In preparation for a 5 month dive trip this fall/winter I am rereading my OM-D E-M1 mark ii manual and writing up a tips&tricks document. Yes I know it is a bit late but there are still a lot of them around and I expect much will apply to newer models and probably other brands as well. The document isn't ready for release yet but I just discovered something I would like to try out on my next trip and thought would interest others. I may be reinventing the wheel but if I hadn't heard about it then I am probably not the only one.
I like focus peaking to confirm areas in focus while maintaining an overview of the composition (unlike magnification which can be a bit disorienting). But cameras autofocus with the aperture wide open. So for my 60mm F2.8 macro lens, focus peaking shows the area in focus at F2.8, not the F11 or whatever I may have set on camera. You can force the camera to stop down the aperture with the DOF preview button but by default if you release the button the aperture opens up again. However, you can use menu D2>Settings>Lock>On to keep the aperture stepped down after you release the button. If you now activate focus peaking it shows the much enlarged DOF! Due to live view boost you can do this without the image getting to dark. Great!
This is actually quite educational to do at home and see how aperture and other factors affect DOF. With DOF preview locked on, you can alter your aperture and see things change. I think it could also help me underwater for macro shots of stationary subjects. However, you do have to remember to switch it off, because if you don't the autofocus will hunt like crazy. That itself is an interesting educational experience. It shows that having a wide-aperture lens can really help with autofocus performance, even if you never shoot it wide open.
