BetterPhoto Q&A
Category: Questions with Sample Photos

Macro work and Depth of Field

I currently own a Tamron SP 60-300mm with 1:1.55 macro. With this lens it is necessary to get approximately 1.25" from the subject and the lens must be fully extended to almost 12". At this position the maximum apature is ~f/5.4. In order to shoot without a tripod it is necessary for me to shoot at 1/125 minimum (and most of those are not particularly sharp) and 1/500 for clear shots. Since I am looking to enlarge the photo (11x14 or larger) I cannot afford the grain in faster films (400ASA tops).In an outdoor setting with available light I have very few choices; drop to a slower shutter, or shoot full open and accept the ~2mm depth of field. Wow, that was a lot of intro material. On to my question:

Would I notice a significant increase in depth of field with a 90mm or 60mm 1:1 macro lens? What would I get in terms of focus distance? Getting one inch from most creatures startles them, and they don't stick around for you to meter and focus. I would like to be able to get the shot from a little further away.

Any other helpful information on macro gear would be appriciated (not going to by a ring flash though... too many $$).

Thanks.

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May 28, 2001

When maintaining the same magnification by decreasing focal length and moving closer, the DOF shrinks at almost exactly the same rate by moving closer as it grows by decreasing the focal length. The end result is almost exactly the same DOF (assuming lens aperture also remains the same). I posted a graph here showing this for non-macro distances a while back; it's the same at macro distances too:
http://www.betterphoto.com/gallery/dynoGallDetail.php?photoID=942
S = focus distance
Sn = near edge of DOF
Sf = far edge of DOF

The main effect from using a shorter or longer lens in making macros is being able to get closer or farther from the subject, and the perspective it has. Focus distance "S" is not from the front of the lens either. It's from a specific optical point inside the lens; how far inside the lens this point is can vary greatly by lens design (especially with modern zoom lenses). At non-macro distances greater than about 10X the focal length, it's not enough to worry about. With macros having magnfications of 1/4X and larger, exactly how far the subject distance is from the front of the lens can be much different from the optical definition of focus distance.

In short, you're boxed in a little by high magnification with very shallow DOF's and slower film speeds requiring tradeoffs between shutter speed and aperture settings.

A couple of suggestions:
1. If at all possible can you use a tripod with cable release, perhaps with a ball head? Admittedly, this would slow you down and require great patience waiting for a good shot.
2. Aftermarket ring flashes are made by Phoenix, Sunpak and Vivitar. They're less expensive than most OEM ring flashes. Don't know if these are still "too many $$" for you.

Footnote:
(I've never been a big fan of this and would not do it for personal reasons.) Wondered about how a few of the stunning insect macros I've seen were made. Discovered they were "staged" by freezing the insect and then placing it onto the plant, sometimes in a studio with highly controlled lighting and background. Allows a tripod, more light, tighter apertures and slower shutter speeds.

-- John

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May 28, 2001

Thanks for the explanation, John. Good run-down of a tough problem.

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May 28, 2001

A lot of macro shooters I know (I am certainly not one) like to shoot insects first thing in the morning. They do this because it is still cold and the insects are not moving around and often times they may be covered in dew or even frost. Which makes for really cool pictures.

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May 28, 2001

Thanks again gentlemen.

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May 30, 2001

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May 30, 2001

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May 30, 2001