Friday, April 11, 2003
Dave Samuels
Celestron NexStar 11 GPS
In December, 2002, I bought a NexStar 11 GPS from Charles at ScopeCity in
San Francisco. It rained for about two weeks solid and I couldn't really
get it out to test it until after the Scope City return policy had expired.
After fussing around with the NexStar for about a month, I spoke to Sam
Sweis, the manager at ScopeCity SF, about my displeasure with the NexStar as
a scope that I would be able to use for astrophotography purposes. So, Sam
allowed me to trade my NexStar 11 GPS up to a Meade LX200 GPS 12" w/ UHTC.
Of course I paid the difference but I could hardly believe that Sam would do
such a thing for me. (There are several reasons why I believe that the
Meade is a better product than the NexStar for my purposes. If you are
interested, I can fill you in on "my" product comparison opinions in another
letter.)
Anyway, Scope City was sold out of the 12" Meade's. So Sam ordered one for
me. He said that Meade had been taking about 30 days to fill the orders,
but he'd try to pull some strings for me and get it in sooner. If memory
serves me correctly, it came in at about the two-week mark. Good going Sam!
Meade LX200 GPS 12" #1 - First Light
Jan 17, 2003, I drove home with the scope and tested it that night for about
a few hours before it started raining. However, the scope didn't seem to
GOTO correctly. The GPS worked ok with 'location' but it couldn't GOTO
anything within about 50-300 arcminutes of accuracy. The specs called for 2
arcminute GOTO precision.... way different than I was getting. (Since
earlier this year, Meade specifies 1 arcmin GOTO accuracy
(http://www.meade.com/catalog/lx/12_lx200gps.html), Prior to that, it was
spec'd at 2 arcmin. Be sure to get one of the newer ones.)
I fussed around with it for weeks, whenever the sky was clear. I went to
star parties and compared it with a friends Meade LX200GPS 10". I learned
that you are really supposed to TRAIN DRIVES and also CALIBRATE SENSORS
before really trying to use the scope and expect any kind of pointing
accuracy. The whole time I was having these problems, in the back of my
mind there was room that I was doing something wrong. So I kept trying. I
started to keep a log of my observing sessions an pointing precision errors.
I also found that if you choose HIGH PRECISION MODE, I was almost able to
find some dark galaxies. But it was a lot of work. (Other problems arise
when using High Precision Mode; like you can't use the SEARCH SPIRAL mode...
all it does is go back to the alignment start instead of search spiral
mode... stuff like that).
After showing Sam my observing logs and the lack of precision I was getting,
he said that he'd take care of me, no matter what. Meade and Scope City
offered several suggestions about how to test the scope to see if we could
determine what the problem was. So, I did those tests and couldn't
determine any kind of consistency. One very clear night in March, while
observing with a friend and his LX90 8", my scope just wouldn't even align
itself. It was stuck during the alignment phase. It was throwing PROC.
TRAP 2 exceptions and all sorts of problems. (The LX90 advertises 5 arcmin
precision. I was using it to help me find things in the sky and then I'd
slew my expensive 12" manually to the location). There were other problems
related to tracking and jumping during slow speed slews and tracking.
Although you except 'minor' shift while focusing with the primary mirror, I
was experiencing excessive focus shift in addition to the other problems.
So, after talking to Sam and Meade, we determined to send the unit back to
Meade. At the expense of Meade, they sent a delivery truck to my house to
pick up the scope for repair. Meade was determined that the electronics
were messed up somehow, the drive encoders were messed up (causing the GOTO
problems), and etc. Sam said that he'd pull those strings again if he
could... not promising anything, but he'd try to get the scope put in the
front of the line. Meade was suggesting that the normal turnaround was
about 30 days.
Well, including a shipping snafu on the part of the trucking company, the
scope was returned to me in 14 days. Good going Sam and Meade! I anxiously
mounted the scope in the living room during the daytime and trained the
drives. Everything seemed ok. The electronics were upgraded to 1.5c
firmware version, etc. They had cleaned the dew spots on the corrector
plate, polished off some tape I had on the body from my Rigel QuikFinder and
things were looking good.
Meade LX200 GPS 12" #1-repaired - First Light
When it got dark, I took the scope out to the driveway to give the GOTO
system a test. The alignment went smoothly. (I don't expect the alignment
stars to be very close during alignment because I have never seen them very
close... the first alignment star was about 1.5 optical tube assembly widths
away).
I CALBIRATE SENSORS, power down, and align again. A little better this
time. (the CALIBRATE SENSORS step points the scope at the North Star
(Polaris) and asks you to center it in your eyepiece. Based on the amount
you have to move the scope to center it, an accurate measure of your
magnetic deviation, elevation, and level can be compensated for in its
software). The alignment stars were Capella and Kocab. After alignment, I
had the scope slew back and forth between them. They were way off...
between 5-30 arcmins and getting worse with each GOTO. GOTO Jupiter was
even worse... off by about nine degrees. GOTO Polaris... way off!... The
GOTO problems were still there!
I called Meade customer service the following day and they suggested some
tests, which I tried that evening. One of the tests I performed was a
LANDMARK test by aiming at a house across the street and check if it would
GOTO that LANDMARK every time (the old scope couldn't do that). The AZ
drive was off but the ALT drive was off more each time I tried it. It
seemed that the newly repaired scope still couldn't point within spec. So,
I called Meade again and they issued an RPL (replacement) number. This
time they were pretty sure that it was an Opto/mechanical alignment
problem... probably caused by shipping. (Looking back, this might have been
the original problem too, although all the alignment stuff is performed and
checked when you send in for repair) When the scope came back to me through
the trucking company the outer box was damaged and I pointed this out to the
shipping company. But they said it was a screw on the side of the truck
that snagged the box, not caused by dropping it or collision with anything.
NEVER ACCEPT A TELESCOPE WITH A DAMAGED BOX. Meade should put damage shock
sensors on their boxes when they ship their large telescopes. Neither
Celestron, nor Meade use shipping shock sensors. Even if they can test and
certify the scope before it ships, how are we to know that it really passed
the tests or that someone just signed it off in a hurry? Where is the
documented evidence that it passed within what tolerances? Do they adhere
to the "Good Manufacturing Practices" specification? If they are going to
blame shipping without using shock sensors, a friend suggested that maybe we
shouldn't by telescopes from Meade until they figure out how to ship them
without damage during shipment. What do you think? Besides, the mirror was
not locked and the focus was not turned all the way to one end when shipped
- as they require us to do in the manual.
When Meade told me they wanted to replace my scope, at their expense, I
started to worry about their ability to be able to test a scope before it
ships. After all, they can't really take out all the scopes and star test
them, can they? Could they, perhaps, make an artificial sky and test them
there? It would be a very large building since the 12" and 16" scopes have
a minimum focusing distance of over 80 feet. On a non-GPS unit, they could
have it point to something on the horizon... but without overriding the GPS,
they'd need an artificial sky or something.
Sam put me in touch with someone high up in the Meade hierarchy. I spoke
with him and he assured me that they do have a way of testing these units
and that he can vouch for the fact that their "process" does work. He said
they have an artificial sky and that each scope is tested with it. (I still
have a hard time believing this. Does anyone know the facts surrounding
this?) He said that a lot of other testing is done as well to assure
quality before shipment. All that goes out testing is invalidated as soon
as it is bumped in shipping though.
I RECOMMEND SCOPECITY, SF
Well, he didn't have to do it, but Sam offered to trade me scopes. Even
though it is not a Scope City policy to do this, Sam made a special
consideration for me in this case. Partly because he treats locals - of the
bay area - kind of as family. He happened to have one 12" GPS with UHTC,
like mine that had just come in. He'd take my bad one and the RPL number
and give me his. I checked with Meade to see if it was ok with them and
they made some changes to the address on the RPL order and it was taken care
of. I drove to ScopeCity the next day, and there was a 12" in an unopened
box right by the door of the showroom waiting for me. I don't know where
you'd find a retailer like Sam Sweis anywhere in this world today, but I'd
recommend purchasing from him and ScopeCity. In fact, I am personally
inclined to pay a few more bucks and purchase accessories from him than
purchase them elsewhere on the Internet. While I was without my scopes, he
even offered to give me a "loaner" 10 inch GPS. He didn't have to do that.
As far as buying a 12" scope versus a 10" scope versus a Celestron 11" or
14", I do have opinions that I might put in a comparison table soon and post
it. It would be nice to have been able to look at an objective table of
features, etc, before I bought my Celestron prior to trading up to a Meade.
I don't believe that it is entirely possible because people have different
goals for their scopes and different types of viewing. I was looking for
something I could do serious astrophotography with within a year of
purchasing the scope. (the delay is due to the budget and price of CCD's,
wedges, guiders, heaters, etc.)
Incidentally, don't even think of getting a scope this large without the
following accessories:
1. Carry case. You are supposed to transport the scope with
the RA/DEC brakes UNLOCKED and it wobbles all over the place while you are
carrying it... Just get a case. I got the cheaper soft case (about $200).
The JMI hard case is $300 more but it has wheels built in.
2. Dew removal/prevention system like the Kendrix (Even one
night of viewing will start to accumulate small dew spots that will
accumulate over time.
3. Dew shield. I made mine with about $8 of plastic from
TapPlastics and some duct tape. It should extend at least 1/5 times the
diameter of the scope. Don't forget to account for at least 6 inches of
length to overlap the tube enough to stay on firmly without vibration in the
wind, etc. You also don't want it to sag. Leave enough diameter to deal
with the Kendrix heating system.
4. Battery Power. Because you are going to use the dew heaters
(2.75 amphours for the 12", less for smaller scopes), you're going to need
some serious battery power. There are lots of articles about this.
Consider getting enough battery power for all the gizmos and possibly a
laptop. If the laptop battery fails, you'll have a backup for it. Some
people recommend heaters for the laptop... hence, even more battery power.
It adds up quickly. Even if you are just running the scope and the heaters,
you are at about 4 amphours. A 13 amphour battery could only sustain that
load for less than 2 hours. A typical night out for me is about 8 to 12
hours. Anyway, get battery power... remember to consider portability. A
large 1000 amp battery might be too heavy for you. Get one that won't leak
if it tips in the back of your car.
5. Some kind of luggage cart for your scope.... wheels! This
scope body weighs in at over 70lbs... some say closer to 80. If you haul it
in/out of your car to/from the house, you'll want to do that in the case...
adds another 30 or so pounds. I'm a strong guy but this thing is so big, it
is too awkward to move consistently without risking bumping it on something
or tripping... you got my meaning?
6. A/C Adapter. Meade does not come with one. You can fill
the fork arms with 8 C-cell batteries (at the cost of the extra weight of
the batteries - isn't this scope heavy enough as it is?) and it will run
about 20 hours on those. But you will eventually need power for heaters,
autoguiders, laptop, etc.
Optional Necessities
7. You should have a cross-hair eyepiece, probably 12mm, for
accurate alignment. Might be a good idea to get one that can later be used
for guiding.
8. Caps. Get some caps for your diagonals, etc to keep the dust
and dew out of your system. Meade doesn't provide covers for all the things
that have openings. A little trick I found is that 35mm film cases fits
nicely into a 1.25" hole. (check out www.ScopeStuff.com. They sell
inexpensive caps for all scope 'orifices')
9. I think it is a good idea to put a clear filter on the back
of the scope to keep dust out of the tube.
All these accessories are carried by Scope City and usually in stock.