Red dot finder

Don't be shy! If you're just starting out, here's the place to ask that first question

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millsey
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Joined: Sat Jul 07, 2012 6:48 pm
Location: Chelmsford, Essex
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Red dot finder

Post by millsey »

Hi, just came across this forum, and thought it worth asking what is probably a dumb question :oops:
I brought a Celestron Astromaster 130 about 6 months ago, but try as I might I just cannot see how the red dot finder can be used to find a star or planet ? The instructions say just look through with both eyes open and line up - but this doesn't seem to work for me ? So far I have just studied the moon as I can find this easily by aiming the scope manually !!
I searched this forum before posting, so apologies if the subject has already been covered.
Thanks for any help :)
John
David Frydman
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Re: Red dot finder

Post by David Frydman »

Dear John,
Welcome.
I had a red dot finder and used it a bit, but preferred an optical finder.
Someone on this forum who actually uses one regularly will probably advise you.
But I just wonder if you wear glasses and whether you have good stereo vision.
In other words do you have a dominant eye that does not easily line up with the other eye.
Also is everything in focus.
There is an astro club somewhere near you.
I think Rachel who posts here mentions it sometimes.
There are also several others living in Chelmsford.
My firm where I worked was based there a long time ago.
If you look at the Federation of Astronomical societies it will list clubs near you.
I think there is a link here.
If you try to line up the Moon and the red dot finder does that work?
Maybe the stars or planets are too faint or are out of focus.
Do you have bad light pollution?

Regards, David
David Frydman
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Re: Red dot finder

Post by David Frydman »

Dear John,
You have to align the finder so the finder and the telescope are pointing in exactly the same direction first using a bright object, maybe the Moon, before you can find other objects with it.
If you are looking with the finder using the right eye and that does not work, try using the left eye.
Use the lowest magnification eyepiece on the scope.

Regards, David
The Bat
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Joined: Thu Sep 04, 2008 3:36 pm
Location: Gt Dunmow, Essex
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Re: Red dot finder

Post by The Bat »

Hi John

Best thing with any kind of finder is to align it in the daytime. Find an easily identifiable object such as a chimney or lamp-post in the main telescope. Then look through the finder to see if your red dot is centred on the same thing you can see in the eyepiece. If not, then you need to adjust the screws on the finder until the red dot is in the right place.

As to actually using it, we have sometimes found that when people come to us with problems using red dot finders, sometimes they are looking through them slightly crooked instead of straight through. If there are two rings forming your finder, you need to make sure that they are lined up when you look through, like a gunsight. With a red dot finder, I personally find it easier to use with one eye, as you can only see unaided eye stars with them. With a magnifying optical finder, it helps to keep both eyes open because you see many more stars with an optical finder.

If you still have trouble, you could always it along to one of our meetings of the North Essex Astronomical Society. You could bring it to one of our public lectures (next one is on Weds 18th July) or one of our public observing events at Great Notley Discovery Centre (next is a solar observing day on Sat 21 July at midday). One of our members will be more than happy to give you a hand. Details are all on our website.

Hope that helps. :D

Rachel
Celestron C8-S XLT
CG5 mount, dual axis motor driven
Imaging Source DFK21AF04.AS camera
North Essex Astronomical Society
millsey
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Re: Red dot finder

Post by millsey »

Thanks David & Rachel for your advice, if it ever stops raining I'll try to give it some serious time. I had noticed the need to get the two circles lined up, but perhaps I wasn't persevering ! I work in Braintree, so maybe I'll have to drop off at the Discovery Centre on a public event.

John
Eclipse
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Re: Red dot finder

Post by Eclipse »

I found the best place for a red dot finder was in the trash, and my poor back agreed 100%. My SV102ED currently sports a green laser pointer for coarse finding, and a 50mm optical finder with a 90 degree eyepiece for finer adjustment.
Coronado PST with SME-40 double stack H@ filter
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