Challenge Pictures:
"Hooded Pitcher Plant" - Aaron
"Georgia in January" - Aaron
I managed to get the depth of field I wanted (shallow) for the hooded pitcher plant but not the Georgia in January shot. I forgot the admonition to be close to the subject if you want to blur the background. But I made do anyways. BTW, I edited these using my iPad. It was fun.
"Jen and Liz" - Matt
I had fun playing with the different lenses, distances, and apertures while the subjects and lighting stayed roughly the same. After reading the article and playing around with the camera a bit, I realized that I knew these things by instinct, but never really formalized the logic. If you want to blur the background, then zoom in, open up, and get close.
So, some thoughts. I really like using a long lens for portraits, but tend to be limited by light. It's great outside on cloudy days. Otherwise, the shutter speed often needs to be faster than the available light will allow. On the other end, 18mm is great for landscapes but you need to get really close to people to fill the frame. Distortions in the perspective start to be an issue. For people, I generally default to a 50mm because I can open up wide and be far enough back that the perspective is pretty good. Overall, fun challenge. Looking forward to seeing what others post. Good choice, Cary.
"Snowy Depths of Field" - Cary
With a light dusting of snow Saturday morning, I spent some time in the woods of my yard playing with lenses and depths of field. My goal was to try and answer the question of to which of the three factors (aperture, focal length, distance) is depth of field most sensitive. I have an extension tube which moves the lens away from the camera a set distance, thereby shortening the minimum possible subject distance. This allows you to get very, very close to the subject. The top shot of the acorn is with my 50mm prime and the extension tube so the front of the lens is less than 2 inches from the subject. As you can see, even at f/8 the depth of field is tiny - maybe half a centimeter at best. At lower apertures (this lens goes down to f/2), it is razor-thin.
The middle shot (of the same acorn) is with my 70-300mm all the way out at 300mm. The subject is about 3 feet from the front of the lens, just about the minimum focus distance for this lens at that focal length. Even at f/22, the max possible for this lens, the depth of field is relatively small. Maybe a centimeter or so?
The last picture is with the same lens and focal length but at a distance of about 12 feet. The depth of field at f/8 is about a good foot or so. I took many more shots at various apertures and focal lengths and concluded that depth of field is most sensitive to distance. As for the ranking of the other two, I'm less sure of the order but I'd lean towards focal length as being the more sensitive factor.
Bonus Pictures:
"Snowy Woodpile" - Cary
A light dusting of snow makes most things look more interesting, I think. And in case you're wondering, as far as I know this woodpile is still
snake-free.
E-3 w/ 70-300mm @ 70mm, 1/80 sec @ f/5.6, ISO 100
The Challenge:
SouthernShots (more or less) Weekly Challenge
Theme: The Physics of Depth of Field
Due: Wednesday, February 9, 2011
Explanation:
This time we're going to explore another physical aspect of our lenses as it relates to depth of field, the zone of area in front of the lens that is in focus. Most photographers know that a wide-open (low f-stop) aperture will decrease depth of field. However, there are two other factors that also impact depth of field: lens focal length and camera-to-subject distance. As lens focal length increases, depth of field decreases. Additionally, as the camera-to-subject distance decreases, so does depth-of-field. Here's a good web page with more detail and example pictures to illustrate:
Now here's the challenge: explore the three factors that affect depth of field and post your best/favorite shot. Or, for bonus points, post a diptych or triptych demonstrating two or three of the factors or the same shot with narrow and deep depth of field, etc... whatever suits your fancy. Basically, explore these factors photographically, post your best shot(s) and then I'd like to start a conversation on our results to see what the group's consensus is on which one has the biggest impact on depth of field based on our experiences. We can start the conversation in our text that we post with the shots and then continue in the comments.
Have a great time exploring the physics of depth of field and happy shooting!
Cary
"My Favorite Smile" - Mike
