another victim here.....
I really like the lens but today while mucking about in my back garden, and trying my MC7 2x TC I noticed suddenly I was getting overexposed shots. I took the lens off and the lever stayed in wide open position, little flick by finger and it was back to normal, after another 10mins the same happened again.
I'm going to return it....
I shame I really liked this lens, but I'm not running a risk having to check every signle shot for exposure.
I hope I'll be able to return it, since I bought it used, but there is 6 months warranty from the shop, so it should be OK.
BR
good luck to other owners,
Peter