UNDERSTANDING

Allen Baxter WHAT IS EXPOSURE?

• IT IS THE AMOUNT OF LIGHT THAT REACHES THE SENSOR. • PHOTOGRAPHICALLY SPEAKING EXPOSURE IS THE AMOUNT OF LIGHT FALLING ON AN OBJECT AND HOW WE CHOOSE TO RECORD THIS INTERACTION TO ACHIEVE THE DESIRED LOOK FOR AN IMAGE. • IT IS SUBJECTIVE BECAUSE WE ALL HAVE DIFFERENT TASTE, BUT THE BASIC PROCESS OF EXPOSING AN OBJECT CORRECTLY ALLOWS US TO ADJUST THE VARIABLES TO ACHIEVE THE DESIRED LOOK FOR THE IMAGE. VARIABLES THAT CONTROL EXPOSURE

• – THIS IS THE OPENING IN THE LENS. IT DETERMINES THE VOLUME OF LIGHT THAT ENTERS THE CAMERA. • SPEED – THIS IS THE DURATION THAT THE SHUTTER STAYS OPEN ALLOWING LIGHT TO REACH THE OR . • ISO – THIS IS THE SENSITIVITY OF THE SENOR TO LIGHT. EXPOSURE TRIANGLE

We can change exposure by adjusting one or all three ISO variable to achieve the desired result.

APERTURE SHUTTER APERTURE (FSTOP) • THIS IS THE OPENING IN THE LENS AND IS USUALLY VARIABLE OR ADJUSTABLE. • IT DETERMINES THE AMOUNT OR VOLUME OF LIGHT THAT ENTERS THE CAMERA • IT IS A SERIES OF OVERLAPPING MOVABLE LEAVES LOCATED IN THE LENS. • EXPRESSED AS: F/1.4 • ALSO CONTROLS OR THE IN AN IMAGE. • F/1.4 IS A LARGE OPENING. LETS IN MORE LIGHT. LESS DEPTH OF FIELD • F/22 IS A SMALL OPENING. LETS IN LESS LIGHT. MORE DEPTH OF FIELD • F STOP ABOVE F/16 START TO GET EFFECT OF DIFFRACTION • 1.4, 2.0, 2.8, 4.0, 5.6, 8.0, 11.0, 16.0, 32.0 LENS APERTURE LENS APERTURE

• THIS DETERMINES HOW LONG LIGHT IS ALLOWED TO STRIKE THE IMAGE SENSOR OR FILM. • TYPICALLY MADE OF A SERIES OF CURTAINS THAT OPEN AND CLOSE AND IS LOCATED IN THE BODY OF THE CAMERA IN FRONT OF THE SENSOR • ALLOWS YOU TO FREEZE ACTION OR IMPLY MOTION IN AN IMAGE. • CREATING IMAGES THAT IMPLY MOTION OR STOP MOTION • A KEY VARIABLE IN PREVENTING CAMERA SHAKE AND GETTING SHARP IMAGES. • GENERAL RULE IS USE 1/LENS • 50 MM LENS SO USE 1/50 SEC SHUTTER SPEED • 200 MM LENS SO USE 1/200 SEC SHUTTER SPEED • IMAGE STABILIZATION OF LENS HELPS THIS AND WILL ALLOW YOU SHOOT AT A SLOWER SHUTTER SPEED AND HELP ELIMINATE CAMERA SHAKE. • 1 SEC, ½, ¼, 1/8 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000 SEC ISO

• IT BRIGHTENS YOUR PHOTOS, BUT IT IS NOT PART OF YOUR “LUMINOUS EXPOSURE,” SINCE IT DOES NOT AFFECT THE AMOUNT OF LIGHT THAT REACHES YOUR CAMERA SENSOR (THE DEFINITION OF EXPOSURE). INSTEAD, IT MERELY BRIGHTENS A PHOTO IN-CAMERA AFTER YOUR SENSOR HAS ALREADY BEEN EXPOSED TO THE LIGHT. • THIS IS THE SENSITIVITY OF THE SENSOR TO LIGHT. • THE LARGER THE NUMBER THE MORE SENSITIVE IT IS TO LIGHT. • CAMERA NATIVE OR BASE ISO: BEST • 100 – 200. SOME NEWER AS LOW AS 64. • NATIVE – IS THE ISO SETTING THAT DOES NOT REQUIRE THE CAMERA TO INCREASE THE VOLTAGE TO THE SENSOR AND PROVIDES THE BEST AND IMAGE QUALITY. ISO - CONTINUED

• EXTENDED RANGE ISO: DEGRADED IMAGE QUALITY • LOW’S OF 50 • HIGH’S OF 12,800

• AMPLIFIED – IS AN ISO THAT REQUIRES AN INCREASE IN VOLTAGE TO THE SENSOR. THIS IS WHEN NOISE STARTS TO CREEP INTO THE IMAGE. THE HIGHER THE ISO THE GREATER THE NOISE. • SIMULATED – CAMERA USES A SOFTWARE ALGORITHM TO SIMULATE HIGHER OR LOWER ISO. WILL SEE AN INCREASE IN NOISE OVER THE NATIVE SETTING. EXPOSURE TRIANGLE RECIPROCAL EXPOSURE THE BELOW SETTINGS WILL PRODUCE THE SAME EXPOSURE FOR A GIVEN ISO

Fstop 2.0 2.8 4.0 5.6 8.0 11 16 22 Shutter 1/8000 1/4000 1/2000 1/1000 1/500 1/250 1/125 1/60 HEART OF THE TRIANGLE THE LIGHT METER

• HOW DOES THE LIGHT METER WORK: • LIGHT METERS MEASURES LIGHT AND RELATES THAT EXPOSURE ON A SCALE. • “ZERO” SCALE READING IS INTERPRETED AS 18% GRAY. • READINGS TOWARD THE + ARE BRIGHTER. • READINGS TOWARD THE – ARE DARKER.

+ | | | | | | | | | 0 | | | | | | | | | -

• WE CAN CHANGE THE EXPOSURE BY ADJUSTING THE FUNCTIONS IN THE EXPOSURE TRIANGLE: • APERTURE • SHUTTER SPEED • ISO METERING MODES

• MATRIX / EVALUATIVE METERING

• CENTER WEIGHTED METERING

• SPOT METERING UNDERSTANDING THE HISTOGRAM

• NOT ALL CAMERA OR SOFTWARE MANUFACTURERS CREATE THEIR HISTOGRAMS TO LOOK EXACTLY THE SAME, BUT THEY ALL TELL THE SAME STORY. THE EXACT NUMBERS AREN’T CRITICAL; INSTEAD, UNDERSTANDING THE TONAL VALUES OF EACH QUADRANT IS THE KEY TO MAKING EFFECTIVE EXPOSURE ADJUSTMENTS. • A PHOTOGRAPHIC HISTOGRAM IS A SIMPLE GRAPHICAL ILLUSTRATION OF THE TONAL AREAS OF AN IMAGE FROM SHADOWS THROUGH MIDTONES TO HIGHLIGHTS. • ON THE GRAYSCALE, 0 IS BLACK AND 255 IS WHITE, AND 128 IS NEUTRAL GRAY. • THE CAMERA’S SENSOR RECORDS VISIBLE GRAYSCALE TONES FROM LIGHT TO DARK. • IT ALSO RECORDS DENSITY OF EACH (RED, GREEN, BLUE). • WE WANT TO RECORD AS MUCH DETAIL AS POSSIBLE WITHOUT BLOWING OUT HIGHLIGHTS (BLINKIES) ON THE HIGH END OR BLOCKING UP SHADOWS ON THE LOW END. UNDERSTANDING THE HISTOGRAM

• NEUTRAL GRAY (OR 18% GRAY) LIES IN THE MIDDLE OF THE HISTOGRAM – 128 ON THE SCALE. CAMERA SENSORS ARE FAR MORE SENSITIVE TO THE RIGHT OF THE MIDPOINT; IN FACT NEARLY 75% OF THE SENSOR’S RECORDING ABILITY IS TO THE RIGHT OF 128. EXPOSING TO THE RIGHT (ETTR) IN-CAMERA WILL MAXIMIZE THE QUALITY OF YOUR IMAGES, GIVING YOU THE MOST DATA POINTS TO WORK WITH IN POST-PROCESSING. UNDERSTANDING YOUR HISTOGRAM UNDERSTANDING YOUR HISTOGRAM UNDERSTANDING YOUR HISTOGRAM

Clipping of shadows. of highlights. Losing detail in the Losing detail in the shadows. highlights UNDERSTANDING YOUR HISTOGRAM

This histogram reveals a severely underexposed . Because most of the sensor’s recording ability is in the right half of the histogram, this exposure is sacrificing quality. And the histogram slams up against the left wall, meaning there is zero detail in the shadows, just pure black. UNDERSTANDING YOUR HISTOGRAM

This histogram displays a normal, broadly lit scene mostly dominated by midtones, with enough dark and light tones for decent contrast. All tones are captured without blowing out highlights or blocking up shadows. depth is limited, however. Perhaps this was a foggy day? UNDERSTANDING YOUR HISTOGRAM

This histogram reveals a severely overexposed photograph. However, because the sensor records most of its data to the right, this exposure has more latitude for correction than an underexposed shot. Nevertheless, any data that hits the right wall at 255 is blown out (pure white) and unrecoverable. UNDERSTANDING YOUR HISTOGRAM

This histogram includes data in all zones from dark to light with no blocked up or blown out areas. It also includes most of the recorded data on the right side, maximizing quality. A photograph with this histogram would be ideal in in terms of successful post-processing. would be bright, whites white, and sensor noise in the shadows would be kept to a minimum. SPECIALIZED HISTOGRAMS No two histograms look alike, and there are times when they might look unusual. High key and low key are good examples of when a histogram doesn’t fit the standard model. But they tell you exactly the same thing – where to place your exposure values for maximum effect and quality. In the case of a high key image, most of the data is to the right – just like a standard ETTR histogram. What is different is that a high key image will have little or no dark to contend with. The idea is to keep the image as light and ethereal as possible and to include only enough dark values necessary to create some definition. A low key image is almost entirely on the dark side with only enough light tonality to help define the subject. As such, low key photography does not lend itself easily to ETTR exposure metering. Nevertheless, it is advisable to expose as far to the right as possible, then bring down the tones later in post-processing. This helps reduce digital noise in deep shadows. HISTOGRAM

• TRY TO SHIFT YOUR HISTOGRAM TO RIGHT SO THAT YOU CAPTURE THE MOST DATA (SATURATE THE SENSOR). CONTROL IMAGE EXPOSURE IN POST PROCESSING. • WATCH YOUR HISTOGRAM AND “BLINKIES” TO PREVENT OVEREXPOSING OR PUSHING YOUR HISTOGRAM TO FAR TO THE RIGHT. • EITHER EXTREME ON THE HISTOGRAM INDICATES THAT YOU ARE LOSING DATA. • IMAGE SENSORS DO HAVE A SMALLER DYNAMIC RANGE THAN YOUR EYES AND THEREFORE CANNOT CAPTURE AS WIDE A RANGE OF LIGHT AS OUR EYE. • SOME SITUATIONS MAY REQUIRE BRACKETING EXPOSURES TO CAPTURE ALL THE DATA. • COMMON TECHNIQUE IS TO USE (HDR) CAPTURE: • 3 OR MORE IDENTICAL IMAGES (5 OR 9) • NEUTRAL EXPOSURE • +1 EXPOSURE • -1 EXPOSURE CAMERA EXPOSURE MODES

• APERTURE PRIORITY – YOU CONTROL THE APERTURE AND THE CAMERA ADJUSTS THE SHUTTER SPEED TO ACHIEVE A “ZERO SCALE” OR 18% GRAY EXPOSURE. • SHUTTER PRIORITY – YOU CONTROL THE SHUTTER SPEED AND THE CAMERA ADJUSTS THE APERTURE TO ACHIEVE A “ZERO SCALE” OR 18% GRAY EXPOSURE. • PROGRAM – THE CAMERA CONTROLS BOTH APERTURE AND SHUTTER SPEED TO ACHIEVE “ZERO SCALE” OR 18% GRAY EXPOSURE. • MANUAL – YOU CONTROL BOTH APERTURE AND SHUTTER SPEED TO ACHIEVE THE DESIRED EXPOSURE. EXAMPLE OF IMPLYING MOTION BY USING SLOW SHUTTER SPEED

1/40 F/8.0 EXAMPLE OF IMPLYING MOTION BY USING SLOW SHUTTER SPEED

1/30 F/14 EXAMPLE OF INTENTIONAL CAMERA MOVEMENT USING SLOW SHUTTER SPEED

1 SEC EXAMPLE OF HIGH SHUTTER SPEED TO STOP ACTION

1/640 F/8.0 EXAMPLE OF HIGH SHUTTER SPEED TO STOP ACTION

1/800 F/11 EXAMPLE OF SHALLOW DEPTH OF FIELD F/1.8 FOCUS ATTENTION ON SPECIFIC AREA EXAMPLE OF SHALLOW DEPTH OF FIELD F/2.0

FOCUS ATTENTION ON SPECIFIC AREA EXAMPLE OF SHALLOW DEPTH OF FIELD F/2.0

FOCUS ATTENTION ON SPECIFIC AREA EXAMPLE OF SHALLOW DEPTH OF FIELD F/3.5

FOCUS ATTENTION ON SPECIFIC AREA EXAMPLE OF SHALLOW DEPTH OF FIELD F/2.0

FOCUS ATTENTION ON SPECIFIC AREA EXAMPLE OF MACRO WORK AND USE OF F/32 TO ACHIEVE ADEQUATE FOCUS THROUGHOUT FROM FRONT TO BACK EXAMPLE OF EXTREME DEPTH OF FIELD – FOCUS STACKING FRONT TO BACK IS IN FOCUS EXAMPLE OF EXTREME DEPTH OF FIELD – FOCUS STACKING FRONT TO BACK IS IN FOCUS EXPOSURE MATRIX

•EXPOSURE RELATIONSHIP MATRIX.XLS