Blasted OM-D focusing

Started 4 months ago | Discussions thread
Timur Born
Senior MemberPosts: 3,765
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Re: An example.
In reply to Louis_Dobson, 4 months ago

Louis_Dobson wrote:

Left Info Up/Down gives me three schemes, but doesn't seem to give me an option to set a smaller focus box...
Twist lens / spin dial enables me to set 14X, which I THOUGHT set the camera to use the smallest focus box?

Some things to clarify:

  • The real focus frame is slightly larger than what the camera displays. This is the same with other cameras, too (like Canon 70D).
  • AF-S (S!) on the E-M5 and E-M1 seems to have a tendency to stay on the last focal plane it was set to. If you are using more than a single focus frame this even leads to the focus frame wandering over the screen in order to stay on the last focal plane/object when you pan the camera (no tracking enabled). And there seems to be a tendency to favor object coming in front from the left side than from the right side.

I sometimes can focus on a very small object in front with the smallest AF frame and then pan the E-M1 a up to two AF frames distance to the right and focus will still repeatedly stay on the small front object (well outside the AF frame). If I pan to the left instead focal plane changes quite immediately to the background once the AF frame is away from the front object.

The E-M1 offers an option to change the "sensibility" of how much the focus reacts to changes of the focal plane, but that option is labeled for AF-C (C!) use.

  • The smallest AF frame of the E-M1 is smaller than the 14x frame. I expect the E-M5 to offer the same after the firmware update, but didn't update mine yet.
  • Zoom AF on the E-M5 still uses the whole zoomed in frame to decide on what to zoom. It stills tends to keep the last focal plane.

Zoom AF on the E-M1 displays a center AF frame inside the 14x frame (roughly the size of 9 AF boxes), and it does focus inside that frame. So you really get the smallest possible AF area possible, even smaller than the smallest normal AF frame. No idea if the new E-M5 firmware includes this, too.

  • It can help a lot to prefocus on something close before taking shots of objects in front of a further away background. This is because of the front object being so blurred when out of focus that the camera doesn't even recognize it being there unless it does a full scan through the whole focal range. And the Olympus cameras really don't like doing that unless for a last resort. Furthermore blurred out front objects may seem to be inside the AF frame, but once in focus you realize that they really where not (just blurred to apparently bigger size). Can also be the other way around, like in these examples where the blurred front allows the background to be inside the AF frame, but once you focus to the front it the background is completely out:

  • Last but not least, the E-M5 (didn't check with the E-M1 yet) seems to really dislike focusing close to the close focus limit of a lens when it can find something else to focus on instead. So if you are shooting dogs close to the minimum focus distance of a lens and these is someone/something right behind the dog then it's not unlikely that the camera will grab that close background instead.
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