So the tool seems to be popular according to the stats, which is great! I thought I may as well complete the swiss-army-knife approach to the UI by adding support for eyepieces which I've just done.
Yeh yeh, eyepieces. I think I have one somewhere. Maybe. I'd have to check.
Now the tool is a lot more useful for purchasing decisions I think.
Example Link to Tool
(you may need to clear your cache if you've visited the tool recently)