Furball on the left is our Bearded Collie named Vertti, or Memorylane One for the Sun. Vertti is my official and eager tester for action capable cameras. Very few cameras pass through his test with flying colors because this buddy can move in so many directions at one time. Vertti is a living example of Heisenberg uncertainty principle...
I always map auto focusing into a thumb button in every camera where it is possible. In DSLRs I map there continuous auto focusing. Then with a press of a button my subject is in focus. If it is a moving subject I just keep the button pressed and I´m ready to take a picture or a series of pictures any moment I want to.
With Olympus E-P2 I had to map there single AF because E-P2´s continuous AF is no good. It just hunts back and forth and can´t lock on anything. With E-P3 this is changed and now I can map continuous AF into thumb button. Focusing is just like single AF with non-moving subjects and with thumb butten pressed I can follow many moving subjects. Now, define ”many”...
While E-P3´s single AF might be at same level as D3x´s single AF, continuous AF is not. With a good DSLR like D3x, I can follow an erratic subject, like a running dog easily, keep focusing and shooting, and most shots are sharp if shutter speed is okay. With E-P3 the first problem is Live View. VF-2 viewfinder is not refreshed for too much of the time. Following the dog, composing and shooting continuously at the same time is difficult. This is simply an area where an optical reflex viewfinder is still better than electronic viewfinder. The sensor’s double duty takes too much time from viewfinder. The second fact is that algorithmic prediction of focus seems to be slightly lacking in E-P3. With a DSLR there´s a shorter time gap between the latest distance information and actual exposure than with a live view camera. DSLR can predict better where the focus should be when the shutter goes. And finally E-P3´s shooting rate of 3 images per second is not so good for action series. All of this may lead into problems in following the subject, keeping composition and getting sharp images. For dogs running I would not choose E-P3 as my camera. And if I had to, I would not use sequential shooting but single shots while following the dog and trying to get peaks of action. This technique seems to improve the percentage of keepers a lot.
Playing children are now easy, mostly. Sports from audience or at the side of track is easy, mostly. Aeroplanes are easy, mostly. Cars are easy, mostly.
”Mostly” because the actual speed of movement is not decisive. What counts is the rate of change of distance. Anything very fast far away is not moving fast relative to the camera. The closer the movement gets the more difficult it becomes. Below I have a simple exercise which shows how first differences are small but then there´s a lot of change at the end. This car is approaching at about 40km/h (the speed limit on this road):
Images above are 100% crops. Eight consecutive images with E-P3. Lens M.Zuiko 40-150mm 1:4-5.6. Focal lenght 40mm, aperture 4. Continuous AF. Images are oversharpened so that only sharp sharpens, unsharp doesn´t.
Below the original cropping of the first and last image. I´m standing quite close to road. This is a situation which E-P3 handles quite well up to eight image except for composing getting difficult in the end. The ninth image was unsharp.
OTHER FOCUSING ISSUES
Nikon gives AF range as -1 - +19 EV for D3x. Olympus gives values 0-18 EV for E-P2 and 0-20 EV for E-P3. Between these values AF should detect and lock. Now EV 0 corresponds to 1 second at aperture 1 at ISO 100. I tested Olympuses with Lumix 20/1.7 lens. AF was able to lock reliably down to 1” (EV 0.5, ISO 200) with E-P2 and 4” (EV -1,5 !!, ISO 200) with E-P3. I tested D3x with 50/1.4. AF locked reliably down to 2” (EV 0, ISO 100). My target was black blocks on white, 50/50. At EV 0 I really can´t see through D3x viewfinder. VF-2 with E-P2 is noisy as hell at EV 0.5 but doable. What I really was surprised with was VF-2 quality with E-P3. Noise is gone, you actually can see perfectly well what you are doing at EV -1,5 through VF-2.
In real life situations there usually is something brighter you can focus on. Now it was totally uniform grayness/darkness for my eyes. D3x and E-P2 results are logical enough. I´m not saying my EV numbers are absolutely correct as such, this was my way to measure. I don´t know what kind of targets they use at Nikon or Olympus. But EV -1,5 for E-P3??? (NOTE: AF assist light was NOT on.) I checked many times and that´s the result I got every time relative to the others. The difference between E-P3 and others was... well huge, marked, notable, pleasant and annoying. With moving subjects the point is to look for a contrasty area as quickly as possible. Otherwise there might be nothing where AF can lock on.
And, yes, there is now an AF assist light for low light situations if you really want to get noticed by your subjects...
E-P3´s face recognition has new features. You can choose if it uses left or right eye to focus on, or you can set it to focus on the nearest eye. Portrait and glamour shooters are going to like this one!
You can also focus by touching anywhere on rear OLED screen. E-P3 focuses and takes a picture. It was kind of cool among people with 12mm wide angle. Nobody realised if I was just flipping through my images or what. Works great with IBIS. This feature can be set on and off by user directly on screen.
One thing I´m missing is focus confirmation for manual lenses. Ages ago we had a focus column in Leaf software for their three shot backs. You turned the focusing ring and watched column go up, up and then started to drop. The you turned just a bit backwards until maximum and bingo. Something alike shouldn´t be too hard to implement.
And then there is zone focusing with 12mm/2.0 lens... But that´s again another story.
-p-
March 7, 2012 at 13:39 