American Association of Variable Star Observers (AAVSO)
Wed, 10/29/2014 - 15:57

Good day,

I notice that he guidelines recomment stopping scopes down to 80mm?

Would it be acceptable for me to use my Meade ETX 125 at full aperture?


David (JDAC)

Aperture size

Hi David,

Oh sure, the average of all observer's aperture size in the AAVSO database is 100 mm.The issue is, I think, what is easiest and most comfortable for you. Using a small aperture scope allows you to have the full disk of the sun in the eyepiece, so perhaps a 25 mm eyepiece will allow that? Also, perhaps more important than aperture will be magnification. If there is too much magnification (above 64 X) then you may start counting 'pores' rather than sunspots (see attached .ppt)

Also, will the ETX 125 allow you to track the sun? I think most Meade scopes don't allow that.