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On my drive in today, I was thinking about my sunset pic from the other night. This shot was taken a couple of days ago, right off my back deck. (Yes, I have a nice view).
The exif info is stripped out of it, but it's as follows.
Focal length 200mm
F/3.2
Shutter Speed 1/200 sec
ISO 1600
Since I was shooting with my 70-200 f/2.8, and I had my camera in Shutter priority mode with the shutter speed at 1/200 as to minimize visible camera shake in the final image (things were moving to quickly for me to pull out my tripod). As a result, I got a final F-stop of f/3.2. That's a pretty wide open aperture, which we normally associate with a shallow depth of field, yet looking at the picture, most of it is pretty sharp and the depth of field appears infinite. How'd that happen?
I did a quick pull on google earth and measured the distance from roughly my house to the mountain in the shot. I figured, in round numbers, that it was about 12 miles away, or 70,000'. Plugging this info into the Depth of Field Calculator, it gives me the following. This is a great site, and I have it bookmarked on my smartphone.
Subject distance 70000 ft
Depth of field
Near limit 1351.3 ft
Far limit Infinity
Total Infinite
In front of subject 68648.7 ft
Behind subject Infinite
Hyperfocal distance 1378.5 ft
If you look at the near limit number, which is the closest point of acceptable sharpness, it's a meer 1351 ft away, and extends to infinity. Since everything in the frame is farther away than than 1351 ft, then the entire image is in focus even almost wide open with an F-stop of f/3.2. This would be counter intutive to me (and most of us) had I not done the math (albeit after the fact). I would have thought that I needed a smaller aperture and tripod to get everything in sharp focus. In this case, distance was my savoir.
The bottom line here is knowing a little bit the math and physics behind photography can help you utilize and exploit the limits of your equipment....
To see more of my photography, visit my website www.landshapephotography.com/
On my drive in today, I was thinking about my sunset pic from the other night. This shot was taken a couple of days ago, right off my back deck. (Yes, I have a nice view).
The exif info is stripped out of it, but it's as follows.
Focal length 200mm
F/3.2
Shutter Speed 1/200 sec
ISO 1600
Since I was shooting with my 70-200 f/2.8, and I had my camera in Shutter priority mode with the shutter speed at 1/200 as to minimize visible camera shake in the final image (things were moving to quickly for me to pull out my tripod). As a result, I got a final F-stop of f/3.2. That's a pretty wide open aperture, which we normally associate with a shallow depth of field, yet looking at the picture, most of it is pretty sharp and the depth of field appears infinite. How'd that happen?
I did a quick pull on google earth and measured the distance from roughly my house to the mountain in the shot. I figured, in round numbers, that it was about 12 miles away, or 70,000'. Plugging this info into the Depth of Field Calculator, it gives me the following. This is a great site, and I have it bookmarked on my smartphone.
Subject distance 70000 ft
Depth of field
Near limit 1351.3 ft
Far limit Infinity
Total Infinite
In front of subject 68648.7 ft
Behind subject Infinite
Hyperfocal distance 1378.5 ft
If you look at the near limit number, which is the closest point of acceptable sharpness, it's a meer 1351 ft away, and extends to infinity. Since everything in the frame is farther away than than 1351 ft, then the entire image is in focus even almost wide open with an F-stop of f/3.2. This would be counter intutive to me (and most of us) had I not done the math (albeit after the fact). I would have thought that I needed a smaller aperture and tripod to get everything in sharp focus. In this case, distance was my savoir.
The bottom line here is knowing a little bit the math and physics behind photography can help you utilize and exploit the limits of your equipment....
To see more of my photography, visit my website www.landshapephotography.com/
