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Very good solution for finders...

emadmoussa

By emadmoussa
in The Astro Lounge

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Delboy_Hog

Delboy_Hog

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Not too sure that I'd want my guide camera set up like that, to be honest.

OK for visual though

Could you help a newbie (technically when it comes to ds imaging, I'm not even a newb yet, I'm a newb-to-be!) and suggest why not?

Would it be down to how sturdy it is...or isn't?!  My first thought when I saw this was "great, I can get my finder on it so I can always have a peer through when I want to, and when I get my finder-guider sorted (on the scope I don't even have yet, but that I'm currently saving for!) this would be a great solution to prevent me from having to drill into my scope to create holes for a new shoe" (I'm definitely not brave enough!)

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emadmoussa

emadmoussa

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Could you help a newbie (technically when it comes to ds imaging, I'm not even a newb yet, I'm a newb-to-be!) and suggest why not?

Would it be down to how sturdy it is...or isn't?!  My first thought when I saw this was "great, I can get my finder on it so I can always have a peer through when I want to, and when I get my finder-guider sorted (on the scope I don't even have yet, but that I'm currently saving for!) this would be a great solution to prevent me from having to drill into my scope to create holes for a new shoe" (I'm definitely not brave enough!)

I really don't see why not - a small guide scope should work perfectly fine. I stand corrected.

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Zakalwe

Zakalwe

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Could you help a newbie (technically when it comes to ds imaging, I'm not even a newb yet, I'm a newb-to-be!) and suggest why not?

Would it be down to how sturdy it is...or isn't?!  My first thought when I saw this was "great, I can get my finder on it so I can always have a peer through when I want to, and when I get my finder-guider sorted (on the scope I don't even have yet, but that I'm currently saving for!) this would be a great solution to prevent me from having to drill into my scope to create holes for a new shoe" (I'm definitely not brave enough!)

No problem...it's a good question.

A guidescope's job is to lock on to a star and to track any "movement" in the star. Any apparent movement means that the guiding system issues a command to the mount to move the scope to bring the star back to the same spot.  Now the guide camera and imaging camera don't "know" what the other is doing. The system works on the principal that any star movement in the guide camera is assumed to reflect the whole system going slightly off track. Now, if the guide camera moves (perhaps due to it's mounting flexing) it will issue a movement to the mount. This will blur the image in the imaging camera. Bear in mind that guiding systems can detect movements on the sub-pixel scale.

From this, it's clear that the guiding system must be mounted as rigidly as possible. Any flex is a Bad Thing. IMHO, mounting a guide scope and camera on a standard finderscope mounting is prone to movements- after-all, in most finderscopes the scope is held in place by a rubber ring and a spring-loaded plunger. Putting that whole ensemble on a couple of brackets that are slide-fitted together and held with a single screw, then hanging another finder and RDF off the same tiny bracket looks to be a recipe for flexing and movement.

Hope that help...please ask if I haven't made myself clear.

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Zakalwe

Zakalwe

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I don't know about you, but personally the normal finder brackets never worked for me...very difficult to align and easily knocked out of alignment...

They are a bit rubbish, aren't they? Especially if you are lifting scopes on and off the mount.

I wouldn't trust them at all for holding a finderguider. I'm happy to be proven wrong, but a standard finderscope bracket looks totally unsuitable for guiding.

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leelee970

leelee970

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I agree with Emad and Zakalwe. the finder bracket is find for visual but when you look at the mechanics the finderscope is held one end by a rubber O ring and the other end  is spring tensioned by two plastic screws and a spring loaded one...... hummmm,

I myself mounted an 80mm scope and used oversized tube ring (which I drilled and tapped) to make a cheap but effective guide scope. The tips of the screws are not protected but then again I’m not too worried about damaging my ever so expensive guide scope (£20).

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emadmoussa

emadmoussa

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I agree with Emad and Zakalwe. the finder bracket is find for visual but when you look at the mechanics the finderscope is held one end by a rubber O ring and the other end  is spring tensioned by two plastic screws and a spring loaded one...... hummmm,

I myself mounted an 80mm scope and used oversized tube ring (which I drilled and tapped) to make a cheap but effective guide scope. The tips of the screws are not protected but then again I’m not too worried about damaging my ever so expensive guide scope (£20).

The finder scope that came with my GSO dob is still in the box unopened...can't be bothered even looking at it. While visually OK, stability is totally rubbish.

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Delboy_Hog

Delboy_Hog

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I really don't see why not - a small guide scope should work perfectly fine. I stand corrected.

Whoops, Sorry Emad, I wasn't trying to correct you, in fact I was agreeing with you - I thought this was a really good find...I figured this had solved my pending query about how to get a finder-guider and a finderscope on in one go!  :smiley:

Hope that help...please ask if I haven't made myself clear.

Very helpful Zakalwe, thank you!  They always seem fairly solid, the way the shoe screws into the top of the scope, so I was forgetting that the finder itself is held in by very easily moved springy things.

I don't know about you, but personally the normal finder brackets never worked for me...very difficult to align and easily knocked out of alignment...

Ha ha, yes, the amount of times I've head-butted my finder in the dark and knocked it out of alignment is crazy.  Though that might say more about my clumsiness (or the size of my head?) than the stability of the finder! :rolleyes:

There's a "two shoe" version of this available from somewhere, too.  Might be more practical for visual use.

James

Whoops, clicking on that link on the work computer triggered an IT access blocked, on account of attempts to view "weapons" :eek:  ...either we've got a very sensitive IT filter or I've completely misunderstood what a finderscope is actually for!

You mean this one?

orion%20dual%20finder%20mount.jpg

Ah, thanks Emad!  So two rocket launchers instead of three...  :grin:

And thanks all for helping my understanding.  Does look like a good piece of kit, but it seems perhaps there are better ways of setting up the guiding equipment.  Gratefully noted!  :icon_salut:

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Zakalwe

Zakalwe

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Very helpful Zakalwe, thank you!  They always seem fairly solid, the way the shoe screws into the top of the scope, so I was forgetting that the finder itself is held in by very easily moved springy things.

The problem is that a guiding system will detect movement of less than the size of a pixel. Thats a tiny fraction of a millimetre. That, at least in my mind, means that the mounting system needs to be as rigid as possible.

And thanks all for helping my understanding.  Does look like a good piece of kit, but it seems perhaps there are better ways of setting up the guiding equipment.  Gratefully noted!  :icon_salut:

You're more than welcome. Glad to help.

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