35mm as meter for L and M formate

I have number of meters, an old Soligard spot meter, a Weston Ranger 9, Western Master VI, and few incident meters. Last week I took my Minolta 600 with 50mm 1.8 lens and used it in matrix mode. For spot metering I put on a 70 to 300 and used the spot metering mode, then for incident metering took the inversa dome from the Weston Master 6 and just stuck into 50mm lens, seemed to work as well as my meters, and I take pictures. The Minolta 600 is larger than my Ranger 9, but not much bigger than the spot meter. With a 28 to 80 zoom I can match my wide and short tele.