Affordable Tripod Mounts for Onstep Steps

Howard Dutton

I just hope he takes the "Celestron Astromaster 130 EQ" scope out and has some fun with it.  Take some shots of the moon and planets through it and some wide field shots with the camera on the mount OTA ring.

That's a 5" Newtonian on a little GEM.  I actually had a similar size (130mm f/5) Meade 'scope given to me and passed it on to a friend of a friend with an interest.  It had Autostar goto but probably the worst mount I've ever seen up close and personal LOL.  Still usable despite the mount and the optics were half-decent once I collimated them properly... and probably that was the first time they ever were.  I'm pretty sure the mount on the Celestron above is better and more usable even if it isn't goto.  Given that wobbly awful fork mount vs. a small GEM, I'd put my money on the GEM.

George Cushing

I don't look at retail mount pricing often. So I was a bit shocked to see the price of a Celestron AVX is $900. Used they are selling for as little as $350. And from what I read they seem to have reliability problems. If you're involved in repair and service as I have been, you deal with folks who have spent significant sums on equipment only to face the frustration of either expensive repair parts or useless obsolete equipment. Conversions to the OnStep system, even if some of the work is farmed out, are about half the price of a commercial motor control board replacement. Moreover, it frees the user from the constraints of a product created for a mass market and permits more freedom to design for one's needs.

As a DIY product it forces the user to become involved in the design and construction of the system gaining an understanding of it. This removes the mystery of how things work for those who may not have this understanding, thus gaining experience that will help them deal with the greater world we are entering into. I'm told my new truck has over 200 sensors and microprocessors. 

Mark Christensen

I"d like to second what George says and add one more consideration - maintenance when you have vanishing vendors (or vanishing parts). The electronics industry moves fast and doesn't think in terms of decades of maintenance. We need to if we expect to be in this avocation for decades. I'm heading into my 6th and hopefully have a few more in the barrel.

I've fixed a couple of friends commercial mounts and getting spares is either impossible or expensive. Why? Often the design choices made by the engineers at the major manufacturers make it very hard or impossible to get drop-in parts and their supply chain doesn't provide spares. Aside from main worm gears and wheels most of the mechanical stuff can be fixed with commercial parts (bearings and the like), or a bit of machining or sheet metal work.

Electronics is another matter...I've had to fix and in some cases adapt older electronics which the manufacturers would not support, or wanted the entire 40lb mount shipped to even look at, or wanted outrageous sums (like $1,400) to replace some simple, older, electronics. That kind of quote is equivalent to telling you to go away.

If you've made it yourself you'll know how to fix it and you can make design choices that make it easier to fix.

For example, many GOTO mounts use servo motors with encoders. The astro-makers pick odd-ball gear box ratios and then things like 256 counts/per rev (64 lines) reflective encoders. 100, 200, 512 and so on are very common numbers - a dime a dozen on AliExpress. Not so for the 256 number, esp. in reflective (as opposed to transmissive) encoders. The mount manufacturers solution is to sell you a complete motor+gearbox+encoder. There are other solutions that are much cheaper but are not a drop in.

This is typical of what you encounter with commercial electronics - maybe OK with a $200 cell phone you replace every few years. Not OK with a telescope mount where the electronics is (or should be) a small fraction of the cost. Mounts last for decades, at least mechanically.  The problem is the electronics, which may not be robust and probably uses parts that are not or will not be available in a decade or less.

Another potential problem is the software - often the manufacturers farm that out and then don't get control (or understand) the source code. At least one manufacturer has a GOTO mount still for sale for which they freely admit they can not do updates to the software. And they won't provide the software to the user community. Again, fine for a piece of disposable electronics like a cell phone.

So we have to make our own plans - the manufacturers don't seem to think in terms of decades of operation and maintenance. Maybe at their price point and the size of their market they can't.

Mark Christensen
PS: I do this kind of work for friends for my amusement, I don't need the business.

George Cushing

I agree with all that mark says. Even if you do repairs as a business, what do you have to charge for tech time? The local appliance place is $85 an hour. Our new $700 washing machine wasn't working properly. I ran the deep self-diagnosis and it found no issues. The service guy diagnoses insufficient water supply. The cause: $60 hoses that are designed to stop high flow rates in the event of failure. Service call $150. New cheap hoses $20.

You can't be in control of everything, even though I try. But at least OnStep let's me be in control of something!