I purchased this lens 10 months ago. The Compound shutter was blocked and I send it to repair. Now I still have two problems:

1 - the shutter speed is very innacurate ( 1/30 sec = 1/60 sec - It seems to shoot more quickly than normal speed - but Iīve not test it because I donīt know how). The repair man told me that the compund shutter use a little compressed air cylinder with a piston that control the shutter blades blabla. In time the cylinder loose the air compression, so the piston go more fast.

2 - the front element is blocked so I canīt remove it.

Now I want to know if this lens is a good quality lens. Iīve loked on web but Iīve not meet anything about this model ( image circle or other specifications ) Itīs worth to send it for change the shutter? If I want to sell it how can I ask for it?