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Wednesday, June 5, 2013

Photography: Chapter 5

About lenses

Well, you can easily guess that the most critical piece of photographic equipment other than the camera itself is the lens. Since lenses can be passed on from one camera to the next and are a huge factor in the overall quality of the image, therefore, most photographers spend a lot of money to purchase high quality lenses

Let’s start with what role the lens plays in the photography. 

Camera uses the lens for many tasks such as focusing on a subject, metering a scene, delivering and focusing the light onto the camera sensor. The lens also decides the amount of the scene that will be captured (the frame).

Lenses are composed of optical glass that is both concave and convex in shape. By definition, a lens in context of photography is an optical lens or assembly of lenses used in conjunction with a camera body to focus the light coming in from the front of the lens onto the photgraphic film/ sensor. The amount of light that enters the camera is also controlled by the lens, the size of the glass elements, and the aperture mechanism within the lens housing. Most lenses these days include things like the autofocus motor and, in some cases, an image-stabilization mechanism also

While in principle a simple convex lens will suffice, in practice a compound lens made up of a number of optical lens elements is required to correct (as much as possible) the many optical aberrations that arise

Let’s understand what optical aberration is and how it can impact the image

Optical aberrations occur when points in the image do not translate back onto single points after passing through the lens. This can cause image blurring, reduced contrast or misalignment of colours. Optical aberrations are present to some degree with any lens. This is a very critical parameter that determines the cost of the lens

Lenses are typically divided into three or four groups depending on the field of view they deliver

Wide-angle lenses cover a field of view from around 110 degrees to about 60 degrees. Wide-angle lens allows more of the scene to be included in the photograph and is very useful in situations where the photographer may not be able to move farther from the scene to photograph it; such as architectural, interior and landscape. For a full-frame 35 mm camera, a lens of focal length 35 mm or less is considered a wide-angle lens. An ultra-wide-angle lens is a lens whose focal length is shorter than the short side of film or sensor. For 35 mm film or full-frame sensor any lens shorter than 24 mm

A normal lens has a field of view that is about 45 degrees and delivers approximately the same view as the human eye. A normal lens will have a focal length between 35 and 80mm. Normal focal-length lenses are useful for photographing people and for most other general photographic needs

Telephoto lens is a lens in which the physical length of the lens is shorter than the focal length. They can range in length from 135mm up to 800mm or longer and have a field of view that is about 35 degrees or smaller. Telephoto lenses are ideal when you can’t get close to your subject e.g. in a sports arena or in a bird sanctuary, since they have the ability to greatly magnify the scene, allowing you to capture details of distant objects. Pictures taken on telephoto lens tend to look 'flat', and a bit more two-dimensional

"Close-up" or macro lens are used for extreme close-up photography, usually of very small subjects, in which the size of the subject in the photograph is greater than life size. The ratio of the subject size on the sensor plane to the actual subject size is known as the reproduction ratio. A macro lens is a lens capable of reproduction ratios greater than 1:1

And based on focal length flexibility there are two kinds

Prime lens is a fixed-focal-length, or uni-focal lens. Zoom lens on the other hand has a variable focal length. Prime lens is less versatile than a zoom in terms of focal length range but is often of superior optical quality, wider maximum aperture, lighter weight, smaller size or lower cost. A prime lens has fewer moving parts, fewer optical and a less complicated lens formula. Therefore, they suffer from fewer problems related to optical aberration. Because of simple optics, prime lenses usually have a larger maximum aperture which allows photography in lower light and a shallower depth of field

50mm f1.8 prime lens are quite popular; renowned for delivering quality in a nominal budget
If your camera is with a crop sensor, 50mm is a perfect length for head and shoulder portraits
Wider aperture of prime lens offers small depth of field; hence ability to isolate subjects from the background i.e. more creativity
Prime lenses generally offer sharper, crisper shots than a zoom lens and the only downside that I see with a prime lens is that your feet become your zoom. But I believe that can make you a better photographer. Not being able to zoom your lens to get the shot, you need to think, you need to get creative

Zoom lens on the other hand is a one box solution; variety of focal lengths in one package. This means that if you want to shoot different focal lengths on a day, you do not have to carry around a bag full of lenses. So, prime or zoom? Answer depends on what you shoot. Subjects in fast moving environments need zoom. For portrait work, I will advise to go for prime

Monday, April 29, 2013

Photography: Chapter 4

Popular rules and guidelines

Digital cameras these days make a lot of decisions during the shooting process, and it’s important that you understand what it’s doing and why. I always recommend to use manual settings so as to have better control and understanding of your camera. Therefore, it’s very important to understand and use these rules and guidelines

Sunny 16 rule

Sunny 16 rule help to check your current exposure settings. Before digital cameras, photographers had to carry light meters with them. But if they didn’t have time to take a light reading, or they didn’t want to bother with carrying the equipment, they could resort to Sunny 16 rule.

The rule says, on a sunny day set aperture to f/16 and shutter speed to the reciprocal of the ISO for a subject in direct sunlight e.g. on a sunny day and with ISO 100, one sets the aperture to f/16 and the shutter speed to 1/100 second (or 1/125 as on some cameras this is available setting nearest to 1/100 second)

If you want to play with the values of aperture or shutter speed (for creativity), use this rule to ensure proper exposure. A list of reciprocal settings would all produce the same exposure result e.g. for Canon EOS 60D, the list is as depicted below:


Golden hour

In photography, golden hour is roughly the first hour of light after sunrise, and the last hour of light before sunset, although the exact duration varies between seasons. During these times the sun is low in the sky, producing a soft, diffused light which is much more flattering than the harsh midday sun. Typically, lighting is softer and warmer in hue and because the contrast is less during the golden hour, shadows are less dark, and highlights are less likely to be overexposed.

In landscape photography, the warm colour of the low sun is often considered desirable to enhance the colours of the scene

The golden hour rule can be applied to any type of outdoor photography. It is more obvious for landscapes and city scenes. However, it also works well for outdoor portraits, shots of flowers etc.

There are many photographers who follow this rule very rigidly and always try to do their outdoor photography during golden hours only.


Rule of thirds

It proposes that an image should be imagined as divided into nine equal parts by two equally-spaced horizontal and two equally-spaced vertical lines and that important compositional elements should be placed along these lines or their intersections

Belief is, that aligning a subject with these points creates more tension, energy and interest in the composition than simply centring the subject would


References
1. Wikipedia
2. Internet


Thursday, April 18, 2013

Photography: Chapter 3

Motion & depth of field

Let’s start with aperture first. So what is aperture?

An aperture is a hole or an opening through which light travels to the photographic film or sensor

Before discussing “depth of field” and how aperture determines it, let’s understand what is collimated light. Collimated light is light whose rays are parallel, and therefore will spread slowly as it propagates. In other words it does not disperse with distance (ideally), or will disperse minimally (in reality)

The aperture determines how collimated the admitted rays are, which is of great importance for the appearance at the image plane. If an aperture is narrow, then highly collimated rays are admitted, resulting in a sharp focus at the image plane. If an aperture is wide, then un-collimated rays are admitted, resulting in a sharp focus only for rays with a certain focal length. This means that a wide aperture results in an image that is sharp around what the lens is focusing on and blurred otherwise

Depth of field (DOF) is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image. The area within the depth of field appears sharp, while the areas in front of and beyond the depth of field appear blurry (as depicted below)



So the crux of the above discussion is that smaller the opening, greater the sharpness of objects from near to far (as depicted below, this one was clicked with aperture value of f/16)


A large opening means more blurring of objects that are not at the same distance as the subject you are focusing on (as depicted below, this one was clicked with aperture value of f/5.6)


Shutter Speed

Shutter speed controls the length of time the light strikes the sensor; consequently, it also controls the motion blurriness of the image

Excessively fast shutter speeds can cause a moving subject to appear unnaturally frozen. This is because, the less time light hit the sensor, the less time subject has to move around and become blurry. Therefore, fast shutter speed gives more control to freeze the motion of a fast-moving subject (as depicted below, this one was clicked with exposure time of 1/500 sec)


Slower shutter speeds are often selected to suggest movement in a still photograph of a moving subject i.e. intentionally blur subjects (as depicted below, this one was clicked with exposure time of 2 sec)



References
1. Wikipedia
2. Canon EOS 60D from Snapshots to Great Shots by Nicole S. Young




Saturday, April 13, 2013

Photography: Chapter 2


Exposure Triangle

In my last blog, we touched upon the topic "amount of light" or exposure, and how critical it is for photography. Technically, a photograph should be neither overexposed nor underexposed. A proper or correct exposure can be defined as an exposure that achieves the effect the photographer intended.

Every photographic film or a sensor has a physically limited useful exposure range. If, for any part of your photograph, the actual exposure is outside of this range, the film or sensor can't record it accurately. Out-of-range values would be recorded as "black" (underexposed) or "white" (overexposed) rather than the precisely graduated shades of colour and tone required to describe the "detail"

Shutter speed along with the aperture of the lens determines the amount of light that reaches the film or the sensor; which implies that the shutter speed (also called f-number) and aperture are two key aspects of photography. The third key aspect that completes "Exposure Triangle" is ISO as depicted below.


Let us understand all three namely ISO, Shutter Speed and Aperture one by one.

ISO is the measure of a photographic film's sensitivity to light. Higher the sensitivity, the less light is required for a good exposure, these films are commonly termed as “fast films”. Conversely, insensitive film requires more exposure to light to produce the same image density as a more sensitive film and these are commonly termed as “slow films”. The term ISO was coined during the film days, however, is also used for digital cameras with sensor instead of film. During film days, the film roll you used in the camera decided the ISO number, therefore, photographers use to put the kind of film roll suited for the type of photography assignment e.g. to cover a sporting or live events such as car race or cricket match, they will normally use “fast films”.

With the advent of digital cameras, you have the option of choosing from a range of ISO values based on your requirement. In digital cameras, ISO numbers usually start at 100 and then double in sensitivity as you double the ISO number. So 200 is twice as sensitive as 100. Cameras these days support a very high value of ISO e.g. Canon EOS 60D has ISO range of 100-6400 (expandable to 12800).

One important thing to keep in mind; higher ISO introduces electronic artefacts that appear as speckles in your image termed as “Noise”. The reason for this is the camera is trying to amplify the signal to produce visible information. The more the image needs to be amplified the greater the amount of noise will be and grainier the image will be. Therefore, try to shoot with the lowest ISO setting possible for maximum quality.

There are few thumb rules for choosing the ISO value, depending on your level of available light. For sunny days, use a low ISO such as 100 or 200. Cloudy days might require ISO of 400.For night time shots; you’ll probably need ISO of 1600.

As I told earlier, proper exposure is crucial to creating a good photograph. The exposure is measured in units of exposure value (EV), sometimes called stops. The combination of the aperture, shutter speed, and ISO is used to achieve a proper exposure value (EV) for the scene. Change to any one of these factors requires changing one or more of the other two to maintain proper EV. This is referred to as reciprocal change. Multiple combinations of the three can give the same EV. Deciding which combination to use is one of the creative aspects of photography. In cameras with interchangeable-lens, shutter speed and ISO are camera properties. Aperture is a lens property

Now let's talk about shutter speed & aperture. Let’s say you are shooting outdoors, on a sunny day, which implies that the ISO value is fixed (say 100). Now multiple combinations of the shutter speed & aperture can give same exposure. Then why not choose any value for these two. That’s where creativity comes.

“Motion & depth of field”

We will discuss this in the next chapter. Chapter 3

Saturday, March 30, 2013

Photography : Chapter 1


I cannot exactly remember when and how it all started. I was quite young and my father bought this simple point a shoot camera with a film roll. He allowed me to use it to click few family photographs and somehow the results were good. This experience off course was very new and exciting for me and perhaps started my love affair with photography.
For a very long time, I had this view, that only good gear can create good photographs. I always wished I could afford a very expensive high end camera. Then somewhere along the line I realised photography is an art; similar to painting. Tools are important, but tools alone can never create a masterpiece. As Steve Jobs once said; Technology alone is not enough. Its technology married with liberal arts that yield the result.
Photography is also science. It was only until recently (about 5 years ago), I realised that if I understand the science behind photography, I will be in a better position to create good photographs and perhaps a masterpiece someday.
Internet again turned out to be my biggest channel to learn these basics. I came across few experts on this subject and learned a lot from them. Some of these guys post regular blogs/ podcasts on photography and I will try to share further details in my future blogs. Along with my friends, we created a group and visited number of places in and around New Delhi to experiment and learn this science.
In last few years, social media esp. Twitter has grown very fast. It has provided people with a channel to reach masses. And last week, I also decided to share some of my knowledge of photography and I stared writing tweets on this subject. 
I would like to add here that I am not an expert or a professional. I am learning and along the way, I think there are few things which I can share with others. Via this blog I will try to consolidate and elaborate on whatever I discussed on Twitter in previous week/s. Source for most of my information on this blog is internet
Let’s start this journey with basics!
Chapter 1: Understanding the Camera
What does a camera do?
A Camera freezes a moment in time. Focuses light through a hole onto a light sensitive film. Invention that led to photography and the camera was Camera obscura; an optical device that projects an image of its surroundings on a screen. Light from an external scene passes through the hole and strikes a surface inside, where it is reproduced, upside-down, but with color and perspective preserved (see the picture below).

For more information on Camera obscura, follow the link to Wikipedia page http://goo.gl/VFcm
Modern, portable version of the camera obscura is called Pinhole Camera. It is a light tight box with photo sensitive paper at one end and a “pinhole” at the other. The pinhole camera works by uncovering the pinhole to let a certain amount of light into the box.

The technical term for this “amount of light" is exposure. Two factors that control the exposure into the pinhole camera are "time"(how long you leave the hole open) and "size of the hole". These are basically the same two important things you control with your SLR Camera.  "Time"(how long you leave the hole open) is shutter speed & "size of the hole" is aperture

Many of us think that the Digital single-lens reflex camera (DSLR) is the one with detachable lens (something like Canon60D). However, most digital cameras today are technically DSLRs. SLR camera typically uses a mirror & prism system that permits the photographer to view through the lens and see exactly what will be captured. Contrary to TLR (twin-lens reflex) cameras where the image could be significantly different from what will be captured. TLR cameras with viewfinders had two optical light paths: One through the lens to the film, and another positioned above or to the side (rangefinder)


TLR

Rangefinder

Thursday, April 5, 2012

Callous DNA


"Callous,indifferent, self-centered cowards - that's all we are.  Wonder how we gotdemocracy"

Someone tweeted this on twitter and I realized, that for some time now, I havebeen thinking exactly the same thing, about us, Indians

When I was a child, my grandfather used to tell me stories from our independencemovement. And I often wondered how brave heart were those people, who weredriven by one common cause; India's independence. The passion, so strong, thatthey were happily willing to sacrifice everything, including their lives, forthe cause they believed in. To me, sacrificing one’s life, is perhaps the mostdifficult thing to do. 
Not just independence,there are numerous other examples, where people stood together, for each other,to fight against the common cause

Today, almost 64 years later, all of us have become so selfish and indifferent,that any issue, no matter how big it is, if is not impacting us, will not matterto us.  At the maximum, we may voice our support using the easiest ofmeans or channels (internet, social media, twitter, Facebook etc.)

Most of us are guided by the logic that as a very small individual, we will notmake any difference to the situation. Moreover, we have our own worries, life,office, family to support and where is the time for all such things? And it is,anyways, not impacting us, so why should we bother. Number of victims,therefore, soon becomes some statistics for us. They may spur some anger,frustration initially but soon we are back to normal, and then these becomejust numbers in a newspaper

I heard somewhere, that in some western countries, people, if they reach earlyto their offices will park cars farthest in the office parking. This is for theease of their colleagues who might get late for office. I cannot imagine suchthings here in our country. We are kind of people, who, if given theopportunity are always ready to jump the queue. If we cannot show such basic courtesiesto our fellow citizens, how we can imagine that we will stand up for them whensome wrong is done upon them


This attitude, somehow,somewhere got imbedded in to our DNA all along the way. We always think ofourselves or our families, and hardly care for others. I am not sure, whatfactors are responsible for this attitude; over population, poverty, limited resources.The seeding perhaps started when our parents/ teachers taught us that there arelimited resources for which we have to compete, be it seats in premier educationinstitutes, or good jobs etc. That in turn led to selfishness

I once tweeted “The problem with most of us, who know that it is wrong and wantthe situation to change, is that we think someone else will come and change itfor us”


I am not sure; however,there are few things that I believe we can do, if we want to become catalystsfor this change. We should stand up and support people who we think arefighting for good cause against the system. It is not possible to change the thingsovernight, however, if we start electing our leaders/ representatives wisely,we will one day see the change we are looking for.

In the movie “rang debasanti”, there is a dialogue which is apt for what I want to say, “There aretwo ways of living a life. One, accept whatever is happening and live. Two,accept the responsibility to change and do it”


This is our country, and we all have to take responsibility to make it abetter place to live for ourselves and for our coming generations

Wednesday, February 1, 2012

Dil Ka Hujra Saf Kar


Dil Ka HujraSaf Kar

TulsiSahib

It is said that oneMuslim devotee Sheikh Taqi was coming back from Haj with a group of otherdevotees. Since the journey was too long they had to break their journey forthe night. They pitched their tents in an open field, which happened to be nextto an ashram of Hindu saint named Tulsi Saheb. When Tulsi Saheb learnt thatpilgrims of Haj were resting outside the ashram, he could not resist fromcomposing the following couplet in urdu language to remind them that they werewasting their time and energy

Dil ka hujra saf kar, jana ke ane ke liye,
Dhyan gairo ka utha uske bithane ke liye.

Cleansethe chamber of your heart, so that the Beloved may enter,
Removeall the foreign impressions, so that He can take His seat there.

Chashme dil se dekh yaha jo jo tamashe ho rahe,
Dilsita kya kya hai tere dil satane ke liye.

Seewith the heart's eye the astonishing spectacle of this world,
Whatheart ravishing scenes appear there to entice you.

Ek dil lakho tamnna us pai aur zyada havis,
Phir thikana hai kaha uske tikane ke liye?

Oneheart, with many desires, and always the lust for more,
Whereis there any place for the Lord to come and reside?

Nakali mandir masjido me jae sade aphosa hai,
Kudarati masjid ka sakin dukh uthone ke liye.

Itis a great pity that, going in the false [imitation] temples and mosques,
Theindweller of the true mosque [the human body] is made to suffer.

Kudarati kabe ki tu maharab me sun gaur se,
A rahi dhur se sada tere bulane ke liye.

Weshould listen with attention in the prayer niche of the true Kaaba,
Thesound is coming from the Court of the Lord and is calling you.

Kyo bhatkata phir raha tu e talashe yar me,
Rasta shah rag me hai dilvar pai jane ke liye.

Whyare you wandering around lost in search of the Beloved?
Theway to reach the charming one lies through the shah rag.


Murshade kamil se mil sidak aur saburi se taki.
Jo tujhe dega faham shah rag ke pane ke liye.

Odevotee, meet the Perfect Master with sincerity and patience.
Hewill give you the secret to find the shah rag.

Goshe batin ho kushada jo kare kuch din amal.
La ilaha allahu akbar pai jane ke liye.

Ifyou do the practice for a few days, the inner way will open before you.
Itis the path to reach Allah, the One God, the Most High.

Yah sada Tulsi ki hai amil amal kar dhyan de.
Kun kuran me hai likha allahu akbar ke liye.

Thisis the call of Tulsi: O practitioner, do the practice with concentration.
Thekun [Shabd] described in the Koran, will take you to Allah, the Most High.