From a recent bunch of photos taken on our Thailand holiday, I (accidentally) found that using ISO 400 in sunlight often gave quite horrible over-exposure which didn't sound right as every other camera I've owned will give a decent result with ISO 400 in sunlight.
This prompted me to investigate what the camera is doing with shutter speeds and apertures at various focal lengths. I switched to Step Zoom to make life easier and tests more repeatable. There seems to be some anomalies in the aperture ranges so I had to do the tests a few times over to prove that this chart is right.
|
R3 Lens Focal length |
Equivalent to 35mm camera |
Aperture range found |
| 4.6mm | 28mm | 3.3 to 5.0 |
| 5.8mm | 35mm | 3.9 to 5.9 |
| 8.3mm | 50mm | 4.5 to 6.9 |
| 14.0mm | 85mm | 4.8 to 7.4 |
| 17.3mm | 105mm | 4.2 to 8.3 |
| 22.3mm | 135mm | 4.5 to 8.8 |
| 33.0mm | 200mm | 4.8 to 9.6 |
The 400 ISO overexposure problem occurs at the wider angles because the shutter speed limits at 1/2000 and the aperture cannot close down small enough to get a correct exposure. I presume that the R3, R4 and R5 all use the same lens/aperture mechanism.
All the more reason to always run the R3 at the slowest ISO setting you can manage or leave it on Auto ISO.