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LX 75 goto mount questions.

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#1 sopticals

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Posted 15 April 2011 - 10:36 PM

Hi all,
Just bought a used 6 year old 8" f5 Skywatcher newtonian with LX75 goto mount with StarGPS.The Meade Autostar hand controller has custom software instaled to run the StarGPS.

Being a push/pull dob man this technology is a quantum leap.What are the strengths/weaknesses with the LX75 with the StarGPS etc?

What are the issues with maintaining proper function of the mount?

Please can you rate on a scale of 1-10 the difficulty of mastering use of mount?

Any suggestions on source of easy to follow manual for the operation of mount?

Can the LX75 as equiped be used for astro-photography? If not what are the problems?

If you own/have owned the LX75 what do you like/dislike about it?

I have yet to pick up the scope but have been assured its in very good working condition.

Thanking all in advance for your inputs.

Stephen. :question:

#2 rmollise

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Posted 16 April 2011 - 07:50 AM

Hi all,
Just bought a used 6 year old 8" f5 Skywatcher newtonian with LX75 goto mount with StarGPS.The Meade Autostar hand controller has custom software instaled to run the StarGPS.

Being a push/pull dob man this technology is a quantum leap.What are the strengths/weaknesses with the LX75 with the StarGPS etc?

What are the issues with maintaining proper function of the mount?

Please can you rate on a scale of 1-10 the difficulty of mastering use of mount?

Any suggestions on source of easy to follow manual for the operation of mount?

Can the LX75 as equiped be used for astro-photography? If not what are the problems?

If you own/have owned the LX75 what do you like/dislike about it?

I have yet to pick up the scope but have been assured its in very good working condition.

Thanking all in advance for your inputs.

Stephen. :question:


Is it working? Then don't worry about it and don't start tinkering.

It would be impossible to put a 1 - 10 figure on the mount's difficulty. Some folks build radio transceivers for fun, some can't program a VCR. Best advice? Read the manual, then read it again. If it's not clear, come here and ask questions.

The 75 can be used for photography. Problems? It's a mid-sized inexpensive Chinese mount. The biggest problem is that astrophotography is a difficult art no matter what the pedigree of yoru equipment.

The LXD 75 can be OK. I don't like the Autostar much, and the mount has a reputation for transfer gears that come loose and slip over time.

#3 Charlie B

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Posted 16 April 2011 - 08:47 AM

What are the issues with maintaining proper function of the mount?

Please can you rate on a scale of 1-10 the difficulty of mastering use of mount?

Any suggestions on source of easy to follow manual for the operation of mount?

Can the LX75 as equiped be used for astro-photography? If not what are the problems?

If you own/have owned the LX75 what do you like/dislike about it?

I have yet to pick up the scope but have been assured its in very good working condition.



First - let me recommend the book "A User's Guide to the Meade LXD55 and LXD75 Telescopes" by Martin Peston. This book is part of Patrick Moore's Practical Astronomy Series. This book will help you master the mount. It is not more difficult to use than any other GOTO mount and has some software that helps.

Like Rod, I'm not too fond of autostar. You need to install it for the drivers, but you don't have to use it. I used Nebulosity and PhD guiding for capture and autoguiding. I'm a big fan of Nebulosity and think that it made astrophotography with the LXD75 easier.

I used the LXD55 and LXD75 for imaging for about 3 years and found the following problems:
The gear's stock setscrews seem to be pot metal and come loose. Steel setscrews are only a few dollars at scopestuff and easily replaced.

I like the portability, but found it too light for my setup.

Backlash adjustmets are a pain - use the method by Mark Jordan at LXD75 Mainenance 101.

Your 8 inch plus guiding may be a bit heavy for the mount and cause clutch slippage - balance is critical to get this to work. A smaller scope would be better. I only imaged with my 8 inch when at star parties, where I could put a lot of time into balance and alignment on the first night, knowing that I would have other full nights for imaging. Even then, I tended to use smaller scopes and telephoto lens on the camera.

Good luck with your imaging.


Charlie B

#4 michael hester

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Posted 16 April 2011 - 02:35 PM

I just got done with re-tweaking my LXD75 to remove the backlash from the RA axis and tighten it up a bit.

1. Maintaining it:
Its a German Equatorial and with that you have to practice balancing its 2 axes. It will be properly balanced when it feels equally hard to move the axis you're balancing on each side. Balance with all your gear in place.

GEM also has to be polar aligned. The LXD75 comes with a polar scope in it so you can use that to align the mount.

2. 6/10
The Autostar controller is slightly more user friendly than other brands (so far as i have used, its definitely more friendly than the iOptron controller). It will guide you through what you need to setup. Follow steps in your manual to setup the mount. The 8 inch newt is probably too heavy for that mount though. Even though its in a CG-5 class its probably more comparable to the CG-4.

3. Meade has the manual online for it. You can use that and it's pretty good. They don't really tell you how to use the polar scope though: Find the little dipper, with the mount pointed toward polaris align the counterweight bar to point to kochab, then put polaris in the circle in the scope.

LXD 75 is astrophotography capable. You will be guiding with either ascom or envisage if you have a meade camera. The mount has periodic error correction on it, and you might need to train that. The manual tells you how. I would not put your 8 inch newt on it for photo though, its too heavy. The mount probably has a max 15lb payload. Make sure that the pole that attaches the mount to the base has a washer on the bottom side of it. The mount can be fairly wobbly unless you can tighten it down. I think a 3/8 washer stack will let you tighten that enough.

I've used a dual refractor setup on top of this mount effectively.

Clear the DEC backlash by pressing UP on the controller till the guide star moves, that will definitely help your guiding when you do that.

Final thoughts:
The mount is good for a light to moderate payload. For visual with a max 8 inch CAT or a refractor its great. For larger instruments you need something with a larger payload. The software is more user friendly than other systems. Its a GEM so you'll need to get used to a GEM.

#5 Charlie B

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Posted 16 April 2011 - 03:06 PM

I forgot about another problem. The polar scope on all three of my mounts became loose and almost impossible to keep aligned. I finally fixed this by replacing the alignment setscrews with thumbscrews and installed a second support washer in the front of the polar scope.

After the modifications, the polar scope worked fine, but I learned that I could align the mount using the "1 star alignment" routine followed by the 2 star alignment until the polar alignment was good enough. After that, I almost never used the polar scope.

Also, buy plenty of batteries for the polar scope. I constantly left the light on and killed the batteries. I usually bought Maxell LR41 alkaline cells in 10 packs.

Regards,

Charlie B

#6 Scott in NC

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Posted 16 April 2011 - 06:30 PM

Backlash adjustmets are a pain - use the method by Mark Jordan at LXD75 Mainenance 101.


Charlie B, thanks for sharing that link. I had never read that website before, and had actually been wondering if someone had put together a concise guide for LXD75 maintenance.






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