Where does a downwind join officially start?
I was recently flying north towards my destination airfield whose ATC have an ATZ but no radar.
Lets say the runway runs east/west and the westerly runway was in use. I was instructed to report downwind left for r/w 27. As I reached this point and just before making the call I noticed another aircraft turning downwind left to right ahead of me. This aircraft was in the circuit and had just reached circuit height in the crosswind leg. I followed the aircraft along the downwind leg and completed the circuit, landing as normal.
On the ground the other pilot suggested I should have joined the downwind leg further west as this would have reduced the opportunity for conflict. I did not disagree, but in reality would still have only called downwind left 27 at the same point on the circuit rectangle. I was surprised ATC did not warn of the other aircraft in the circuit especially having no radar.
I have no argument with the other pilot or his logic, but my question to the forum is : was I wrong to route for a downwind join as I did? Should I have gone much further to the west ? If so how far is much further? Or was I ok to head directly to the start of the downwind leg, and the possibility of conflicts with traffic in the crosswind leg is just something to be wary of?