Meade LX90 Owners please help

[Sirius1066 (Earl)]

Hi guys,

I just purchased a Meade LX90 8" ACF GPS UHTC and took delivery on Monday.

Tonight it saw it's first light. Overall I was really happy with it. Once alignment was done it slew straight to every object I chose. The optics were great, got some wonderful views of Saturn, Mars and took some reasonable pictures of the Moon with my iPhone held up to the eyepiece. It was heaps of fun.

The one issue I have is that I was expecting it to have Level North Technology. However I couldn't get that to work or even find it. I had to level and point it north manually.

Does this scope come with LNT or am I confused. I couldn't find anything about it on the Meade site. Any help you can offer would be appreciated. I would also love any other suggestions.

Clear Skies

Earl.

[tonybarry (Tony)]

Hi Earl,

I have an LX90-10" ACF purchased about a year ago. It did not come with LNT either. The word from Bintel was that it did not help much in alignment.

My personal opinion is that LNT is a Good Thing. It was on my previous LX90-8" and that scope was a great bit of kit. I used it heaps and it never missed a beat. Initial slews were within a finder of the target star.

However, the new LX90 did come with a poxy compass / bubble level which can live in the eyepiece holder of the diagonal. That device is supposed to be as good as LNT. I use it, but don't expect my initial slews to be Anywhere Near the target stars, unlike the real LNT module.

Moral of the story - Meade giveth, Meade taketh away.

Enjoy the new scope - the Autostar / Audiostar is a very good bit of gear, despite no LNT. I have found that tracking (unguided following of a target) is very much better on the new LX90 than on the older one. I can now do 20 second exposures at f/5 with a good chance of round stars rather than egg shaped stars. The old LX90 was limited to about 2.5 seconds exposure when tracking at the same f ratio.

Regards,
Tony Barry

[acropolite (Phil)]

I wouldn't fret over the lack of LNT.

I'm of the opposite opinion to Tony on LNT, my early model LX had LNT, I quickly found that the easiest way to get accurate alignment was to manually set level and point the OTA to north. I found the LNT to be quite hit and miss depending on the proximity of any magnetic materials nearby. With accurate manual alignment I found that slews were usally close to the centre of the field of a 14mm ep, the LNT would sometimes achieve that but not consistently.

[DavidTrap (David)]

+1 for Phil's opinion

DT

[mozzie (Peter)]

when i owned my lx90 i removed the lnt module it did work but as i had the scope in a pod i did 2 star align..the lnt module had a problem with over riding the autostar when parking scope and would never be accurate when turned on ended up getting andrewj to sort some programming out through bintel so as to be able to use park mode..

[jenchris (Jennifer)]

Don't have it on mine - I use a compass and a small brickies level - takes all of 20 seconds to set it if I'm using Alt Az - I have it on a wedge mostly now anyway

[Sirius1066 (Earl)]

Thanks for you reply guys.

I took it out again tonight. Since I didn't spend an hour tonight trying to get a non existent LNT to work, manual leveling north took all of 30 seconds. Very simple! The first alignment star it picked was Sirius and nearly slew to it. it was about 2 degrees outside of the FOV of my finderscope. I was hoping for a little better than that. Any Advice?

The second star it picked was Antares. It slew straight to it and was within the 26mm eyepiece. I was over the moon about that.

For the rest of the evening it slew directly to every object I picked. No dramas at all. Overall a fantastic result.

[jenchris (Jennifer)]

As it should be, it's what mine does too.
Your local magnetic north may be out a little with the programmed one, the first star corrects for that

[DavidTrap (David)]

Agreed.

Probably means you were slightly off when you pointed the scope "north". Very easy to do. Lot of metal in the scope and tripod, so your compass can be affected. Doesn't take much to be outside of a 5 degree field of view on your finder. I seem to recall AndrewJ saying you can undo the locks and manually centre your first star, as it's only working out it's "model" based on how far out it is with the second star.

Two pieces of advice to get good pointing with an LX-90:

a. level the tripod carefully - use a bubble level

b. train the drives on a distant terrestrial

c. take your time accurately centering the stars, ideally with a reticle eyepiece

If I did the above, I was rewarded with accurate goto across the sky and tracking that would leave an object within the field of view of a 12mm eyepiece for hours on end.

DT

[acropolite (Phil)]

The first alignment star it picked was Sirius and nearly slew to it. it was about 2 degrees outside of the FOV

Mine has always been the same, the alignment stars are never close. I seem to remember reading somewhere that the alignment stars are deliberately placed a little out, and the slewing process to the star is a necessary part of the alignment process (perhaps correction as Jen suggests). I can't remember where I read it though.

As David said, once aligned, tracking and slews are very accurate.

FWIW at my usual place of observing I use true north marked from the shadow of a vertical stick at solar noon as per this thread.

[AndrewJ]

Gday Phil

I seem to remember reading somewhere that the alignment stars are deliberately placed a little out, and the slewing process to the star is a necessary part of the alignment process

Old wives tale
The scope uses dead reckoning to centre the first star.
It does a "synch" on that star, and thats why the second slew gets much closer. After the first star is centred, all the autoaligning generated info is discarded.

The three things that affect the first slew are
a) base level
b) north setting of OTA
c) level setting of OTA.

If you have a semi permanent spot where you set up
do a two star align then tell the scope to slew to AZ = 0, Alt = 0 ( via the Hbx )
Note the line the OTA makes as that is the "true Nth" for that spot.

Andrew


closer to level an

[Sirius1066 (Earl)]

Thanks guys,

Great advice. It is cloudy and raining tonight so will need to try the advice tomorrow.

I just downloaded an App for my iPhone called Scope Tools. Anyone know how good the true north compass is in that.

It might solve the problem of magnetic north being off at my location.

[acropolite (Phil)]

Most likely as good as useless, if your'e observing in the same spot use the Solar Noon method, it's 100% accurate.