Question 1

I've a C90 celestron spotting scope, 1250 mm of optical focus. I use it for astronomical view as well. Will this eyepiece work with it..??

Accepted Answer

a 2.3 give you over 500 power,a c90 can handle a max with good viewing about 180 power,take 1250 divide by mm of lens,how about a max of 6mm

Question 2

Will the 2.3mm eye piece fit the astro master 130eq? Thx!

Accepted Answer

Basically no.  It will "fit," but it will not be usable because it will be too much magnification.  Magnification is your focal length of the scope (650mm) divided by focal length of eyepiece, so 650/2.3= 282 power.  About 175 power would be max for that scope, but a 5mm at 130 power would probably be plenty.  You'd likely get more use out of a 9mm for 72X

Question 3

How does this compare with the Celestron Luminos for planetary viewing?

Accepted Answer

X-Cel LX have less light scatter and are better suited for planetary viewing. Luminos have better light transmission and wider field of view and as a result are better EPs for DSOs

Question 4

re x-cel 25mm I have celesstron first scope 80 eq  900mm focal  is this good for moon view Would I see whole moon or the craters well etc.? 80mm f/11

Accepted Answer

This eyepiece would provide 36 power through your scope, so you would be looking at the whole moon.  To determine what power an eyepiece would provide divide the focal length of the telescope by the focal length of the eyepiece (900/25 = 36 magnification).  I basically see the entire moon in my eyepieces up to about 90 to 100 power.  Too see craters in more detail you need to have around 150 magnification or more so to accomplish this with your scope you need to have a 6mm eyepiece (900/6=150).  Also your scope's theoretical maximum effective magnification is about 160 power, to determine the theoretical maximum of a telescope you take the aperture of your scope in inches 80mm is 3.15inches and multiply that by 50, therefore 3.15inches X 50 = 157.5 max power.   The moon however is a big bright easy user friendly target so you might be able to get away with 200 power for looking at the moon but not anything else really, unless you get a scope with more aperture.   So if you want to have a go at studying the craters a bit closer, to do that in your scope you could get a 9mm eyepiece that would give you 100 power and then use a 2X barlow lens that would double your magnification, but you may have a slightly cleaner image at 150 magnification.  However, some say the multiplier for theoritical maximum magnification is 60 not 50 per inch of aperture which would put your telescopes max power at 189 instead of 157.5.  Anyways I wouldn't try to anything beyond than 200 power through your scope.  Hope this helps.

Celestron 93317 1-1/4-6 mm Omni Series Eyepiece

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