Posted by Danny Laureys on February 26, 2008 at 12:41 PM
Hi,
I noticed that in landscapes a lot of the shots are very sharp from front to infinity. I'm trying to figure out how to accomplish that since on the new zoom lenses there are no settings on the lens to help you out with that. I do know that small lens openings is very helpfull. Thank you for your time.
As time allows I "fiddle" with it. Call it bracketing, but at the time I shoot I'll use a range of focusing points in an image along with a range of apertures. My eyes are getting too old to effectively use the DOF preview button on my cameras, so "bracketing" my DOF for later evaluation on the big screen back home is valuable.
Posted by Buck Ward on February 26, 2008 at 10:19 PM
I also sometimes fiddle with the exposure settings to get the depth I want, but if I can afford the speed, I will use f11 or f16, or sometimes f22 to maximize the DOF and eliminate the need to bracket. With a wide angle lens, getting a front-to-infinity depth, can be attained with a larger aperture than with a longer focal length.
Full DOF is less critical if your composition doesn't include elements that are close to the camera.
Posted by Danny Laureys on February 26, 2008 at 10:39 PM
Thanks everyone for all the input.
Posted by Lon Overacker on February 27, 2008 at 12:02 AM
Danny,
To clarify what Buck was saying, it should be clear that the "larger aperture" I believe he is talking about is actually the larger "f-stop" number, ie. f/22. Which technically is a smaller number because it's 1/22 not 22. But f-stops are always referred to as 5.6, 8, 11, 16, etc. The actuall aperture (lens opening) is smaller for greater depth of field and shallower DOF for the larger lens openings (2.8, 4, 5.6.) Buck was correct in referring to longer focal lengths - but actually that's more a matter of field of view, rather than DOF. In other words, if you have a 200mm lens at 5.6, you will have exactly the same amount of DOF with a 50mm at 5.6, AFTER you crop the 50mm image to the equivalent of a 200mm field of view. I hope that makes sense.
Aside from the technicals of DOF, many digital users now use the technique of multiple exposure blending (taking 3 different exposures of the same scene and blending them in PHotoShop to increase the dynamic range. Now, this same technique is being used by blending multiple images taken with different focus points. For example, one image taken at f/11 with the foreground in focus may be combined/blended with 2 additional images at f/11 focused on the middle ground and then focused on the background. In effect, you now have an image that is sharp from front to back. This allows the use of a lens at it's best performing aperture (usually in the middle, f/11, f/16 for example) and still obtain a final image that has tremendous DOF.
Hope this helps.
Lon
Posted by David Bostedo on February 27, 2008 at 12:26 AM
Lon - I don't think your DOF explanation is quite right. The DOF for a given aperture is the same regardless of focal length IF the subject is the same size in the image. Cropping to the field of view of a longer focal length will not yield the same DOF. Moving your camera closer with the 50mm so that the subject is the same size in the frame as the 200mm WILL yield the same DOF. The difference is that the focusing distance changes. Image magnification (size in the frame) and aperture are ALL that determine the DOF. Here's a good example/article showing this from Luminous Landscape.
Posted by Lon Overacker on February 27, 2008 at 12:35 AM
Moving your camera closer with the 50mm so that the subject is the same size in the frame as the 200mm WILL yield the same DOF
David - thanks. You are correct. That's what I was trying to say - or at least I understand that and my explanation wasn't the same thing. Thanks for catching that.
Discussion
6 repliesI noticed that in landscapes a lot of the shots are very sharp from front to infinity. I'm trying to figure out how to accomplish that since on the new zoom lenses there are no settings on the lens to help you out with that. I do know that small lens openings is very helpfull. Thank you for your time.
Danny Laureys
Full DOF is less critical if your composition doesn't include elements that are close to the camera.
To clarify what Buck was saying, it should be clear that the "larger aperture" I believe he is talking about is actually the larger "f-stop" number, ie. f/22. Which technically is a smaller number because it's 1/22 not 22. But f-stops are always referred to as 5.6, 8, 11, 16, etc. The actuall aperture (lens opening) is smaller for greater depth of field and shallower DOF for the larger lens openings (2.8, 4, 5.6.) Buck was correct in referring to longer focal lengths - but actually that's more a matter of field of view, rather than DOF. In other words, if you have a 200mm lens at 5.6, you will have exactly the same amount of DOF with a 50mm at 5.6, AFTER you crop the 50mm image to the equivalent of a 200mm field of view. I hope that makes sense.
Aside from the technicals of DOF, many digital users now use the technique of multiple exposure blending (taking 3 different exposures of the same scene and blending them in PHotoShop to increase the dynamic range. Now, this same technique is being used by blending multiple images taken with different focus points. For example, one image taken at f/11 with the foreground in focus may be combined/blended with 2 additional images at f/11 focused on the middle ground and then focused on the background. In effect, you now have an image that is sharp from front to back. This allows the use of a lens at it's best performing aperture (usually in the middle, f/11, f/16 for example) and still obtain a final image that has tremendous DOF.
Hope this helps.
Lon
David - thanks. You are correct. That's what I was trying to say - or at least I understand that and my explanation wasn't the same thing. Thanks for catching that.
Lon