Mamiya C330 TLR and Zone System

Hi:
If my question does not give it away I will tell you that I am new to most of this.

I recently bought a C330 and have aquired a 55mm, 80mm and 135mm (all of them are black). I have shot some T-Max 400 test film to establish a modified ASA (Zone System approach), developed in T-Max 7 minutes at 20 degrees C.

The results of the test for the 55mm and the 80mm indicate a modified ASA for both of ASA 800.

Of all the reading I have done of this subject, a rating greater than the manufactuers ASA seems to be a very rare outcome.

Your comments would be most appreciated.

Todd

Your shutters may be slow. They probably need a CLA, but meanwhile you can just apply your personal EI to them and test periodically in case they loosen up with use. Calumet makes a shutter tester that costs about $80 last I checked. It's not so important that the shutter is accurate, as long as it's consistent and you know the actual speed.

David is most probably right about your shutter speed(s). My C330f lenses are mostly right on target but from time to time I've had them cleaned and checked. I do not think it unusual for one's EI to be a stop higher than rated. However, I found TMY film to be a little tricky for Zone system use. I would suggest you try TXP or PXP. And good luck.