you are right, the bellows are very long when I shoot these, almost reaching the end.. so far so good, I have no need to use the macro chart yet.
I am using 210mm and the subject is big enough ( so far ). If I start to shoot those little flowers, then perhaps I will need to use the macro compensation chart.
I normally shoot at F8 ( lens widest is F6.8 ).
There are several locations that is good for flower shoots in Singapore.
- The Botanical Gardens ( orchid garden ) is one of them. But you have to pay to get in.
- Guang Ming Shan has lots of nice orchids also, but the location is not in the favor of the morning light.
do share your shots here

Billy