Quote Originally Posted by Steve Smith View Post
If I get a bit of spare time tomorrow I might do some experiments with my Weston meter with its invercone and a Zeiss Ikophot with it's flat diffuser to see what the variance is as I thought the invercone behaved as a dome rather than a flat receptor as you suggest. I suppose I should go and read that chapter again!.

I haven't read all of the book yet. Discussion of the Invercone appears to be spread throughout the book. My first impression is that they may see the Invercone as having a cardioid response pattern, but that's not based on a complete reading.

It's a new book to me. I'd heard of it, but haven't seen it locally available or widely discussed in the US. My hardback 1981 copy was ordered through abebooks for US$1 and US$2.99 shipping. It appears to be technically very solid, although a bit dated in areas where some equipment is concerned, but it is based on a 1952 edition with revisions until at least 1981. Well worth a read. They do discuss under what conditions it's necessary to depart from standard metering techniques, and what methods of departure are effective.