How is Manual Focusing Supported on the GXR M-Mount Unit? - Overview | Manual Focus | Support for Manual Focusing | Conclusions | Appendix: General Manual Focusing Methods

On this page, I describe how focusing works with the GXR with the M-Mount expansion unit. This unit uses manual lenses only and therefore has to be focused manually.

Note: For the other camera units, see the Manual Focusing.

 

How is Manual Focusing Supported on the GXR M-Mount Unit? - Overview

The GXR M-Mount unit offers only one method for focusing manually: The user sets the focus manually by turning the focus ring of the (manual) lens.

Manual focusing is furthermore supported in several ways:

Enlargement was considerably improved and focus assist introduced with firmware update 1.40 that accompanied the introduction of the M-mount expansion unit.

 

Manual Focus

The M-mount expansion unit offers only manual focus. Therefore, there isn't even a "Focus" item in the "Shooting" menu (and nothing that you can assign to the "Adjust lever settings"). Thus, you set the focus by turning the manual focus ring of the lens that you use with the M-mount expansion unit.

Manual focusing can be performed using:

For example, you set the focus on the lens in advance and correct it using the viewfinder/LCD screen. See also the "Appendix Manual Focusing Methods" below.

 

Support for Manual Focusing

This section is nearly identical to that for the GXR camera units, but not completely.

Depth-of-Field Display

Most manual (or range-finder) lenses offer a depth-of-field indication on the lens. This allows you to apply the so-called "zone focusing" method or to set the "hyperfocal distance" (everything is sharp beginning at a certain distance to infinity).

    

Photo: Distance scale on manual M-bayonet lenses - Leitz Elmar-C f4/90mm (left) and Voigtländer Color Skopar Pancake II f2.5/35mm (right)

Magnification

A section of the picture can be magnified 2x, 4x, or 8x (since firmware update 1.29) ("Enlarged View mode"). The enlarged section is either shown in a section of the display ("Enlarge Part", lower quality) or full screen ("Enlarge All", better quality) (since firmware update 1.40). The enlarged section can be moved in either mode.

Note: The Ricoh GXR manual as well as the menus sometime use the term "magnification" and sometime speaks of "enlarge"...

Basic Procedure

Thus, by repeatedly pressing the "Menu" button for about a second, you can cycle through the magnification modes.

         

Photos: No magnification (left), "Enlarge Part" (center), and "Enlarge All" (right); in the latter case, a small display indicates where the enlargement is located in the image

Details

If you want to avoid cycling through the modes you can can set either "Enlarge All" or "Enlarge Part" to one of the function buttons Fn1 or Fn2. I use this setting for the M-mount expansion unit, but not for the regular camera units (there, I reserve the respective function button for switching between AF and MF). For the M-mount expansion unit, I set one function button to "Enlarge All" and one to "Focus assist" (sometimes, I change the arrangement...).

Magnification ratio can be set in the "Shooting" menu (item "Magnification" ratio). You can change the magnification ratio dynamically by pressing the selftimer button for more than a second. Then you can select between a magnification of 2x, 4x, or 8x.

You can move the enlarged section of the screen ("Mode Target") by pressing the "Adjust lever" button, then selecting the AF/AE setting in the fifth tab of the "Key Customs Settings", and using the direction buttons. Personally, I find this function only useful if the camera resides on a tripod.

When you half-press the shutter-release button in "Enlarge All" mode (fullscreen), magnification is turned off, and you see the image in normal magnification so that you can frame the photo. This is not the case for the "Enlarge Part" mode (but the manual does not distinguish between both modes). Personally, I prefer the behavior of the "Enlarge All" mode. It also allows me to switch between framing and focusing at will.

Last, but not least, in the "Setup" menu you can set that enlargement is turned off after shutter-release (item "Zoom Display Release") so that you have to turn it on when you need it again:

"Secret" Information

Now comes information that you cannot find in the manual. First, the quality of the 4x and 8x enlargement has clearly improved since firmware update 1.40. Secondly, the image quality of fullscreen mode is considerably better than when only a section of the screen displays the enlarged section. For manual focusing it is, therefore evident that only an enlarged fullscreen view is useful - I often use it even without focus assist.

The manual is also not clear about the different behaviors of the "Enlarge Part" and "Enlarge All" modes: It tells that pressing the shutter-release button half down turns off magnification. Actually, this happens only for the "Enlarge All" mode - one more argument that speaks for using this mode...

My Preferred Settings

Currently, I initiate magnification mode "Enlarge All" by pressing the "Fn2" button. Usually, I set the magnification ratio to 4x or 8x.

Focus Assist

The GXR offers two methods for supporting manual focusing:

There is no cycling through the focus assist modes as there is for the screen magnification mode and macro modes. You have to select the mode in the "Setup" menu, item "Focus assist selection" (Mode 1 or 2). There is also no button for selecting a focus assist mode (after pressing it for a second). Actually, there is no button available any more, but maybe Ricoh will find a solution... As you can see, Ricoh is inconsistent here in comparison with the magnification and macro modes...

Most users prefer focus assist mode 2, whereas I prefer mode 1 or no focus assist at all, that is, only full screen magnification. Focus assist can, of course, be combined with screen magnification.

         

Photos: No focus assist (left, focus assist mode 1 (center) and mode 2 (right)

 

Conclusions

There is no alternative to manual focus when you use the M-mount expansion unit. Thus, here the question is how you can do it with ease and fast. The "normal" screen display is usually not appropriate for focusing manually, because the EVF/LCD screen resolution is too low. Therefore, you have to pursue the following two routes (or combine them):

Both approaches have their advantages and disadvantages and "their" applications:

I found out that with fullscreen magnification I can usually do without focus assist, particularly because here you can simply press the shutter-release button to view the complete image for framing. Releasing the button is no problem, because there is no autofocus that needs to re-find its target and consumes time.

I also set the unit to turn magnification off after taking a picture (menu "Setup", item "Zoom Display Release" -> "on") , because starting with an enlarged view can be disturbing (which is in my opinion worse than having to press a function button for enlargement once again).

 

Appendix: General Manual Focusing Methods

In the following, I describe general manual focusing methods. The sections on zone focusing was adapted from Roger Hicks' and Frances Schultz's Photo School, the one on hyperfocal distance in part from Wikipedia.

Zone Focusing

Procedure for zone focusing with a lens that has a depth-of-field scale:

This sets the lens into a "snapshot" mode that does not require further focusing.

    

Photos: Zone focusing demonstrated with a manual lens (at f4.5, range from 1.2m to 5m; left) and with an AF lens (at f8, range from about 1.2m to 5m; right)

Distance Estimation

For non-moving subjects, I simply estimate the distance of the subjects and set the distance on the lens accordingly. This is easier than one might expect, particularly when using lenses with a short focal length and middle-to-small apertures. There is also an old rule of thumb that the zone of sharpness extends to one third in front of the distance you set and two thirds beyond it.

Pre-Focusing

Pre-focusing can be regarded as a variant of distance estimation, namely one for moving subjects (Roger and Frances call it a variant of zone focusing, but there is no zone here...). You set your lens to the distance at which you expect the subjects to appear and wait until they come into (pre-)focus. Typical applications are sports and action photography.

Hyperfocal Distance

According to Wikipedia, definition 1 (the one that I find more useful), the hyperfocal distance is the closest distance at which a lens can be focused while keeping objects at infinity acceptably sharp. When the lens is focused at hyperfocal distance, all objects at distances from half of the hyperfocal distance out to infinity will be acceptably sharp.

But how do I know this distance for my specific lenses without having to perform calculations and brood about which circle of confusion I would accept?

In practice, I accept the circle of confusion that the lens maker decided for (there are differences between lens makers...) and proceed in the following way:

I could confirm that I am correct at DOFmaster (Hyperfocal distance). By the way, if you proceed as described above, you can also verify that the closer depth-of-field-mark is set to about half the distance that you actually set indirectly this way, namely the hyperfocal distance.

Note that this procedure only works for lenses with a depth-of-field scale. In all other cases more effort is needed (See DOFmaster -> Hyperfocal distance)...

Also note that setting the hyperfocal distance is most useful for wide lenses with a large depth-of-field.

    

Photos: Hyperfocal distance demonstrated with a manual lens (at f8, hyperfocal distance about 1.8m, range about 0.95m to infinity; left) and with an AF lens (at f8, hyperfocal distance about 4.5m, range from about 2m to infinity right); the latter is probably not optimally set

Final Word

You can mix this all up at your will: You can either decide for a distance and keep the 1/3-2/3 rule in mind, or you look for a range, which you can also manipulate so that one end is infinity...

 

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02.01.2012