced and there was more clearance between the slider and baffle tube.
I finally got a night of "average" seeing here in S.E. Michigan on May 21st, The seeing settled down shortly after epsilon-Lyra cleared the aforementioned lilac bush. The components where so clearly split that at 500x I could have driven a truck between them. Each had a nice airy disk with beautiful diffraction rings dancing about. This is something that I had NEVER seen with the old optics. I was able to confirm that the collimation was dead on. Also, to the extent that the seeing allowed, I was able to see that the inside/outside focus diffraction patterns were very close - indicating the new optics were well corrected. With seeing as it was, I was just barely able to split zeta Bootes (0.8" sep) and I think that if I could have another night like that one in March, It would be no problem. To put it simply, the optics were the best of any SCT I have looked through to date.
The coatings on the old optics were missing on half of the corrector plate, and I suspect that this really killed off light transmission. With the new optic set, under mag 4.2 skies and a 3/4 moon, M82 and M81 actually showed some detail. M13 was well resolved but washed out in the ambient light. I am also now certain that the bad coatings were causing some kind of focusing problems because more light was get through the upper half of the aperture then the lower half and they always looked "whacked" even after careful collimation.
I finally got a night with some good seeing. WOW! I was able to split zeta Bootes (0.8" sep) without a problem. I would say that the actual result looked a bit better then the aberrator program suggested it would. Epsilon-Lyra was such a clean split that it was no longer even a remote challenge. I guess I will have to find another "test" target now. These optics are simply the best I have ever seen in a SCT.
But wait, there was another surprise... The extra mirror slop and new focus knob made me wonder if I was also given a new mirror slide and/or any parts of the LX200GPS mirror lock mechanism included. The easiest way to check this was to remove the focus knob and have a peek. After removing the knob, sure enough, there was a BIG gear inside that was not there before! A few quick rotations with my finger proved that I was also given a fully functional mirror lock mechanism! The only problem was that there is no knob to make it work - see below....
REPORT UPDATE (July 2002)
On a night of good seeing and remarkable transparency I took a look at some nice summer planetary nebulae. Now remember, I'm observing in mag 4.2 skys. NGC7008 took on a question mark shape with a couple of brighter stars making up the "period". It was quite visible and actually looked like a couple of the astrophotos I looked at. M13 was resolved as well as I have ever seen it in my mag 4.2 site (back yard). NGC6826 was simply awesome! This was the first time I had observed this nebula. The "blinking" nature of the "Blinking Nebula" was instantly noticeable. With averted vision at 96x this was a bright nebula with a bright central star. Using "direct" vision most of the nebula simply "blinked" into nothingness, leaving the central star with the small halo of the inner ring of the nebula still visible. At 250X the blinking stopped. The light thru-put of the UHTC optics really showed the improvement.
REPORT UPDATE (Jan 2004)
I have been investigating selling this OTA and moving to a smaller scope with a flatter and wider field (A Vixen VC200L). In the process of describing my OTA to a potential buyer I realized this page required another update. First, I did finally get a mirror lock knob out of Meade and I installed it in the Spring of 2003. The mirror lock is a bit tighter then a factory installed "GPS" OTA, but it works well! The mirror image shift is a bit less then it was without the lock knob. The other improvement has be the addition of a 3" Clement Focuser - but that is another story....
The Last Word
The focus slop is a slight minus (although it improved after the installation of the Mirror Lock Knob), but these optics are SO much better then the old set that I'll happily take minor focus issues over the so-so optics. At half the cost of a new UHTC OTA (if one were even available by itself) and 1/12th the cost of a 10" Ritchey-Chretien OTA, I am very satisfied. In my case, It was well worth the $$$ I paid to upgrade. However, if my old optic set were good and the coatings were in good shape, I would NOT suggest getting a full optics replacement only to get the new coatings. If, however, you are planning to get a full optics replacement because your existing optics are poor, then it may would be worth it to weigh the extra costs for the UHTC option. So far, I'm Happy!
For advice and a simple guide for those wishing to buy their first telescope, click here...