The Director of Photography: Preparation

 

As schedules get tighter and budgets decrease, perhaps the most effective way a cinematographer can reclaim lighting time on the set is to invest time in preparation. Without good preparation, too much time on set will be spent answering unnecessary questions and trying to steal time to make arrangements for upcoming shooting days, which are not, as yet, fully organized. Thus, with good preparation, a DP’s time can be better deployed.

The most effective way of releasing time is to publish, before the first day of principal photography, a series of documents that allow anyone connected with the necessary arrangements to quickly, and easily, refer to the DP’s requirements and make their contribution without further reference to the cinematographer. Two things need to happen for this to be without trauma and to be effective. Firstly, the cinematographer has to give the time to the project. Secondly, they have to have a system in place to produce the documentation efficiently. If you are comfortable using a computer, then things are easier.

There are four publications a DP may provide the production with, all serving a different purpose:

The camera equipment list;

The lighting equipment list;

The film stock breakdown;

The technical schedule.

 

The camera equipment list

 

The camera equipment list will probably be published twice. The line producer, or production manager, will usually ask the DP early on in the production run-up for a guess, or wish list, of the equipment that will be required as the basic kit in order to get competitive quotes from different suppliers. This does not take away the DP’s right to nominate a preferred supplier. It is important that this list is reasonable and not an “if only I could have” list. At this stage of pre-production, one does not want to frighten the budget controllers with a foolish amount of equipment. It is more important to list a reasonable kit in order that comparative estimates of different suppliers’ prices may be obtained. Once the supplier has been chosen, the recce is over and a basic list can be decided upon, it is vital that you provide this new list as soon as possible. This is not only so that a firm quote can be obtained, but also, more important to the DP, to ensure that the chosen supplier can deliver all their requirements or, if they need to subcontract some equipment, they then have sufficient time to make the necessary arrangements.

 

The lighting equipment list

 

As with the camera list, in all probability the production office will need an early lighting equipment list in order to obtain comparative costings from differing suppliers. Unlike the camera list, where a close guess of the requirements can be made from reading the script, with the lighting list it is very difficult to give a reasonably accurate judgment of one’s needs before having seen all the locations; nevertheless, a list to base budgets upon will be requested. The gaffer and the DP usually solve this by offering a list from a previous film that had a similar script and schedule – this at least provides a starting point. The suppliers will be able to give a rough estimate from this, as all the accessories are fairly standard. During the recce, the gaffer and the DP are continually updating the list of the lighting equipment they will need to carry as the standard kit, together with a daily extras list that will eventually become part of the technical schedule. As soon as the technical recce is complete, they will sit down with a laptop and compile the full list of all the lighting equipment they will require. Requirements for the generator and lighting equipment truck do not go on the lighting list. The gaffer makes these arrangements directly with the lighting company. The same applies to cherry pickers and towers; these will appear on the technical schedule together with any equipment required on a daily basis.

 

The film stock breakdown

 

Not long before filming starts, the DP will be asked what film stocks they will be using and what quantities they estimate they will use of each stock. There is a simple and accurate way of doing this: a list should be made in scene number order with, for the reference, day or night, interior or exterior and a very brief description of the scene as a reminder. Then comes a column for the filters the DP expects to use and finally a column for each type of film stock the DP intends to use.

 

 

The technical schedule

 

Using almost any diary program on your computer you can generate a very accurate daily list of all your requirements for the whole of a film. Referring to the production’s draft schedule, enter the scene numbers you are going to shoot on all the given dates. Having prepared your agenda in this way as you go round the locations on the technical recce, all you have to enter are the changes from the normal kit. Publish this technical schedule as widely as possible and as soon after the last recce as is humanly possible. Apart from having saved the first assistant director and the line producer a lot of effort, you have now made it possible for the production office, should location dates change, to easily track your extra requirements just by looking at the old date, seeing which scene number the equipment relates to, and posting the requirements to wherever the scenes move to in the new schedule as planning progresses. By producing this kind of technical schedule you make it easy for the office to keep the production on track and you have created a situation whereby you will be bothered far less on the set as things change. Hence you get more time to do what you really enjoy – shooting the movie!

 

 

Camera Crew

 

Before a camera crew is formed for any production, the DP will probably have had an interview with the director and the producer. Particularly in television, it is quite normal for them to interview perhaps three DPs before making their choice, even if there was a clear favorite right at the beginning. It is a fortunate DP who is well known enough to the director and producer to be asked to shoot their film without having to be interviewed. Once the DP is confirmed they will start to look for their operator. Most DPs have a preferred operator with a second choice in mind in case the first is already booked on another production. It is quite acceptable for the director to have a significant input into the choice of operator as, fi at least, the director will often work very closely with the operator to choose and set up the shots. In America it is equally common for the operator to work solely with the DP. The DP will, if this is the director’s preferred way of working, most probably have had several meetings with the director and design department to set the overall look of the film, and as the director and DP often travel together on an away job there is plenty of time for them to discuss finer points before they reach the set. If they are not travel- ling together it is usual to have a discussion about the next day at the end of the day’s shooting or, if the director doesn’t want to commit themselves, first thing in the morning, perhaps at breakfast. Once the operator has been chosen they will be asked to nominate a focus puller and clapper loader. These appointments will always require the approval of the DP, the producer and probably the director. The camera crew works in a very supportive way – that is, each grade is only as good as the support they receive from the colleague around them. The individual crew responsibilities from the trainee through to the DP are therefore as follows.

 

The trainee

 

Many years ago it was common to have a trainee on the crew. Restrictions to budget and the collapse of both the studio system and large television stations then caused producers to be very reluctant to sanction the very small costs of having a trainee.

Things have now improved for trainees for the curious reason that most directors now wish to work with video assist, and that facility comes with batteries, cables, monitor stands, etc. Providing the director does not want to record the video image, in which case a trained video technician is the answer, most producers now see the trainee as an economical way of having the video assist organized and kept running.

 

The clapper loader (AC2 or 2nd AC)

 

From the focus puller’s point of view, the most important part of the loader’s job is to bring them just about every part of the camera they may need during the shooting day. The focus puller must never leave the camera, so the loader could be thought of as the legs of the focus puller. A good loader will have the camera car, or truck (fi even a seven-ton truck will usually be referred to as the camera car) very neatly organized with everything in its place and always in the same place so that it can be found quickly, even in the dark. A good loader will learn to anticipate which pieces of equipment will be needed and when they will be needed; they will then be able to be standing by with all the parts needed before they are asked. Magazines will be adjacent as and when the camera is close to needing reloading and will be loaded with an appropriate film stock. All this must be done without cluttering the set; it is not an acceptable solution to have everything that might be needed very close to the camera. Too many people will get cross at continually tripping over the camera boxes and if you are working outdoors then the slightest amount of rain will cause dreadful panic as equipment is put away. Good anticipation is essential to being a successful loader.

The focus puller (AC1 or 1st AC)

 

Keeping the main action sharp is the prime responsibility of the focus puller. In addition, they are the one most concerned with the camera itself. It is their task to build the camera each morning and to put it away at the finish of shooting. They must keep it and the lenses scrupulously clean. They must carry out any front-line maintenance on the camera and its associated kit. Keeping the main action sharp is done, in the main, by using a tape measure, after which the depth of field is calculated using a Kelly calculator, Samcine calculator or depth of field charts. It takes a great deal of talent and experience to become a good focus puller, and a fine understanding of exactly what the audience will be looking at at any given moment during a scene. Currently, there is a trend for focus pullers to use infrared range finders. They are very accurate if used with skill. My worry about these devices is that although many of them say they are perfectly safe, we are in a litigious society. Let us suppose the focus puller had put the infrared dot on the forehead of a major star and within a few months that star developed any kind of eye problem – would you want to be in court as the defendant? I would not. Let’s stick to the tape – unless we have monumental insurance. When shooting with lenses with very long focal lengths the focus puller may decide to take an eye focus – that is, focusing the lens that is, focusing the lens through the viewfinder. This is because, with long focus lenses, a very small movement of the focus barrel of the lens may move the plane of focus quite a long way into the set. Before taking an eye focus it is important to know how to set the focus on the eyepiece. First, you rack the focus to a distance which puts the image as out of focus as can possibly be achieved. You then focus the viewfinder on the cross in the middle of the viewfinder. If you now refocus the lens you will have perfect focus.

There is an old trick for obtaining perfect focus that works better in some viewfinders than others. Having obtained what you believe to be a perfectly sharp image, immediately behind the cross in the centre of the viewfinder rock your eye very slightly from side to side. If you are in perfect focus the cross and the image will appear to move together. If you can see any apparent movement between the cross and the image you are not in perfect focus. This is known as parallax focusing, because if you see movement there is a parallax error between the plane of focus of the image and the plane of the cross on the focusing screen. When the image is perfectly formed on the focusing screen, and is therefore sharp, there will be no difference in the position of the image and the cross engraved on the screen and therefore no parallax error. There are many tricks of the trade and good focus pullers are worth their weight in gold, quite literally, for if the focus puller is first class then the DP may choose to light to a wider aperture and thereby save the production a considerable sum on the lighting budget. The focus puller is responsible for setting the stop on the lens as directed by the DP. The focus puller rarely leaves the camera. The operator must be free to go off with the director and the DP to recce the coming set-ups, etc. The loader will bring the focus puller the bits of kit needed to build the camera for the next shot. You could say that, during the shooting day, the camera belongs to the focus puller. At the end of every printed take the focus puller will check the gate for any hairs or scratches. If all is well, they will then give whoever is on continuity, the details of the shot. This will include the focal length of the lens, the focus setting and the stop. On some crews the loader does this, especially if they are keeping very full notes for themselves or the DP.

The camera operator

 

The duties of the operator may seem self-evident, but have you thought of the many different ways that the operator may be asked to interact with the director, the DP, the rest of the crew and often continuity? It is common fi for a director, after giving initial guidance to the DP and usually in the presence of the operator, to leave the DP to their own devices and to work very closely with the operator. In America, most often, the director only talks to the DP; the DP then directs the operator. Vital to the relationship between the DP, the operator and the director, fi way of working, is the ability of the operator to feed back to the DP updates of the director’s requirements, which may have happened while the DP was lighting the current set or away pre- lighting another. When setting camera flags for backlights, etc., the operator must be certain that they are not flagging off light important to the DP’s vision of the scene. A continual dialogue between these two most important technicians is imperative. Fi, the DP or the gaffer sets the flags, in the USA it’s the grip’s job. The operator is usually nominated by the DP, but this is a nomination that must always be cleared with the production office. Many directors are as concerned to hire the most appropriate operator as the right DP. It sometimes happens that the director will nominate the operator and ask the DP’s approval. As you will appreciate, for a DP to have a regular and admired operator can be an advantage to everyone. While the operator is responsible for all the camera movements during the shot, they are not responsible for the physical movement of the camera between shots. This falls to the team of focus puller, loader and grip. During a shot the travelling movement of the camera is the responsibility of the grip, working under the direction of the operator.

 

The grip or dolly grip

The grip is primarily responsible for the camera dolly and all the movements made by it. They are also responsible for moving the tri- pod to the next set-up; the focus puller will usually take the camera. Never move a camera while it is still on the tripod. I have seen one fall off in these circumstances – not a pretty sight and very embarrassing. The grip is responsible for building, or supervising the building of, any construction needed to support the track or boards the dolly is going to run on. The leveling and smoothness of the dolly’s working surface is vital to the success of a dolly shot. Front-line maintenance of the dolly and its kit are down to the grip. Very often, they will have built or had built many special bits to enable them to fix a camera to almost any object. A good and experienced grip’s van is an Aladdin’s cave.

 

The gaffer

 

The gaffer is the chief electrician and works directly for the DP. Some DPs will set their own flags and barn doors and some won’t – it just depends on how they like to work together. Very often, the DP will be closer to his gaffer than any other member of the crew. They are vital to his success.

 

It is said that one very well known and much respected American DP, when asked by a student what was the single most important thing they could do to improve their photography, replied ‘hire the best gaffer you can afford, even if you have to give them part of your fee’.

 

The best boy is simply the gaffer’s best boy. On a large crew, the gaffer will plot the cable runs and how to fix and support the lamps – it’s the best boy’s job to organize the lighting crew and actually move and fix the lamps. On most small units, say three sparks in total, the gaffer acts as his own best boy.

 

Crew protocol

 

On any film set, the camera crew always arrive at least half an hour before the call on the call sheet. The camera will be built and ready on the tripod or dolly before the call time and will be positioned roughly where the first shot of the day is expected. Breakfast is usually taken after the camera is prepared. It will not be taken after the call; if you arrive too late for breakfast, tough, the camera comes first. It is your responsibility to be on time. More technicians lose work through bad timekeeping than anything else, so don’t be late – be half an hour early and get into the habit. On a feature film, it is traditional for all the other technicians to call the DP and the director “Sir”; the DP very often calls the director “Sir” as well, perhaps because in the first few days he can’t remember their name and the habit just sticks. You may not approve but you may also get fired if you don’t. If “Sir”’ has become your habit, then working with lady directors or DPs can cause embarrassment.

 

The Camera

In essence, a motion picture camera is a couple of boxes, one with a lens on the front and a mechanism inside capable of dragging a length of film down a specific distance at least 16 times a second, and the other containing a suitable length of film to feed the mechanism with space remaining to take up the film after exposure. When the pictures from this device are projected by a similar mechanism they give a valid representation of the original scene, with all the movements contained therein correctly displayed in a realistic way.

 

Frame rates

 

At the turn of the century, a taking frame rate of 16 frames per second (fps) was becoming common practice. At this time, both cameras and projectors were still very much hand cranked and most were geared such that a constant cranking speed of two turns per second resulted in this frame rate, which was very convenient. Those in the industry who were beginning to consider themselves artists would have preferred a higher rate, since this reduced the flicker on the screen, hence the phrase “going to the flicks”. The film producers and distributors, on the other hand, were seriously opposed to an increase in frame rate, as this would use more film and therefore put up costs. Little has changed.

 

By 1926, the American Society of Motion Picture Engineers (SMPT, later the SMPTE) Standards and Nomenclature Committee recommended camera cranking speeds as follows:

Regarding camera speed we recommend as a recommended practice: a camera cranking speed of 60 feet per minute (16fps), with a minimum of 55 feet and a maximum of 65 feet when normal action is desired, in connection with the Society of Motion Picture Engineers recommended practice of 80 feet per minute projection speed (21fps).

 

To recommend different taking and projection speeds may now seem ridiculous, but what they were trying to do was to set a standard for a frame rate that was perceived to be correct on viewing. Try turning the sound off on your television and notice how the action suddenly seems to be slower, despite your certain knowledge that it cannot be. It would be uncharitable to think that the theatre owners were keen to reduce the length of the shows so as to pack more audiences in – wouldn’t it?

 

The result of this is that from the turn of the century to the coming of sound, the camera frame rate was set at roughly 16 frames per second. When sound recorded optically on the same film as the picture came in around 1927, the frame rate of 16fps or 60 feet of film per minute was too slow to make an adequate sound recording using the optical recording techniques available at the time. A faster speed was needed to enable more frequencies to be recorded. By now, it was known that the flicker apparent in a film projected at 16fps, or thereabouts, started to disappear above a projection rate of 20fps.At 30fps it appeared to disappear completely even on the most demanding scenes, these usually being those with pronounced highlights, as flicker is more discernible in the brighter areas of a scene.

 

In America, the mains electricity has a frequency of 60 cycles per second (cps); therefore, a standard synchronous electric motor there will have a shaft speed of 1440 revolutions per minute. This gives a shaft speed of 24 revolutions per second. The Americans, who after all pioneered the making of the talkies, therefore chose the very convenient frame rate of 24fps as being almost totally free of any flicker, producing a linear film speed sufficiently high to enable good sound to be recorded next to the picture on the same piece of film and being absurdly simple to drive the projectors at a constant speed from a simple synchronous motor; 24fps is still today the world standard frame rate for theatrical motion pictures.

 

For television, matters are slightly different. The television scan rate is inexorably linked to the frequency of the local mains; therefore, in America, where the local mains frequency is 60cps, the televisions will display a complete picture 30 times per second. To overcome the discrepancy between the theatrical cinema frame rate of 24fps and the television rate of 30fps they, effectively, show every fourth frame twice. For high-quality commercials for television in the USA, it is not uncommon to increase the taking rate to 30fps.

 

In the UK and other parts of the world, where the mains frequency is 50cps, this results in a completed frame rate of 25fps. It is normal to shoot at 25fps if the film is intended only for television release. Feature films are still shot at 24fps and, when shown on television, run 4 per cent faster than in the cinema and therefore the overall duration is also reduced by 4 per cent. This makes little difference – remember the SMPE 1926 recommendation of a taking to projection discrepancy of 25 per cent. The only perceivable drawback is a very slight change in the pitch of the sound, which would only be noticeable to someone having perfect pitch. I have only ever known one person comment on this effect and today pitch correction circuitry is available at a very reasonable cost.

 

The intermittent mechanism

 

The heart of a film camera, the mechanism that enables it to take a series of still pictures, is known as the intermittent mechanism. To be successful, a film camera must divide the picture-taking cycle, usually evenly, between a period where the film is absolutely still and revealed to the taking lens and a period when the light from the lens must be blanked off to enable the film to be pulled down to the next position ready to expose the next frame. To do this, a number of devices are employed:

 

1) A shutter to blank off the aperture while the mechanism pulls the film through ready for the next frame to be exposed. 2) A channel, or gate, in which to position the film accurately. 3) A device to pull the film down to its next position, usually a “claw”. 4) Loops of film top and bottom of the film gate to act as reservoirs during the pull-down period.

 

The shutter

In a film camera the shutter is usually a rotating disc placed immediately in front of the film gate and having a segment removed to allow light to pass to the aperture for exposure while, for the other part of the cycle, the remaining part of the disc rotates to blank off the light during the period in which the film is moving to the next frame to be taken at the same blanking rate as the camera frame rate. Figure 4.2 shows a classic 180° shutter between the taking lens and the aperture in the film gate. Some cameras use a twin-bladed shutter, often known as a ‘butterfly’ shutter, as illustrated in Figure 4.3.This is claimed to be better balanced and therefore reduce vibration and, as it has two blades, the shaft speed can be reduced to half that with a 180° shutter and this is said to help reduce camera noise.

 

The film gate

Behind the shutter will be the film gate, which is made to a very high accuracy in order to keep each frame in exactly the same position, laterally, as its neighbors. The gate is usually several frames long and will have a slot in it to allow the claw to enter the perforations in the film and another to allow a register pin if this is used in the camera’s design.

 

The claw

The most common mechanism for moving the film from one frame to the next is known as a claw, simply because when they were invented they looked like an animal’s claw, an arm with a hook or nail on the end. Figure 4.4 shows an early Williamson mahogany-cased, hand-cranked camera, which has recently shot some very good pictures. Despite its age, it graphically shows the classic layout of an intermittent mechanism. Figure 4.5 shows the current Panavision lightweight camera mechanism, one of the best in the business. Despite being much more sophisticated, it has remarkable similarities to the Williamson – two sprockets top and bottom of the camera box and claw, now much more sophisticated and precise, with the addition of a register pin. In order to improve the vertical alignment, many cameras now provide a register pin or pins that are inserted into perforations adjacent to the aperture just as the claw is retracting and remain there for the duration of the exposure.

 

The horizontal bar with the drilled holes right in the middle of the picture is the register pin operating leg; there is a drop bar just behind the gate to locate the actual register pins in the two perforations at the bottom of the frame. In this camera, the claw mechanism is operated by a link mechanism, which can be seen just below the register pin actuating bar.

 

In many camera mechanisms, one of the complications is that if the gate is straight the claw must have some means of converting the rotary motion of the drive shaft into an absolutely straight movement at the claw tip, as in the Williamson layout. This can lead to inaccuracies, vibration and noise. The Panavision mechanism echoes the earlier Mitchell mechanism in curving the bottom of the gate so that the claw is only required to follow this curved portion of the gate. This design leads to a very vibration-free claw movement of superb accuracy, which is incredibly quiet.

 

The claw mechanism has to be made to the highest possible tolerances, as the distance each frame is moved must be identical and must be repeated, exactly, every time. When you realize that, during a 10-minute roll of film, the claw will have pulled 16000 frames of film through the camera, you get some impression of both the precision and durability required of the claw mechanism.

 

The loop

Between the box holding the reserve and used film, known as the film magazine, and the box containing the camera mechanism and the camera gate will be one or two sprocket wheels with teeth that engage with the film’s perforations and geared to the claw mechanism, thus ensuring a constant supply of film both to the gate and taking the film away after exposure. As the sprocket will be running continuously and the claw only acts intermittently above and below the gate, the film is allowed to form loops. The loop above the gate forms a reservoir of film ready for the claw to pull it through the gate; this action then enlarges the loop at the bottom of the gate ready for the sprocket to take it away.

 

The complete cycle of an intermittent movement is shown in Figure 4.6. In film strip A, the frame being exposed is just coming to the end of its full exposure. The shutter is starting to close, the claw is entering the appropriate perforation and the register pin is withdrawing. In film strip B, the shutter is closed, the register pin is fully retracted and the claw is commencing the pull-down. In film strip C, the shutter is still closed, the register pin still withdrawn and the claw is halfway through the pull-down. In film strip D, the shutter is still closed, the register pin still withdrawn but the claw is nearing the end of its travel and starting to slow down. In film strip E, the film has come to rest, the shutter is starting to open, the claw is withdrawing and the register pin is nearly fully in to its perforation. In film strip F, the shutter is fully open, thus starting the exposure, the register pin is fully locked into its perforation, thus holding the frame being exposed absolutely still, and the claw is travelling upwards behind the gate to return to the top of its travel. In film strip G, the shutter is still open, the register pin is still in and the claw has nearly reached its topmost position. In film strip H, the shutter has closed, the register pin has withdrawn and the claw has entered the perforation relating to the next frame and is just starting its pull-down. The cycle is now complete – the mechanism is back to film strip B and will now commence the whole cycle again.

 

The reflex viewfinder

Early film cameras had viewfinders either by the side or above the taking lens. The viewfinder, therefore, didn’t see exactly the same frame as the cameras lens. This is known as parallax error, as the optical axis of the taking lens and that of the viewfinder will point in the same direction but will run parallel to each other. This problem was first overcome when a German company, Arnold & Richter, introduced their Arriflex 35 mirror reflex camera to the world at the 1937 Leipzig Fair. This camera totally revolutionized the way film cameras were designed from then on. The Arriflex did not have its shutter running flat to, and in the same plane as, the film gate but had it angled at 45° to the gate and the aperture. Furthermore, the front surface of the shutter had a mirrored surface, so that when the shutter was closed the light that was blocked from the aperture was now sent off at a right angle. This image was then displayed on a ground glass whose distance from the lens, via the mirrored shutter, was exactly the same as the film aperture. A second fixed mirror, or prism, then sent the image on the ground glass to the viewfinder optics. Thus, the image in the viewfinder was identical to that on the film, as they shared the light from the lens on an alternating basis. The original Arriflex was organized so that the mirrored shutter sent the light horizontally to the viewfinder. Today, cameras divide between those that send it horizontally and those that have the shutter beneath the lens and send it upwards to the viewfinder. Interestingly, Arriflex have made cameras with both configurations.

 

Viewing screens

The ground glass viewing screens of the early reflex cameras have now been replaced with a slice of an end-on bunch of fibre-optics cut, and ground flat, to produce a focusing screen. This greatly reduces vignetting at the edges of the image, is much more critical of exact focus so that the camera operator can determine the focus more easily, forms an image far brighter than a ground glass and has less brightness fall-off in the corners of the frame.

 

There is a very reliable way of setting your eyepiece to your natural vision. Point the camera at an object less than six feet, or two metres, away, and now rack the lens to infinity – use a lens of at least the “normal” focal length and focus the viewfinder ocular on the cross in the middle of the viewfinder, if there isn’t a cross focus on the line around the viewfinder mask. Now refocus on the scene and you will be able to eye focus perfectly.

 

The film magazine

In order to be able to change from one roll of film to another at any time, both the feed roll of film and the take-up roll are housed in a light-tight container provided with a light trap, through which the film can exit and re-enter the box – this assembly is known as the film magazine.

 

 

Lenses

 

Artistic decisions

 

When you come to order a lens set for a picture, you are faced with a number of interesting problems and choices. These relate to:

 

Definition or sharpness.

Speed or maximum aperture.

Contrast, or how quickly does black become white?

Do you need prime lenses, a zoom or both?

What focal lengths do you need? Should you include extreme wide angle or telephoto?

 

Lenses have developed dramatically over the last 20 years. During this time there have been two areas where lens designers have concentrated their efforts – speed and definition. In doing this, they have developed some amazing lenses but we, as artists, do not always want enormously high definition images nor always need a large maximum aperture.

 

It is common, especially on feature films these days, to shoot with some kind of diffusion filter on the lens – so why do we assume that the character of the picture will be what we desire when a high definition lens has some of that definition destroyed by a filter? Could we not choose a lens that has the natural characteristic we desire without needing the filter – and would that be an advantage?

 

The fundamentals

 

In order to achieve a higher definition when tested on a lens chart, which usually contains finer and finer black and white lines, the lens designer trades contrast against definition. If you want to resolve black against white, you need a lens with high contrast and very little internal flare; this adds to the measurable definition under these conditions. If, on the other hand, your main consideration is a long tone range, you might trade off a little contrast and a lower measured definition in order to get a gentler, and perhaps more pleasing, gradation. Given that the current fashion is for a slightly diffused, ‘natural’ image, then you might trade off a little speed, contrast and definition for a lens that gave you what you wanted without the need for filtration.