The Basics of Digital Photography - II (How are pictures formed, and what is an SLR camera)

Ok so we’re itching to get our hands dirty with the real thing. So let’s rush thru this techie part that I promised.

How are digital photographs ‘formed’?

The camera housing (a fancy name for the body of the cam) consists of a series of lenses among other things. They are in those spout-like things that peep out of the cam the moment you switch it on. As you must have guessed, light enters the camera system through these lenses.

Now, when I say ‘light’, don’t imagine a ray of luminance. ‘Light’ refers to the image of whatever is being captured on camera.

So this light (in other words, the visual details of the image to be captured) passes through the lens arrangement, and falls on a screen of sorts. (You may equate this screen to the retina of the human eye. In fact, the entire camera can be equated to the human eye system. Think about it!)

This screen is a photo sensor – which means it can sense light (Duh!) – and has a series of dots (pixels). The sensor could be one of two types in a digital camera:

. CMOS (Complementary Metal Oxide Semiconductor)

. CCD (Charge Coupled Device)

CCD sensors offer very good image quality, but are very expensive. CMOS sensors on the other hand are not as good as CCDs with respect to image quality, but they are the reason for the fall in digicam prices over the years - they are much cheaper to manufacture!

Back to the topic. Remember the light we spoke about? As it falls on this sensor screen, the pixels get to work. Each pixel studies the bit of light that falls on it, and converts that information into electric charges. This two-dimensional array of charge-information is conveyed to the processor in the camera, which converts the information to a digital format. That is, the charge info of each pixel is converted to a corresponding series of 0’s and 1’s. And all the series of all the pixels are stored in the memory card in a file format supported by the camera (good old jpg for instance).

So that is how digital images are formed in a digital camera. May not have been much of a value add, but if you understand this, you will understand the working of ISO settings later when we get to it.

The other topic to be addressed in this edition is the reason why SLR’s are what they are – Single Lens Reflex.

Technology wise SLRs are very similar to any other camera but for one major difference.

They are honest.

Seriously.

These Point-n-Shoots and Prosumer cameras lie through their teeth.

The insider info is this: In these ‘cheating’ cameras, there are two paths for light:

. One for the light that you see on the camera’s viewfinder (LCD screen on the camera or the small electronic viewfinder where you see the image on the camera before clicking)

. Another separate path for the light that actually falls on the sensor screen!

So what this means is that WYSI-so-not-WYG! They are very similar, but they actually aren’t the same. The odds are that you may not have noticed this in regular usage of the cameras. But it’s happening alright. Every time you click a pic, those blasted PnS’s and Prosumers snigger heartily, and call you a loser. (In all probability, that’s the sound you hear when you click).

If you want to test this, keenly observe the edges of the image you see in the camera’s viewfinder. Then click the picture without shaking. Now transfer the image to a computer and observe the edges in the picture. Voila! The proof of the cheating lies in the seeing.

But good ol’ SLRs aint so!

There is only a single path of light inside an SLR camera housing. The light that comes in through this path falls on a reflex mirror that is at an angle to the path of light. Now, a part of the light is sent to the viewfinder (through a prism) for your preview, while the rest goes to the sensor. So WYSI-really-WIG!

An artist’s (my) rendition of the above scene would look like this:

In principle this is the only difference between SLR cameras and other lesser mortals. But it so happens that camera makers put in a lot of other great things in an SLR. Like very powerful processors and the works. (Their logic is right. Only someone who hates even the minor cheating done by the other cameras would go for an SLR. And since he is such a picky person, one might as well load the cam with a lot of goodies and milk every penny out of him; he won’t mind. In fact, he will gloat about it to his friends).

Practically, some differences one would find between SLRs and other cameras are:

SLRs	Lesser Mortals
Extremely fast operation – click at the press of the button	Yawwwnnnn
Goes into your backpack	Goes into your back pocket
Very expensive	Priced much lower than SLRs
When you buy an SLR, you decide on which cam to buy, which lenses to buy, which filters to buy and so on (though standard packages are also available at shops).	You just decide which cam to buy and get the box from the shop.
Above all: Awesssssssome picture quality	Pic quality depends a lot on ur luck and astrology predictions for the day

This is not an exhaustive list; just hints at the major differences.
So that’s some gyan to chew until my next, which will introduce you to the world of photography jargon.

Keep clicking..

The Basics of Digital Photography - I (Types of Cameras)

I have been wanting to write on this topic for a long long time now. Simply cos' this is something I have been picking up from numerous sources. Wanted to put all of this in one place, so that any amateur who wants to get deeper into photography can do so without feeling insecure about his/her ignorance of the subject :) We'll take it slowly step-by-step.

Disclaimer: I am no pro-photographer. I have just been learning online and on the field in the past year and a half. This series is a result of that. If at any place, you feel I'm wrong, or if you can add greater value, do comment away to glory. Let's learn together!

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All self-respecting photography primers begin with a note on the various types of cameras available in the market. So let me follow suit, though I don't know how much of a value add this is.

Typically cameras can be categorized as:
1. Point-n-Shoot
2. Prosumer
3. Professional
For you marketing guys out there, these could be the three 'P's of photography :P
And one P of a smiley.
(Sorry! :))


Point-n-Shoot:
These are basically the kiddos - small and cute.
Typically lower resolution (around 6-8 Megapixels) and lower zoom range (3x-6x). (W'll define these terms specifically later; for now, just understand that these are the most important specifications of any camera, for an amateur).
Most inexpensive of the lot (Priced less than Rs 10,000 to 12,000)
Easiest to handle, both because of the compactness, as well as the simplicity of features and controls. Every control has an auto mode. But the latter is its failing. It's nice to have such alarming simplicity when you start. But slowly as you discover the world of photography, you would start *HATING* Point-n-Shoots for their over-simplification and approximation of a lot of stuff.
Typically Point-n-Shoots look like biscuits :)

A point-n-shoot from the GE stable. Small in size, 4x zoom, but awesome resolution (12.1 Megapixels)

Prosumer
These are the mid-level cameras and are also called 'advanced point-n-shoot'.
All controls have auto settings, but also manual overrides for most of them.
Typically higher resolution (8 - 12 MP) and zoom (10x - 18x) than point-n-shoots.
Priced between Rs 12,000 and Rs 25,000 usually.
The cam that I have - a Sony DSC H3 - is a prosumer cam.

A Sony DSC H3

SLR
Single Lens Reflex cameras are the mean machines - the ones that serious photographers use.
Extremely high flexibility --> manual controls for EVERYTHING you can imagine. (They do possess auto modes too, but who would want to use them!)
Very high speed operation. This means that when you click, the response of the camera in shooting the image would be faster than in PnS or Prosumer type cams. Also, the camera gets ready to click the next pic very fast.
Have larger sensors --> in English, this means a better quality of pictures.
Very high resolutions (12.1 MP - 25.5 MP!)
One major difference in purchasing SLRs is that one would have to purchase an entire kit, as against walking out of the shop with a single piece of equipment. Typically, the SLR kit would include the body of the camera and lenses at the bare minimum level. The body is the square part of the camera that one would hold, and the lens is the barrel that extends at front. These have to be bought separately. There are different types of lenses for different usages. More on them later. Additionally, there are many more components a pro would have in his SLR kit, lets not bother ourselves with all that for now.
So basically the zoom range of the camera depends on the lenses one buys along with the body.
And the defining characteristic of SLRs is that they are extremely expensive!! Actual prices depend on the kit one buys, but they could range from Rs 30,000 to lakhs!

An Olympus SLR

Left: Body with lens attached
Right: Separate lens, detached

Well, then. Those were the basics about the different types of cameras one could buy.
The next post would be a bit technical, with details on how photos are 'formed' in a digital camera. We would also see how an SLR cam differs from an ordinary one. One need not know all this to click good pictures, but I believe knowing this gives one greater confidence. And extra knowledge doesn't pain, does it?

Keep clicking...

Why do my eyes look eerily red in some photos?

Am sure this has happened to all of us: When posing for a photo, we smile heartily. That is, initially. But the photographer does not click. He keeps twiddling with the controls, awaiting the right moment, which would ALWAYS arrive just after we stop smiling and literally start saying cheese, in a meek attempt to sham a smile.

After all this rigmarole, we rush over to the photographer to look at the picture. And our eyes look as red as #FF0000.

This phenomenon is called "red-eye" (now, you didn't guess that, did you?).

Why does it happen?

Visualize a room having a window with curtains. The wall opposite to the window, is red in colour. The curtain can be opened or closed to control the amount of light passing through the window.

The human eye has a very similar structure. The wall is the retina, which is red because it is rich in blood cells. (For the girls, the shade of the colour is what you would call "blood red")

In front of Retina the Wall (akin to Rahul the Wall) is the window with the curtain - the iris. It is designed to let in an optimum amount of light. So in very bright conditions, the iris will close as much as possible, allowing little light to enter the eye. In dark conditions, the iris will open as wide as possible to gather all the light it can grab. (So the iris is similar to us in being discontent with what it gets by default)

When we take photos in low-light conditions, the iris of our eyes would naturally be wide open. When the photographer clicks, a blinding flash appears..

And everyone dies..

No, I mean, the flash is fired from the camera. The white light from the flash falls on the eyes of the people posing for the photograph. (On other parts of the anatomy as well. But we are interested in the eyes only. For now). This light is of very high intensity and is fired at very short notice. This short duration is not sufficient for the iris to close completely. So by the time the camera stores the photo, the iris is still wider open than it should be, meaning the retinal wall is still largely visible. And remember, it is red in colour. This is what is reflected as red-eye in photographs.

How do we avoid red-eye effect then?
After a picture is taken, one can remove red-eye by software means. There are so many tools that do this.
But a way of eliminating red-eye from occurrence itself is called "advanced strobing". Most new digicams have this feature. If you set "Red-eye reduction" to "on" and try taking a picture in low-light conditions with flash, the flash would be fired twice. The first time is just to trigger the iris into closing, and the second time is to take the actual picture. So by the time the picture is taken, the iris would have closed and blocked the (literally) bloody retinal wall.

So the next time someone wonders why red-eye occurs in photos, you would be able to tell them....
.... where to look for info right? (He he.. My Google analytics reports can do with more numbers)