For my science fair, I need to take measurments (to scale) on a telescope, for example, I need to be able to point it towards the moon, and measure its radius. Now, my problem there is how will I measure this? Since my eye will be in the way, I cant use a ruler to find a crude measurement, so I was wondering how I can do this. I dont want to spend much money on this, so I dont want to buy an adapter for my camera to attack to my telescope. Can I just shove my camera lense into the lense of the telesope viewfinder, and take a snapshot? I asked my stepdad, but he doesn't know much about telescopes (was more interested in microphysics.) So do you guys have any idea how I can do this? The pictures wouldn't have to be nice. I can't just eyeball it, since for the project I'll be looking at some pretty far off objects. If I'm not being clear on something, feel free to ask.