As I mentioned earlier, that ISO is one of the most tricky aspects in digital photography and it is analogous to the film speed in the old school cameras. But that definition doesn't help us much. Recently I was able to get my hands on a really good book called Understanding Exposure by Bryan Peterson. Its really good and highly recommended if you wish to gain insights in your equipment's operation. As Bryan mentions, we should consider the ISO number as the number of worker bees in the camera.. What worker bees? But trust me stay with me on this discussion it will make sense. We all know that if we have to shoot in low light situation, we crank up our ISO to 400 or 800 to have a correct exposure and in bright sunshine we can get the gig done with a much lower value of ISO...
Analogy: Lets consider the camera's aperture as a water tap from which water is flowing continuously and there are bees working on your camera sensor who are ready with their buckets to collect the light (water) and each bee has bucket with same capacity as any other bee. Now, no matter where or when you shoot, you need to have a correct exposure for shooting tach sharp images. So the total amount of light required for making a good image is constant. When you have more light (bright sunshine), you employ lower number of bees to fetch the light to your sensor thus a lower ISO, but in lower light situations if your shutter speed is high, for carrying the same amount of light you need more worker bees so a higher ISO number. So we crank up the ISO. Its all about getting the correct exposure.
Thus, in a low light situation if you are taking pictures using a longer exposure, the number of worker bees required is less, because they spend enough time on the sensor to obtain the required amont of light, where as in bright light their photo-buckets gets filled in a relatively less time, thus enabling higher shutter speed.
Now, a little experiment as suggested by Bryan. If you point your camera to a subject read the exposure on the camera metering. Say you read an ISO of 100 at an aperture of f/11. Crank up the ISO to 200, you will find that the aperture size required for making the correct exposure is f/22. Similar, trials can be conducted by setting the camera on shutter priority. If a shutter speed of 1/250 at ISO 100 gives you the correct exposure, a shutter speed of 1/500 with an ISO of 200 will give you the correct exposure..
Over exposed photos are examples of photos where the buckets of your worker bees are overfilled and they spilled the water (light) from their buckets. Similarly, under exposure refers when their buckets are not completely filled with light. Thus making the photo underexposed or darker because there was not enough light..
Things to remember:
1. Its all about getting a correct exposure.
2. Remember this formula for the photographic triangle
ISO X Aperture X Shutter Speed = Constant. (Rules of inverse proportion)
For a given ISO, you will have at-least 5 to 6 camera settings for the correct exposure. It depends what you want to do with your shot. Control your depth of field or freeze the motion or get some creative blur. They determine your shutter speed and accordingly aperture size is determined by the camera and vice versa depending whether your camera is on Shutter priority or Aperture priority.
I learned all these from The above mentioned book. Its really good and really cheap. worth a purchase. I hope I was able to make ISO clear to some extent. Any further questions let me know. Keep Clicking... :)
Saturday, January 2, 2010
Saturday, December 26, 2009
Photography: Things one should know
Hey folks, I was not sure about the title of this blog. But, recently I have been reading a lot and so I thought may be its a good time to share few things I know, which helped me taking good shots.
The balance of 3: Shutter Speed, Aperture and ISO
Any good photograph is a balance of the above three things, so lets look at them one by one:
Shutter Speed: Have you ever clicked a picture at night with a point and shoot camera, tried to capture the sky-line and found that you have just one dark picture, in which nothing is visible. I had that problem a lot of times. When you click the picture the curtains behind the image sensor opens and lets the light impact the image sensor (film in old school) cameras. Now, without light, you cannot generate an image, we know that. So, if the shutter is open just for a fraction of second (ideally 1/250 or 1/500) in Auto mode, not enough light impacts the sensor and we fail to create an image. So, ideally the shutter speed should be slow, say 1 sec or more when you take pictures at night. I will go in detail later on.
Aperture: Aperture is another key factor in taking good photographs. We can think of the camera aperture as something similar to our IRIS. If you are in a dark room, our iris expands and lets more light in and so we can see the things in dark. On the other hand, if we go out in the bright sunshine. the IRIS contracts, and let less light inside our eyes, thus compensating the bright light. This happens involuntarily and so we don't notice it. Similarly, in a digital camera the aperture size dictates whether you are letting less or more light inside your camera, depending whether you are in bright or dark situations. The aperture size is generally stated as f/22, f/8 etc. The higher the denominator the smaller is the aperture because it is represented as a fraction of the full-aperture size.
ISO: Now, what is ISO, everyone at some point of time or the other is intrigued by this term. Well its analogous to the film speed in the film cameras. But, does that definition help us. I don't think so. Think it like this, when you are in a low light situation and you cannot have a long exposure (slow shutter speed), just crank up the ISO. But, if you have a tripod just keep it low as low as 100 or 200 (slowest your camera allows). Lower ISO makes the picture less noisy, if you crank up the ISO to 1600 or 3200, the picture becomes grainy and it won't be what we call "tach sharp". So only crank up the ISO when long exposure is not possible because of lack of tripods or any steady camera holder. I hope this minimum knowledge helps.
Combining all 3 key-elements: Ok, so now if you have a general understanding of these 3 main features, you can combine these 3 things to shoot great pictures, of-course there are more to it than just these 3 things. Normally, you can set your camera to any ISO you want to (lower or higher). So, you are left with only 2 other parameters aperture and shutter speed. Now, depending on whether you keep your camera in Aperture priority or shutter priority, if you choose one the other is automatically decided by the camera to get a correct exposure, unless you are in manual mode where you have the power to control both.
Few more terms: There are more technical jargons one should know and using that knowledge one can give a creative look to their shots. Few techniques are discussed here:
Depth of Field: What is depth of field? If you have seen those portraits where the subjects looks sharper than the background, and you always want to do that but just don't know how to do it? Here is a quick tip. First you should know, that depth of field means how much of your picture is in sharp focus. A shallow depth of field means less of the photograph is in sharp focus, whereas a massive depth of field means large portion of the snap is in focus. So how to achieve a narrow depth of field.
Set the camera to aperture priority and use the highest aperture value and shoot the portrait. The larger the f number the shallower will be the depth of field. For typical portraits you are looking at f/11.
Capturing Night Landscapes: Capturing a well-lit skyline is everyone's dream. People starting with point and shoot cameras almost find it impossible to do, at-least it was the case with me. But I am going to tell you how it can be done. So hang on. Get a tripod. Do this favor to yourself if you want to take good tach sharp images. Find a good angle and set your camera on tripod. Set the camera to manual mode. Set aperture to the maximum possible typically f/11 and the shutter speed to 1 or 2 seconds (do experiment with different shutter speed to get the desirable result). Set the camera to self-timer. This is important to eradicate any vibration due to your fingers clicking the camera. Set the ISO to lowest possible may be 100 to remove any noise. That should be it you should get a good picture of sky-line well lit up at night.
For dSLR users Set the camera to above mentioned settings. As you are setting the camera on tripod, switch off any vibration reduction mechanisms within the camera. If your camera allows use mirror locking and use cable release or self-timer mode to shoot the picture.
Capturing trail lights at night: In the night you might be interested in capturing the trail lights of fast going cars, they add a dramatic effect to the pictures. Actually you are trying to induce some blur in your picture to give that effect. So set the camera to manual mode. Use aperture f/11 and set shutter speed to 20 to 30 sec. A 30 second shutter speed works well for me, and you will have the desired trail lights in your picture.
Adding Blur to your pictures: Oh snap!! what did I just say adding blur. Well yes! adding blur can give very good effect on your pictures. Just set the camera on tripod and increase the shutter speed to 10 sec during day while shooting a waterfall or a fast moving vehicle to add some motion to your pictures. Trust me you will be astonished with the results.
Taking pictures of monuments: Well if you know what I mean, anyone going to Paris returns with an image of Eiffel Tower, everyone going to Pisa, returns with a snap of him/her trying to support the leaning tower as if it will fall..:)
So, what to do if you have to take pictures of places which are shot to death, if you know what I mean. Go to those places when the weather is bad or early morning or late late night, when they look a little different and you may end up getting a 100 dollar shot if not million....:D
Also keep experimenting with your composition and taking pictures from different angles.. open eyes look around.. everything is beautiful in its own way. All we are trying to do is to make an attempt to capture the beauty, it is long way to reach perfection..
This blog contains no new information, I just happened to read a lot presently so just felt like sharing what I learned through experimentation. Its like taking notes when I read or see some tutorial. Hope it helps anyone looking for some quick information...
More to come as I learn.....
The balance of 3: Shutter Speed, Aperture and ISO
Any good photograph is a balance of the above three things, so lets look at them one by one:
Shutter Speed: Have you ever clicked a picture at night with a point and shoot camera, tried to capture the sky-line and found that you have just one dark picture, in which nothing is visible. I had that problem a lot of times. When you click the picture the curtains behind the image sensor opens and lets the light impact the image sensor (film in old school) cameras. Now, without light, you cannot generate an image, we know that. So, if the shutter is open just for a fraction of second (ideally 1/250 or 1/500) in Auto mode, not enough light impacts the sensor and we fail to create an image. So, ideally the shutter speed should be slow, say 1 sec or more when you take pictures at night. I will go in detail later on.
Aperture: Aperture is another key factor in taking good photographs. We can think of the camera aperture as something similar to our IRIS. If you are in a dark room, our iris expands and lets more light in and so we can see the things in dark. On the other hand, if we go out in the bright sunshine. the IRIS contracts, and let less light inside our eyes, thus compensating the bright light. This happens involuntarily and so we don't notice it. Similarly, in a digital camera the aperture size dictates whether you are letting less or more light inside your camera, depending whether you are in bright or dark situations. The aperture size is generally stated as f/22, f/8 etc. The higher the denominator the smaller is the aperture because it is represented as a fraction of the full-aperture size.
ISO: Now, what is ISO, everyone at some point of time or the other is intrigued by this term. Well its analogous to the film speed in the film cameras. But, does that definition help us. I don't think so. Think it like this, when you are in a low light situation and you cannot have a long exposure (slow shutter speed), just crank up the ISO. But, if you have a tripod just keep it low as low as 100 or 200 (slowest your camera allows). Lower ISO makes the picture less noisy, if you crank up the ISO to 1600 or 3200, the picture becomes grainy and it won't be what we call "tach sharp". So only crank up the ISO when long exposure is not possible because of lack of tripods or any steady camera holder. I hope this minimum knowledge helps.
Combining all 3 key-elements: Ok, so now if you have a general understanding of these 3 main features, you can combine these 3 things to shoot great pictures, of-course there are more to it than just these 3 things. Normally, you can set your camera to any ISO you want to (lower or higher). So, you are left with only 2 other parameters aperture and shutter speed. Now, depending on whether you keep your camera in Aperture priority or shutter priority, if you choose one the other is automatically decided by the camera to get a correct exposure, unless you are in manual mode where you have the power to control both.
Few more terms: There are more technical jargons one should know and using that knowledge one can give a creative look to their shots. Few techniques are discussed here:
Depth of Field: What is depth of field? If you have seen those portraits where the subjects looks sharper than the background, and you always want to do that but just don't know how to do it? Here is a quick tip. First you should know, that depth of field means how much of your picture is in sharp focus. A shallow depth of field means less of the photograph is in sharp focus, whereas a massive depth of field means large portion of the snap is in focus. So how to achieve a narrow depth of field.
Set the camera to aperture priority and use the highest aperture value and shoot the portrait. The larger the f number the shallower will be the depth of field. For typical portraits you are looking at f/11.
Capturing Night Landscapes: Capturing a well-lit skyline is everyone's dream. People starting with point and shoot cameras almost find it impossible to do, at-least it was the case with me. But I am going to tell you how it can be done. So hang on. Get a tripod. Do this favor to yourself if you want to take good tach sharp images. Find a good angle and set your camera on tripod. Set the camera to manual mode. Set aperture to the maximum possible typically f/11 and the shutter speed to 1 or 2 seconds (do experiment with different shutter speed to get the desirable result). Set the camera to self-timer. This is important to eradicate any vibration due to your fingers clicking the camera. Set the ISO to lowest possible may be 100 to remove any noise. That should be it you should get a good picture of sky-line well lit up at night.
For dSLR users Set the camera to above mentioned settings. As you are setting the camera on tripod, switch off any vibration reduction mechanisms within the camera. If your camera allows use mirror locking and use cable release or self-timer mode to shoot the picture.
Capturing trail lights at night: In the night you might be interested in capturing the trail lights of fast going cars, they add a dramatic effect to the pictures. Actually you are trying to induce some blur in your picture to give that effect. So set the camera to manual mode. Use aperture f/11 and set shutter speed to 20 to 30 sec. A 30 second shutter speed works well for me, and you will have the desired trail lights in your picture.
Adding Blur to your pictures: Oh snap!! what did I just say adding blur. Well yes! adding blur can give very good effect on your pictures. Just set the camera on tripod and increase the shutter speed to 10 sec during day while shooting a waterfall or a fast moving vehicle to add some motion to your pictures. Trust me you will be astonished with the results.
Taking pictures of monuments: Well if you know what I mean, anyone going to Paris returns with an image of Eiffel Tower, everyone going to Pisa, returns with a snap of him/her trying to support the leaning tower as if it will fall..:)
So, what to do if you have to take pictures of places which are shot to death, if you know what I mean. Go to those places when the weather is bad or early morning or late late night, when they look a little different and you may end up getting a 100 dollar shot if not million....:D
Also keep experimenting with your composition and taking pictures from different angles.. open eyes look around.. everything is beautiful in its own way. All we are trying to do is to make an attempt to capture the beauty, it is long way to reach perfection..
This blog contains no new information, I just happened to read a lot presently so just felt like sharing what I learned through experimentation. Its like taking notes when I read or see some tutorial. Hope it helps anyone looking for some quick information...
More to come as I learn.....
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