Hi Kman
I'm sorry that I'm not good at English..so..I'm not sure I can explain in text clearly. Would you plz to email me:
williamcaicb@hotmail.com, so that I could get your emial address and I could reply you a figure to illustrate which of the time that need to be measured. This might me easier for me to describe. Also, I could email you the method to calculate to the distance between the Earth and the Sun.
In addition, please never say yourself a layman
Practise makes perfect
You are gonna make a lot of improvements after this Venus Transit
Cheers!
Beluga