Any interesting projects with an ETX125?

[vineyard]

Hello,

I have an old ETX125 (f15) - it's in very good condition.  I don't use it anymore, so am wondering whether it might be worth selling it to someone who could make more use of it.

But before I do that, was wondering are there any interesting projects that could be done with it to turn it into a dedicated scope.  (For example, I did think of putting a wedge on the back, since with the obstruction it's probably the same (or less) free aperture as a 4" frac - but then read that that would be a v-e-r-y bad idea for the secondary mirror!).

Any clever ideas?

Cheers,

Vin

[Anne S]

We owned an ETX105 about 15 years ago. If you still have the original tripod you can adjust it to make the scope an equatorial one. As to damaging the secondary, the tube will be at the same angle when you slew to an object, regardless of how it's mounted.

[Laurieast]

2 hours ago, vineyard said:

but then read that that would be a v-e-r-y bad idea for the secondary mirror!).

Why?

[vineyard]

7 minutes ago, Laurieast said:

Why?

I think it depends on how the secondary is attached - I've read in some places (CN if I recall) that if the secondary is glued, then the reflected sunlight hitting the secondary could melt the glue.

Ah sorry, I just realised I was clumsy - when I was saying "wedge" in the original post, I meant a Herschel WL wedge rather than a tripod wedge.  Apologies.

[catburglar]

I’ve had each size of ETX at one time or another- the optics have always been great…Your ETX125 would make a great WL solar scope with a front mounted filter rather than a Herschel wedge.

My current 90mm OTA, mounted on and SW Heritage Virtuoso tabletop mount and with a Baader Astrosolar film from mounted filter is my white lite solar setup. Ready in 2mins, with no cool-down issues and good enough (although not perfect) tracking simply by eyeballing where north is.

I always found the goto accuracy a bit temperamental on the ETX’s (I had the older generation- I’ve no experience with the newer observer models), but you could probably align it at night and then park it and move it indoors. As long as you eyeball the home position reasonably you’d probably get tracking as good as the heritage when you unpark it in daylight.

[vineyard]

Thanks @catburglar yes that is what I'm leaning towards. So you deforked it?  I'm curious if it could be turned into some form of crude spectrohelioscope - will ask on Solarchat!