Years ago I got the Adams books and read them and used them to develop my shooting and darkroom styles. The man was a genius. I also got his book on the Polaroid Land Camera and went from it being next to a point and shoot in results to a preferred film format. He used a SEI Photometer in much of his shooting as well as a Weston Ranger 9. Years ago a friend in the photo business got a SEI in trade and I picked it up from him. It took quite a bit of time to get used to it but the results were amazing. I concentrated on Tech Pan shooting and development so I eliminated one variable and as it really could be developed from high contrast to low contrast, had a tonal range that was amaziing and made great b&w tranparencies, I used it almost exclusively until it was discontinued.
I have since sidelined the SEI for most use, having picked up a Ranger 9 along with the optional Adams Zone System dial. I power it now with a pair of CHRIS MR9 adaptors and it is dead on accurate. I also got the incident dome and a new 2nd leather case so good to go as the meter looks brand new. If you have a chance to get a 9, I can not recommend it highly enough. Adams was not overstating just how good the meter is.
The Adams' books are a must read for everyone who knows the lens must point towards the subject.