Asahi Pentax L-X User's Guide download pdf (Page 14)

Because black & white infrared film records light rays which focus

differently than light in the visible spectrum, when shooting it is necessary

to adjust the focusing ring accordingly. After focusing normally on the

subject, note the subject-camera distance on the lens distance scale and

turn the focusing ring until that distance setting aligns with the orange

infrared index mark.

In the top photo, the lens is focused at infinity (i) for normal photography;

in the bottom photo it has been adjusted for infrared photography by

moving the infinity mark to the orange infrared index.

NOTE: Compensation is not required when using infrared

color films.

DEPTH OF FIELD SCALES

Depth of field is the area in acceptable sharpness in front of and behind the subject in focus at a particular f/stop setting. Depth of field can be checked

visibly by activating the depth-of-field preview while looking through the camera viewfinder. If more precise information is required, however, the depth

of field scales engraved on most camera lenses provide a convenient means of determining the approximate distances.

The numbers engraved on either side of the depth of field scale represent f/stops. To read the scale, look at the distance scale of the lens opposite the index

marks on the depth of field scale representing the f/stop set on the aperture ring. For example, in the photograph the lens is focused on a subject 5 meters

away. At f/4 the depth of field is from approximately 4 to 7 meters. At f/5.6, the depth would be increased from approximately 3.6 meters to 7.9 meters.

DEPTH OF FIELD TABLES

Dist. scale 0.45m 0.6m 1m 1.6m 2m 3m 5m 15m i

f/1.4 0.447

~ 0.453

0.595

~ 0.605

0.984

~ 1.017

1.557

~ 1.645

1.932

~ 2.073

2.846

~ 3.172

4.579

~ 5.506

11.712

~ 20.868

52.938

~ i

f/2 0.446

~ 0.454

0.593

~ 0.608

0.977

~ 1.024

1.539

~ 1.666

1.904

~ 2.106

2.785

~ 3.252

4.420

~ 5.757

10.707

~ 25.077

37.070

~ i

f/2.8 0.445

~ 0.455

0.590

~ 0.611

0.969

~ 1.034

1.516

~ 1.694

1.869

~ 2.152

2.708

~ 3.365

4.225

~ 6.128

9.609

~ 34.313

26.491

~ i

f/4 0.443

~ 0.458

0.586

~ 0.615

0.956

~ 1.049

1.483

~ 1.737

1.818

~ 2.224

2.599

~ 3.550

3.962

~ 6.786

8.329

~ 76.783

18.557

~ i

f/5.6 0.440

~ 0.461

0.580

~ 0.622

0.939

~ 1.070

1.441

~ 1.799

1.754

~ 2.329

2.468

~ 3.832

3.659

~ 7.922

7.075

~ i

13.268

~ i

f/8 0.436

~ 0.466

0.572

~ 0.631

0.915

~ 1.103

1.383

~ 1.901

1.667

~ 2.506

2.294

~ 4.351

3.284

~ 10.585

0.572

~ i

9.300

~ i

f/11 0.430

~ 0.472

0.562

~ 0.644

0.887

~ 1.148

1.316

~ 2.047

1.569

~ 2.771

2.109

~ 5.242

2.911

~ 18.301

0.562

~ i

6.776

~ i

f/16 0.422

~ 0.482

0.546

~ 0.667

0.844

~ 1.231

1.219

~ 2.348

1.430

~ 3.386

1.861

~ 7.978

2.450

~ i

0.546

~ i

4.672

~ i

f/22 0.413

~ 0.496

0.529

~ 0.696

0.798

~ 1.349

1.120

~ 2.855

1.294

~ 4.545

1.631

~ 21.588

2.061

~ i

0.529

~ i

3.410

~ i

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Asahi Pentax L-X User's Guide Page 14

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