FILTERS: TYPES AND USES

I felt that this post should be on filters. Now that you know what shutter-speed and aperture is, you may be probably getting blown-out images sometimes while shooting in longer exposures.
    Don't know what a blown out image is? Here is one.....
                

It is what we call an over-exposed image. An image gets over exposed when too much light enters into the camera

 

The converse also happens; at faster shutter speeds in low-light conditions, the image gets fairly under-exposed.

In the middle of the day, suppose you are shooting waterfalls with the golden shutter speed of 1/3 seconds, to get that silky effect. In daylight, 1/3 seconds is a very long-exposure time. It will let too much light enter into the camera and leave hardly any identifiable parts in the image. There will be cases when you'll have to shoot with longer exposures, upto 3 minutes!! (I'll mention later how to achieve those long exposures). In normal conditions, keeping the shutter open for 3 minutes in daylight will make the image fully WHITE.
Don't get stressed, there remains a solution.
The solution is called "Filter".

So, what is a filter??
A filter is a thing which gets attached to your camera, and lets you shoot images in broad daylight with longer exposures, cut down reflections in water to make the image more vivid, etc etc.
Basically the filter used to reduce light entering into the camera so that longer exposures can be attained, are called "Neutral Density Filters", and filters that cut down reflections, make the colors more vibrant are called "Polarizing Filters".




NEUTRAL DENSITY FILTERS: A neutral density filter reduces the amount of light entering the camera. For long exposures during daylight, a neutral density filter is the accessory you need. There are types of ND filters, differing basically in the amount of light they let in. In other words, there are ND filters of different strengths. Their strength is measured in stops, usually 2-stops, 4-stops, 8-stops, 10-stops etc. A 2-stop ND filter (also called ND-2) will reduce the amount of light entering into the camera by 2 times, and a 4 stop ND filter will do that by 4 times, allowing you to leave the shutter open for longer times.

A Tiffen ND filter.

POLARIZING FILTERS: A polarizing filter is used primarily for darkening skies and cutting down reflections and glares. If the sky looks pretty boring and flat, you can attach a polarizing filter to add some vibrancy to the sky. Also on a sunny day, water surfaces reflect sunlight, which, when captured on camera, looks lifeless, as the true color of the water isn't captured by the camera. There also you can attach a polarizing filter to cut those reflections. I'll write about polarizing filters vastly in my later posts. This post was primarily intended for ND filters.


How to achieve long exposures of 30 secs or more..??Go to the manual mode of you DSLR, find "Bulb Mode", and switch to it. You're gonna need a remote shutter or cable release to shoot in bulb mode. The shutter opens when you press the remote button, and remains open until you press it again. It allows exposure times even up to hours. I'll write about bulb mode in a separate post later.


Check out this amazing tutorial by Scott Kelby. I was aching to post the tutorial in my blog, but couldn't do so before writing about shutter-speed, aperture, tripod and filters. This amazing tutorial will give you a fair idea about long-exposures (the bulb mode), aperture, ND filters and usage of tripods.

https://www.youtube.com/watch?v=3_dKH2mLt0c

APERTURE: PORTRAIT AND LANDSCPAE PHOTOGRAPHY

Now that you've got a basic idea what aperture is, I'll move on to photography specializations. In this post, I'll discuss about two specializations, namely Landscape Photography and Portrait Photography. Because the two types depend largely on aperture, I'll include them in this post.
So, what aperture has to do with these two?

In landscapes, how'll a photo look if some parts of the photo are in focus, and some are out of focus? Yeah, you are right, TERRIBLE!
And in portraits, how will the photo look if along with the subject, all the other parts of the photo are largely in focus? Yeah, the face will not earn any extra attention. Suppose you are a very cute girl, or a very handsome guy; and you want to show that off in photos. Will you not be vexed if your face gets blended in the photo, along with the background?

So, try to recall from my previous posts, with what this whole "In focus out of focus" thing is related?? Hats off if you remember, its Depth of field. And Depth of Field redirects back to aperture.

So, you want every inch of a landscape shot to be in focus, so you have to choose a lower aperture, i.e. higher f-number. Recall that line.
And for a portrait, you will want only the face to be in focus, and the rest of the shot out of focus (so that attention remains primarily on the face). For that you'll need a larger aperture i.e. lower f-number.


LANDSCAPES: Use a tripod. You want the photo to be tack-sharp, and even a small out-of-focus part will ruin the photo. So, a tripod is must. Next, consider the scene you want to capture. Does the foreground have some noticeable elements or not. If the foreground has noticeable parts, and you want to include those in your photo tack-sharp, choose no less than f/22. You might wonder, why limit yourself to f/22, when some lenses allow up to f/40!! Well, at those lower apertures, a thing comes into play...that's called Diffraction. Small holes diffract light rays, so will your aperture do, which will make the photo soft. Even at f/22, photo will be soft, but anything lower than that, your photo will be ruined.
If your foreground doesn't hold a great importance, choose f/16 or f/11. Remember, the golden f-number for landscapes is f/11. In point-and-shoots who don't allow up to f/11, choose the lowest possible. Most likely, it'll be f/8. At f/8 also, you'll get good landscape shots.
Take a look at my landscapes:

Periyar Tiger Reserve, Kumily, Kerala, India. Shot at f/11.

Kovalam Beach, Kerala. Shot at f/11.

Hajaratbal, Srinagar, Kahsmir, India. Shot at f/8.

Confluence of Indus and Zanskar Rivers, Leh, India. Shot at f/11

 

Chang-la, (la means mountain pass), Changthang, Ladkah, India. Shot at f/8.

  

PORTRAITS: Use a tripod. Get married to it. For portraits, you want the face to be in focus, and the background out of focus, so choose a higher aperture i.e lower f-number. The golden f-number is f/2.8. If you want the eyes to be tack-sharp, you have to use specialized lenses (which will cost heavy in your pocket), which allow f/1.8. F/2.8 will give you good portraits.

 I don't have portrait photos of anybody, except mine. No one clicked it for me, those were self-portraiture.

At pangong Lake, Ladakh, India. Shot at f/4.5

At Gulmarg, India. Shot at f/4.5. See, how the background is out of focus.

I forgot I had this one...

It also shows the use of the rule of thirds. Clicked in Nainital, India.

GETTING OFF AUTO: THE MANUAL MODE

Now, it's time to get off auto, and start shooting in manual.
                                                             

Shooting in manual might be a bit challenging at first, because you have to set shutter-speed, aperture and ISO at the same time. While shooting in daylight, keep the ISO at the lowest. And as you advance gradually, and master more techniques, your tripod will be your wife during shooting. Like Scott Kelby said, shoot every photo using a tripod; you'll get hang of this fact as you master more skills and techniques. In the broad daylight, photos shot without a tripod may look error-less on the camera's LCD, but when you come home and view those images on your computer screen, you'll notice the image has a noticeable blur. I'm not saying that every image shot without a tripod will have this blur; images shot with very fast shutter-speeds will not show any blur in them. But even in daylight, in normal cases, the exposure time don't go lower than 1/600 secs, which is enough to induce blur in the image due to shaking. So, if you want your photos tack-sharp, always use a tripod.

Now, while setting aperture and shutter-speed, keep one thing in mind:
While setting aperture, moving from one f-stop to the next doubles or halves the amount of light coming into the sensor; and a change in shutter-speed from one stop to the next also doubles or halves the amount of light coming into the sensor. So, if you increase one and decrease another by the same stop, you are letting the same amount of light into your camera as previous.

Now, go out and start shooting. It's very important to understand the inter-dependance of shutter-speed and aperture; and practice is needed before you are finally able to strike the balance between the two. At first, due to improper choice of shutter-speed and aperture, some images will be blown out; some will be silhouetted and some will be blurred. You are to find the perfect balance yourself by shooting more and more images. For knowing aperture, go to aperture priority mode, choose a subject with a prominent background; focus primarily on the subject and shoot images with different apertures; preferably from lowest available to highest available. You will be able to understand the dependance of depth-of-field on aperture yourself. Do the same with shutter-speed: switch to shutter-speed priority mode, and shoot in different shutter speeds (N.B: Use a tripod), until you are finally able to appreciate the dependance of images on different shutter speeds.
Remember, both modes are semi-automatic (also semi-manual) modes; you'll set the aperture yourself, and the camera will choose the shutter-speed itself, and vice-versa. So, there'll be cases where the image will blow-out, be silhouetted etc etc. It's because the camera's processor isn't smart as a human brain; it's unable to appreciate the differences in conditions that the human eye-brain system can.
So, it's your duty to make the camera do what you want it to do. Letting the camera make it's own decisions (the auto mode), and letting it give half of the decision, while you choose the other half (the shutter-speed priority and aperture priority modes), will not give you images as you want them to be. So, if you want your images to be the way you want them to be, switch to manual mode, and start shooting. It lets you into your camera, and explore every corner of the camera world. Mistakes are likely to happen, until you become fully capable to strike the balance between the elements of the 'EXPOSURE TRIANGLE'. But don't let mistakes slow you down. Scrutinize your previous mistakes (recall, I told you to keep previous images in your hard-drive), and correct them as you move on.

ISO: THE BASICS

Have you ever taken a shot, and noticed some 'noise' or 'grain' in the photo? Perhaps, you have. Nope, it has nothing to do with the camera, the player behind it is the camera's ISO setting.
So, what is ISO?

In film photography, ISO (also called ASA) was the measurement of the film's sensitivity to light. The lower the number, the lesser is the film's sensitivity to light. And the amount of grain in the photo, what we also call noise; increases with the increase in ISO number, and decreases with the decrease in ISO.
In digital photography, the ISO is the measure of the light-sensitivity of the image sensor.

Take a look at the two images of the same subject shot with different ISO.

100 ISO                                                                                                           3200 ISO

Notice how the amount of grain increased in the 3200 ISO image.

Higher ISOs are generally chosen in low-light conditions for faster shutter-speeds. In slower shutter-speeds, there remains an increased chance of camera shake, and to eradicate that, you'll need a tripod. So, if you have a tripod, there's no need to shoot in higher ISO, and make the image noticeably noisy.
But, there are cases where tripod might come to no use. In indoor sports events; for sports events at night, there's no point of choosing slower shutter-speeds. In sports photography, the players' actions are frozen in shots, so slower-shutter speeds will do nothing but screw up the image. Those cases require higher ISOs. Also there are ways to overcome those, I'll discuss about it as I advance into later topics. Generally, it's best to shoot in the lowest ISO your camera offers, for Canon DSLRs it'll be 100 ISO, and for Nikon DSLRs it'll be 200 ISO. Maybe some point-and-shoots offer even lower ISOs. I had a Canon SX30IS; the lowest ISO possible in it was 80. Many Canon DSLRs have an ISO up to 25600, which is further extendable to 102400 ISO. There's nothing to get mesmerized about it, they will screw the image up pretty bad.

From a tutorial of a renowned photographer, I learned that four things should be asked to one's self while choosing the ISO.

1. Light: Is the subject well lit?
2. Grain: How much grain do I want in my photo? Will it be grainy or a no-grain image?
3. Tripod: Am I using a tripod?
4. Moving subject: Is the subject stationery or moving?

If the subject is well-lit, if you want little to no grain, if you are using a tripod, and if the subject is stationery; you might want to choose a low ISO, like 100.

If the subject is in dark conditions, you want grain purposely (which most people don't want normally), you don't have a tripod and your subject is moving; then you might have to go for higher ISOs.

But, if possible keep your ISO within 1000. I have taken images at night with 800 ISO, and even though I got the image with much greater light, it had so much noise that I had to discard it. Remember, while shooting well-lit or even medium lit subjects, always go for lower ISOs.
There was a time when I didn't have a tripod; but I used supports to keep the camera on it; and shoot. Of course for exposures greater than 2 seconds, you'll need something to keep the camera on.

There are cases where you have to pump your ISO higher. I had already mentioned two: Indoor sports events and night sports events.
Also in indoor parties, concerts, places where flash is not allowed, you need to push you ISO high. There will be grain in the image, but a grainy shot instead of no shot at all is better, isn't it?



Shutter-speed, Aperture and ISO; together form "THE EXPOSURE TRIANGLE". These three are the basics of a camera, mastering these will help a lot. After you have mastered these, you can move on to specializations of photography. Every specialization involves these three only.

APERTURE: THE BASICS

Mastering aperture puts you into a lot better position in the field of photography. The magic of photography lies behind aperture, and if you master aperture after mastering shutter-speed, you are one step closer of becoming a good photographer.
So, what is aperture?
Speaking most simply, "Aperture is the opening in the lens of the camera". When the shutter is pressed, a hole opens up, which lets the light to come into the sensor, and the image is captured. You can control the size of the hole by setting the aperture.
We usually measure aperture by "F-stops". They are written as f/number. Like f/2.2, f/2.8, f/4, f/4.5, f/6, f/8, f/11, f/22 etc.
The thing that creates confusion is that large apertures (letting a lot of light into camera) are assigned lower f-numbers, like f/4; and smaller apertures are assigned higher f-numbers, like f/22. Which forces, that f/22 is a much smaller aperture than f/4.

Depth of field: DOF implies how much of your shot will be in focus, and how much will be out of focus.

f/4.5

f/22    (Flickr)

The image on the left has the yellow sterns in focus, and the petals are out of focus. This is what we call a shallow depth of field. The image on the right has everything in focus; it has a much higher depth of field.
 Aperture has a profound impact on DOF. Larger apertures (smaller F-numbers, remember!) will decrease DOF, and smaller apertures (higher F-numbers) will increase DOF.
Take the above two pictures for example. The left one was shot with f/4.5, which gave it a shallow DOF, and the image on the right was shot with f/22, which gave it a much larger DOF.
This whole aperture + f-number + Depth Of Field scenario creates a lot of confusion; I myself get confused sometimes. The easy way to remember the dependance of DOF upon aperture is to remember this line:
"HIGHER F-NUMBER MEANS HIGHER DEPTH-OF-FIELD, AND LOWER F-NUMBER MEANS SHALLOW DEPTH OF FIELD". Remember this line, and you're done.

My photos:

F/4.5

F/8

See how the background is out of focus in the F/4.5 shot, and is in focus in F/8 shot.

SHUTTER SPEED: THE BASICS

In my previous post, I had said about shutter-speed priority and aperture-priority modes, but it'll be completely useless unless I define what shutter-speed and aperture is.

So, what is shutter speed?

Shutter speed/ Exposure time is the time for which the camera's shutter remains open after it is pressed. Compare the camera's shutter to your eye.
Close your eyes; after that open it fully for the shortest amount of time you can, and close it again. You'll have a glance of the sight recorded temporarily in your memory.
After that, close your eyes again, and open it and move your head from that sight to another, and close your eyes. Now, you'll have a set of images recorded in your memory, stacked very quickly upon one another, to create something what we call a clip. Now you don't have a glance of only one image, you have recorded the events from opening your eyes, to the point you closed it.
The camera's shutter is the digital counterpart of the human-eye. When it remains open for an extremely short amount of time, like 1/6000th's of a second ( it's way beyond a human eye's capability); the image captured is the one which gets recorded on the sensor for that amount of time. Obviously 1/6000th of a second is the time small enough to freeze all kinds of earthly motion.
Also if the shutter remains open for 15 seconds (its the max. a P-S will allow); the camera's shutter captures all the events that happened during those 15 seconds, and stack them to form a single image.

Here I'm going to give examples of photos captured with different shutter speeds, and you are to spot out the differences.

See how the photos of the same subject(here, a rotating fan) differ, when captured with different shutter speeds. (Google images)

Lets analyze the photos.
In the 2nd photo, the shutter remained open for 1 mS, which was enough to freeze the blades of the fan (remember, the fan is rotating, the camera captured just a glance of its rotational motion).
In the 3rd photo, with an exposure time of 0.25 second, (probably it's the time taken to blink an eye), the camera wasn't able to freeze the motion at all, and it captured what wee generally see through our eyes.
In 0.25 secs, the fan had made a number of rotations, and the camera captured all of them. So, the blades couldn't be perceived like in the 2nd photo.
 In the 1st photo, with an exposure time of 1/60 secs, the camera wasn't able to freeze the motion completely, nor it could capture what we see through our eyes. Thus the result is an intermediate, it shows the blades and we also get a perception that the blades are moving.

For waterfalls, some of you might have seen some silky smooth waterfall images. Have you ever wondered how is it possible? It's achieved with long-exposure (some love to call it slow-shutter) technique. The trick is to keep the shutter open for 1/3 or 1/2 second, and the camera will capture all the water which fell through that 1/3 second. For capturing waterfall with that silky effect, the magic number is 1/3 second. The result is a silky smooth effect. Or, if you want to freeze the waterfall, to show the tiny droplets of water falling, you have to choose a higher shutter speed, to freeze the waterfall's motion.
Take a look at the two photos:

Take a look, hope you are able to differentiate the two

The 1st one was shot with 1/160 sec exposure time, and the second with 1/3 sec exposure time. In the 1st one, the camera was able to freeze the motion, hence showing all those tiny droplets of water falling. In the second, with an exposure time of 1/3 second, the image got the so called "Silky effect".
                                           

Compare the two

 The long-exposure technique is used to create masterpieces, and it opens up many specializations of photography. I'll write separately about long-exposure later.

Take a look at my photos captured with long-exposure:

The sea at night. On the banks of Kanyakumari, India.

Dal lake: Kashmir, in evening

Dal lake: Kashmir, at night.

.

 All these were shot with more than 5 secs exposure time, and I ended up with these photos.

GETTING OFF AUTO: THE SEMI-AUTOMATIC AND MANUAL MODES

After you develop a sense of basic photography, it's time to get off Auto and start shooting with your own settings. Full Manual mode can be challenging at first, so its better to start in "Aperture-Priority" and "Shutter-Speed Priority" Modes, which almost every camera offers. In Canon P-Ss and DSLRs, the two will be marked as "Av" and "Tv" respectively, and in Nikon cameras, the two will be marked as "A", "S" respectively.

Av and Tv in Canon Cameras

A and S in Nikon Cameras

I'll have to define shutter speed and aperture before getting deeper into this topic, so it's better to define those in a separate post, and you'll get the idea of this from there only. Here I'm going to give a brief description.

Shutter-speed Priority Mode: In this mode, you'll have to set the shutter speed of the camera yourself, and the rest will be chosen by camera, the main one being the aperture.









Aperture-Priority Mode:  In this mode, you'll have to set the aperture yourself, and the camera will chose the shutter-speed. 
 Check out my next two posts for shutter-speed and aperture. Remember, the quality of a photo depends on just these two; once you have mastered these, the rest shall fall into place.