My limited experience agrees with retina_restoration, but using Paul Manual’s method with an incident meter, and adding a second shot opened up another stop, just in case. The differences of time of day, season, altitude, and cloud cover are still a mystery.
I just set the ISO to box speed, ie., 200, then overexposed by 4 stops from the unfiltered reading. So for example, at my chosen aperture of f11, a reading of 1/250th without the filter was manually adjusted to 1/15th once the filter was added
It sounds as if using a wide lens such as a 28 mm, an f stop of f8 should keep everything in focus and give a shutter speed that is can be hand-held as well
I shoot SFX and Rollei Infrared in a Mamiya C220 TLR with a IR720 filter. This camera has just a very vague distance indicator and no IR marks at all. The plain old focus and shoot method delivers sharp negatives for me suggesting IR distance compensation is not needed in the near infrared with these films.
There are clearly two camps on this thread. I just know that I've lost good shots in the past from forgetting to make a focus adjustment - though to be fair this was with Rollei IR or Konica IR 750, not SFX.