45 degree corrected image prism

[Eyeball]

Would it be possible to use a 1.25" 45 degree corrected image prism with a Newtonian reflector?

[Cornelius Varley]

You may find that you will not be able to bring the telescope into focus with the added length of the diagonal.

Peter

[Eyeball]

You may find that you will not be able to bring the telescope into focus with the added length of the diagonal.

Peter

You can get a straight erecting eyepiece, which comes with an extension tube if the eyepiece will not focus. Trouble is it is a fixed magnification of 10mm.

[John]

The focussers in newtonian scopes don't have a great deal of travel - typically 30-50mm. As Peter says a diagonal (mirror or prism type) uses up a fair amount of that travel itself so there is every chance that you won't be able to bring an eyepiece to focus.

Refractors and schmidt or maksutov cassegrain designs provide a lot more focusser travel so they don't have this issue.

Of all the scope designs the newtonian is perhaps the one most specifically designed for astronomical use, where the norm is the inverted image.

[LukeSkywatcher]

By the info given here its a good thing that i am getting used to the upside down/back to front world of the Dob. Stars and planets i can deal with. I'm having a bit more trouble accepting my new views of the moon. Everything that was at the top is now at the bottom. Its as if i suddenly live in the southern hemisphere.

With regards to the usual suspects, I have to say that finding M42 was a bit of a task and M45 just looks plain weird.

Spose i will get used to it.

Its like i am seeing ALL these things for the very first time. Its kind of exciting i have to admit. I love the hunt involved with non-GoTo scopes. The Dob has just kicked the hunt up a notch or two.

I have to admit that a couple of times i searched for Mars................i have actually ended up looking at Betelguese..............but it was "twinkling", so i knew i was off the mark as planets do not "Twinkle".

[John]

I've got a newtonian and two refractors so I have to mentally adjust as I switch between them !.

I believe purists prefer to use refractors without a diagonal so they get the inverted image that newtonians produce ......

[LukeSkywatcher]

I've got a newtonian and two refractors so I have to mentally adjust as I switch between them !.

I believe purists prefer to use refractors without a diagonal so they get the inverted image that newtonians produce ......

I'm sure they do. Afterall Mr. Galileo (or Mr. Harriot) didnt have the luxury of a star diagonal. So the "pureist" view is what the Newtonian produces.

I have never tried observing by removing the diag from my refractor and simply screwing in the EP into the tube.

Would that even work?.

If "purists" can do it.............i'm guessing i can do it. I suppose the mirror on the star diag isnt really that important. I must try it sometime. I'm also thinking of not using the counter weights etc on my EQ mount, so that my refractor becomes an Alt-AZ scope.

[John]

.....I have never tried observing by removing the diag from my refractor and simply screwing in the EP into the tube.

Would that even work?....QUOTE]

If your refractor has enough focusser travel, yes. Some refractors are designed so that they will only come into focus with a diagonal fitted though.

[LukeSkywatcher]

.....I have never tried observing by removing the diag from my refractor and simply screwing in the EP into the tube.

Would that even work?....QUOTE]

If your refractor has enough focusser travel, yes. Some refractors are designed so that they will only come into focus with a diagonal fitted though.

Good point. I'm pretty sure (nearly positive) that the threads on my star diag are about 4 times as long as the threads on my 1.25" EPs, So sticking an EP into the OT and getting good focus may be a real issue.

Sorry the focuser wheels themselves have a pretty good distance between min and max so maybe it will work.

[Eyeball]

When I look at the night sky with the naked eye or (in my case) 20x50 monocular, I naturally see it in its normal state. In your minds eye you take in that view. The view you then see with a reflector is not the view that you have previously taken in.

I can memorise the position of a particular target and lock on to it straight away using the monocular, but just cannot do so using the reflector.

Even if it is merely to lock on to a target that I see with the naked eye, I need to have a corrected image of it when using the scope.

What I am trying to achieve is the best way of doing that.

[LukeSkywatcher]

Honestly..............forget seeing objects the correct way up (as your eyeball sees them). Just go with what you have.

[pvaz]

Have you considered standing on your hands while using the monocular?

[Eyeball]

I do not mind looking at an image that is inverted, where celestial targets are concerned it doesn't really matter. My problem is locating those targets when the 'wide-field' view is inverted. I just need a method of overcoming this that works for me.

[pvaz]

I understand. I have a right angler finder that haves the image corrected, and also a telrad.

Maybe you should upgrade your finder.

[Eyeball]

I understand. I have a right angler finder that haves the image corrected, and also a telrad.

Maybe you should upgrade your finder.

That would be the ideal solution if such a finder will fit on the Heritage 130P that I have.