Trying to understand

[Dailydog]

Hi

I'm totally new to macro photography. The first day I got my new lens I just tried it out. I was puzzled by a recurring phenomenon: a thin vertical strip that had sharp focus while the areas around that strip were blurry. I think I could understand a sharp circular area, but not this. Can anyone explain what causes this?

[inkista]

Depth of field. Macro photography always involves razor-thin depth of field--it's a function of the subject distance from the lens. This is why a lot of macro photographers use a tripod and/or a flash as well as a macro lens. You have to stop down (e.g., use f/16) to get as much depth of field as you can, and that generally will require a shutter speed that may be too slow to handhold.

Here's a macro I took at f/11, 1/160s, handheld with a 60mm Macro lens with a reversed 50mm f/1.8 on the front of it:



Note that the DoF really only covers a few millimeters on the quarter: only the NI and Washington's eyebrow are in focus.

[Dailydog]

Ok, this may be a stupid question but, why then do macro lenses seem to become more expensive when they can reach stops of 3.5 or less?

No, I see, I guess you're not telling me I shouldn't use those stops. It all depends on the kind of DOF you want to achieve.

[jiminyClickit]

Dailydog, Welcome

To go to a point I can't even begin to measure, front of a snowflake out of focus, back in focus. Generally ISO 100 and f/2.8 gets these. It is a question of what you hope to show.

[NanSar]

A walk one afternoon with my daughter and her friend discovered these tiny little beauties hidden in the bush.

[inkista]

Originally Posted by Dailydog

Ok, this may be a stupid question but, why then do macro lenses seem to become more expensive when they can reach stops of 3.5 or less?

Not a stupid question. The additional price isn't about the speed of the lens. The additional price is in manufacturing a lens that can still focus while it's very close to the subject. Every other macro technique will severely limit you on framing options--the lens will only focus at a specific distance from the subject. With a macro lens, you have a much wider choice in your working distance.

In addition, macro lenses are among the best performers of all lenses, image-wise. Because they're so precisely engineered for close-focusing capabilities and because they're primes, they're usually among the sharpest lenses in any lineup. My EF-S 60mm f/2.8 Macro is as sharp (if not sharper) than my L lenses.

Just to show you how sharp my 60 is, here's a 100% crop (e.g., one pixel on your screen is one pixel of the photo) of a photo I took with it on my XT.

crop60.jpg