Tamron 24-70 diaphragm problem
Just received my tamron 24-70 VC a couple days ago. Haven't had time yet to use it a lot but I did check the diaphragm. Looking at the blades through the lens the diaphragm doesn't seem to move at all between 2.8 and 3.5. Some decrease in size should be obvious, right? Is there a better way to test this? Any input would be appreciated.