If your grandad's meter looks anything like your photo, then it wouldn't actually be a spotmeter, but a (normal type) reflective light meter; it may even have provision for incident readings, which would be a big plus IMO. There is a technique for using an incident light meter over long distances and I'll be happy to let you know how its done. Usually, an incident light reading is done by hand, inches in front of the subject, but I worked out a way of using an incident reading at a distance - there are several caveats though.
If your grandad's meter looks anything like your photo, then it wouldn't actually be a spotmeter, but a (normal type) reflective light meter; it may even have provision for incident readings, which would be a big plus IMO. There is a technique for using an incident light meter over long distances and I'll be happy to let you know how its done. Usually, an incident light reading is done by hand, inches in front of the subject, but I worked out a way of using an incident reading at a distance - there are several caveats though.