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How to use a finder scope


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Hi guys,

I recently upgraded to a Celestron CPC 800, which came with a bog standard 9x 50 finder scope. I have used red dot finders and Telrads in the past so a finder scope was a new concept to me.

I have aligned this with the OTA and found it a fairly simple process as I did it during the day.

However, I found it fairly difficult to actually use the finder scope at night. I am so used to seeing either a red dot, or a Telrad projected onto the night sky that I found it almost impossible to align the finder onto the star I wanted. I had both eyes open, with one eye trained on the sky and the star I wanted and the other trained on the finder but I just couldn't marry the two together. The whole process was made even more difficult due to the fact that you can't even see the crosshairs of the finder in the dark. I ended up going back to my trusty Telrad in the end and had the GoTo set up in just a couple of minutes.

Now, I'm sure that there are better finder scopes out there than the one that came with the scope, but I wanted to know if there is a knack to using the things? Am I missing something fairly obvious? I should point out that I did check the alignment of the finder scope with the actual telescope during the session (by using a very distant streetlight) and found the alignment spot on so I know it's not that.

Has anyone else had similar experiences? Are finder scopes actually worth the bother or should I just stick to the Telrad?

Would be very grateful for your thoughts on this.

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RACI finders rule: the bigger, the better. Here is my 14x70:

I do not always get along with illuminated reticule finders, BTW, but the advantage of having illumination is that you can switch it off if it annoys, and turn it on again as needed.

Nice set-up, I can see you vague reflection on your SC... :)

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Thanks for the responses... Can't afford to buy anything else for a while now so I think I'll just stick to using the Telrad for now.

I didn't have a problem with the image being upside down and the one in the eyepiece being the right way up - after using a reflector for so long, I'm used to that. It just seemed to me that it was like trying to use an actual reflector telescope to align my SCT! There was no real way to check that the star I was actually trying to centre was the one in the finder. I even tried it with Mizar/Alcor cos they are pretty obvious, but when I thought I'd lined them up, it was only a single star in both the finder and the EP, so no idea what star it was actually on!

Tried it again this afternoon on some terrestrial and nature objects and found the whole process much easier. Think using it at night might take some real practice! :grin:

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I use a Rigel and a right angle illuminated finder (non corrected) for my C925. Rigel get the star into the approximate area, the finder fine tunes the pointing and finally object is centred in the main scope using a wide field eyepiece.

Personally I prefer uncorrected finder that's left right reversed, because the image in my SCT is left right reversed so I prefer my finder to be the same. Using L-R reversed finder means pressing the same buttons on the hand controller will give me the same movement for both main scope and finder, If I use RACI, the left right buttons will be have the opposite effect.

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Well, had another go tonight with much more success! Took your idea Keith and started off using the Telrad to get the approximate area, finetuned with the finderscope, and then lo and behold, object perfectly centred in EP! Wahey!

Still struggled a bit with the crosshairs at times, but I think I'm getting the hang of it now!

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Great stuff. It's really satisfying when you've been having frustrations but then the next time it begins to come together. It's happened to me many times but the rewards are worth the effort. Clear sky forecast for tonight so fingers crossed.

Kerry

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