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Message: <blockquote data-quote="typo" data-source="post: 3183135" data-attributes="member: 83808">Binastro,You certainly don't need any optics to demonstrate disc expansion in the eye. All you need is a powerful but dimmable light source and a pinhole in something like aluminium foil and you can see for yourself in a minute or two. A very well documented effect. You can throw binoculars into the mix if you like, but last time I tried it is made no difference.You do need manual control over exposure but Venus is not very bright in the scheme of things. I once built a million lux light source that would melt plastic in seconds and got very good images at a few millionths of a second.I suggested a phone camera as the very short back focus means you still should have decent f-numbers even on a 2.5mm EP. Some apps appear to give you manual control over exposure but I don't have anything suitable at the moment to test it out.DavidP.S Very cloudy here this afternoon!</blockquote>