The round Earth theory is thousands of years old, yet photos are only a few hundred years old...
What does that have to do with anything? What's your point?
My point is that rejecting photographs shouldn't be a problem at all for REers in trying to prove the the Earth is indeed round. People didn't come to the conclusion that the Earth was round by looking at it, or looking at the horizon for that matter. I find it very tempting to put forward proofs that the Earth is round, that do not involve travelling, modern technology (maybe a calculator would be nice, but unnecessary) or relying on other people's evidence. That's the kind of proof REers should be looking for to 'convince' us that the Earth is indeed round. I don't think it's actually very hard at all.
I still don't see your point.
Evidence is evidence, it doesn't belong to anyone, it's just there. I really don't understand your concept of "someone else's evidence"
People didn't come to the conclusion that the Earth was round by looking at it, or looking at the horizon for that matter.
How do you know?
And why limit yourself on the ways to use to prove something? A picture is worth a thousand words.