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newbie question re lunar magnification


li'l john
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Hello all, I'm brand new to all this, just got my first scope, a little 70mm, 500mm focal length SW Mercury 705 refractor. Only had one opportunity to use it so far due to clouds mainly ( I was warned).

Anyway when using it I was looking at Orion when I realised I was happily de-aligning my red-dot finder (I was just back home from work). I decided to aim the scope at the Moon and re-align which seemed to go well using a 25mm EP (20x). I was unprepared by just how lovely the Moon looked BTW and spent quite a while moving along the terminator when I thought I'd better try to re-align properly with my 10mm EP (50x).

I tried this but couldn't see anything more than a tiny speck or disc that wasn't too bright. I tried refocusing from "one end to the other", as it were but to no avail. I also tried a 2x barlow with the 10mm EP but no joy resulted. I must be doing something daft but can't see what it is.

Can anyone give me an idea of what I did wrong please?

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  • 2 weeks later...

I don't agree with john56. assuming your stated figures are correct (in fact they are - just checked), your scope has a focal ratio of f7.14. based on the aperture I believe you could use eyepieces from around 5mm (100x) to 32mm (15x). you could get this higher magnification with a 10mm in the 2x barlow. if it's working well now this is good news.

on the moon/double stars you might be able to push the magnification a bit so maybe you could get an additional eyepiece - maybe an 8mm but if you buy plossls they will start to get tight on eye relief and you may be better with something a little more comfortable, maybe even one of the cheaper zooms might be a good choice although I am not a fan of them per se.

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