Automatic exposure
QThere are times when I need to set the shutter speed and aperture and leave them be. Such scenes involve setting the camera up so I can freeze the action and maintain a precise depth of field at the same time. A good example is when photographing water droplets falling from rain- drenched foliage. I need to set a fast shutter speed to freeze the water droplet and a wide aperture to maximise the narrow depth of field. Before you ask, I don’t want to use flash! Under these conditions the light does change so using just Manual exposure mode isn’t ideal. The Auto exposure mode options mean the shutter or the aperture needs to be adjusted according to the light level, but I need the aperture and shutter to remain constant. This means fiddling around with the ISO speed setting in order to compensate for changes in the scene brightness. Is there a better way of achieving this with the Olympus OM- D E- M1 Mark II? Dean Roper
AYes, this is certainly possible with the E- M1 Mark II through the use of Auto ISO. Some cameras only offered Auto ISO as an alternative to adjusting either the shutter speed or the aperture automatically, but the E- M1 Mark II also allows Auto ISO in Manual mode, so this is precisely what you need. In the Custom settings menu under the E1 (Exp/ISO/Bulb) settings check that ISO Auto is set to All so that ISO Auto can work in all exposure modes, not just auto modes. It’s also useful to ensure that the ISO Step setting is set to 1/3 EV because larger step settings could result in visible variability in correct exposure as the ISO is the only variable that can be adjusted. You also need to determine what upper ISO limit you are willing to tolerate in terms of noise and reduced dynamic range. This can be customised under ISO Auto Set. Because you only have ISO to play with, especially if the ISO upper limit is high, it’s important to ensure the exposure is spot on, so experiment with the various metering mode options to best cope with the kind of conditions you can expect to face. Q&A compiled by Ian Burley