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Collimation Advice on Schmidt Newts

Started by Rod Kaufman, 09/26/2011 04:12AM
Posted 09/26/2011 04:12AM Opening Post
I recently purchased a new meade f5 schmidt newtonian ota directly from meade.(This is the improved LX75 version and not the older LX55 and they're blowing them out at a discounted price btw) I intend to use it primarily for imaging. The collimation appears to be off with my EZ laser collimator: the laser dot appears about an inch or so outside of the doughnut on the mirror and the return laser dot from the primary is on the periphery of the face of the laser collimator. Normally, in a newt, you'd simply adjust the screws on the secondary to place the laser dot in the doughnut and then adjust the primary to place the return image of the laser dot on the target face of the laser collimator. At present, I can't even get the cap off the secondary on the schmidt newt to get to the screws. Assuming I can eventually get to the screws, does the process with the laser proceed in the same fashion as in a newt or is it different? I understand the mirror needs to be offset in a schmidt newt but this is supposed to be done at the factory.
Anybody out there have one of these scopes and can offer some advice?
Posted 09/26/2011 02:50PM #1
Hi Rod,

I had one of those a while ago. You need to get the cap off the front to get to the screws. There was a thread about it on CN along time ago.

John
Posted 09/27/2011 05:33AM #2
I was the one who started that thread a while back. I purchased an old SN6 on AM and wanted to replace its horrendous focuser. In order to remove the focuser and install the new one (a nice Crawford Machine Shop 2-speed) I had to remove the corrector.

Despite a week of trying and lots of advice from this forum, I had zero luck. Those machine screws refused to budge.

So, in a flash of inspiration, I took the scope to a gun shop. The gunsmith had the screws off in 10 minutes. He said the heads were a small star drive. I had been trying a small Phillips screwdriver.

I replaced those screws with black Phillips-head machine screws from Home Depot.

So my advice to you is either get yourself a set of small star drive bits. Or, even better, take the scope to a gunsmith, have him remove the screws and replace them with normal screws.

Be careful not to drop the nuts down inside the OTA They could scratch the primary mirror or could get lost or wedged somewhere in there.

That scope now works fine with its new focuser. My grandchildren will love looking at the Moon, Jupiter and Saturn with it. I'd like to give it to them next year. But first I need to find a suitable cheap go-to mount to go with it.
Steve Gaber
Oldsmar, FL