A history of world tanks and miniature filming techniques
Updated: June 2012
Shipping themes in many forms have long been popular movie subjects, encompassing many genres including swashbuckling pirates, fantasy, historical epics and war. Nearly every major studio in Hollywood used to have its own tank facility to support this. Now most of them have long gone, converted to car parks or the land on which they stood sold off as housing developments.
Shooting out in the ocean was an option, one that has been more in favor in recent years, but it is well known in movie making that filming at sea is at least three times more difficult (and 3 times more expensive) than shooting on land.
In the golden years of the Hollywood studio system where there was a specialised department for every facet of production, it made economic sense to have a dedicated tank, the cost of which could be amortised over many productions. Fox studios had a tank named after its head of visual effects Fred Sersen which was demolished in 1960 when the land on which it stood was sold off. A new and better tank also named Fred Sersen lake was built for Cleopatra in 1962 at the fox ranch at Malibu. The tank contained about 3 million gallons of water at 36 inches deep. It had sloping sides allowing vehicles to be driven into it and preventing wave echoes from bouncing back. In a straight sided tank, any waves produced would hit the side and bounce back. This can look odd when the two opposing waves meet, ruining a carefully generated wave pattern. The Sersen lake, like many tanks, was trapezoid in shape. The back wall was the longest at 370 feet and also shorter in height allowing a flow of water over its edge. The water that spills over the curved top is collected in a trough and pumped back into the tank so that there is a continuous flow maintaining a constant water edged horizon.The tank was 300 feet from front to back with the front wall, where the camera is usually placed, much shorter at 198 feet wide. At the back of the tank was a giant screen much like an old drive in theatre, angled back at 14 degrees to catch the sun. This screen was 366 feet wide by 85 feet high covered with plywood panels and a layer of canvas on which would be painted a sky scene. It had an electrically driven multi level platform for use by the scenic artists. Behind the screen was a reservoir which held 4 million gallons of water and giant pumps which could fill the tank in 100 minutes and drain it in 50.
There is a tank at Pinewood studios still in use known as the Paddock tank which is very similar to the one just described. It has a deeper well in the middle. In 1960, Toho Studios in Japan completed a tank known as the “Big Pool”. It measures 289 x 236 feet (88 x 72 metres) and has a depth ranging from 2 1/2 to 5 feet (0.8-1.5 metres).
Cinecitta in Rome has a tank 236 x 477 feet (72 x145 metres) and 5 foot deep (1.6m). It has a 282 feet long, 59 feet high (86 x 18 metres) backdrop screen. The tank holds 2,720,972 gallons (10,303 cubic metres) of water. It was used as a harbour in Martin Scorcese's "Gangs of New York" (2002).
Fox Studios built a massive tank facility in Baja, Mexico for the blockbuster film "Titanic". The facility had some of the world's largest stages and certainly the largest exterior tank. In 2007 it was sold to a group of investors but the facility was effected negatively by local drug wars in the area. The government is recently trying to bring back productions by offering a cash rebate.
In the late 2000's the Spanish government built a tank 328 x 262 feet (100 x 80 metres) and 3.9 feet deep (1.2 metres) in Alicante as part of its new big studio investment. The plan was to create a new economic activity in the Valencian region.
One of the most well known tanks for model ship effects is the one on the island of Malta. It has been used for many model ship movie visual effects most notably “Raise the Titanic” in 1980. There are in fact three tanks built at this facility two of which have the real sea and sky for a background. The shallow tank is 300 by 400 feet (91 x 122 metres) and 6 ft deep (1.8m deep) with a deeper pit in the centre and takes 8 to 10 hours to fill.. The Deep water tank is more of a rounder shape 354 by 162 feet wide (108 x 49 metres) and 36 feet deep (11 metres), taking about 15 hours to fill. There is also a smaller insert tank 50 by 30 feet (15 x 9 metres) and 12 feet deep (3.6 metres).
Shipping themes in many forms have long been popular movie subjects, encompassing many genres including swashbuckling pirates, fantasy, historical epics and war. Nearly every major studio in Hollywood used to have its own tank facility to support this. Now most of them have long gone, converted to car parks or the land on which they stood sold off as housing developments.
Shooting out in the ocean was an option, one that has been more in favor in recent years, but it is well known in movie making that filming at sea is at least three times more difficult (and 3 times more expensive) than shooting on land.
In the golden years of the Hollywood studio system where there was a specialised department for every facet of production, it made economic sense to have a dedicated tank, the cost of which could be amortised over many productions. Fox studios had a tank named after its head of visual effects Fred Sersen which was demolished in 1960 when the land on which it stood was sold off. A new and better tank also named Fred Sersen lake was built for Cleopatra in 1962 at the fox ranch at Malibu. The tank contained about 3 million gallons of water at 36 inches deep. It had sloping sides allowing vehicles to be driven into it and preventing wave echoes from bouncing back. In a straight sided tank, any waves produced would hit the side and bounce back. This can look odd when the two opposing waves meet, ruining a carefully generated wave pattern. The Sersen lake, like many tanks, was trapezoid in shape. The back wall was the longest at 370 feet and also shorter in height allowing a flow of water over its edge. The water that spills over the curved top is collected in a trough and pumped back into the tank so that there is a continuous flow maintaining a constant water edged horizon.The tank was 300 feet from front to back with the front wall, where the camera is usually placed, much shorter at 198 feet wide. At the back of the tank was a giant screen much like an old drive in theatre, angled back at 14 degrees to catch the sun. This screen was 366 feet wide by 85 feet high covered with plywood panels and a layer of canvas on which would be painted a sky scene. It had an electrically driven multi level platform for use by the scenic artists. Behind the screen was a reservoir which held 4 million gallons of water and giant pumps which could fill the tank in 100 minutes and drain it in 50.
There is a tank at Pinewood studios still in use known as the Paddock tank which is very similar to the one just described. It has a deeper well in the middle. In 1960, Toho Studios in Japan completed a tank known as the “Big Pool”. It measures 289 x 236 feet (88 x 72 metres) and has a depth ranging from 2 1/2 to 5 feet (0.8-1.5 metres).
Cinecitta in Rome has a tank 236 x 477 feet (72 x145 metres) and 5 foot deep (1.6m). It has a 282 feet long, 59 feet high (86 x 18 metres) backdrop screen. The tank holds 2,720,972 gallons (10,303 cubic metres) of water. It was used as a harbour in Martin Scorcese's "Gangs of New York" (2002).
Fox Studios built a massive tank facility in Baja, Mexico for the blockbuster film "Titanic". The facility had some of the world's largest stages and certainly the largest exterior tank. In 2007 it was sold to a group of investors but the facility was effected negatively by local drug wars in the area. The government is recently trying to bring back productions by offering a cash rebate.
In the late 2000's the Spanish government built a tank 328 x 262 feet (100 x 80 metres) and 3.9 feet deep (1.2 metres) in Alicante as part of its new big studio investment. The plan was to create a new economic activity in the Valencian region.
One of the most well known tanks for model ship effects is the one on the island of Malta. It has been used for many model ship movie visual effects most notably “Raise the Titanic” in 1980. There are in fact three tanks built at this facility two of which have the real sea and sky for a background. The shallow tank is 300 by 400 feet (91 x 122 metres) and 6 ft deep (1.8m deep) with a deeper pit in the centre and takes 8 to 10 hours to fill.. The Deep water tank is more of a rounder shape 354 by 162 feet wide (108 x 49 metres) and 36 feet deep (11 metres), taking about 15 hours to fill. There is also a smaller insert tank 50 by 30 feet (15 x 9 metres) and 12 feet deep (3.6 metres).
Dump Tanks, wave machines and various equipment for simulating storms at sea at the Malta tank. The blue cylinders are air cannons which are powered by a large volume of compressed air which can be released instantaneously blasting out a quantity of water into a fast moving spray. The two tall structures either side are the dump tank shutes down which fall a huge quantity of water which is then kicked up into a wave like crashing of water. The other blue structures between the shutes with long thin white pnuematic (or hydraulic) rams are the wave machines which cycle up and down pushing on a shaped displacement volume in the water to produce the rolling swell.
The models in the photos below have also been constructed at the Malta facility.
One of the most important factors in a realistic scene is the breaking up of the watersurface. A real ocean is never still even on windless calm day. A small body of water at rest, such as that in a large tank, can be very mirror like in appearance and a dead giveaway of the smaller scale. To be convincing a tank needs waves and wind.
Mirror like water in the Malta tank is possible when there is no wind. This is more common in the early morning.
In Universal's "U-571" the Deep Tank was used for all underwater model filming. The tank had a filtration system added to its water intake system in order to ensure maximum clarity. The late VFX supervisor Peter Dolmen then 'complained' that the water was so crystal clear that he was forced to add impurities to make it look more natural as the open sea. He claimed that visibility using the filtration system was often as good as 60 feet. Here is a video of an underwater clarity test conducted in 2006 inside the Deep Tank when the water was sitting in it for about 10 months. The clarity and consistency is quite good for water sitting idle for so long. The Insert Tank has its own permanent filtration system which ensures the best clarity. Here is behind the scenes underwater footage taken in 2007.
Waves effects can be generated by a squad of effects personel armed with nothing more than a plank of wood which is randomly pushed up and down in the water producing a general ocean swell. Slightly larger waves can be produced using 44 gallon drums or similar sized plastic drums manipulated in the same way. The finer rippling of the surface is done with large fans placed down one side of the tank. These fans are very tricky and time consuming to place so that there are no dead spots in evidence. The blast from one fan can affect another and the natural wind from the wrong direction can cancel the effect out altogether. If the budget allows a second row of fans can be placed on the other side of the tank so that if the wind shifts they are ready to go saving considerable time in moving and adjusting the fans to the other side of the tank. Sometimes these powerfull fans have been made from recycled aircraft with their wings cut off. They produce a powerfull blast but are typically incredibly noisy and hard to control. Even old jet engines have been pressed into service, an example being for Ridley Scott’s “White Squall”, where the storm was whipped into a frenzy of wind and sprayby the powerfull blast. Motorised and hydraulically powered wave machines have also been developed to generate the base level of wave action.
For storm sequences and tidal-like waves more elaborate equipment is required to produce the larger waves and spray required. The most common piece of equipment for producing a really big wave is the dump tank. This consists of a water tank mounted high up on a tower, able to release all its contents in an instant and a shute down which the released water slides. When the large volume of water drops into the tank it produces a large wave which can travel a short distance before it is dispersed. The model being filmed is placed as close to the shute as possible so that the wave is at its tallest and most powerfull when it hits and swamps the miniature. Sometimes the end of the shute is fitted with a kicked up end which rather than dumping the water into the tank, sends it up into the air and looks like a breaking wave. Dump tanks can be adjusted in the amount of water dropped or used in multiples depending on the ferocity of the effect. Rain and spray is achieved with fire hoses and these days the high pressure sprayer or cleaner can be used to produce very fine water drops which look to scale.
Waves effects can be generated by a squad of effects personel armed with nothing more than a plank of wood which is randomly pushed up and down in the water producing a general ocean swell. Slightly larger waves can be produced using 44 gallon drums or similar sized plastic drums manipulated in the same way. The finer rippling of the surface is done with large fans placed down one side of the tank. These fans are very tricky and time consuming to place so that there are no dead spots in evidence. The blast from one fan can affect another and the natural wind from the wrong direction can cancel the effect out altogether. If the budget allows a second row of fans can be placed on the other side of the tank so that if the wind shifts they are ready to go saving considerable time in moving and adjusting the fans to the other side of the tank. Sometimes these powerfull fans have been made from recycled aircraft with their wings cut off. They produce a powerfull blast but are typically incredibly noisy and hard to control. Even old jet engines have been pressed into service, an example being for Ridley Scott’s “White Squall”, where the storm was whipped into a frenzy of wind and sprayby the powerfull blast. Motorised and hydraulically powered wave machines have also been developed to generate the base level of wave action.
For storm sequences and tidal-like waves more elaborate equipment is required to produce the larger waves and spray required. The most common piece of equipment for producing a really big wave is the dump tank. This consists of a water tank mounted high up on a tower, able to release all its contents in an instant and a shute down which the released water slides. When the large volume of water drops into the tank it produces a large wave which can travel a short distance before it is dispersed. The model being filmed is placed as close to the shute as possible so that the wave is at its tallest and most powerfull when it hits and swamps the miniature. Sometimes the end of the shute is fitted with a kicked up end which rather than dumping the water into the tank, sends it up into the air and looks like a breaking wave. Dump tanks can be adjusted in the amount of water dropped or used in multiples depending on the ferocity of the effect. Rain and spray is achieved with fire hoses and these days the high pressure sprayer or cleaner can be used to produce very fine water drops which look to scale.
An aircraft propeller engine (left) being used as a windmachine. To the right is a wavemachine.
Wave effects set up to oppose each other with a life-size boat set in the middle.
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Dump tanks, or so called "tip tanks"
Rainheads in action.
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There has been many attempts to reduce the size of the resulting water drops from all this mayhem which as has already been noted is a major complaint against miniature photography. The size of a water drop is mostly a product of water tension and sometimes detergent is added to the water to reduce this. Only a very small amount should be used as too much starts producing obvious foam. There is foam on sea water but unlike dishwashing foam, salt water foam breaks down very quickly. Floating alcohol, which has a very small surface tension and consequently small droplet, has been tried but proved too problematic, including the fact that it is flammable. The most successful method is in the use of compressed air particularly in a storm sequence. Wherever large droplets are regularly thrown into the air, usually from the bow crashing into oncoming waves, carefully aimed compressed air nozzles can be made to blast the droplets thrown up into a finer spray. Generally the air from the fans will contribute to this destruction of the droplets as well.
One other ingredient is usually added to the water and that is a blue dye. This dye does nothing to colour the water’s surface but reduces the opacity of the water to help hide the many hoses, cables, ropes, tracks and other equipment used to control the models and generate various effects. It is impossible to light the water as it is transparent, the bottom of the tank recieves all the light and is therefore best made a dark colour or black so as not to be visible in the shallow depths. It is the reflective nature of the water’s surface that imparts the colour that is photographed and that is contributed by the painted sky backing or at some facilities the real sky.
The camera angles are usually low enough that the reflected sky is all that is seen. Higher camera angles such as a point of view (POV) from an aircraft or helicopter present difficulties in that the bottom of the tank may be seen. In this case more than a dye may have to be employed to make the water more opaque. One solution is to add diatomasceous earth, a white powder used in pool filters, which is actually tiny plankton skeletons. This when added to the tank makes for a very realistic micro-particle-filled sea water, helping to cloud it without looking milky. It will gradually sink to the bottom and needs to be kept agitated with a blast from a hose or fanned underwater to keep it swirling in suspension. It is also good for underwater shots again contributing that swirling particulate found in sea water. It does contain a silicate which in its dry powdered form is an inhalation health hazard. Once in the water it presents no known hazard unless you intend to breath the water and then it will be drowning that will kill you, it is easily filtered out by most pool filters which contain it anyway.
Sources – The technique of special effects cinematography by Raymond Fielding – Focal Press, Special effects Wire Tape and Rubber Band by LB Abbott – ASC press, Malcolm Scerri-Ferrante - PCP.
Model Control
In miniature visual effects work usually the maxim “simpler the better” is employed and most miniature ships have been moved across the tank by pulling an underwater rope. Usually divers are employed to man-handle the ship into position and to stop it before it hits the wall of the tank. Sometimes a ship might be moved during the shot by a hidden diver on the off camera side of the model. Although using the term “diver” here, in one meter of water aqualungs aren’t usually required. In fact where a "diver" can be substituted by a technician in a wetsuit or waders. Divers need to be fit as they will spend a long time in the water during shooting and will also need to be pretty strong. Because the models are usually shot at an over-cranked camera speed they need to be moved pretty quickly through the water. The miniatures can have a great deal of mass when ballasted to sit at the correct water level, making them very difficult to stop when moving at speed.
In the past there was two schools of thought in regard to the building and moving of these miniatures. The British system referred to the models having an open bottom, having no buoyancy, not needing any ballast and riding on trolleys on tracks set on the bottom of the tank. This meant that the models were not at the whim of any waves in the tank and rode steadily in all seas. For smaller scales of models this was probably an asset as it precluded any unnatural bobbing up and down, to give away the scale. The American system on the other hand was to build the models as ships, ballasted to float at the correct water line and free to interact with any waves thrown at them. This means a system of ballasting needs to be employed, preferably one which takes place after the model is moved to the tank. The obvious answer is to provide containers that can be filled with water once the model is floated. Sometimes sandbags are placed into the hulls or lead shot. Any batteries used for practical lighting can also figure in the total ballast. Most radio control ship modelers are surprised at the amount of ballast required for their relatively small models to be brought to the waterline,. When the models are 40 feet or more long, you can understand that the issue of ballast needs to be considered very carefully indeed. Most ships are turned by the action of the rudder which is generally at the rear of the vessel. This means that a ship is turned by swinging the stern around at the rear. To get a model ship which is being pulled by a rope attached under the bow to turn accurately requires the pulling of a second rope attached at the stern to simulate the action of the rudder. It is not uncommon to find aspects of these models operated by an effects man concealed within the model. He may be employed to operate a rudder, pull on running rigging ropes to set sail angles, fire miniature cannon, or actually pilot the thing around the sea.
The huge 60 foot oil tanker built by Derek Meddings’ crew for "The Spy Who Loved Me" was reportedly operated from within the catamaran like hull. The catamaran layout was to allow the bow to open and swallow a large model nuclear submarine. Wolfgang Peterson mentions on the DVD commentary for Das Boot that originally the largest U-boat model (11.2 meters/37 feet) was controlled by a diver concealed inside, but he became very seasick and subsequently the sub was towed by a boat out of shot.
In more recent years radio control has been employed as it has got more reliable and less prone to interference. A runaway model 6 meters long could do some serious damage both to itself and any one in its way.
Where a shoot takes place on the open ocean, auxiliary boats are used to tow the models on a long submerged cable so they keep out of shot and don’t leave an unnatural wake destroying the scale of the shot. Shooting of any sort is notoriously difficult at sea due to the unpredictable nature of the weather and waves, that and coordinating a camera boat and tow boat and it is for this reason that many Hollywood studios built there own tank facilities.
One of the largest ship models for film was that for "Raise the Titanic" (1980). It weighed 10 tons, had a height of 12 feet and length of 55 feet (3.6 x 16.7 metres). It was made in parts in the UK and put together at the Malta tank facility where the film was shot. It took eight workers three months to complete the assembly job. The model is reported to have cost over one million dollars at the time.
One other ingredient is usually added to the water and that is a blue dye. This dye does nothing to colour the water’s surface but reduces the opacity of the water to help hide the many hoses, cables, ropes, tracks and other equipment used to control the models and generate various effects. It is impossible to light the water as it is transparent, the bottom of the tank recieves all the light and is therefore best made a dark colour or black so as not to be visible in the shallow depths. It is the reflective nature of the water’s surface that imparts the colour that is photographed and that is contributed by the painted sky backing or at some facilities the real sky.
The camera angles are usually low enough that the reflected sky is all that is seen. Higher camera angles such as a point of view (POV) from an aircraft or helicopter present difficulties in that the bottom of the tank may be seen. In this case more than a dye may have to be employed to make the water more opaque. One solution is to add diatomasceous earth, a white powder used in pool filters, which is actually tiny plankton skeletons. This when added to the tank makes for a very realistic micro-particle-filled sea water, helping to cloud it without looking milky. It will gradually sink to the bottom and needs to be kept agitated with a blast from a hose or fanned underwater to keep it swirling in suspension. It is also good for underwater shots again contributing that swirling particulate found in sea water. It does contain a silicate which in its dry powdered form is an inhalation health hazard. Once in the water it presents no known hazard unless you intend to breath the water and then it will be drowning that will kill you, it is easily filtered out by most pool filters which contain it anyway.
Sources – The technique of special effects cinematography by Raymond Fielding – Focal Press, Special effects Wire Tape and Rubber Band by LB Abbott – ASC press, Malcolm Scerri-Ferrante - PCP.
Model Control
In miniature visual effects work usually the maxim “simpler the better” is employed and most miniature ships have been moved across the tank by pulling an underwater rope. Usually divers are employed to man-handle the ship into position and to stop it before it hits the wall of the tank. Sometimes a ship might be moved during the shot by a hidden diver on the off camera side of the model. Although using the term “diver” here, in one meter of water aqualungs aren’t usually required. In fact where a "diver" can be substituted by a technician in a wetsuit or waders. Divers need to be fit as they will spend a long time in the water during shooting and will also need to be pretty strong. Because the models are usually shot at an over-cranked camera speed they need to be moved pretty quickly through the water. The miniatures can have a great deal of mass when ballasted to sit at the correct water level, making them very difficult to stop when moving at speed.
In the past there was two schools of thought in regard to the building and moving of these miniatures. The British system referred to the models having an open bottom, having no buoyancy, not needing any ballast and riding on trolleys on tracks set on the bottom of the tank. This meant that the models were not at the whim of any waves in the tank and rode steadily in all seas. For smaller scales of models this was probably an asset as it precluded any unnatural bobbing up and down, to give away the scale. The American system on the other hand was to build the models as ships, ballasted to float at the correct water line and free to interact with any waves thrown at them. This means a system of ballasting needs to be employed, preferably one which takes place after the model is moved to the tank. The obvious answer is to provide containers that can be filled with water once the model is floated. Sometimes sandbags are placed into the hulls or lead shot. Any batteries used for practical lighting can also figure in the total ballast. Most radio control ship modelers are surprised at the amount of ballast required for their relatively small models to be brought to the waterline,. When the models are 40 feet or more long, you can understand that the issue of ballast needs to be considered very carefully indeed. Most ships are turned by the action of the rudder which is generally at the rear of the vessel. This means that a ship is turned by swinging the stern around at the rear. To get a model ship which is being pulled by a rope attached under the bow to turn accurately requires the pulling of a second rope attached at the stern to simulate the action of the rudder. It is not uncommon to find aspects of these models operated by an effects man concealed within the model. He may be employed to operate a rudder, pull on running rigging ropes to set sail angles, fire miniature cannon, or actually pilot the thing around the sea.
The huge 60 foot oil tanker built by Derek Meddings’ crew for "The Spy Who Loved Me" was reportedly operated from within the catamaran like hull. The catamaran layout was to allow the bow to open and swallow a large model nuclear submarine. Wolfgang Peterson mentions on the DVD commentary for Das Boot that originally the largest U-boat model (11.2 meters/37 feet) was controlled by a diver concealed inside, but he became very seasick and subsequently the sub was towed by a boat out of shot.
In more recent years radio control has been employed as it has got more reliable and less prone to interference. A runaway model 6 meters long could do some serious damage both to itself and any one in its way.
Where a shoot takes place on the open ocean, auxiliary boats are used to tow the models on a long submerged cable so they keep out of shot and don’t leave an unnatural wake destroying the scale of the shot. Shooting of any sort is notoriously difficult at sea due to the unpredictable nature of the weather and waves, that and coordinating a camera boat and tow boat and it is for this reason that many Hollywood studios built there own tank facilities.
One of the largest ship models for film was that for "Raise the Titanic" (1980). It weighed 10 tons, had a height of 12 feet and length of 55 feet (3.6 x 16.7 metres). It was made in parts in the UK and put together at the Malta tank facility where the film was shot. It took eight workers three months to complete the assembly job. The model is reported to have cost over one million dollars at the time.
The "Raise the Titanic" model as it stood in 1987. (Photo © PCP)
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PCP founder Malcolm Scerri-Ferrante in 1987 stands by the huge scale Titanic model used in "Raise the Titanic" (1980). This was the largest ship model to be built in its time.
(Photo © PCP)
A screen-shot from the film "Raise the Titanic" (1980)
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Camera, Lighting and Lens
A fundamental factor in making models appear life size and massive is to shoot them at high camera speeds. Without this the miniature ships would bob up and down on the tiny waves in a most unconvincing fashion. This is easily demonstrable if you play the shot at a faster speed. Take any movie model ship scene and play it back from between 3 and 4 times fast forward and you will get an approximation of the actual speed at which the model was moving. Suddenly the true temporal scale is revealed and the enlarging effect is greatly diminished, the model looks smaller, back to the size it really is. There is an old rule of thumb that was used to determine the appropriate frame rate at which to shoot a miniature. Generally the square root of the scale denominator would be calculated and used as a multiplier to set the camera speed. For example a 1/16 scale miniature would be shot at around 96 frames per second (fps), the square root of 16 being 4, and 4 times 24 fps equals 96 fps. A larger 1/4 scale model would result in a 2 times increase to 48 fps. This formula was generally a good place to start and usually some testing would take place to finalise the speed setting. It follows from this that the smaller the scale the faster you need to shoot and eventually you reach the limit of what is physically possible for the camera to achieve. The reliable old work horse, the Mitchell High Speed 35mm Camera, if well maintained, was capable of speeds of up to 128 frames per second. The latest Arri Alexa is capable of 120 frames per second.
Here is a reference video of a model filmed in Malta's shallow tank for the German film "Der Skipper" (1989). The model was nearly five feet long and the camera was overcranked.
Some of the model ship explosions for Tora Tora Tora were filmed with a camera capable of 360 frames per second, that is 15 times normal speed and about as fast as it is technically possible for an “intermittent movement” to shift the 35 mm film through the camera. There are cameras which can go faster, they generally move the film through the camera continuously, using a rotating prism to scan the image onto the film as it slides past the aperture. Speeds in the thousands of frames per second can be had here coupled to specialised lighting fixtures which synchronise to the high speed and short exposures. Cameras with the afore-mentioned intermittent movement produce a far steadier image as the film is held stationary by some pins whilst the frame is exposed. Once that is done, the pins are withdrawn, the film is slid to the next frame and parked for the pins to be inserted and the next frame exposed again, hence the term intermittent, it’s a start stop process. It takes a fair bit of expensive precision engineering to get a mechanism that can do this start stop process at such high speeds reliably without ripping the sprocket holes in the film or folding the film up inside the camera like a concertina. Many a take has had to be re-staged because of a camera jam. It is not unusual to record destruction sequences with more than one camera to be sure of getting the shot. A second angle can always be used in the edit anyway. It can be advantageous filming fast speed on 16mm film, a smaller and cheaper negative for TV format. Because the film is smaller, of less mass and a shorter distance between frames, the cameras are able to run at faster speeds. An Arri SR which can get up to 250 frames per second and a Photosonics Actionmaster is capable of 500 frames per second. The latter camera which was prone to jamming but small scale explosions for example they look absolutely massive at 500 frames per second.
The faster the film is transported through the camera the less time each frame is exposed to light. Higher speed shooting requires more light to get an exposure on the film. In a studio one can add to the number of lights used or use larger and more intense fixtures. Outdoors in sunlight you might think that it would be a simple matter of just opening up the aperture of the lens. Unfortunately this would result in a shorter depth of field, rendering the extreme foreground and possibly the background “soft” or slightly out of focus. Let us examine this scenario, you are to photograph a real ship and a model of that same ship out on the ocean. The real ship in order to get all of it in frame would be some distance from away. You would most likely have the lens focused at infinity. The ship, the sky and clouds in the background several kilometers away as well as the waves and the smaller model in the foreground near you, would all be in focus. If you now photograph the model so that it takes up the frame in the same way the full size ship did, you would have to be much closer to the model. Your focus setting would have to be adjusted down from infinity resulting in a shallower depth of field, causing some softening of the extreme foreground and background focus. This is another of the tell tale signs of a miniature effect. There are some amazing shots of model railroad layouts that are of a very small scale, but photographed with a pinhole camera attachment using long exposures that look pretty convincing. This is due to the ability of the pinhole to image sharp focus from the lens to infinity at the cost of low light admittance. The reverse of this effect proves the point, in the many examples of the tilt shift lens photography seen on the web, where real objects like city streets and cars are made to look like tiny toys by throwing the foreground and background out of focus, usually in combination with speeding up the action.
Wide angle lenses are generally preferred over a standard or telephoto lens as they give a twofold benefit. The first is that wide angle lenses tend to exaggerate perspective which helps in making a miniature appear larger. Secondly a wide angle lens generally has a larger depth of field assisting in keeping everything from close to the front of the lens element to the far background in focus. Sometimes a longer lens is called for to simulate what you would use if you were shooting a full size ship from another ship or helicopter and you wanted to get in close. It also can compress the depth and make a stormy sea look more chaotic and dramatic.
Originally movies were shot for a 1/1.33 format, that is 1 unit high by 1 and 1/3 units wide, not much more rectangular than a square. Widescreen introduced various ratios up to 1/2.66 which is 1 unit tall by 2 and 2/3′s unit wide. When widescreen came into vogue, it presented problems for miniature photography. Anamorphic widescreen compresses the image horizontally using a special lens so you get a wider view than normal into the same 1.33 frame. There is a cost for this extra bit of glass and that is lower light transmission. As the aperture is opened to compensate, there is a smaller depth of field. Wider angle lenses are more difficult to make anamorphic so there tends to be only longer focal lengths available. Generally Anamorphic lenses are not able to focus as close as the traditional ”spherical lens” which means you cant get as close to make your tiny model look big enough. Often the model sequences in a film would be shot spherically and optically cropped and squeezed later in an optical printer. Of course this meant throwing away the top and bottom of your film frame in the process, leaving you with less resolution (more grain) than the rest of the film. An example of this is in the movie "Sink the Bismarck", one of the all time classic model ship movies. You certainly don’t notice any change in resolution during the model sequences, there’s too much glorious model action going on. There is an attraction in a widescreen composition created by an Anamorphic lens. The lenses create a very distinctive horizontal flare (extremely popular as a digital recreation) and because of the lower depth of field they give an image of soft creamy separation of subject and background, though admittedly, not good for miniatures.
Another important aspect of filming is the camera position or point of view. When shooting a miniature, one way to help with realism is to think of the camera and operator as the same scale as the model. If for instance you are shooting a ship leaving the dock, your camera would probably be on a tripod roughly at eye height above the wharf. If the model was 1/24th scale and you shot a 1/24th scale model from the same position it would look like you were either on a cliff looking down or in a very stable helicopter. To achieve a comparable shot the camera would have to be 1/24th of eye height off the ground. Perhaps you do want to have a shot looking down at the ship from the air. To convince an audience that you didn’t just mount a camera on a tripod and shoot a model you would need to introduce a simulation of both the motion and very subtle vibration you get from shooting from a helicopter or aircraft as you would have had to capture a real ship. A simple method of achieving a realistic pulsing vibration is to use a variable speed drill with a bent bolt in the chuck as an offset weight. The drill is strapped to a board attached to the tripod head. The drill trigger is pulsed on and off to produce a subtle cyclic vibration in the resulting footage which looks very much like that taken from a helicopter. Similarly the physics of shooting from a boat or another ship would need to be simulated to produce a realistic effect. The camera can be mounted in a box with a clear window to shoot through and floated on the water surface guided by the operator. Nowadays there is also a telescope lens attachment to bring the lens view to water level or below. This gives the benefit of a natural wave motion and getting the lens down as low as it can go to the surface of the water. The camera-person should always ask themselves how would I get this shot if it were real and then scale down the camera position or camera move to match the miniature. For realism, the image gathering process must be simulated as much as the image gathered. The unrealistic camera position or impossibly mobile camera move is another miniature shot giveaway.
To summarise: a model shot has a better chance of success in the realism stakes if taken at high speed, with enough light to enable a small aperture (t/f-stop), to get a large depth of field so that everything is in focus. Sounds easy enough…
Source - Model Ships In Cinema
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