Mein kleines Mondlicht,

Not a few times during my practice, upon stating the need for supplementary lighting or other photographic procedures, have I heard a client grumble ‘but there’s enough light! Why do you need all that for?’

One is trained to take it in stride, but in confidence I tell You that such complaint is so vexing because there are, essentially, only two ways to clarify one’s proceedings: a terse reply, or a long expostulation; and both are quite likely to upset the client and still leave him perplexed.

In a nutshell (and not at all trying to be terse with You), the shortest answer to the ‘don’t we have enough light?’ question is ‘not for the camera, no. The camera sees things way differently than our eyes do’.

And because the camera sees it differently, it is not uncommon that it doesn’t have enough light to…

  • freeze motion.
  • …yield all of the subjects in focus.
  • …record noise-free images.

See for Yourself:

Plate 1. It was a sunny Sunday; yet, in spite of all the light pouring into the church through the large windows and all the lights being on inside, there just wasn’t enough light for the camera to freeze motion –not that the people were making fast movements: note the woman in the foreground: she’s practically immobile. (50mm, 1/8 sec @ f/5.6, ISO 800)

Plate 2. Again, nobody in the cathedral was groping his way around (there was ‘plenty of light’, all the lights being on for the ceremony), but as far as the camera was concerned the church was pretty dim, and the large aperture needed yielded too shallow a plane of focus; thus, only the priest on the right is sharp. The priest behind the bishop looks soft (clearly out of focus), and the bishop is not only out of focus as well, but the camera couldn’t freeze his slight motion (slow shutter speed) and he came out right blurry. Furthermore, the image contains noticeable noise due to the high ISO –although it’s not as bad as on the one below. (35mm, 1/30 sec @ f/4.5, ISO 1600)

Plate 3. Dismally dim conditions for the camera, forsooth. Very high ISO had to be used to compensate for the small aperture, and the resulting noise rendered the image utterly unusable. Opening up the aperture would have gathered more light, but in this case a small aperture was needed in order to keep everyone in all rows in focus. The rather faster shutter speed used to freeze motion didn’t help either. (35mm, 1/80 sec @ f/11, ISO 3200)

 

Is the camera dumb or something?

Yes, and no. :-p

A camera, however sophisticated, is nothing but a machine that follows unquestioningly the logic given to it by its maker. Thus, it’s not dumb in the sense that it’s lazy or incapable, but it’s indeed dumb in the sense that it lacks reason, and –more important– wisdom.

Thankfully, the camera it’s not (shouldn’t ever be) the one trusted with making the decisions, but the photographer: a thinking human who, being acquainted with how the camera works, its potential and limitations, can manipulate such variables to obtain photographs possessing good image quality.

What is ‘Image Quality’ anyway?

In essence, image quality boils down to a few simple things:

  • Optimal Contrast
  • Optimal Colour
  • Optimal Detail and Sharpness

When any of these is lacking we say that the quality of an image has been degraded or lost.

Now, upon the whole, one can’t really blame clients or bystanders for wondering why one would need a flash (or a longer exposure time) for many photographic situations. To our eyes, given scenes or surroundings don’t look half dark: a sunny morning with enough daylight pouring in through the windows, all the lights turned on inside a church or well-illuminated interior space, a pleasant spot on the shade, &c., &c. Truly, in most of these scenes, anywone would claim and proclaim that there is ‘plenty of light’.

What gives then?

The conundrum essentially lies on the great difference between how we see and how the camera sees.

 

Saccadelic Visions

In a natural process –of which we are usually completely unaware and that takes only microseconds–, our eyes flick from one area to another, automatically accommodating for the variations in brightness, scanning the scene with rapid movements called saccades; the visual information thus collected is relied to the brain, which then constructs a perception of the scene in which essentially all detail is visible[1]Ilex Press, Michael Freeman's Perfect Exposure (Burlington: Focal Press, 2009) 50-51 . Hence, since our Human Vision System is able to perceive the full dynamic range of a scene in some millionths of a second, not only do we see well enough in dim-litten locations, but we also readily assume that in such places there is ‘enough light’.

The camera, however, does not work that way. Not being able to perform saccades, a camera cannot see full detail in deep shadows and bright highlights at the same time. Instead, the camera relies on its own ‘visual system’: the Exposure Triangle (the brains) and the metering modes (the eyes); and these tell it that in the same location where a man’s eye can see a fly crawling on a black countertop there is ‘not enough light’.

As a matter of fact, one-shot full dynamic range visualisation is a kind of holy grail that camera manufacturers have been trying to reach for years; alas, in spite of their noble efforts, extensive research, and variety of approaches, a camera that sees as our eyes see has not yet been constructed (and most likely never will be). Such limitation was one of the problems that gave rise to the HDRI craze and other multi-shot techniques –computerised crutches for  lame imaging devices.

 

All for one and one for all

The good ol’ Triad, familiar to all photographers –budding, amateur, and professional–, is at the heart of the camera’s ‘visual system’. Although, maybe I should say ‘at the head’, since the Exposure Triangle is more like said system’s brain.

Illustration 1. The ‘brains’ of the camera’s ‘visual system’, the reciprocal relationship between these three settings determine the exposure.

 

If the Triangle is the brain of the camera’s ‘visual system’, its eyes are the metering methods –incident or reflective– and the metering modes –evaluative, average, centre-weighed average, and spot.

Plate 4. Even in these days of ultra-sophisticate cameras, using an incident light meter is still the most accurate and reliable method to determine the right exposure.

Plate 4. Even in these days of ultra-sophisticated cameras, using an incident light meter is still the most accurate and reliable method to determine the right exposure.

Whilst cameras can ‘see’ and measure, through the lens, the amount of light reflected by the subject or scene and suggest appropriate exposure settings (or go right ahead without asking if You are using any of the Auto modes), the most accurate and reliable method of exposure determination is to use an incident meter to read the actual quantity of light that is falling on the subject, then manually plug in to the camera the reported ISO, aperture, and shutter speed settings.

Of course, just going about metering and turning dials willy-nilly isn’t bound to get us good exposure values, let alone photographs. The Exposure Triangle is a reciprocal system: pushing in one direction necessarily detracts from the opposite one: it’s all a compromise.

In order to know which directions to pull towards we need to know what we want from our photograph.

Do we want everything or most of it in full focus? Is it a photograph of a group of people arranged in rows where all faces need to be rendered sharp? These situations call for a small aperture number, which means less light getting to the film or sensor, which in turn means we need either a slow shutter speed to let in more light, or a higher ISO value to increase the sensitivity to light of our film or sensor. What to choose?

Are we photographing subjects that are moving –either talking to each other or fidgeting at a social gathering–, or in full swing or run –a dance or a hockey match? These images require fast shutter speeds, which means (again) less light reaching the film or sensor, which in turn means we require either a high ISO or a wide aperture. Once more, what to choose?

Well, let the downsides guide You –that is, choose your nemesis:

 

Illustration 2. Beware and take care of the pitfalls of the triangle, for there lies a freak at each angle.

Illustration 2. Beware and take care of the pitfalls of the triangle, for there lies a freak at each angle.

 

You saw clear examples of these freaks in Plates 1, 2 & 3. I need explain no more.

 

Mehr Licht! (And stop fooling around)

Clearly, if the problem is that, compared to our eyes, the camera is blind as a mole and spits out dark photos, the solution is flashingly simple: add more light!

 

Plate 5. To our eyes the church didn’t look that dark: it was a sunny morning, with enough daylight pouring in through the stained glass windows so that we would all have been able to read small letters. Yet, the camera rendered the image as if it had been taken on some evening in Decembe.

Plate 5. To the eyes of everyone present the church didn’t look that dark: it was a sunny morning, with enough daylight pouring in through the stained glass windows that we would all have been able to read small letters. Yet, the camera rendered the image as if it had been taken on some evening in December. (35mm, 1/30 sec @ 5.6, ISO 400)

Plate 6. More light! Even a puny flashgun atop a lightstand can make all the difference. (35mm, 1/125 sec @ f/5.6, ISO 200)

Plate 6. Even a puny flashgun atop a lightstand can make all the difference. (35mm, 1/125 sec @ f/5.6, ISO 200)

 

You can see that by using supplementary lighting I was able to shoot at a faster speed (ensuring no blurriness due to subject’s movement), maintain my chosen aperture (all subjects in focus), and use a lower ISO speed (less noise = better image quality).

So now You see why all that (flashes, procedures, and baffling tricks) is so very much needed. Ah, if only everyone would see it too…

It is true that the Triangle is a fixed, balanced, and reciprocal system, but most of the times we can cancel out the weakening resulting from the compromise by reinforcing the compromised corner.

And with that, I finish this epistle and remain again silent, but ever and ever Yours.

HVG.

 


To know more:

^^1. Ilex Press, Michael Freeman’s Perfect Exposure (Burlington: Focal Press, 2009) 50-51.