Image Critique #8

Welcome to 2009. and farewell to 2008. The end of the year is always a hectic time for me, and my blog posting has reflected that. "Sporadic" would be a kind characterization. "Absent" would be much more accurate though.

To get back into the swing of things, I am going to try to catch up on the back log of images that I have sitting here waiting for critique.

Today's image is kindly submitted by Alison Dubois. Her comments are as follows:

"I took the photo while hiking on the east side of the main road through Sedona, Arizona in a secluded area that was void of other people. The scene seemed to coalesce somehow for me into a simple beauty and I find the photo to be serene despite its chaos of shapes and colors.

Details: Taken approximate 2:30pm, Canon Digital Rebel XT, Manual, 1/2 second, F16, 44mm, ISO-800"

This is a nice shot, and I certainly see what Alison saw when she took this shot. A few observations though:

- The image is overexposed. Based on the "Sunny 16" rule of exposure, if it was sunny out, at ISO 800, the shutter speed should have been 1/1000 of a second. 1/2 of a second is about 10 steps too much light here, but I'm going to guess and say that it was fairly heavily overcast, which would buy you about 4-5 stops, still leaving this image well overexposed. The other explanation is that some of this exposure information is incorrect, but the image is overexposed regardless. The rock cliff face in the upper right hand corner is particularly overexposed.

A Quick Adjustment to the Levels and Some Dodging and Burning

-I'm not a big fan of shooting with a 35mm and then cropping after the fact to an 8x10 format. Unless you are composing your image in the field so that the 2 inches you cut off of the top or bottom of this image are superfluous, then you are removing compositional information that you thought was valuable at the time you shot it. I prefer to use the entire frame and present the work as it was shot. If someone is going to pay $80-$100 for a photographic print, they should be quite capable of dropping another $10 to have a matte cut to a 8" x 12" or a 6" x 9" window. Typically, people that spend $80 - $100 on a photograph aren't running into Wal-Mart for a $3.99 matte and frame.

- To me, the reflection line is too centered. If you look at he peak where the water meets the land on the right hand side, it is almost exactly dead center. As opposed to a feeling of serenity here, I get a feeling of conflict and confusion as the top and bottom halves of the image fight for attention. Off setting that line either higher or lower would create one half of the image that was dominant and the other half of the image would work as a compliment for. I would like to see the rest of the images from this session.

- There is no detectable image blur at this size, so it would appear that there was a tripod used for exposure. This is good, because at 1/2 second exposure time, hand holding the camera is out of the question.

- If the f16 was used for Depth of Field, shooting with a 44mm at this distance, you would have gotten plenty of Depth of Field opening up the aperture a couple more steps.


Thank you for submitting Alison.

Submissions are always accepted by emailing an image that is a minimum of 500 pixels wide. Please include any information that you feel is pertinent to the shot. <>Contact Scott

Never Surrender - Understanding Exposure and Why it's Important

Everyone knows it happens, but most people don't know how it happens or why it happens.

The automation of cameras has made users lazy. You can just set it to "Automatic" or "Program", press the shutter button, and voila, a properly exposed image.

Q. "Why do I need to know all of this stuff if the camera will figure it out for me?"

A. Because it gives you control, and surrendering creative control of your work to a machine is never a good idea.

Exposure is the process of allowing the appropriate amount of light into your camera for the appropriate amount of time to properly expose your cameras sensor or film. To understand exposure, you need to understand three things; ISO, Aperture, and Shutter Speed. Contrary to popular belief, there are a hundred different combinations for any given scene that will give you an identical and proper exposure.

Let's talk about these three elements individually.

ISO

ISO is the same as "Film Speed". I know, there is no film in a digital camera. But there is a sensor and when you adjust the ISO, you are adjusting the sensors sensitivity to light, the same way that changing film to a film with a different film speed would make the film either more or less sensitive to light.

Common ISO's are:

100
200
400
800
1600
3200

100 is the "slowest" or least sensitive to light, and 3200 is the "fastest" or most sensitve to light. If you look at these numbers closely, you'll see a pattern here. Each number is either double or half of the number on either side of it. This means that each ISO is either twice as sensitive to light, or half as sensitive to light, as the ones right above and below it.

Shutter Speed

Shutter Speed is the amount of time that the shutter is open and allowing light to pass through onto the film or sensor.

Common shutter speeds are:

1/2
1/4
1/8
1/15
1/30
1/60
1/125
1/250
1/500
1/1000
1/2000
1/4000

Please note that these are all fractions of a second. Some cameras eliminate the fraction, just using the denominator as an indicator. I once had a student proclaim "There is no way that I can hold still for 125 seconds!" She was both right and wrong. She was right that she could not hold still for 125 seconds. She was wrong in thinking that the proper exposure time was 125 seconds. It was 1/125th of a second. It's much easier to stay still for 1/125th of a second.

Now look at this list of numbers.... do you see the pattern? Each shutter speed is either twice as fast or half as fast as the one on either side of it. Each time you move the shutter speed one step, you are either letting light in for twice as long or half as long as the previous shutter speed you were using.

Aperture

Aperture is the number that refers to the size of the opening in your lens that controls the amount of light that is let through the lens. This light is stopped prior to reaching the film or sensor by the shutter. Do not confuse "aperture" with "f-stop". They are similar and related, but not the same thing.

Common apertures are:

1.4
2.0
2.8
4
5.6
8
11
16
22
32

This is where it can get tricky. The smaller numbers at the top of the list are the larger openings, letting in more light. The larger numbers at the bottom of the list are smaller, letting in less light. The aperture of a lens is very similar to the pupil of your eye, expanding and contracting to let in the proper amount of light for any given subject. While it may not be readily apparent, each aperture in this list is either twice as large or half as large as the aperture on either side of it, letting in either twice as much light or half as much light as the neighboring openings.

Smaller Number = Larger Opening
Larger Number = Smaller Opening


Putting it All Together

It is the combination of these three things that gives you a properly exposed image. The "Sunny 16" rule states that on a bright sunny day outdoors, if you set you camera to f16 and your shutter speed to the inverse of your ISO (or as close as you can), you will get a proper exposure. The red lines on the chart below show the exposure recommended by the "Sunny 16" rule. From that point, all of the other exposures are extrapolated. All of the white lines on the charts are also proper exposures.




Starting from the suggested red line exposure, if you want a faster shutter speed, all you have to do is adjust your aperture the same amount of steps in the opposite direction. If you want a different aperture, all you have to do is adjust your shutter speed the same amount of steps in the opposite direction. See how easy that is?

Why do you need all of these options? Control. You want to control how your final image looks. Shutter Speed controls motion, and Aperture controls Depth of Field, so by adjusting your exposure based on these factors, you can control how much Depth of Field you have or you can control how much Motion is shown in your photographs.

In my next installment of "Never Surrender", we'll discuss how controlling the Depth of Field and Motion will affect your final image.