OM System OM-1 - Manual Focus
Although the OM System OM-1 features one of the best autofocus systems ever developed, there are rare situations where manual intervention by the photographer is in order.
Also, adapted lenses usually have to be manually focused, either because the adapter does not communicate with the camera or because they are manual focus lenses in the first place.
Thankfully, the OM-1 offers a wide array of features to achieve critical focus even under the most challenging circumstances.
OM-1 Manual Focus Basics
To engage manual focus with a native Four Thirds or Micro Four Thirds lens, the following options exist:
1) AF/MF switch (Four Thirds and Panasonic lenses).
2) Manual focus clutch (most OM System Pro lenses and Panasonic Leica f/1.7 zooms).
3) Change the focus mode setting in camera (either via the super control panel or with a function button).
AF/MF switch (Panasonic).
MF clutch (OM System).
Function button (OM-1).
Focus by Wire
Most Four Thirds and Micro Four Thirds lenses utilize focus by wire. The step size and therefore the precision when manually focusing depends on the autofocus motor and can vary from lens to lens.
Manual Focusing Technique
Two basic optical concepts have to be understood to truly master manual focusing: Critical focus and depth of field.
Critical Focus
Critical focus describes the part of the image that is optically in focus.
Not taking field curvature into account, the plane of critical focus is perpendicular to the optical axis of the lens. The plane has no depth.
Plane of critical focus.
Depth of Field
Depth of field is the distance between the nearest and farthest points of a scene that are in acceptably sharp focus.
It is important to know that the depth of field does not extend evenly from the plane of critical focus.
The near to far distribution is as follows: The acceptable focus beyond the plane of critical focus extends further than it does in front of the plane of critical focus (towards the camera).
Depth of field and plane of critical focus.
Manually Focusing
Focusing aims to move the plane of critical focus so that important parts of the subject are in perfect focus or lie within the depth of field.
Manual Focusing Technique
aka “Overshoot, undershoot & back”
1) Focus the lens to infinity or at least further away than the distance of the actual subject.
2) Adjust the focus until the subject is first in- and then slightly out of focus.
Note: By doing so, you will be able to see how critical focus with the current lens actually looks like. Often focus is missed because the object was only in acceptable, but not critical focus.
3) Lastly, turn the focus ring in the opposite direction until the subject appears critically sharp for the first time.
Critical focus is now achieved and the photograph can be taken.
Manual Focus Assist Functions
The OM System OM-1 offers three different manual focus assist functions: Focus Zoom, Focus Peaking and Focus Indicator.
Focus Zoom (Magnify)
Focus Zoom magnifies a portion of the Live View image.
Utilizing Focus Zoom is the best method to achieve critical focus.
The position of the zoom frame can be changed, just like an AF target area (e.g. by using the multi selector).
The magnification can be set by rotating the front or rear dial when zoomed in.
Zoom frame.
Magnified view.
Tip:
When half-press image stabilization is set to [On] ([MENU]-[Camera1]-[8. Image Stabilizer]-[Image Stabilizer]), the IBIS will be active during Focus Zoom, regardless of whether the shutter button is pressed or not, stabilizing the Live View image. This greatly facilitates focusing, especially at higher magnifications and with telephoto lenses.
Focus Peaking
With Focus Peaking active, the OM System OM-1 performs a global contrast detection calculation and highlights areas with high contrast.
Focus Peaking offers an easy way to achieve acceptably sharp focus, but is not suited for achieving critical focus reliably under all circumstances.
False positives are possible, especially in low light due to image noise.
Calibrating Focus Peaking
For best performance, the detection threshold has to be adjusted.
Access the settings via [Menu]-[AF]-[6. MF]–[Peaking Settings] or while Focus Peaking is active by pressing the [INFO] button (recommended).
The “Highlight Intensity” sub-setting determines the focus peaking detection threshold.
The higher the setting, the more tolerant the contrast detection calculation.
If a very soft or very fast lens is mounted, a higher setting is recommended. Otherwise, the OM-1 might not detect any contrast or highlight only very few pixels which can be hard to spot.
If a slow lens is mounted or the shooting conditions are very dark, a lower setting is recommended. Otherwise, too many pixels will be highlighted, leading to false positives.
Focus peaking settings overlay.
Focus Indicator
When active, the OM-1 will display a digital focusing scale. This function is only available with a Micro Four Thirds lens attached.
It helps to visualize the set focus distance.
Focus Indicator.
Focusing Aids in Practice
To utilize the various focusing aids, they have to be enabled either manually or automatically.
Focusing Aids – Automatic Operation
Note: Only available when a Four Thirds or Micro Four Thirds lens is attached to the camera.
Automatic focusing aids can be enabled via [MENU]–[AF]–[6. MF]–[MF Assist].
Whenever the focusing ring is turned, the OM-1 will automatically activate the selected focusing aids. When the focusing ring remains idle for a moment, normal Live View resumes.
Fully compatible with the OM-1: Four Thirds and Micro Four Thirds lenses.
Focusing Aids - Manual Operation
Regardless of lens, Focus Zoom and Focus Peaking can be mapped to a function button. They both operate independently of each other, but can be used in combination as well.
Pressing the designated function button engages or disengages the respective focusing aid. To completely disengage Focus Zoom, hold the assigned button and the green box will disappear.
When LV Close Up Mode is set to [mode1] (see [MENU]–[Cogwheel]–[2. Operations]–[LV Close Up Mode]), half pressing the shutter button will disengage the Focus Zoom.
Focusing Third Party Lenses – Expert Knowledge
When a Micro Four Thirds or Four Thirds lens is mounted, the focus operation will be conducted with open aperture. Then, the depth of field during focusing is relatively thin and almost matches the plane of critical focus.
However, when an adapted lens is mounted, the focus operation will be conducted with the lens stopped down to the set working aperture. The depth of field can be relatively deep and the plane of critical focus can then be harder to identify.
To mitigate the issue, this procedure is recommended:
1) Set the shooting mode M and activate [S-OVF].
2) Open up the aperture and focus the lens. Utilize focusing aids, if necessary.
3) Stop down the lens to the desired working aperture. Double-check the focus if the mounted lens is prone to focus shift.
4) Take the photograph.
Note: The viewfinder image will retain brightness regardless of the set f-number.
General Recommendations
If achieving precise, critical focus is desired, utilize Focus Zoom only.
When shooting a lens stopped down in reportage and street photography, Focus Peaking facilitates fast focusing.
When sufficient light is available, combining Focus Zoom with Focus Peaking set to “low” can yield satisfying results.
