The problem with DSLRs
Today I took two photos using my Olympus E-520 DSLR, together with the 50mm macro lens. Both wide open at f/2. First, Tuna the cat in the garden:
Tuna the cat, April 2014
And a short time later, a clay cat in our bookshelf:
Clay cat in a bookshelf
As you probably can see, that 50mm macro lens is wonderfully sharp, even when used wide open at its maximum aperture of f/2.
Still there’s something wrong with the first photo. The focus point seems to be on the nose instead of the eyes, which means that when you “pixel-peep” (look at the photo in its original size, with 100% magnification, so one pixel on screen is one pixel of the original image), you’ll see it.
Two reasons are responsible for this:
The first one is the fact that my Olympus E-520 DSLR has only three focus points when using its normal phase detection autofocus, which means you’ll have to “focus and recompose” (put the middle focus point over the eye, let the autofocus do its thing, and then move the camera to get the frame and composition you want, which is with the eye off-center). This movement of the camera after focusing is most probably responsible for the slight blur you see here, and the higher the amount of megapixels on the sensor, the more you would notice this.
The second possible reason for the slight shift of focus might be something like front- (or with other camera/lens combinations) back-focusing. This can happen when using phase detection autofocus because of a slight misalignment of the focus sensors and the image sensor. Better cameras (like the Olympus E-620, E-30 or E-5 to name their latest but discontinued models) offer the possibility to perform an autofocus-microadjustment of your camera and lens combination, and can store this information for several lenses you might have.
Still this won’t prevent you from the first possible reason, which means moving the camera after acquiring focus. So if your DSLR has more focus points than mine, chose the one which is on the eye, and don’t move the camera after focus acquisition.
I took the second photo using live-view on the rear LC display, and with the contrast-based autofocus used in this mode. This one is lots slower, especially on DSLRs which aren’t optimized for this mode. But it is also lots more precise as you probably can see. Even with f/2, here the eyes of the clay cat are perfectly (or purrfectly?) sharp. In this mode, you can use magnification on the display (I used 10x here), and move the green focus area rectangle exactly to the point where you want it.
This works for inanimate objects like for this clay cat, but for anything that lives and moves, this method is by far not fast enough.
And that is, in general terms, the problem with all DSLRs. You can either use phase detection AF which is fast but not very accurate, or you use contrast AF which is lots better, but in most cases far too slow.
The solution? Try any current µ43rds camera (at the time of this writing, the Olympus lineup would be, from lowest price to highest: the E-PM2, E-PL5, E-M10, E-M5, E-P5, and the E-M1). These cameras nowadays offer a very good “nearest eye detection” AF, which is really usable, and ultra-precise. Their electronic viewfinders let you magnify the picture even when using the viewfinder, which is perfect if you want to manually focus older lenses. The “keeper rate” (of pictures in good focus) is much higher, not only because of the perfectly fast contrast-based AF, but also because with this live view even in the viewfinder you’ll see over- or underexposure even before taking the shot. Same with a wrong white balance. It’s an electronic image alright, it might not look as good as a big and bright optical viewfinder on first glance, but I got used to it after about a week or so.
I still love to hold and use my E-520, but even with its 10 megapixels I have to consider and think about autofocus as much as I think about exposure when taking photos with it. These mirrorless cameras pretty much free you from that – what you’ll see is what you’ll get. In most cases, my E-PL5 delivers much better results than my DSLR. I still carry both, the “Pen” camera with the PanaLeica 25mm lens, and the DSLR with that 50mm macro, but if I had two of these mirrorless bodies, the DSLR would gather dust on the bookshelf – as nice as it is to hold it.
Thanks for reading.