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Work in progress

This document never progressed beyond being a work in progress. I no longer have an E-30, so it won't change. I hope it's helpful in its current state, but please don't rely on it. Use in conjunction with the Olympus manual.

I bought an Olympus E-30 in May 2009. On the whole I'm very happy with it, but the documentation is pretty terrible, and some of the firmware gives me the impression that it was released in a hurry. I've spent a considerable amount of time trying to work out how specific functionality is implemented, and how to use it to its best. This page is (currently) a work in progress describing one aspect, the autofocus system. It draws on Olympus' documentation, a review by Andrzej Wrotniak, and my own experience and experimentation.

Terminology

Before we get started, we should look at the terminology that Olympus uses. I've devoted a separate page to this issue. Here you should know that I don't use the term “Sensor AF” on this page, since it's ambiguous. What Olympus calls “Imager AF” (in English) I call “Contrast AF”, and what they call “AF Sensor”, I call “Phase AF”.

What you need to do

Once focusing was simple: you looked through the viewfinder and turned the focus ring until the part you were interested in was in focus. That's all in the past: autofocus may have made it easier to focus—most of the time—but it has also made things more complicated. Here's what you need to consider:

What focus tool to use

The camera can detect focus using one or both of two different methods, depending on the viewfinder in use. In addition, it is capable of recognizing faces in some cases, and focusing on them instead of the predetermined positions in the image field.

Which mode to use?

With all these modes to choose from, which do you use? If you're using the conventional viewfinder, the “choice” is clear: you can only use phase AF, which also happens to be the fastest. If you're using Live View, it depends on the reasons. My use of Live View is for macro and long-distance photography, where I would probably use manual focus, so the question doesn't arise. But in general, I'd expect Live View to be most convenient when you're taking snapshots, and under those circumstances face recognition and quick response are the most important, so I've go for contrast AF.

What to focus on

The E-30 has three different ways of focusing:

These methods can be combined up to a point: you can set the camera up to perform sensor AF on demand when you're in manual mode, and you can combine imager AF and sensor AF: the initial focusing is performed with the imager, and the sensor performs fine-tuning before the photo is taken. Olympus calls this Hybrid AF.

Which AF mode?

Which mode do you use? Until proof of the contrary, I'd say “Sensor AF mode when using the viewfinder or when you care about the exact focus point, and Imager AF mode otherwise”. But I don't use Live View much; possibly Hybrid mode would work better for the times when I would use it.

What to focus on

When using phase AF and a supported lens, the camera chooses a focus point for you; there doesn't seem to be any way to influence it beyond using face detection.

In phase AF mode, or when the lens does not have support for contrast AF (“Imager AF”), the camera uses 11 sensors arranged in the following pattern:

Image

They can be used on one of four different ways, though the manual is unclear about this point and claims two or three modes. In one place Olympus calls it an AF Area, in another place an AF target mode. I'll stick with the latter term.

  1. In “all target” mode, the autofocus system uses any of these points to determine focus. This can be a problem unless the distance to the subject is quite uniform; you could end up focusing on something in foreground and having most of the image out of focus. In such cases, it's better to use one of the other modes.

  2. In the “dynamic single target” mode, the autofocus uses a specific sensor, but if it can't get focus with that sensor, it uses one of the adjacent ones. The centre sensor position can be moved around, which can mean that fewer than 5 sensors are actually available, as in the image on the right:

    Image
  3. The “single target” mode works in the same way, except that the camera does not try alternate sensors if it can't focus using the selected sensor:

    Image
  4. The “single target” mode can be further refined to what Olympus calls the “small single-target AF mode”. The manual text describing small-single target AF mode is not very clear:

    The camera focuses using one selected AF target. This is useful for accurately focusing on the subject after composing the shot. With M, you can focus using a range that is somewhat larger than one AF target, but you can only set the range within the AF target.

Which target?

Setting these modes is particularly complicated:

Changing targets

Once you have decided on a target mode, selecting one is done with similar, sometimes overlapping methods:

  1. Use the “direct button” menu
            symbol . In general, you can move the targets up and down with the rear wheel and left and right with the front wheel. Read on to the next item for modifications to the way this works.

  2. With the custom symbol custom symbol described on page 94, you can determine what happens when the front wheel gets to the end of the target sensors:

    1. If it is set to OFF, it moves to the last sensor on the middle row, even if it was above or below, and then stops:

      custom symbol
    2. If it is set to LOOP, it moves to the last sensor on the current row and then changes to “all target” mode. Moving further then starts again at the other end of the current row:

      custom symbol
    3. If it is set to SPIRAL, it moves to the last sensor on the middle row, even if it was above or below, and then stops:

      custom symbol
  3. You can move between modes 1 and 2 (“all targets” and “dynamic single target”) and the current choice of mode 3 or 4 (“single target” and “small single target”) by holding down the “direct button” menu symbol and turning either wheel. I haven't been able to find any reference to this in the manual.

When to focus?

When do you perform the focus operation? A video camera typically focuses continually, but that's not necessary on a still camera, and it can waste a lot of power. The E-30 focuses when you ask it to, typically by pressing a button, but there are a number of options. There are three basic focusing modes:

Single AF and continuous AF modes each have a variant which allows manual correction after focus has been achieved (S-AF+MF and C-AF+MF), so in total Olympus describes five different modes. Unfortunately, C-AF+MF seems terminally damaged: as soon as you adjust the focus manually, the “continuous” function changes it back again. The manual states (page 55):

My experiments confirm this. On the other hand, S-AF+MF works well, and I can't see any good reason to ever disallow manual corrections—about the only one I could think of is if you have problems keeping your hands off the focus ring—so I'd suggest one of the combinations S-AF+MF, C-AF or MF.

Focus mode modes

You have a number of choices of how to activate autofocus in each focus mode. Olympus confusingly calls these choices modes, so clearly they're focus mode modes, though they avoid calling it that.

In principle, there are three ways to invoke autofocus:

  1. Press the shutter button half way.

  2. Press the shutter button all the way.

  3. Press the AEL/AFL button (“Autoexposure lock/Autofocus lock”).

As the name suggests, the choices are made in conjunction with autoexposure. Set them via menu symbol . The settings are described on page 95 of the manual, which shows them as a table, but maybe the following overview will be easier to understand:

Manual focus mode

Single autofocus mode (S-AF and S-AF+MF)

Continuous autofocus mode (C-AF and C-AF+MF)

Indicating “in-focus” state

(no more to come)