We all have an interest in cinematography. That's why we're here. This club has been instrumental in my learning, and my confidence with a camera. My films have always been solo efforts, my locations of my choosing, and my editorial decisions mine alone. It was the nature of my work that dictated this solitary pursuit of my hobby. At the turn of the century, I went to my company uniform stores for the last time, which allowed me quality time at home. I soon determined to join in club productions. Before too long I was aware of some of the shortfalls that must be common amongst many enthusiastic amateurs.

With the help of some seriously experienced members, I helped write the 'Protocols for Film Directors. During further shoots, other problems became apparent. I'll leave the acting department for future discussion, just don't start me on that tract. I found myself asking fellow cameraman for advice, that was not always forthcoming. Nothing personal, it was just a grey area question. So I made my first mistake - I wrote to our Chairman, Bob Bennet, to express my concerns at some of the misconceptions apparent amongst ourselves.

Mistake, well yes, he collared me to give a chat one club evening about the very technicalities that were being ignored. So I had to brush up, learn and be able to disseminate this information for all to criticise.

Having listened to a veritable pile of professional bull-shitters in my time, I came to the conclusion that you cannot fully understand a subject, until you can explain it to your grandmother. I borrowed books, asked questions and started to realise the holes in my own perception. I have split the subject matter into eight parts, but let it not be forgotten that they all come together to make an entirety. But first, lets make a wish list about our cameras:

1. All electronic menus should be subcontracted to Nokia cell phones, they seem to be user friendly.
2. All the main controls should be analogue dials.
3. Audio levels should be manual dials.
4. Zoom lenses should have three manual barrel rings, one for focus, one for zoom and one for iris. And they should be marked in their units, as they are on 35mm cameras.
   They should also have end stops, and not be able to continually rotate.
5. And while we at it, my wife asked me to call for all car bumpers the same height.

So, lets have a chat about these 8 topics, which are - White balance. Exposure. Aperture. Shutter speed. Gain. Focus. Batteries. Tripods. Sound we’ll leave until another time. One aspect I ought to emphasise. I will try not tell you that this or the other is of no consequence, but only for interest, as this will be the only thing you remember! My mind is full of such fill-ups snippets from a life time of trying to better my learning.

White balance (There is also black balance, but don’t worry too much. Usually black balance needs correcting after a long period of camera non-use! Not likely with such a productive club as this.)
The white balance is about as important a subject as it can be. Now I know colour temperature, florescent light, daylight bulbs and all other types of light, have some obscure meaning in our minds. Lets keep it simple with an example. But first some optic physics.

Refraction is what happens to light passing through a liquid, glass and to a lesser degree, air. It bends. The net result of this refraction is the wonderful sight after a good rain shower, and I am not talking about girls in ‘T’ shirts, I am of course referring to the - rainbow. We all know the 7 colours, starting with red, and ending in violet. There's a clue here, red is warm, blue is cold. Now we are getting somewhere. The white light has been split up by refraction into component colours varying on its differing wavelength.

As an example of this phenomenon, consider the cameraman at an afternoon football match. The game starts with the sun in the south western sky. As the game progresses, the sun sinks towards the horizon. The light rays have to travel through more of the atmosphere, as the sun's declination continues. We know this as the light takes on an orange tinge, but what of the white balance? The players' shirts will become a different shade of hue. So we must consider an artificial light source in relationship to its temperature. Blue is Cold, such as a florescent tube.

The clever little processor in our skulls can somehow accommodate all these facets and allow us a constant and equal hue whatever the light source. Not so the amazing chips inside our cameras. Luckily some genius came up a way to datum the light value to a constant standard. The white card. What ever light is falling on it, we can adjust our balance to make it just that - white. Now of course you understand why it is pointless to do this task with a coloured filter in front of the lens. Filters are for effect, and a subject all to themselves.

We know that the three chips each record one primary colour. If we mix any two, we have our secondary colours. But, and this is the clincher, if we mix all three, we have a white! And that white is our datum to work backward from, to record accurately all those colours of the rainbow. Or the ‘T’ shirt, which brings me neatly onto exposure.

Exposure is a combination of all those manual controls we so often ignore. And to be fair, the manufactures of higher end amateur cameras do not make the controls easy, or readily available. They are there, but are more fiddly than they might be. This must assume the manufactures are confident with their automatic programmes. It also indicates they have small and dextrous fingers, great eyesight, an anorak memory, and a degree in overloaded menu options.

Exposure is the amount of light passing through the camera to the recording medium. A varying combination of shutter speed and aperture. In my youth, I was given an apt piece of advice. Set the shutter speed to the ASA value of the film, and the brightly lit will be f11, the dull f2.8 Perhaps over simple, but a workable rule of thumb. These amazing DV tapes can be assumed to be around the equivalent of 400 ASA. This isn’t exactly true, it varies with lens specifications and usually rated around 1000 lux at F11. Lets move on!

But anyway, pretty fast in comparison to the 40 ASA of Kodachrome 2 Super 8mm film. Or the 25ASA of standard 8.

It has been said that the camera is the most expensive of exposure meters. Yet we tend to rely on the little LCD screen with all sorts of light falling on it, where our wonderful eyes can accommodate for any inaccuracies. In manual mode, there is an exposure level incorporated in the screen. By zooming onto the centre of the scene's action, the shutter and aperture can be accurately set, then zoomed out to the required focal length - and left! Right – Wrong! As we have smaller lenses, the F-number changes with the zoom. At full zoom, there may be as much as a full stop less light falling on the chip than at wide angle. So there is a clever little devise called the Zebra stripes. These show the over-exposed areas. A very useful exposure meter, when understood and appreciated. Apparently we should not close down the aperture to eliminate the stripes, a little over-exposure looks good. I am going to expand on zebra patterns, so please bear with me.

The problem of judging the brightness and contrast with the eyepiece, and the little LCD screen, is the age-old one of how easy it is to fool the human optic receiver. The longer we look at a white scene, the more normal it looks. The zebra stripes show where a scene is over exposed. OK, I said no formulae in the opening, but lets talk about percentage. For arguments sake we have set the zebra patterns to 80%. What this means to us, is that the view finder will show stripes over areas, where the reflected brightness is over 80%. Stay with me! Our picture is given an assigned brightness of values between 1 and 100. But white is white I hear you say! Hold a white card to a backlit window. They are both white, but the window is brighter, much brighter. And how can anything be blacker than black? Look at the difference between a black-card and black felt.

If you were a film man, you will know that at the moment, video has a very much smaller latitude to contrast than film. By a ratio of nearly ten to one. This translates in its ability to record a wide range of contrast. I am labouring this point somewhat, for it is important. So what does this means to us, the video cameramen?

An under exposed image or area will look muddy and grainy, and the camera may have the temerity to record the scene as 0 black.

An over-exposed image will look white, with jagged, weird edges. The camera circuit might then compress the over-exposed areas, and record them as 100% white! Thus a suggested setting for zebra patterns could be 80% white.

As an example of zebra pattern use, film someone as a mid shot against a white wall. Note the zebra patterns on the wall, then when we do the close up, the wall should have a similar zebra pattern to make the two shots compatible.

To put this far too simply, and this is for interest only, there are 100 units of contrast between black and white in video, but 1000 units of contrast on film.

So down to the nitty gritty starting with Aperture. The chips prefer wide aperture, but the lens have their best definition at half range f-numbers. Most cameras will have a neutral density filter to give a larger f. number. But of course, lens properties dictate depth of field, through a combination of f. numbers, focal length and chip size. Just to confuse us even more, f-number is a direct function of focal length and the diameter of the optic.
Not all 3 chip video lenses have the same light admission, which I’ll explain later, so the light falling on the chips may differ. Thus the professional world have introduced a T-number to account for this f-number discrepancy. For all intense and purposes - forget it!

Shutter speed is perhaps the easiest variable to understand, yet it is misunderstood. From our earliest fledgling camera use, we tried for as high a speed shutter speed as possible. This helped make the shot free of shake. The rule of thumb for shutter speed was to have a speed equal or greater than the focal length of the lens. A wide angle lens having more latitude to shake rattle and roll than its telephoto brother. On a still camera the shutter actually opens and closes as set by the shutter speed. When I progressed to ciné, the rotating shutter blade angle could be reduced, which had the effect of making the shutter speed higher for the constant film speed.

What of the video attributes? Now be aware, that the dv tape is still going at a constant speed, and will be viewed at 25 frames a second. So, like my previous cine camera, it is the shutter angle opening that is closing to make the effective shutter speeds. I could change the feet per second of ciné film through the gate, to make a slow-motion shot. This had the effect of also changing the shutter opening time, or shutter speed. Not so on our video camera, where the tape speed is constant. So far so good. To achieve an extra level of quality, the actual taking mechanisms somehow records in two half frames, first even lines, then odd lines.

As our eyes see at no faster than approximately 25 frames a second, we accommodate the interlacing. Any faster shutter speed creates its own problems, just as the film cameras. An aeroplane filmed at too high a shutter speed looks wrong, for the propeller appears to slowly rotate, due to the strobing action between shutter and engine rpm. A waterfall can be made to look unrealistic, for the water droplets are visible, whereas we are used to seeing a curtain of descending water. Likewise filming a fight scene, the punch is too accurate, and will show the fist missing the thrown back head. But for sporting action, this higher shutter speed is a fantastic boon. Remember, we are still shooting at 25 frames a second; we are simply capturing each of these images in a shorter span of time.
Some cameras can record at shutter speeds of less than the 25 frames a second. To do this the camera provides a smeared image. For instance, at ¼ th a second shutter speed, the camera will only record about 6 images a second. This will produce a semi-slowed motion look.

For a multi camera shot, in an ideal world, White balance, Exposure, Aperture, Shutter speed should all be the same. This of course, makes the work of the editor easier. The camera director should have available his white card, and once the lighting is set up, assure himself of the white balance for each camera.

The unit of Gain is measured in decibels, for that is the unit of noise. And noise is something we recognise as a deterioration of the captured image In the broadcast world, they do not go above 3 dbs. 6 dbs of gain is a doubling of the effective light by computer enhancement. Thus it appears as if we have more light falling on the chips. It is a price to pay, but as a practical observation, a 6 dbs gain is barely noticeable. Should the cameraman be requiring 12 or even 18 dbs gain, then his options are limited anyway. Perhaps it is a little like pushing a 100 ASA film to 200 ASA in the dark-room developer tank of old.

We all know about focus. It is a function of focal length and aperture. The depth of that focus is a prime weapon of our armoury. The attention of the eye is directed to the easiest point of view. The sharpness is all important. We can accentuate that by putting the background, and or, the foreground into a hazy blur.

We are sucking eggs here, but long focal length lenses are telephoto. Actually they reduce the angle of view, and a side product of this optical law is a need for accurate focusing. Because they have such a small angle to the subject, the camera side of the lens has a greater angle to deal with to allow a nice pin sharp image. Pin sharp because that is where all the rays are gathering together, to our point of reference, on the magic chips. If they are not together, they are trying to meet at some other point, either behind or in front of our chip, and the result is that hazy mess.

The wide angle lens is the lower numbered focal length. With this piece of glass, focusing becomes far less critical, for the big angles are now in front of the lens. This does decrease the cameraman's artistic flair, for the depth of focus is so large. Another facet is a noticeable distortion of close objects. If that close object is the leading lady, she just may not appreciate that less than flattering enlargement of her nose. As an aside, we are programmed to feel a protective attraction towards big eyes and small noses. Thus seals and puppy dogs are cuddly, whereas Warthogs have to fend for themselves. The geometry of both lenses is such that a smaller hole, i.e. f-number, significantly cuts down this angle, and thus allows more leniency in focusing. I.E. a greater depth of field.

This depth of focus is not equi-distance either side of the datum focus distance set. There is a greater margin in focus towards the infinity side. This is valuable tool.

The auto-focus function is also a valuable tool. It works by comparing contrast. Remember we have less latitude to contrast with video, so a correctly exposed scene will auto-focus faster and more accurately. FACT! A picture that is out of focus has less contrast than an in focus scene. Black will appear grey when out of focus! So the camera hunts for a position of maximum contrast. Yes, hunt. Some are quicker than others, and are not necessarily focusing on what you would wish. Dust on a window, even a filter can be enough to start the hunt. Consider a subject being interviewed, who then bends down; the auto focus will now go to the back wall!

Its use is only worthy when the limitations are appreciated. And of course to you, the cameraman's requirements. One notable example is to frame the shot, put the subject out of focus, start the camera running, and select auto focus. (Use a LANK controller!) this can produce a nice effect. Similarly, focus can be used most effectively to take the viewers point of interest as the focus is pulled.

Before leaving focus, I want to just touch on chips, and a myth. If we referred to chips in metric, we could quickly compare their size to film. A ¼ inch chip is 6mm. Think of super 8mm film. Cameras that use 3 chips enhance the surface area, and beam splitters divide the light to the primary colours, one for each chip. This beam splitting causes an optic problem and a lens design compromise, for the primary colours focus at different wavelengths. Thus our amateur cameras do not have inter-changeable lenses. Professional ones do, but they take the beam splitter into consideration while adjusting the back focus of the three primary colours.

In the future chips will be bigger, and better. They will then achieve higher resolution and fidelity of colour. Thus there will be no need to divide the work amongst three chips, and we will have only the one chip. Thus there will be a shorter distance between flange and chip. Then the millions of excellent still and motion lenses can be used. As an aside, we will be getting closer to the film look, for the depth of field will be smaller as the chips area is larger, and approaches the film format size. It is for the same physical reason that 8mm had more depth of field than 16mm film, which in turn had more depth of field than 35mm film. The artistic armoury will be enhanced as the chips become bigger.

Batteries are the powerhouse, and again have characters that need to be disciplined. They are made up of numerous cells, each delivering 1.2 volt. The bigger the battery, the more capacity, or ability to produce the level of current to work our camera. Almost anybody can blind me with talk of neutrons, and the theory of which way they actually flow. For my sake alone, I think of each cell as a tube of water, with a tap to release the flow, which will turn the treadmill inside our Canons, Panasonics or Sony's.
They are all the same depth, 1.2 units. But they can be wider, so the capacity goes up. Thus when the tap is opened, the flow starts. Charging is topping up the water. And this is where we can have a problem. If we don't use the battery for a while, then sediment can form in our analogy tubes, and fill the base. Thus when we top up, the sediment-ed tube reaches the top first, and tells the ball-cock of a charger that no more water is needed. Of course the neighbouring, un-silted tubes are not full, thus the life of the battery is shortened by one errand cell.

Please don't try this at home, but I have it in my mind that should you get a dirty big hose pipe and power flush the silted tube, you might just clear it, and thus allow a full charge for all the tubes.

I think we will leave this discussion and just say that constant use and trickle charging can pay dividends. As in many things in life, little and often can work wonders.

Tripods are natures way of stopping camera shake. Panning with a slow motion selection could iron out a handheld ciné camera , but we cannot do this with the video constraints already mentioned.

Now, our skulls have some stabilisation system that is either still patented, or not fully understood.

Camera technicians have developed two very good systems. The cheaper cameras might have a digital idea that is bloody clever. What it does is reduce the framed image by a few %, and then look for a vertical and horizontal marker line. Now when the camera moves, the gizmo holds the reference marker lines steady, and allows the few % edging of the frame to be a two dimensional buffer. And it works very well! The down side is a slight loss of quality, as the image size had to be reduced. Thus you can fully understand why it is a pointless task to have the camera steady button on, whilst the camera is on a tripod, and detrimental if it is being panned.

The other system is optical stabilisation. It uses more power, is slightly bulkier, but does not corrupt the image quality. In the old days it was done by gyro’s, now it is micro processors and motion sensors moving a variable angle prism. As far as I know, its all done with mirrors, so it's got to be bad luck to drop such a lovely bit of kit.

Which brings be to care and attention; I am sure by now you don't care anymore, and I must have lost your attention, so, thank you for your time. I hope I have done some sort of justice to this subject, by scratching the surface of our fascinating hobby, and may I leave you with just one thought.

When parachuting out of an aeroplane, consider this, and it applies to our cameras. If you do not fully understand how to use the equipment, or make it work to your advantage, you have the rest of your life to sort it out. Good filming.

Frank Bond

Much of this was taken from the excellent book by Jon Fauer called SHOOTING DIGITAL VIDEO.

info@bristolvideo.org.uk