[Klaus]

Just a question about the T aperture, is it just like the other aperture or it acts by just decreasing the amount of light entering without affecting DOF, because in the latter case it is very handy if you need to shoot outside wide open without having to add ND filters

 

The effect on the T vs f aperture isn't really described in the manual - it only says that you should use either aperture ring but not both in conjunction. The T aperture is stepless though thus this is the choice for movie lovers. 

 

I suppose in the very theory the T-ring controls the APD effect but at the end of the day it is also an aperture. I'm not sure why you really want to reduce the effect because that is the sole point of the lens.