The Olympus “Live Composite” mode is one of those hidden gems you don’t normally get around to until you had the camera for a few months. It’s particularly useful for night time long exposures, it prevents images being over exposed and it keeps noise levels very low even when exposing for 15 mins or more. To find this mode you put the camera in manual mode and then ramp the exposure up beyond 60 seconds where you will find Bulb, Live time, and Live Composite.
You dial in to Live Composite, then hit “menu” and you can enter your exposure step time. This is the time each image will be exposed for and then over layed one on top of the other, automatically in the camera. It only adds light and will not let you over expose as long as your step time is correct. (for instance if your camera at F4 and ISO 200 requires a 2 second exposure and you set your step time for 2 seconds you will be fine).
During daylight you can use an unconverted camera and an infrared filter to get long exposure times that will work with “Live Composite”. Water and Clouds work well.
The above image was taken using 37 x 3.2 second steps @ f7.1 (total 120 seconds). Oly 9-18mm lens, unconverted OMD E-M5 mkii.
I did a quick behind scenes video making an IR Live Composite image. The link is below, have fun.