What is the use of a finder?

[farunj]

Hello everybody,

I am just wondering, what is the use of a finder for a goto scope? I mean the point of a goto scope is that it slews to an object in the database. So what's the need of the finder?

[Breakintheclouds]

Once you've got the scope set up, a finder isn't necessarily useful. But you'll need it for finding your alignment stars when doing the set up

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[Psychobilly]

Apart from getting the first alignment star into the FOV of the main scope not a lot...

On the Obs setup I used to do the alignment with the guide scope/cam combo...

Peter...

[farunj]

Thanks again! I suspected it was not of much use once the scope is aligned!

[ronin]

Many goto's are Mak's and SCT's these days and they will have a narrow field of view, a 25mm plossl in a 1500mm FL Mak will give less then a degree and that is small. Using Meade as an example you start out Level and North however either of those will not be totally accurate they are both a best guess usually, say thay are 2 degrees out, easily more.

The scope assumes perfection, so slews off to the first alignment star and so is 2 degrees off of the first star by 2 degrees and as it has a 1 degree view you see nothing, no alignment star to sstart with. That is when you use the finder with it's bigger view.

Additionally you may not bother to use the full goto, just put the scope down roughly set up and get going, you would then use the finder as on any other scope to aim the main scope at the patch of sky.

[Psychobilly]

I do use a finder on a DSLR/Camera lens setup even when using wide angle lenses... I mount a RDF in the hotshoe

I was thinking of asking a "supplementary" what is the use of an ep

Peter...

[sueandruth]

It gives a nice wide FOV if required

[baggywrinkle]

The RDF is Ok for doing an initial alignment but if you want real accuracy then a 9 x 50 finder combined with a narrow FOV EP (best still one with a reticule) will give good results.

I am getting (it is on its way) a dual mount fior both the finder scope and an RDF for my ED80. I like the RDF for general setting up but the 9 x 50 for accuracy and hunting out objects when the GOTO is not going to so accurately. A 9 x 50 finder is a powerful wee instrument, like having half a set on bins.

I also changed the 9 x 50 on my ED80. the original was a straight through, I now have a right angled one. Save doing yoga and ninja like moves when getting aligned,

[dmahon]

If you have a GOTO scope, once accurately aligned the finder is of no use.

If you have a GOTO scope with a camera and computer attached, the finder is of no use at all (use Elbrus, Astrotortilla or http://www.astrometry.net).

[Tinker1947]

There is the other side to the coin, some people like to find DSO without the GoTo, so a RDF or in my case a Telrad do a very good job, my Messier list were all found without GoTo, once the Telrad is set put a star in the centre and a 5mm EP will show it in its centre, there very good....

[farunj]

Thanks a lot everyone for the info! Cleared my doubt!