It is as dependable as tax time. The camera forums are populated by experts who tell me you can’t get a creamy bokeh out of a Micro Four Thirds lens because the crop factor doubles the depth-of-field. Sigh….
While I know that facts won’t interest most of those guys, they might interest you. And my goal here is not to rag on the forum trolls, but rather, to help those of you who might be tricked into believing them. They are dead wrong.
The featured picture in this post shows a female northern cardinal (Cardinalis cardinalis) against a clean background and demonstrates my point. I shot it at f/5.6 using my Olympus OM-D E-M1 X camera. According to those camera forum experts I referenced, that would mean I should have the same depth-of-field as f/11 on a full-frame camera. Ok – so what? The bokeh in this picture is just fine for my taste.
It doesn’t matter whether or not you use a full-frame or micro four thirds sensor. What matters is:
- How long is your lens?
- How close are you to your subject?
- What aperture gives you the narrowest DOF for your given lens?
- How far is the background from your subject?
- What sort of diaphragm blades does your lens have and how many of them are there?
These factors have WAAAAAAAAAY more to do with “creamy bokeh” than the size of your sensor.
I’ll break it down for you.
Let’s start with the fact that I am using a telephoto lens. In this case, the Olympus M.Zuiko Digital ED 300mm f/4 IS PRO Lens. ( That is important because of what follows.)
Longer lenses have shallower depth-of-field. And as I’ve said before, as subject to camera distance decreases, so does depth-of-field. Always. Every time. No exceptions. Ever. Period. It’s easier to see (and prove) using telephoto lenses.
So if I am using a telephoto lens, and I am close to my subject, my DOF may be less than an inch, even at f/22!!!
In the case of the female cardinal image below, I was shooting at f/5.6, so I actually had to stop down to get enough DOF to get the bird in focus. Wide open would be f/4. Note that the tree branch is out of focus on the left side of the frame? The DOF here is very skinny because I am very close.
The creamy bokeh is helped by the fact that the background is 50 yards from the bird. If you have even six feet between your background and your subject, you may have enough distance to help achieve a clean background in the photo.
Lastly, while not as impactful as subject to camera distance, the lens design itself can impact how creamy the bokeh. In the case of this image, the lens has nine (rounded) diaphragm blades. This definitely helps with the look I want to achieve.
Sensor size affects DOF only in that changing the sensor size on a camera requires changing the focal length to get the same picture. While it’s always nice to have super fast glass, you can apply what I have shared here to just about any situation and you should realize that even if you’re not using M43 and still want creamy DOF, but can’t afford fast glass, just get closer to your subject, and aim for at least six feet of distance between your subject and the background (more is better) and you will be fine.
I hope this helps.