better finderscope/telrad/flip mirror indecision

[troypiggo (Troy)]

I'm not happy with the finderscope on my ED80, nor the one on the C8. Frustrating pointing at objects high in the sky, having to kneel down and crane neck in all weird direction to not bump camera focus etc. Thinking of other options.

I do kind of like using the finderscope where you look through with one eye and look at the real object with the other eye and align the 2 overlapping objects. Downside is the abovementioned awkward when overhead.

Started thinking about 90 degree or diagonal type finders.

At Astrofest I saw and quickly looked through a Telrad for the first time. Pretty cool, but don't you have similar problems if overhead targets?

And I've heard about these flip mirror systems. 90 degree eyepiece, illum crosshair maybe? Is it ok to put them on the imaging scope or preferable/recommended to keep them on the guide scope?

Any thoughts, clarifications, or opinions on the above?

[peter_4059 (Peter)]

Troy,

They each have their strengths and weaknesses. Flip mirror works fine on the imaging train as long as you can still achieve focus however the field will typically be narrower than your finder. Telrad has no magnification so won't be able to see dim objects - just the star field. You don't need to have your eye near the telrad to use it so it's not like the finderscope issue for overhead objects. Right angle finder puts the eyepiece in a better position for viewing however as you point out you can't view through both eyes. I've ended up using all three (telrad on the main scope and the right angle finder and flip mirror on the guide scope).

You're welcome to come and give mine a try if you want.

Peter

[rogerg (Roger)]

For the ED80 I'd use just a telrad or other red-dot-finder. For my Megrez90 I just use the William Optics red dot finder and great. An advantage of them over the finder scopes is that you can be some distance back from them and still use them - I often look at my red dot finder from about 50-100cm away due to viewing convenience.

For the C8, I think you'd need some magnification so a red dot finder on it's own would not be sufficient, but I could be wrong.

I have a friend who has a telrad and 90 degree finderscope on his dob. Works well for him. Personally I don't like the 90 degree finder because with all finderscopes and red dot finders I rely on having both eye's open and overlaying the two images, so to speak. You can't do that with a 90 degree one.

Roger.

[mithrandir (Andrew)]

The standard finder on my C8 is fine - as long as the target is below about 50deg. Beyond there you need to be either vertically challenged or young and I'm neither.

I have a Meade 2" flip mirror I can put on the back and it is fine with my DSLR or CCD, as long as I don't want to use an SCT style reducer. Then it will not focus.

You have to be really careful adjusting the mirror stop. If it isn't dead right, an object on the cross point of a 12mm illuminated reticle will not even be visible on the CCD.

I have an ST80 guide scope on of of the C8. I'm going to get an Orion flip for that so I can use it as a finder for objects above 50deg and save my back and neck.

As for a Telrad - I've run out of holes to attach one.