## Friday, August 19, 2011

### Trying to explain Shutter Speed!

Now that we’ve understood aperture and what it controls, its time to understand the second aspect of the photographic triangle. Its known as “Shutter Speed”. Its defined as the duration for which the camera’s shutter stays open.

Along with the aperture, the shutter speed determines how much light reaches the image sensor. The longer the shutter stays open, the more light can get inside the camera to make the exposure.

Shutter speed being a measure of time, its values are expressed in seconds…or, most cases in microseconds. For example, values like  1/1000, 1/500, 1/250, 1/125, 1/60, 1/30, 1/15 and such. These values shows the fraction of a second that the shutter stays open. The bigger the denominator the faster is the shutter speed. And, if you notice, with every change of the shutter speed, the light entering the camera is either doubled or halved

(It’s the same in case of the aperture too! That with every stop down of the aperture, the area of the hole that opens, halves.  Its just not as obvious as the shutter speed and beyond the scope of this blog to explain the math behind that!)

Since, the amount of light that one would need to make a perfect exposure is fixed, it means…any changes in aperture will have to be compensated with a corresponding change to the shutter speed (considering we are not changing the ISO value!) , for the same exposure.

Say, you are able to get a perfect exposure at

aperture = f/5.6

shutter speed = 1/125

ISO = 400

Now lets decrease the depth of field in the picture, say, we want to drop down the f-number..to, f/2.8.

That would mean, moving the f-number by 4 stops…

f/5.6, f/4.8, f/4, f/3.3, f/2.8

To not change the exposure, we would have to make a corresponding change to the shutter speed by raising the shutter speed by 4 stops.  That would be

1/125, 1/250, 1/500, 1/1000, 1/2000

So, to get the same exposure with a shallow depth of field, The values will now have to be

aperture = f/2.8

shutter speed = 1/2000

ISO = 400

Keeping this in mind, you wonder, if the exposure needs to be the same…why would one want to change shutter speed?! Lots of reasons..

You can use low shutter speed to show the effect of moving objects in your pictures..  You can use high shutter speed to freeze an action. For example..in the picture below..when P was jumping on her trampoline..a shutter speed of 1/500 sufficed at f/2.8, ISO 200 to catch her in action.

You would slow down the shutter speed if you want to show some motion blur in your picture.   Blur is not always bad… Sometimes, it can be used creatively, to show motion in your picture.  Almost like a still video, as paradoxical as that sounds..For example…in the picture below, you can see that Hubby dear was trying to throw the rope up somewhere!!  You can almost see the rope flying up. Isn’t it?

Or in here, that K was trying to lift a box of cheerios! The exposure values for this was  f/2.8, shutter speed of 1/6 sec and ISO of 200.

When a slower shutter speed is selected, a longer time passes from the moment the shutter opens till the moment it closes. More time is available for movement in the subject to be recorded by the camera.

Now that we know, slow shutter speeds cause blurs, what is the minimum shutter speed that one could use to have a picture taken so, there’s no blur?

If you are hand holding your camera, ( and considering you have a static subject! ) most photographic pros consider having a minimum of 1/60  shutter speed.   (That should roughly be about the focal length of a 50mm lens, for a full frame sensor.)

Some cameras give you the ability for very slow shutter speeds also. For example, 1”, 10”, 30”…measured in seconds. Why would you needs such shutter speeds? Suppose you want to take a shot of a night scenario. This calls for very long shutter speeds, measured in seconds..For eg.

This image was exposed , for 30 seconds at f/16 and ISO of 200.  (You can see..there’s still,  a slight blur in this image..caused by the action of clicking the pic itself…To get tack sharp images..as the pros call them..they suggest using remote release cables or wireless shutter release or just plain self timer to release the shutter ).

To click such images,  you would first fix your camera, to a TRIPOD, then,  set your shutter speed to a value that gives you the best shot and click, considering that you have moved your mode dial on the camera to Shutter prority mode, or, the “S” mode!

You can use low shutter speeds to picture night skies, where you want to show how the stars move over a period of time. You can use it to show light painting, by making patterns with sparklers as you hold them. You can use it to picture streets at nights.

The picture below shows a light trail of a vehicle that was passing by my tent at a camp ground. You could use such shots to creatively picture city streets..at night. The light trails left by passing vehicles leave beautiful patterns.

There is another use of slow shutter speeds. Do you remember seeing posters of water falls were the water fall looks so silky smooth. This is achieved by using low shutter speeds too. One would need to use special filters to achieve these effects like neutral density filters. They cut the amount of light reaching the camera..allowing the photographer to use a very low shutter speed even during the day!…Here’s my experiment, I did at my kitchen sink!!! Which obviously shows..that I wasn’t thinking much in terms of being creative !

See, how the flow of water is softer in the second pic. Its because I had used a neutral density filter (0.6) on the lens..which required a longer exposure compared to the exposure of the first pic, thereby making the flow of water look softer.

Now that you know some things you could do by controlling shutter speed. Don’t forget to turn the mode dial on your camera to “S” and try out some shots that you had just been wondering how to!

You know, after writing all this…I come across this clip from Calvin and Hobbes and I thought it was worth mentioning for all that effort

Calvin: As far as I'm concerned, if something is so complicated that you can't explain it in 10 seconds, then it's probably not worth knowing anyway.

## Sunday, August 7, 2011

### The ABC’s of Photography!

Introduction or whatever!!

Recently, back in India, as I clicked the pictures of my family, I spoke to them of the camera settings and other fundas while clicking…My brother had remarked

“Why don’t you write a blog that explains the basic concepts in photography that one would need to know to click a decent pic…..in layman terms?!”

That had gotten me thinking of what one would need to know. What was the information I would have wished I had known when I first got a hand on a camera.

It had gotten me thinking of how cameras had become cheaper and owing a DSLR is no more a dream for a non professional. In spite of owning one,  how I had found most people, using them as point and shoots (Me included, for so many years!!!).

Surely, we’ve come a long way from the “film roll” times where, every click took away the option of another click. Every click meant more money, even to view it (Thank you LCD!!!!)

(Recently, the kids and me were going through the index prints of  numerous rolls that I had clicked of their infanthood and before that…of Hubby’s and Mine, of Hobbes.  Some roles had good pictures while most of them were either blurry, overexposed, or just wasted clicks that today, I wouldn’t have bothered to get them in print. But, how do you know until you see the picture!!!)

And every click meant that there was no room for experimentation, the shot had to be good, creative, and there was no scope for mistakes.   Photography was a field that was left only for the fiercely passionate kind of people with an extra buck to spare.

Today, not only can one own a decently priced DSLR, one can shoot a couple of hundred times in a span of a few minutes, just to get that good shot to share with friends or (annoy them!!!)…, or, display them on your digital frames, leaving more room on your table for other stuff , like  “Ganesha” art ..

So, I thought I would share, in these series of blogs, the basics that I have learnt.  I myself am no far from a beginner, when it comes to understanding my camera, and its myriad options.

I wish I had known some of these facts, I now know,  years ago when I had wasted so many rolls and used my D40 as a point and shoot and wondered why the bokeh’s I sometimes see were not consistent.  I had wondered if I could even control that!

Even today, when I pick up my camera, I’m learning something new and I feel that I haven’t progressed at all!  And the worst is when you actually know what to do..but, don’t remember to do so, and find your pictures not coming the way you’d think they should, only to realize later…your ISO setting or the white balance settings had not been reset from the last time you changed them.

As the word photography, Photo+Graphy means…writing with light without which there wouldn’t be any thing to write. Right?!  As basic as this sounds…it does get intimidating and challenging to get this light in the right amount.

How can one get a perfect exposure? How we can get the correct amount of light to light up the sensor,  to create this wonderful picture you have in mind?!  (The sensor in your digital camera is the light sensitive computer chip, the equivalent of a film roll.)  It all revolves around 3 settings on your camera called…

1.  Aperture or f-stop

2. Shutter Speed

3. ISO  (remember those film roles with ISO #s of 100, 200, 400, 800..)

They are also known as the Photographic triangle that when set right, will get you the most wonderful picture with everything appearing the way it should, the way you had envisioned it in your mind.

Lets first understand what an Aperture means.

Aperture or f-stop:

This refers to how wide the hole in the lens opens, when you take a picture. This determines how much light passes on to the sensor.  It can also be expressed in terms of f-stops or f-numbers.  The lower this F number, the wider the opening is and more light that reaches the sensor.

Do you remember coming across this information on pictures… f/2, f/2.8, f/3.3, f/4, f/5.6, f/8, f/11, f/16, f/22 .  At f/2 , the lens is supposed to be wide open, which means a lot of light can enter through the lens, which means that,  its not possible for the camera to see the whole image clearly.

What?!!

Just like you remember, when the ophthalmologist had put those drops in your eyes to dilate it. Do you remember, trying to open your eyes when your eyes are fully dilated?  Its difficult to see things clearly because of that blast of light entering your eyes. It’s the same in case of the camera. The picture gets a bit blurry,  while the subject you want to focus on, stays clear!

Aperture and Bokeh:

Bokeh is a word that comes from Japanese meaning ‘Blur’. By lowering the Aperture, i.e., when the f-number is the smallest enough, one can get dreamy portraits of your subject with blurred out surroundings, with bubbles of light in the background.  It gives a lot of situations to get creative with your pictures.

For eg

As we start to raise the f-number, the lens opening gets smaller and the blurs start to disappear.  The picture starts to get clear.  At f/8 or f/11, most of the surroundings of the subject becomes clear. This is called the sweet spot for most lens.  Watch the difference in the pictures below…The only thing I varied below is the F-stop.  Can you guess which one is the picture with a lower F-stop?!

At higher f-stops, everything in the picture is crisp and clear. This way, one can use the Aperture mode to be creative, using wide open apertures for creating pictures with beautiful bokehs, to make the pictures softer, to create portraits and smaller apertures to picture landscapes.

Opening the camera wide (lowering the f-stop or f-number) in low light conditions,  is another way to use ambient light/surrounding light,  to lighten up your photograph.  It gives the scope for one to get creative with light, rather than make your picture feel like a snap shot.

Aperture and Depth of Field:

Changing the Aperture also gives a 3-dimensional feel to your pictures which can be expressed in terms of DoF, Depth-of-Field.  The wider the aperture, the shallow the DoF which explains the blurred surroundings even better. So you see, Aperture controls the Depth of Field.

For landscape pictures, where you want the whole composition to be clear,  raising the f-number, or Aperture value will help you achieve that.

For group photos where people are standing at various distances…f values of f/11 or higher are used.

Aperture Mode:

Now that you know the pluses of controlling the Aperture on your camera, why don’t you move that dial from “P” mode or program mode, which in other words means, automatic mode of your camera (On a Nikon) to the “A” or “Av” mode on your DSLR camera.

In this mode, while you set the Aperture value, the camera decides the Shutter speed, for you, when you click a picture.

( You must wonder that there is another mode that is called “Automatic mode” in your camera. On a Nikon, it has a flash symbol on it, or a green box. This mode forces the flash to fire if the light is not enough while the P mode lets you decide when the flash is to be fired.)

Now that you’ve moved the mode dial to the “A” or “Av” mode on your camera, you’re in Aperture mode.  Its so much easier to deal with one aspect at a time, rather than you have to deal with setting everything on the camera, like you would do in the “M” mode, or the Manual.

Why would I want to get to this mode. Exactly for the same reason that I explained earlier. If I’m taking portrait shot and I want that 3 – dimensional, softer feel to the pic, I want the subject to stand out against its surrounding, when I feel I could use the boken effects in the blur to enhance the picture, when I don’t want to emphasis the surroundings of the suject, instead use the colors in the surrounding to make the picture bright..I would use this mode. In fact, most times this is the default mode that I am in.

In my next blog…lets see how shutter speed effects a picture or, when would one find it necessary to be in “S” mode.