Relocated Blog

Please find this blog at its new home at blog.jordanldavis.com

Sorry to keep bouncing around. Hopefully this is the last time. I will not be updating this blogger blog any more.

Depth of Field

Depth of field or DOF, is a term used to specify the area of a scene that is in focus. A “shallow depth of field” has the subject sharp in focus, but the rest of the foreground and background is out of focus. The background and foreground appear soft. This is a great technique for getting your subject to stand out from the background. Take a look at this picture. You can see how I’ve made the background flowers out of focus so that subject flower stands out more.

Here is an example of where I didn’t do a great job separating the subject from background. I wanted just the first tulip to be the center of focus, but all the background is in focus too, and it’s distracting:

There are three things the affect the size of your Depth of Field: Focal length, aperture, and distance from the subject. I will go into the technique more later, but to summarize:

• Focal Length: The more zoom, the shallower the DOF
• Aperture: The wider the aperture (small F-Number) , the shallower the DOF
• Distance from subject: the closer to the subject, shallower the DOF.

The Basics - Aperture

Aperture is one of those photography terms that intimated me at first. It sounds quite technical, and even the units, F-Numbers, don’t make a lot of sense. Changing your aperture is a very powerful tool to a photographer, and there are many reasons why you’d chose a certain value, however, it again all comes down to light. In combination with shutter speed, aperture controls the amount of light hitting your image sensor. The more light, the brighter your image, the less light, the darker your image.

Technically, aperture refers to the size of the opening in the lens. Take a look at the example below. The top image is a wide or large aperture (lots of light), while the bottom image is a smaller aperture (just a small amount of light).

The other hard to grasp part of aperture is the numbering system. Aperture uses F-numbers or F-stops. It seems counter intuitive to me, however, the smaller the number, the larger the opening. So in the pictures above, the top lens might have an aperture of f/2 while the lower image has f/16. A trick I use to help me remember how F-numbers work was given to me by my photography professor… “think about inflating a cartoon bike tire. If you inflate it with a lot of pressure, the hole in the middle will get smaller” More pressure = tighter aperture = higher F-Number. Not sure if that helps you, but it works for me.

These images are all shot keeping the shutter speed constant and just adjusting aperture (which will cause them to be under/over exposed).

Overexposed with wide aperture: 1/10 sec, f/5.6

Proper Exposure with medium aperture: 1/10 sec, f/11

Underexposed with small aperture (big f-number): 1/10 sec, f/22

Aperture also has another effect on your images beyond how bright or dark your image is. After all, why would you need 2 ways to control this, shutter speed and aperture. What aperture does is also change the amount of your image that is in focus. This is referred to as the depth of field. I’ll cover depth of field in a later post, however, to illustrate the effects, take a look at the three images I’ve shot below.

Exposed properly, but with different aperture/shutter speed combinations, so you can see the depth of field effects.

½ sec, f /22 (all 3 quarters are in focus) – Slow shutter speed because aperture is small. This lets in enough light.

1/10 sec, f/11 (Center quarter is in focus, but back is out of focus, and most of front is out of focus) – Faster shutter speed because less light is needed when aperture is larger.

1/40 sec. f/5.6 (center quarter is the only one that is in focus) – Even faster shutter speed because aperture is all the way open.

This was another resource that I found helpful if you want to learn more:

http://www.photoaficionado.com/situationroom/aperture.html

Shutter Speed

Shutter speed refers to the amount of time that your image sensor is exposed to light. Refer back to my earlier post on the anatomy of a DSLR, and you’ll see that the shutter is in front of the image sensor. So, the “faster” your shutter speed, the less time light (which is the image) is hitting the image. “Slower” shutter speeds, means that the image sensor is exposed for a longer period of time.

Shutters are normally very fast… fractions of a second. That’s all the light you need to make a photo. Shutter speeds range from about 1/6000^th of a second to about 8 seconds. The light you have available to take a picture, determines how you set your shutter speed. 8 seconds, (denoted 8” on the back of the camera) would be used for incredibly low light (ie, Taking pictures of the stars). 1/6000^th of a second (denoted 6000 on the back of the camera) would be used for taking pictures when there is a lot of light available (ie, middle of the day, pointed at the sun).

Under normal, daytime conditions, I shoot in the range of 1/60^th to 1/3200^th of a second. I generally try to use the fastest speed that the light will allow. The faster the shutter, the less chance I will cause the image to be blurry by shaking the camera. This type of blur is called “motion blur”, and causes everything in your pictures to appear out of focus. If I’m going to hand-hold my camera (not use a tripod), I won’t set it below 1/60^th of a second. It is next to impossible to hold still enough at this speed.

Take a look at the three photos below to see the effects of shutter speed. I’ve kept all the variables the same (Subject, time of day, aperture, white balance, iso camera location) except shutter speed.

This image has the “fastest” shutter speed. 1/2500^th of a second.

This image is a little slower. 1/2500^th of a second.

This is the slowest image 1/800^th of a second.

Notice that the photos get darker the faster the shutter speed is. This is because less light is hitting the sensor. 1/2500^th of a second’s worth of light vs. 1/800^th of a second.

So, when shooting in the manual mode, I set the aperture, and then adjust the shutter speed until the image is exposed properly. The camera will also do this automatically for you if you shoot in Aperture Priority Mode.

Apologies for Being Absent

It’s been pretty obvious that I’ve been neglecting my blog. I’m going to make an effort to update it more regularly. Just because my entries stopped, didn’t mean my interest in photography has waned. I’ve still been shooting and learned a couple new things along the way. I’d like to ask a favor of my readers, please make comments. I’d love to hear your feedback on what I’m writing.

Buying a Digital Camera

If you are like me, then buying a digital camera is an overwhelming process. There are literally hundreds of cameras on the market and dozens of places to buy. Prices can range from under a hundred dollars to a several thousand. I’m not an expert on camera selection, but here is the thought process and learning I had when I selected my camera.

I’ve broken the digital camera market down into four “styles” of cameras:

1. Point and shoot compact cameras
2. Consumer model cameras with advanced settings
3. Consumer style D-SLR cameras
4. Pro level D-SLR’s

Each camera has a distinct purpose and situation that they are best suited for. The best advice I have is to choose the one that makes the most sense for your photographic needs, but that also fits in your budget. Buying the most expensive camera isn’t going to make you a better photographer. Knowing how to use the camera you have is what is most important. As the week goes on, I’ll create an entry for each segment of camera and walk you through the defining characteristics of each. I’ll also share what I bought, and why.

For now, a couple resources to check out are:

• DP Review (www.dpreview.com): Checkout the buying guide and camera database
• Consumer Reports (www.consumerreports.org): Good for reliability and feature comparison, but the site charges to see everything
• CNet Digital Cameras (www.cnet.com): This link takes you to the digital camera section. There are a lot of good reviews here.

Just a note here, I’m exclusively talking about digital cameras. If you are interested in traditional film I don’t really have any advice for you.

www.jordanldavis.com is now live

Success!!! I was able to map the domain I bought and point my blogger account to that URL. www.jordanldavis.com is now live and running.

I'm starting this blog to chronicle my experience learning to become a photographer (or at least learn how to use my camera). I've been lucky enough to have the opportunity to enroll in a photography course at the Academy of Art University in San Francisco, and wanted to share that knowledge with friends and families. I'll try to distill each lesson down and post it online so that others can benefit from what I'm learning. It will start out pretty basic with camera instructions, and hopefully get more and more advanced ans my knowledge and skills improve.

I'll also try to post samples of my work and share some of the feedback I get from class reviews. Please feel free to leave me comments, I'll try to reply to them.

Setting Up a Blog

Well, that was easy, I now have a blog. As part of this exercise I'm going to see if I can get this blog to display on www.JordanLDavis.com.