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ETX TECHNICAL TIPS
Last updated: 24 February 2001

ETX 125 Adapter for Manfrotto Tripod

From: davidstenhouse@stenhouse77.freeserve.co.uk (David Stenhouse)

Please find attached a small selection of photos of my adapter and scope.

I have based my design loosely on other adapter plates I have seen on your excellent site, but have chosen to make mine circular, since the scope may slew all the way around during an evening's observing, with me following. There are 6 holes that can take eyepieces, although one lets the lead from the Autostar hang vertically, and another conveniently carries my red-filter torch. Three cut-outs can hold the Autostar, so that one is always handy wherever I am positioned.

The plate is made from 0.25 inch quality ply (obtained at my local hobby shop), and has a doubler at the centre, necessary to allow clearance of the tripod's central fixing stud.

adapter plate

The Manfrotto features three tapped holes which I have used to attach the adapter (using countersunk bolts).

adapter plate To fix the scope to my adapter, I have sandwiched the steel plate supplied by Meade, and used the 2 main tapped holes (0.25 inch, 20 tpi as per the ETX 90). I have also utilised the three fixing points that take the plastic base plate and battery holder assembly, since the castings inside the scope are almost as sturdy as those that take the 2 main bolts. As far as I can tell, these bolts are 3/16 Whitworth. Bolts that are 1.25 inches long are ideal with a washer under the heads. I had to drill out the three holes in the steel plate a little to allow the bolts through. The result of using 5 fixing points is a really solid and trustworthy connection to the adapter. I might add that personally I wouldn't fancy hanging the whole assembly at 53 degrees in polar mode on just the 2 main bolts, given the state of the tappings - see later (as it is, I'm stuck in alt/azimuth mode using my current set up).


adapter plate adapter plate

adapter plate Why the Manfrotto tripod? Simply because I already had one. I will probably save up and purchase something more suitable at some point, but it will do for now. The images that I am obtaining are stable, and the settling-down time after adjusting focus is satisfactory (a few seconds at most). Another nice touch is that once levelled, it is easy to rotate the whole set-up, adapter and all, to line up with North, simply by releasing the clamp on the central pillar.

Why did I choose the ETX 125? Truth is, I didn't! My wife entered my name in a prIze draw just before Christmas being held by the New Scientist magazine, and I won first prize! Truly amazing! The scope came complete with Autostar, and the cable connection kit.

What do I think of the ETX 125? Optically, it appears to be very good so far, although I haven't had a chance yet to take it to a good dark site (light pollution in North Merseyside, UK is dreadful). It certainly gives my trusty 10 inch home-built Dobsonian a run for its money, provided it has had a couple of hours outside to cool down. Optics aside, I'm glad that I didn't have to fork out the necessary 1100+ for this equipment. Plastic gear trains have never been a favourite of mine, and who in their right mind would sit such an instrument on three rubber feet attached to a bendy plastic plate? The thread tapping for the main bolts under the scope is really poorly done, and I'm not too excited about the connectors that have been used for the Autostar, which necessitate visible bare wires. This might be staisfactory, but it looks really amateurish. I like Autostar, and after having 'tuned' the scope (thanks again to your web site), trained the gears, and downloaded and installed the latest firmware and database, have found it to be proficient at finding objects. By the way, the updating procedure for Autostar went without any hitches at all. The only thing that I did do prior to the upgrade was switch off my PC screensaver. For those interested, I'm running Windows 98 Second Edition.

Overall conclusions; a great little telescope that is easy to use. It is going to be excellent for taking away on holiday to some nice dark places.

David Stenhouse
North Merseyside, UK.


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