Olympus OM-1 shutter
I’m using my Olympus OM-1 without the flash sync cable or the Neewer remote flash trigger. To keep the shutter open on the OM-1:
1. Put camera in bulb mode
2. advance film
3. Use the self timer. Start the timer. When the shutter opens, quickly turn off the timer before shutter closes. It might take a few tries to get the shutter to stay open.