Playing with depth of field

pjb923

This is my first attempt at posting pictures here. I have always loved the small DOF you get when shooting near 1:1 macros. These were all taken with either my Nikon D100, or D200 and Sigma 50mm and 90mm macro lenses.

Skippy

Welcome To Dgrin

pjb923 wrote:

This is my first attempt at posting pictures here. I have always loved the small DOF you get when shooting near 1:1 macros. These were all taken with either my Nikon D100, or D200 and Sigma 50mm and 90mm macro lenses.

Nice series ...... I have a question.

In your first shot and your last shot there is a distinct line that shows the image within the line appear very dotted and much sharper than the rest of the image, and on either side of the line the image is amazingly soft... maybe thats the wrong word to describe what I see

It is more noticeable in the first shot of the ladies face, it sort of looks out of place ????

The keyboard shot has a smoother look, but the other images you've posted don't show this line at all, why is that???

Don't get me wrong I like the images you've post, but my eye is drawn to the lines in both those images.

Nice to see another member who is keen on Macro, you'll find quite a few folks in this thread right into Macro, it's nice to learn tips and tricks from everyone........ everyone seems to have their own style, and I bet you do too.

Thank you for posting you rather cool Macro shots, and I hope you continue to share with us ....... Skippy (Australia)

pjb923

Thanks for the comments Skippy.

The first and last shots were taken at the highest magnification of the series. The first shot is actually of a magazine cover, so you are seeing the dot grain of the print. Since it was taken from a distance of a few inches away at a slight angle, the depth of field is virtually zero. Anything that is even a fraction of a inch away from the focal distance will be out of focus. If I had aligned the focal plane to the magazine surface I could have gotten the entire image in focus.

The same applies to the keyboard shot. You are seeing the texture on the keys in the focused area which is extremely small.

Because the other shots are not flat surfaces, the effect is not as noticable. But, you can see it on the wall in the third shot.

Skippy wrote:

Nice series ...... I have a question.

In your first shot and your last shot there is a distinct line that shows the image within the line appear very dotted and much sharper than the rest of the image, and on either side of the line the image is amazingly soft... maybe thats the wrong word to describe what I see

It is more noticeable in the first shot of the ladies face, it sort of looks out of place ????

The keyboard shot has a smoother look, but the other images you've posted don't show this line at all, why is that???

Don't get me wrong I like the images you've post, but my eye is drawn to the lines in both those images.

Nice to see another member who is keen on Macro, you'll find quite a few folks in this thread right into Macro, it's nice to learn tips and tricks from everyone........ everyone seems to have their own style, and I bet you do too.

Thank you for posting you rather cool Macro shots, and I hope you continue to share with us ....... Skippy (Australia)

pathfinder

I see the line of sharpness in the first and last image also Skippy, and this does not look like the transition I expect to see due to a large aperture and its associated shallow DOF, but looks more to my eye like a post processing artifact.

I see the dot image in the first shot due to line printing and its dithering, and the texture of the keys, but the junction from sharp to blurred seems almost instaneous, rather than the more gradual effect seen with a large aperture at a near focal point, like this shot at f4 with Canon 100macro



The transition from the mantis head to his shoulder just does not seem like it is a line drawn in the sand.

I love the narrow DOF shots also, they can be very dramatic and emphsize precisely what the shooter in most interested in having the viewer see. Nice series of shots.

mikeshots

I like the shots as well, but don't really understand the two that were shot from a magazine. If they were shots of a magazine page then the whole image would be on the same plane and wouldn't technically reflect any depth of field, would it? Can't wait to see what the secret is!

pjb923

mikeshots wrote:

I like the shots as well, but don't really understand the two that were shot from a magazine. If they were shots of a magazine page then the whole image would be on the same plane and wouldn't technically reflect any depth of field, would it? Can't wait to see what the secret is!

Only the first shot is of a magazine. The reason the entire image is not in focus is due to the angle that the shot was taken at. If I aligned the focal plane to the magazine I could have achieved focus across the entire view.

Take a look at this DOF calculator.
http://www.dofmaster.com/dofjs.html

Entering the approximate settings used for this shot (D200, 50mm lens, F2.8 at a distance of 2 inches) results in a total depth of field of 0 inches.
Near limit of acceptable sharpness = 2 inches
Far limit of acceptable sharpness = 2 inches
Anything that is not exactly 2 inches from the focal plane will not be sharp.
The transition from sharp to blurry happers over such a small distance that it appears to be instantaneous. The only post processing that was done was color correcting, resizing, cropping and maybe minor sharpening.

douglas

Very cool shots. I dont understand how the depth of field was achieved though, perticularly on the keyboard, where the side of the keys remain sharp even though the depth changes much more than the the top of keys which are fairly flat is blurred.

pathfinder

If these were jpgs, then some sharpening was performed in the camera by definition, was it not??

I completely understand the limited DOF with a large aperature, and a near focal point, but the transition is usually not seen as a straight line or is it?? The area of transition from sharp to blurred usually appears more gradual. I'll experiment with this some this weekend perhaps.

I understand that the magazine page was at roughly 45 degrees to the plane of focus? Or was it much more?? The steeper the angle the more abrupt the change in DOF of course.

Awais Yaqub

wow nice photos