I am new to large format, having obtained a 4 x 5 camera two months ago. I have read that instead of purchasing a hand-held external meter, the TTL metering of a 35 mm camera can be used instead. That is what I have been trying. I compose and meter with a 35 mm camera set at the equivalent focal length of the 4 X 5 lens I am using (i.e. I set the zoom lens on my 35 mm camera at 62 mm to meter for my 210 mm 4 X 5 lens), then set the 4 X 5 lens to the indicated f/stop and shutter speed. About half the time this works well and the 4 X 5 exposure is perfect (Iím shooting Velvia 100 chromes), but half the time the 4 X 5 exposure is too light or too dark. I am using a Nikon F100 set on matrix metering and I know the meter is accurate because 35 mm exposures come out fine, and its meter matches other 35 mm camera meters. Am I taking the correct approach to metering with a 35 mm camera? Should I buy an external meter? Is it possible to accurately meter to properly expose 4 X 5 film every time, or is bracketing exposure commonly done in large format?
Also, the smallest aperture on my 35 mm camera lens is f/22, but the 4 X 5 lens stops down to f/64. How do I extrapolate beyond f/22? For example, if my 35 mm meter indicates an exposure of 1/10 sec at f/22, what shutter speed should I use on the 4 X 5 camera if I set the f/stop at 1/64?