Hi, Im new star gazing and need some help, I recently bought a sky watcher Bk 705 on eBay for £35 to show my little daughter the moon & planets. It came with a 25mm super ( I'm guessing that is a sky watcher SP?) and we had some great views of the moon but I would like to get some more EPs (nothing to costly) to explore the skies more. I have read wathogs post on EPs and done the maths and calculated that the best most common sized EPs for my f7 scope would be 6mm, 9mm, 15mm, and 20mm. The trouble is there are so many manufacters, some are right price but the wrong size some the right