The Fujifilm X-M5 Field School

0 of 54 lessons complete (0%)

Kit lens masterclass: XC15-45mm

Variable aperture, OIS and the low-light limit

Zooming in costs you 1 1/3 stops of light, and no setting gives it back. OIS returns about three stops of camera shake — but the number you actually need indoors is set by your subject moving, not by your hands. Learn the 30/60/125/250 rule and stop guessing.

f/3.5 → f/5.6 = 1.36 stops OIS ≈ 3 EV no IBIS for stills

The rule to write on a card

SpeedWhat it is forConditions
1/30 sAbsolute floor: architecture, a sleeping baby, a still life15-23 mm, OIS on, braced, subject completely still. Shoot three; expect to bin some.
1/60 sEveryday indoor minimum at any focal lengthStatic or slow subjects
1/125 sThe real minimum for people, and the default for family indoorsBelow this you are fighting your subject, not your hands — and OIS cannot help with that
1/250 sKids running, pets, street with walking peopleAnything with hands or feet in motion
Derived from the reciprocal rule plus the measured OIS benefit, then reduced to numbers that survive a real evening with real people.

For reference, the unstabilised reciprocal baselines on this body are about 1/25 s at 15 mm, 1/35 s at 23 mm, 1/50 s at 33 mm and 1/80 s at 45 mm. Adding three stops of OIS suggests 1/3 s and 1/10 s are theoretically possible — treat those as lab maxima, not working numbers.

Unusually honest marketing

Fujifilm declares 3.0 EV of stabilisation. An independent lab measured 2.7 to 3.0 EV at 45 mm across dozens of frames from 1/80 s to 1/2 s and concluded the claim holds within measurement error. Treat three stops as real. Turn IS MODE on and leave it on — except on a tripod, where the manual asks you to turn it off.

How to buy light back

  • Zoom out. Going from 45 mm to 15 mm hands you 1 1/3 stops instantly. Often you can step closer and keep the framing.
  • Move to the light. One step toward a window can be worth two stops — far more than any setting.
  • Raise the ISO ceiling. ISO 6400 with visible grain beats a blurred frame at ISO 1600.
  • Brace and breathe. Elbows in, screen tilted up, exhale, fire. Roughly a stop, free, on every frame.
  • Shoot a burst of three. At the edge of what is holdable, one of three will be sharp.

Assignment: your own OIS number

At 45 mm, photograph a page of text at 1/80, 1/40, 1/20 and 1/10 s — five frames at each speed, OIS on. Repeat with IS MODE off. Count how many are sharp at each speed in each set. The gap between the two sets is your OIS benefit, with your hands, and it is the most useful number in this lesson.