Ricoh GR: Using Snap Focus for Hyperfocal Distance and Zone Focusing - Is It Possible Indoors?

Introduction | Combining Snap Focus and Aperture Values to Achieve (Nearly) Hyperfocal Distances | Exposure Values for Indoor Shots | Combining the Elements: Constraints on Aperture Values | Using DOF Tables and Snap Focus for Indoor Zone Focusing | Final Words | References

 

Shooting indoors is a challenge for most digital cameras. It is fairly dark indoors, irrespective of whether daylight, mixed light, or just artificial light is available. The typically long shutter speeds are a challenge for shooting moving subjects, such as playing children, and for taking hand-held shots in general. Most autofocus systems struggle here, more or less. I was therefore looking for alternatives to using the autofocus system under such conditions and investigated: (1) the hyperfocal distance* (HFD) and (2) zone focusing.

*) The hyperfocal distance (HFD) is a distance setting, where everything from half the hyperfocal distance to infinity is "acceptably sharp."

In both cases, you have to set the distance "in advance," which may contradict people's intention to shoot "spontaneously." Many people also do not know how to set distance manually or use camera modes, such as "intelligent" automatics, that do not allow to do so. This page is not meant for them. It addresses Ricoh GR users, because this camera (and some other Ricoh cameras) has a special feature that makes it easy to set the distance manually: snap focus. This feature allows you to select one of several fixed distances from a menu, which you can put on a function button, for example, for easy access.

On this page, I investigate for the Ricoh GR, whether the two above-mentioned focusing approaches can be combined with snap focus for indoor shots to make manual focusing easier - and shooting faster, because there is no wait for the autofocus to find its target.

 

Introduction

For the above-mentioned reasons, I investigate in the following, whether the hyperfocal distance and zone focusing approaches can be applied successfully to indoor shooting, when snap focus is used to set the distance. The latter is an important restriction, particularly, when you intend to use hyperfocal distances. Snap focus provides five predefined distances (1 m, 1.5 m, 2 m 2.5 m, 5 m; the default is 2.5 m), and when you select one of them, you need to match it with an aperture value that ensures that the image is "acceptably sharp" from half the hyperfocal distance to infinity (for details see below). This requirement typically excludes large apertures (f/2.8 to f/5.6), because these provide only a shallow depth of field (DOF). Small apertures, on the other hand, may provide the needed DOF, but may lead, due to the poor lighting conditions indoors, to long shutter speeds that can no longer be held by hand. Thus, you are in a dilemma as to which aperture to choose, particularly, when you want to use hyperfocal distances.

In the following, I ask, whether this dilemma can be solved for hyperfocal distances and whether zone focusing might provide a viable alternative. To answer this question, I investigate the following aspects (using background information from the listed sources of information from this site):

  1. Combining snap focus distances with aperture values to (nearly) achieve hyperfocal distances
    (see page Hyperfocal Distance and Combining it with Snap Focus for background information)
  2. What exposure values can you expect for indoor shots and, using aperture values derived from item 1, what shutter speeds do they allow at which ISO values?
    (see page General: Physical Limits of Photography: Insufficient Light - Part 2 for background information).
  3. What constraints place the indoor lighting conditions on aperture values when I want to use hyperfocal distances based on snap focus distances?
  4. Using zone focusing to combine snap focus distances with aperture values that deliver sufficient depth of field (based on DOF tables) indoors
    (see page Depth of Field Tables for background information)

 

Combining Snap Focus and Aperture Values to Achieve (Nearly) Hyperfocal Distances

The Ricoh GR has the snap focus feature that allows you to set the distance manually with ease by providing certain fixed distance values that can be selected from a menu (1 m, 1.5 m, 2 m 2.5 m, 5 m; the default is 2.5 m). Therefore, one might ask whether it is possible even indoors to set snap focus to a certain distance and then select an aperture value that offers enough depth-of-field so that this distance is hyperfocal or nearly hyperfocal (M, Av, or TAv exposure modes), making everything acceptably sharp from half the distance to infinity.

The following table taken from page Hyperfocal Distance and Combining it with Snap Focus suggests aperture values, which lead to a hyperfocal (or nearly) behavior for the snap focus distances that the Ricoh GR provides:

 
Nearly Hyperfocal
Hyperfocal
Snap Focus
Distance (m)
Aperture Sharp from ...
to ... (m)
Aperture Sharp from ...
to infinity (m)
5 f/2.8 2.72 to 31.55* f/3.5 2.43*
2.5 f/6.3 1.29 to 42.43* f/7.1 1.22*
2 f/8 1.03 to 37.6* f/9 0.97
1.5 f/11 0.75 to inf f/11 0.75
1 f/16 0.52 to 16.14* f/16 --

*) According to DOF tables (detail table) or manual calculations (with Excel)

A simplified version of the table can be found below.

For street and indoor photography, the "nearly hyperfocal" apertures should be sufficient, because an extension of the DOF to infinity is not needed. For landscape and "tourist" photos, you should close the aperture a third stop more and use the aperture values on the right (except for where it is not possible - the GR does, for example, not offer f-stops beyond f/16...).

 

Exposure Values for Indoor Shots

Now, we have to look at the indoors lighting conditions. Elsewhere on this site (General: Physical Limits of Photography: Insufficient Light - Part 2), I state that you can expect exposure values in a range of EV 5-7 for indoor shots. For indoor shots using artificial light, I extended the range to EV 4-7. The following table includes some additional aperture values and describes the exposure settings for indoor shots (based on the assumed exposure values):

f/2.8
ISO
  f/5.6
ISO
EV 100 200 400 800 1600 3200 6400 EV 100 200 400 800 1600 3200 6400
4 1/2 1/4 1/8 1/15 1/30 1/60 1/125 4 2 1 1/2 1/4 1/8 1/15 1/30
5 1/4 1/8 1/15 1/30 1/60 1/125 1/250 5 1 1/2 1/4 1/8 1/15 1/30 1/60
6 1/8 1/15 1/30 1/60 1/125 1/250 1/500 6 1/2 1/4 1/8 1/15 1/30 1/60 1/125
7 1/15 1/30 1/60 1/125 1/250 1/500 1/1000 7 1/4 1/8 1/15 1/30 1/60 1/125 1/250
 
f/6.3
ISO
  f/8
ISO
EV 100 200 400 800 1600 3200 6400 EV 100 200 400 800 1600 3200 6400
4 3.3 1.6 0.8 0.4 1/5 1/10 1/20 4 4 2 1 1/2 1/4 1/8 1/15
5 1.6 0.8 0.4 1/5 1/10 1/20 1/40 5 2 1 1/2 1/4 1/8 1/15 1/30
6 0.8 0.4 1/5 1/10 1/20 1/40 1/80 6 1 1/2 1/4 1/8 1/15 1/30 1/60
7 0.4 1/5 1/10 1/20 1/40 1/80 1/160 7 1/2 1/4 1/8 1/15 1/30 1/60 1/125
 
f/11
ISO
  f/16
ISO
EV 100 200 400 800 1600 3200 6400 EV 100 200 400 800 1600 3200 6400
4 8 4 2 1 1/2 1/4 1/8 4 16 8 4 2 1 1/2 1/4
5 4 2 1 1/2 1/4 1/8 1/15 5 8 4 2 1 1/2 1/4 1/8
6 2 1 1/2 1/4 1/8 1/15 1/30 6 4 2 1 1/2 1/4 1/8 1/15
7 1 1/2 1/4 1/8 1/15 1/30 1/60 7 2 1 1/2 1/4 1/8 1/15 1/30

*) Do not take the shutter speeds for f/6.3 too seriously - they are "about" values.

You can see that, at an aperture value of f/2.8, you still fare quite well with ISO 800 under these lighting conditions with respect to shutter speeds. At an aperture value of f/5.6, however, even ISO 1600 is "tight" in many situations. Using aperture values above f/5.6 becomes a real challenge to hand-held shots.

 

Combining the Elements: Constraints on Aperture Values

Here is a simplified version of the HFD table from above:

 
Nearly Hyperfocal
Hyperfocal
Snap Focus
Distance (m)
Aperture Sharp from ...
to ... (m)
Aperture Sharp from ...
to infinity (m)
5 f/2.8 2.7 to 32 f/3.5 2.4
2.5 f/6.4 1.3 to 42 f/7.1 1.2
2 f/8 1.0 to 37 f/9 1
1.5 f/11 0.75 to inf f/11 0.75
1 f/16 0.5 to 16 f/16 0.5*

*) Not quite "hyperfocal"...

Now, we need to combine the information from both sources to find out what can be achieved indoors. In my opinion, the results are more or less disappointing:

All in all, using the Ricoh GR snap focus distances to create hyperfocal behavior is not possible (or realistic...) for shooting indoors. The Ricoh GR is a "large-sensor" camera, though, and this may be different for cameras with small sensors. I may check this for small-sensor cameras like the Ricoh CX4 some time in the future...

 

Using DOF Tables and Snap Focus for Indoor Zone Focusing

So the question arises, whether "there is light" if we relax the requirements somewhat, particularly at the far distance. This means that we would use "zone focusing." To answer this question, we need to take a look at the DOF tables for the Ricoh GR.

The following table is based on the DOF table for the Ricoh GR and modified to list the camera's snap focus distances (therefore, I had to add the distance of 2.5 m to this table):

Focal Length: 18.3 mm

Depth of Field (m) for Snap Focus Distance Set
Snap Focus Distance >
1
1.5
2
2.5
5
Aperture V / DOF >
Near
Limit
Far
Limit
Near
Limit
Far
Limit
Near
Limit
Far
Limit
Near
Limit
Far
Limit
Near
Limit
Far
Limit
2.8 0.858 1.199 1.200 2.001 1.498 3.006 1.762 4.304 2.715 31.544
3.5 0.827 1.264 1.140 2.191 1.407 3.459 1.636 5.298 2.427 inf
4 0.810 1.306 1.108 2.322 1.357 3.798 1.570 6.140 2.283
inf
4.5 0.792 1.357 1.073 2.489 1.306 4.268 1.501 7.472 2.141
inf
5.1 0.772 1.419 1.037 2.707 1.253 4.956 1.431 9.879 2.001
inf
5.6 0.751 1.496 1.000 3.003 1.198 6.051 1.360 15.470 1.864
inf
6.3 0.729 1.593 0.960 3.424 1.142 8.047 1.288 42.426 1.731
inf
7.1 0.705 1.718 0.920 4.061 1.085 12.779 1.216
inf
1.602
inf
8 0.681 1.883 0.878 5.135 1.027 37.590 1.144
inf
1.479
inf
9 0.655 2.112 0.836 7.303 0.970
inf
1.073
inf
1.362
inf
10 0.629 2.445 0.793 13.877 0.912
inf
1.002
inf
1.250
inf
11 0.601 2.970 0.750
inf
0.855
inf
0.934
inf
1.145
inf
12.7 0.573 3.914 0.706
inf
0.799
inf
0.867
inf
1.046
inf
14 0.545 6.087 0.663
inf
0.744
inf
0.803
inf
0.954
inf
16 0.516 16.142 0.621
inf
0.691
inf
0.742
inf
0.868
inf

This table is, of course, too complex for a "quick-and-dirty" answer. Therefore, I simplified the table by rounding numbers to two digits, removing the 5 m snap focus distance, and removing apertures beyond f/8:

Focal Length: 18.3 mm

Depth of Field (m) for Snap Focus Distance Set
Snap Focus Distance >
1
1.5
2
2.5
Aperture V / DOF >
Near
Limit
Far
Limit
Near
Limit
Far
Limit
Near
Limit
Far
Limit
Near
Limit
Far
Limit
2.8 0.86 1.20 1.20 2.00 1.50 3.01 1.76 4.30
3.5 0.83 1.26 1.14 2.19 1.41 3.46 1.64 5.30
4 0.81 1.31 1.11 2.32 1.37 3.80 1.57 6.14
4.5 0.79 1.36 1.07 2.49 1.31 4.27 1.50 7.47
5.1 0.77 1.42 1.04 2.71 1.25 4.96 1.41 9.88
5.6 0.75 1.50 1.00 3.00 1.20 6.05 1.36
inf
6.3 0.73 1.59 0.96 3.42 1.14 8.06 1.29
inf
7.1 0.71 1.72 0.92 4.06 1.09
inf
1.22
inf
8 0.68 1.88 0.88 5.14 1.03
inf
1.14
inf

This was still too complex for me. By rounding distances even more, I arrived at the following coarse simplification of the table:

Focal Length: 18.3 mm

Depth of Field (m) for Snap Focus Distance Set
Snap Focus Distance >
1
1.5
2
2.5
Aperture V / DOF >
Near
Limit
Far
Limit
Near
Limit
Far
Limit
Near
Limit
Far
Limit
Near
Limit
Far
Limit
2.8     1.20 2.00 1.50 3.00 1.75 4.30
3.5     1.15 2.20 1.40 3.50 1.65 5.30
4     1.10 2.30 1.40 3.80 1.60 6.10
4.5     1.05 2.50 1.30 4.30 1.50 7.50
5.1     1.05 2.70 1.25 5.00 1.40 10.00
5.6 0.75 1.50 1.00 3.00 1.20 6.00 1.35
inf
6.3 0.70 160 0.95 3.40 1.15 8.00 1.30
inf
7.1 0.70 1.70 0.90 4.00 1.10
inf
1.20
inf
8 0.70 1.90 0.90 5.10 1.00
inf
1.15
inf

Looking at the exposure value table above, I would not close aperture more than f/5.6 to get acceptable shutter speeds at not too high ISO values. Looking at the DOF table above, I would not open aperture more than f/5.6 to get a fairly comfortable DOF range or "zone."

Thus, setting aperture to a value of f/5.6 and snap focus to a value between 1.5 m and 2.5 m, depending on the situation at hand, seems to be the best compromise for the Ricoh GR for me (blue bold-italic numbers). The blue bold numbers might also be still acceptable in situations where the objects are not too far away.

Proposals...

Finally, I would like to suggest two options for how you can set your Ricoh GR for "easy shooting" (snap focus distance 1.5, 2, or 2.5 m):

  1. Set the camera to Av mode (aperture priority), aperture to f/5.6, and to ISO 1600 (or to ISO 3200 if you can accept lower image quality). Then you have to carefully watch that the shutter speed that the camera selects automatically is not too slow.
  2. Set the camera to TAv mode, aperture to f/5.6, and shutter speed to 1/60 sec (like in manual mode). Then you have to watch carefully that the ISO number that the camera selects automatically does not move too high.

The second approach may be the simpler one in practice, because you can check ISO in advance and can make sure that it does not go too high by adapting the shutter speed accordingly. In the end, all depends on your shooting habits and the situation at hand...

Thus, all you have to remember (or write down) for both of these approaches are just a few numbers. Since you estimate the distances anyway, too much precision is not necessary...

 

Final Words

The considerations presented here are valid for an APS-C camera. While they are based on the DOF tables for the Ricoh GR, they apply to other APS-C cameras similarly for a focal length of about 18 mm, or 28 mm equivalent. The main difference between cameras would be their high ISO behavior. The better it is, the better for you.

Cameras with different sensor sizes require different considerations:

Many small-sensor cameras have some anti-shake mechanisms built in, while many APS-C cameras have not. This provides an advantage for small-sensor cameras regarding hand-held shots, but not regarding motion blur (playing children, for example).

In the end, you have to calculate and visually check for each camera what is the optimum, depending on ISO, maximum aperture, and DOF behavior.

 

References

 

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14.02.2016