What is your lens?

Dir. and DoP Partho Mittra shares his mastery over the use of lenses.
Veteran DoP RM Rao in action
Veteran DoP RM Rao in action
The JVC 700E with Standard Canon HD zoom lens
The JVC 700E with Standard Canon HD zoom lens
Shallow depth of field: This is an example of very shallow depth of field. The focus on the subject is very critical along with the aperture. The subj
Shallow depth of field: This is an example of very shallow depth of field. The focus on the subject is very critical along with the aperture. The subj

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It is easy to recognise a DoP’s body of work by the way they use light and lens, pretty much the way you identify an artists’ work by his brush strokes or his use of colour. Chesta Shah Sengupta provides insights on lenses by speaking to experienced imagineers

The human eye is said to be the most ethereal, at the same time the most complex and precise organ in the human body. Perhaps it would still take the human race many more generations to fully understand and comprehend its functioning leave alone replicating it. Little do we realise that our eye can in a split second change focus from the nearest macro to the furthest infinity. It can in a moment close down the aperture of the retina to an astonishing f/80 and yet open it completely, enabling us to see in pitch darkness.

“Expecting a lens to do the same, would be asking for too much, isn’t it? Needless to say it is impossible to replicate the human eye in its complexity, it’s simplicity, it’s adaptability and it’s size.,” says director and DoP Partho Mittra. But, as much as we mortals have tried, the closest we have come to the human eye, is the modern lens - the ‘eye’ of the camera.

Interesting to note is the Dragonfly, known to have 30,000 facets to their compound eyes, giving them a nearly 3600 field of vision. “You can’t isolate a lens from a camera, the two work together as one instrument,” says veteran DoP RM Rao. “Different lenses offer a variety of focal lengths, to cover different areas from diverse distances,” says Rao.

Understanding essential lens terminology

Focal Length (Diagram A)
The focal length of an optical system is a measure of how strongly the system converges or diverges light. “In photography, longer focal length or lower optical power, is associated with larger magnification of distance objects and a narrower angle of view,” says Mittra. Conversely, shorter focal length or higher optical power is associated with a wider angle of view. Therefore in simple terms the focal length is the value that describes the ability of the optical system to focus light, and is the value used to calculate the magnification of the system. The other parameters are used in determining where an image will be formed.

Does that mean then that a 400mm lens should be 400mm long? “If you measure it you will find it is less than 400mm and this is because a camera lens really has many individual glass lenses inside it which make it behave longer than it really is,” says Mittra. “This is called a telephoto lens.”

F-Stop
F-stop is the focal length divided by the diameter of the lens. For eg, a 200mm f/4 lens will be 50mm wide. This is why f-stop is typically written as F/4 meaning focal length over 4 or focal length divided by 4.

Lenses are marked with a series of f-stops. Each one lets in half as much light as the previous one. The light gathering ability of a lens is determined by its area, and f-stops are determined by the diameter.

Exposure
It is the total amount of light allowed to fall on the photographic medium during the process of taking a photograph. Exposure is measured in lux seconds and can be computed from the exposure value (EV) and scene luminance over a specified area. Hence, the correct exposure is determined by the combination of the f-stop and the shutter speed which one uses when taking a photograph.

“A photograph is said to be overexposed when it has a loss of highlight detail, that is when the bright parts of an image are effectively all white known as blown-out highlight,” according to Mittra. “A photograph may be described as underexposed, when it has a loss of shadow detail, that is the dark areas indistinguishable from the black, known as blocked up shadows or sometimes called crushed shadows,” he explains.

Depth of Field
Depth of field is the characteristic of a camera that can be used to enhance the image compression of the photograph. Depth of field, is the sharp area surrounding the point of focus. The magnitude of the sharp area is affected by several factors such as distance between the camera and the subject, the focal length and the aperture.

“It is important to understand how to utilise depth of field in an image composition,” points out Mittra. Citing an example he says, “The subject of the photo can be emphasised by isolating it from its surroundings by using a shallow depth of field. The out-of-focus zone in technical terms is often referred as ‘bokeh’ of a lens,” he says.

Basic construction of a block lens

The photographic block lens may be made from a number of elements. These elements may themselves comprise a group of lenses cemented together. The front element is critical to the performance of the whole assembly. “Lenses are made from different kinds of glass,” says Rao. “Superior polishing and extraordinary coating make a lens special and hence expensive, “ he adds.

Other materials used could include quartz glass, acrylic or even plastic. “The super telephoto lens come in various mounts,” says Mittra. “The Leica M39 mount for rangefinders, the M42 mount for the early SLR’s and the Four Third System for DSLR’s,” he elaborates. “The mounts are determined by the make of your camera,” adds Mittra. “Personally I prefer a 100mm/2.8 Nikkor or a Canon for portraits, as it gives me the shallow depth of field and that helps me isolate the subject,” says Mittra. “It also allows me to photograph the subject in the available light conditions,” he adds.

The 100mm macro is also a superb lens for macro photography. It gives a complete new dimension to the subject. “The Carl Zeiss 105mm macro in my opinion this is one of the best lens ever made for the still camera” says Mittra. “For landscapes, I preferably to use the Nikkor 35mm/f1.8.

Another favourite is the 150mm-500mm/f3.5-5.6 super telephoto. I use the Sigma with the Nikon mount. This particular lens has an opening of f3.5 at 150mm and has an opening of f5.6 at 500mm. Since I am into avid bird photography, this lens proves to be very useful, although it requires a tripod to avoid shakes,” he says

According to Mittra, if you have to choose, then it is more beneficial to invest in a good lens rather than a good camera because the soul of a great photograph lies in the ability of the lens to reproduce the image at the sharpest. Therefore, in the age of digital photography where cameras are in intense competition of packing mega pixels a good lens will give the desired result.

“As motion picture cameras are becoming electronic, lenses too are becoming part of that electronic device and are now called the LDS (lens data system),“ says Rao. According to Rao 99% of cine lenses used in India are either Carl Zeiss, Cooke optics, Hawk or Angenieux. Other lens manufacturers include Canon, Fujinon, Nikon, Nikkor and so on.

P+S Technik’s have good quality affordable lenses called the 16Digital prime lenses for digital cinematography. The optical parts are designed from LINOS Photonics (formerly Rodenstock). “However, as the Arriflex is still the most popular camera used in India, the Ultra prime and Carl Zeiss lenses are the most well-liked,” says Rao. Cooke and Master prime are fast gaining ground.

Zoom lens (Diagram B)

The Zoom lens is considered to be one of the path breaking innovations in photography. It is basically a lens with variable focal lengths. Its construction varies from the block lens because they have a focal length that varies. By rotating the barrel or pressing a button that activates the electric motor, one can change the focal length of the lens.

“As wildlife photography requires prompt action, there is absolutely no time to change a lens,” says Mittra. “One always dreamt of a single lens such as the zoom, with a variable focal length that could give a wide shot as well as a tight shot,” he adds. Prior to the zoom, documentaries were shot with the Arri2C and a three turret lens mount.

While the use of the zoom lens made life much easier for the documentary filmmaker and the still photographer, it has affected cinema quite the contrary way, as according to Mittra it is faster to zoom than to trolley or track. “But the effect of the zoom and the trolley are very different to the trained eye,” he shares. “While the zoom keeps diminishing, negating and constraining the background, the trolley on the other hand creeps on the subject without squeezing the background,” he explains. “On the big screen this effect is very visible.

If one takes time and studies the Hindi films that were made in the late 70’s, 80’s and the 90’s one can notice the ill effects of the use of the zoom lens,” he points out.

Aesthetic Use of Lenses in Cinema

The first thing that the director decides with his DoP, is the choice of his lens which in turn depends upon the mise-en-scene he has in his mind. Light and lensing are perhaps the most potent tools in a DoP’s palette. The depth of field, the aperture controls, the ‘bokeh’ of the lens, the content of the scene, the point of view, the state of the characters’ mind, the location and the emotional content, all determine the choice of the lens that is used for that particular shot in order to achieve the desired effect.

Lenses For Television

In television the production is categorised into ENG (news gathering), fiction (studio or outdoor), multi-camera studio shoots and multi-camera live sports coverage. “While most of the ENG news gathering is done with the DV cams and the JVC100E and other such cameras, these do not have interchangeable lenses. They have fixed zoom lenses either manufactured by Leica or Carl Zeiss,” says Mittra.

“Fiction shoots generally use the variable HR zooms that come with the HD cameras or at the most they use the J11 wide angle or the J14 285mm. Most of these cameras support the 2/3rd mount,” he says. “Another wonderful lens is the Canon J22 with an extender. This lens gives a coverage with the jimmy jib as and one can really venture close to the architecture without getting any distortions. On the other hand the J14 gives a superb depth of field with the optimum focal length that isolate subjects superbly” adds Mittra.

Intelligent Innovations - Partho Mittra, director and DoP

I have a JVC GY-HM700E Pro HD Camera. This camera has the 1/3 rd mount as compared to the 2/3 rd mount that most other HD and the digi cameras have. This camera has the 16:9 format and comes with the Cannon HR zoom. Recently, I sourced an adapter from London called the MTF 1/3rd mount-Nikon mount. What this basically does, is that it makes my Nikkor lenses that I use for my Nikon cameras adaptable to my JVC camera.

Now imagine when I have a 500mm focal length that caters to the 35mm (larger) still format compatible with the 16:9 HD (smaller) format the result is that it becomes a whopping 2500 mm+ telephoto. With this I have managed to take some breathtaking shots from great distances. The adapter also supports a rind that controls the aperture of the lens.

One needs some constant practice to use and operate the camera with this lens but the results are so fascinating that the trouble is worth the effort. This adapter ring has proved to be quite helpful for my documentaries as now I have the choice of the complete range of Nikon lenses to use with this camera.

J11 and the Jimmy Jib
The J11 and the jimmy jib are made for each other literally. The J11 lens is a wide lens with a minimum of 4.5mm as the focal length. This gives a wonderful perspective in the 4:3 as well as the 16:9 format. In the 16:9 format this lens serves its optimum purpose. The best part of this lens is that it does not distort at all and hence I use this lens extensively. But one needs to understand how and when to use it.

I have seen so many directors and cameramen use it just for the purpose of shooting wide masters. This, I feel is a redundant use of this beautiful lens. If one has to shoot masters then one might as well use the normal lens at the 7.6mm. One should not treat this lens as a mere tool that gives you more space to in frame.

I also use the J11 in movement shots. It is my observation that this lens is the most dynamic when the camera is either crossing a foreground or skimming it. It is therefore essential that the camera moves to get the best effect of this lens, and hence this lens is best served when it is mounted on a jib. I have used the J11 a lot in Rajasthan, along the fort walls to establish shots of magnanimous locations. I also call this as the ‘exposition’ lens. In fiction, I am a lot careful that my characters are not dwarfed by the lens, as the J11 is essentially an extreme wide lens.

J14 and J22
Television being essentially a medium of close ups, both the J14 and J22 are wonderful lenses for close shots. J14 is a lens that gives one a 265mm focal length with a f3.5 lens opening, making this essentially an outdoor lens. At its optimum maximum focal length the image produced gives a wonderful ‘bokeh’ as the depth of field which completely diffuses with the background.

This is specially useful when shooting in the limited and morbid locations of Mumbai where one wants to negate the background constantly. I use this lens in most of my close ups along with the J22 with the 2X extender. I also use a little movement in the background in the frame as this gives a nice texture to the frame and the movement is established completely as out-of-focus.

Day-for-night and the long lens

Television is all about the grilling schedules. A few days ago I was assigned to direct a very big fantasy for television called Aryan. This was proposed to be shot in Jaisalmer. Since the requirement of the story was to shoot long night sequences with animals and wide locations, it was impossible to achieve this in the restricted budgets that are allocated for television. Just to light up those locations would have taken us weeks, not to talk about the amount of lights we would have needed. I had to think of an alternative.

I made up my mind, I decided to shoot day-for-night. Since we were doing the project in HD I had the advantages of the camera on my side. I first did some experiments with my digital camera and then translated that to the HD medium. We did some mock shoots along with my cameraman Deepak Malwankar. Shooting outdoors we tweaked the camera colour temperature filter to B which gives a 3200K. This gives the image a overall blue feel.

We then lit the subject with the tungsten light even though we were shooting outdoors. Now we accessed the matrix file of the camera and tweaked the values of red, green and blue and pulled the black pedestal to give a it more contrast. Mixed with that we only used long lenses that squashed the depth of field. We were also working in the apertures of f16 and f11, helped by the bright sunlight, that looked like the moonlight in the day-for-night format.

In the desert where we had the sky we used graduated 9ND along with the ultra-polarizer filters to cut off the sky and give it a blue feel. But with the graduated ND filter along with the polarizer we were restricted with the panning of the camera. The results obtained were stunning and are still regarded as benchmarks in television day-for-night shoots.

Using the wide lens and a shallow depth of field

Achieving the impossible is possible with a little bit of innovation. The wide lens does not give you the shallow depth of field but sometimes especially for ‘thrillers’ one needs the wide frame and a very shallow depth of field. I manage to achieve that by using the J11 lens and take it out of the mount a little bit using the viewfinder. In this manner the focus is retained sharp of the foreground object that is kept quite close to the lens and the background is thrown completely out of focus.

Choosing the camera ND filter while shooting daylight documentaries

I always prefer to shoot by choosing the #1 ND filter, which basically is Clear ND meaning that there is no ND filter in the lens. With this options I can operate in exposures of f22, f16 and f11. This gives me less headache as far as the focus is concerned and especially when I am shooting the birds I need more range in my apertures. If given a choice I will always prefer to shoot with the #1 filter.
 

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