It took some time to find this perfect color changed maple leaf. Placed it against the paved road and clicked. Nice contrast and uniformly lit sky worked for this.

Red leaf on tar

For the next one, I took the leaf and placed it against the dry leaf stems. Did some “photoshoping” to unsaturate the background. The result is this:

Red leaf on dry stems

Next one is related to the topic but not specific to the season. The water droplets fallen from the tree above our parked car had formed a beautiful pattern. Again, an overcast sky made it easier on the sensor and very less photoshoping yielded this:

Water droplets on red metal

So the first part of that is the Chaat Time. Here are the photos:

Tomato Chaat

Sev Puri

Are you hungry?

DOF: What is it?

Depth of field is the nothing but the field behind and in front of the subject that is in focus. It is controlled by the aperture of the lens (larger the apertrue, smaller the DOF). Remember: The smaller the aperture number, the larger the aperture is and hence more light falls on the film/sensor.

DOF: Explained with example

The most popular example to explain DOF is tap and paint. Consider a tap which is supplied with paint source and directly below it is a plate or paper where you want the paint to be applied. Now open the tap slowly such that only one droplet comes out of it. You will notice that the paint falls on the paper/plate and forms an even circle. Now turn the tap to pour the paint fully onto the paper. It fills up the entire plate quickly but not evenly. Now consider the same anamoly for light falling on the film/sensor through the tap called lens. The larger the opening on the lens, the more the lights get scattered and more distorsion in the image. If the aperture is small, the light falls evenly and less the distortion.

This image from Wikipedia explains DOF diagrammatically.

Focus Image

So an object which is focused by the lens, passes the light to the sensor through the aperture setting of the lens falls on the sensor it exposes the picture. But the light from the surrounding objects near the subject falls evenly if the aperture is low therby making them also appear in focus. If the aperture has been increased, it would have just focused the subject and distorted the surroundings.

DOF: Usage

DOF does not necesarily mean bad always. It is sometimes used to add more attention to the subject when focus alone cannot make the subject stand out. On the other side, if we want to keep everything in focus, we need greater DOF and hence smaller aperture. But how small is too small? That is explained in the Hyperfocal Distance section.

Below are some pictures taken at different aperture setting by me. You can see the difference in how the DOF varies by aperture.

F1.8 Aperture Setting	Taken at f1.8 – Shallow depth
F4.5 Aperture Setting	Taken at f4.5 – Shallow depth better than f1.8
F8.0 Aperture Setting	Taken at f8.0 – Medium depth
F22 Aperture Setting	Taken at f22 – Greater depth

DOF: Hyperfocal Distance

A Hyperfocal distance is the minimum distance that when focused by the lens with a particular aperture and focal length of a lens will have everything from 1/2 of the minimum distance to infinity in acceptable sharpness and yield the maximum depth of field.

There is a mathematical formula attached to this which is

Hyperfocal distance in millimeter = (focal length in mm) ^2/(Aperture number * 0.03mm) + focal length

But calculating this while in the field is not only tedious but you would miss the photo opportunity. So there is a cool tool available called DOF Master which you can download and get print out of charts. The chart gives you the distance where you need to set your lens to focus at a given aperture and focal length to achieve the hyper focal setting. Click here to download the chart.

Here is a photo graph taken with Hyperfocal setting.

Yellow Stone

What is Exposure? Simply said, it is the amount of light that it takes to create a photograph or that is allowed to create a photograph. As per the user edited site Wikipedia, http://en.wikipedia.org/wiki/Exposure_(photography), there is no such term as correct exposure. But I would like to add that the exposure that it takes to make the picture appealing is the correct exposure. Example consider the three photos below and tell me if I am correct or not. The first in the left is over exposed, the next is under-exposed and last one is correctly exposed.

Over Exposure

Under Exposure

Correct Exposure

So by Correct Exposure, the amount of light it takes to create a ‘good’ photograph. So ‘correct’ is related to what ‘good’ is defined as. There are 7 f-stops by which you can get a correctly exposed picture. That reminds me that before we define exposures, we must define ‘f-stops’ and before that Shutter speed, Aperture and Film Speed because all these determine the f-stop.

1. Aperture: It determines the amount of light allowed to light to fall on the film or sensor by the shutter. Shutters are of two types :
   

   a.) Leaf shutter: Leaf shutter is like a diaphragm where 3 or more elements operate in a way to allow light to pass through a hole formed in the center. The leaves expand or contract depending on the aperture setting to allow light.

   

   Leaf Shutter

   b.) Focal Plane shutter: Here there are two plane sheets of curtains that moves in a definite interval to form a slit between them. The light is allowed to pass through the slit and fall on the film or sensor. The distance between the curtains is controlled by the aperture setting.The Focal plane shutter is widely used because of its capability to provide high shutter speed.

   

   Focal Shutter

2. Shutter speed: It is the time interval for which the light is allowed to fall on film or sensor. In the commonly used Focal plane shutters, the time is set by the duration after which the second curtain follows and closes the slit. Today the typical speeds achieved in SLR cameras are 1/2000 and 1/4000 secs.
3. Film Speed or ISO: We all know that film records the image. But how fast does it record that image or what is its sensitivity to light? That is determined by the film ISO (or ASA) speed. This ISO number says how much of light in how much time takes the film to be exposed. The rough estimate of film speed can be measured by using Sunny 16 (The rule is quite easy to remember – if you’re taking a photo in bright daylight set the aperture to f/16 and set the shutter speed to be as near as possible to the same number as the film speed.) ISO numbers range from 25 – 6400 where 25 is the least sensitive and 6400 is the most in the range. There might more sensitive than this too . Each higher number is twice as much as that of the previous number meaning that they are twice as sensitive as the previous ISO. So ISO 50 might take just 1 second to expose the picture while ISO 25 takes 2 seconds and ISO 400 takes roughly 8 seconds under the same aperture setting. The only disadvantage of the higher ISO’s are the higher the sensitivity, the higher the grain size and also the noise. (We can discuss more on that in a separate post).

Coming back to the beginning, an f-stop is nothing but the interpretation of a aperture and shutter speed setting for a particular exposure given a constant film speed. So you can change the two attributes keeping the film speed constant to create various exposure setting that would still be the same (from exposure perspective). I should say exposure perspective because more post will come where aperture and shutter speed are “exposed” more!

• Leading Lines:Another important form of composing is using leading lines to the subject. Leading lines is actually employed to direct the eye to the subject.The subject may or may not be positioned at the end of the leading line or the leading line may very well be the subject. But if the leading line goes from one vertex identified in the rule of thirds to another (diagonally), it will make an interesting picture.

Leading Lines

• Converging Lines:Converging lines is equally efficient in bringing the attention to the subject like leading lines. Here we are talking about parallel lines in real life or converging itself.The subject may or may not be positioned at the end of the converging line or the convering line may very well be the subject. Converging line help in lead the eye to the end point where they would meet. So it gives the curious eye of the viewer a path to the subject. Some examples of leading lines can be railway track, a hallway (corridor), inside a subway station etc.

Converging Lines

• Framing:Framing a subject always gives attraction and focus to the subject. Framing need not always be done using exactly a frame. Any object in the scenary that covers the subject can be treated as frame.Framing the subject requires careful attention because the frame that we use could compete for attention along with the subject. So careful review has to be done before choosing the framing object. It should not lead the viewer’s eye away from the subject.The framing object used need not necessarily be in focus. Infact, it is better that the framing device is not in focus as it will not attract the attention.

Framing

• Subject Size:The size of the subject compared to other objects can be an interesting technique used in the composition of a photograph. The brain always directs the attention to the largest thing present in a photograph.When the subject is positioned in such a way that it is the largest object in the photography, the brain unanimously ‘elects’ the object as the subject. The techniques like DOF, Hyperfocal focusing etc can be very helpful in making the subject standout from the rest and yet make an intersting composition.Note in the example below, how statue of liberty is compared with people standing at the bottom. Without the people, it makes little sense for the brain to figure out the huge size of the statue.

Liberty sized

• Identify the subject and theme
• Focus attention on the subject
• Eliminate distracting objects from the picture

All these can be done post exposure or pre-exposure. But the pre-exposure techniques are what I better because it gives you oppurtunity to learn.This issue we will see about Composition Techniques:

• Rule of ThirdsComposition based on the rule of thirds is a simple technique that will improve to improve your photograph and get the best possible attention from viewers. This rule, whose origin can be traced back to the golden mean used by the old masters for composing their paintings, consist of tracing two imaginary lines inside and along the vertical and horizontal sides of the frame area, all equidistant of each other and of the parallel sides, resulting in a grid that effectivelly divides the frame in nine quadrants.

To compose a balanced scene, we should arrange the elements such that they are in clear altough not strict relationship with either the vertices, the lines and/or the quadrants of our thirds. Using this we will end with a well balanced composition. The same principle applies even if you turn the camera to compose for a vertical frame.

The rule of thirds is merely a rule. Sometimes it may be broken to get the best effect. It is not necessary to be followed always. But to break a rule, you need to know the rule in the first place and also the situations that you can or cannot apply it.

Rocker

The horizon in a landscape, a bulky form or something with a contrasty or outstanding form or color should correspond to the thirds. In a portrait, the head, and more precisely the eyes, are the visual center of attention and in a symetric composition we could place the main element in the middle quadrants as the main reference.In the example shown, notice how the rock climber is positioned in the frame. The shadow region covers the left third, while the rock climber is positioned on the right third with his leading hand on the top right intersection.

Here are some of the better photos from each photo shoot along with EXIF details.

This was taken recently on the way to Duluth in a about 1/2 mile long tunnel. With a EF17-40mm lens set at 40mm with an aperture of f4.0 and shutter speed of 0.4 seconds, this was exposed to +0.25ev.

Tunnerl Timed

This cotton candy like firework was captured in Dells, Wisconsin a few years back with my 10D. Taken for 1/20 seconds at f/4 with an ISO of 800 at 70mm focal length.

Fire Candy

Skiing & Snow Boarding are the popular sport in MN, for at least 6 months, which lately has gone up to 8 months. There are many ski areas and Afton Alps is a one near by which has beginner to pro level course. There are also contests held where the skiier has to cross a water pond cut in the middle on the way down from the hill. This was taken with a shutter speed of 1/90sec at f/13 with a 73mm on the lens.

Snow Boarding

This lightning picture is a HDR taken in 2006. It is a combination of 4 different exposures taken in 30 seconds shutter speeds with a 50mm prime lens at f/11.

Thunder Bolt

What’s a Timed exposure article without a seamless flowing vevetty falls, right? Here it is. Its taken in Gooseberry Falls, Duluth, MN.  This is a HDR of 3 different exposures. The 0 eV was taken with 17mm lens at f/22 for 0.3 seconds.

Gooseberry Falls

OK. Enough with the history, lets see some photographs.

This one taken at night with an exposure of 20sec and a fisheye lens.

This one is taken from the steps at the entrance. These exterior is all granite from Saint Cloud, MN.

The Sanctuary with a 4 sec zoom out exposure.

The last one is a combination from 24 different photographs. It has 8 different angles with 3 exposures each combined to give a HDR. All these 8 HDR images are then woven together to get the 180º field of view both horrizontally and vertically. HDR is necessary here since there is electrical lighting and windows that let sunlight in at near the top that had exposures ranging from +0.5 to +1.5ev and at the vertical bottom there are dark woodden chairs which contribute to -1.0 to -2.0ev. So I had to compromise on the exposure a bit and take a +1.0ev, 0ev and -1.0ev for the HDR with Photomatix. Photoshop CS4 did the trick for stiching together the 8 different HDR tiffs.

In the film camera days, there used to be multiple exposure on single frame. Today we can expose in different frames, combine them ‘after the fact’ and finally get one picture. This technique is been popularly called “HDR” or “High Dynamic Range”.

Here is my attempt at HDR (though I should say Photoshop – even CS4 sucks at properly merging the photos. Manually merging them makes it a lot better!)

Non HDR

HDR

Non HDR

HDR