Calculating Long Exposures for Film

[baisao]

I shoot film and would like to know how to calculate long exposures (agnostic of reciprocity) for exposures under 2 minutes using 100 slide film.

I am not asking about reciprocity.

Obviously, I plan to bracket my exposures but to get +/- 1 stop is it better to use a heuristic-based chart like this for determining my EV or should I rely on my Sekonic meter?

It seems that there is quite a large delta between what the meter says the EV is and what the chart(s) suggest it should be. The meter indicates a significantly lower EV.

I question which method is best and do not want to waste $$$ on film and dev to figure this out. Some say that it is better to not use meters but to use the heuristic-based charts (presumably because highlights will be too intense if a lower EV is used). Yet, I can't get my mind around the meter be the incorrect way to determine the EV.

So... chart or meter?

Thanks,
Jim

 

[maddoc]

I have trusted my Leica M7 meter (shutter speed up to 32s in Auto mode) with Velvia50 and exposure was as I would have expected: (color cast most probably due to the light)

On the other hand, about 1 minute results in this:

So depending on light sources in the frame you might have to bracket your shots.

 

[baisao]

Alas, my M6 meter is not as sensitive at the M7's. It gets wonky around EV 6 @ 3200 ISO. So your vote is for the meter, not the charts.

I would like to do some color street shooting at night, showing more detail in the shadows that what I am usually able to accomplish at 1/30th @ 3200. It would be fun to experiment more, but slide film prices have increased and development cost have as well.

As a side note, I have read that Velvia gets a green cast at longer exposures. Provia maintains correct color and is good to 2 minutes without reciprocity should you want to try it again. Enviable shots, BTW!

Cheers!