purplesquid Loc: Vancouver, British Columbia

Does a lens' focal length effect DOF? I'm currently shooting with a 180mm Macro lens, and dof is really,really shallow,(even at f20) would I gain a noticeable difference with say.....a 105mm lens? Thanks in advance.....Craig

purplesquid Loc: Vancouver, British Columbia

Another question: If I had a 180mm and a 50mm macro, both set at f/20, shooting at their closest focus setting, they would have identical DoF?

purplesquid Loc: Vancouver, British Columbia

Another question: Would the manufacturer of said lens make any difference? The reason I'm asking is because other macro shots I see, seem to have a greater DoF than my shots. Just curious if there was anything (short of stacking) i can to improve the DoF of my images.

Nikonian72 Loc: Chico CA

Lens focal length dictates DoF at any given aperture and/or magnification. Basically, as in landscape photography, a wider focal length lens will provide a deeper DoF at comparable apertures.

One of our expert macro-photographers uses a 15-mm macro lens, which means his subject must be 21-mm to 22-mm Minimum Working Distance from lens front element. Notice the incredible DoF he can capture in single images: http://www.uglyhedgehog.com/t-382781-1.html

The longest macro lens to my knowledge is the Nikkor 200-mm. I would like to see/compare DoFs (photographed millimeter rulers) at wide-open apertures of several different focal length macro lenses.

Nikonian72 Loc: Chico CA

No. DoF is a mathematical relationship to focal length and aperture. A Sigma 105-mm macro lens at f/8 will produce identical DoF to a Nikkor 105-mm macro lens at f/8. And a Canon 100-mm wold be so close that you most likely could not see the difference. A Tamron 90-mm macro lens may very well reveal a bit more DoF. For true comparison, ALL macro lenses must be set to Minimum Focusing Distance (1:1 magnification).

As lens focusing distance approaches 1:1 magnification, the actual plane of focus becomes more centered within the DoF (as compared to 1/3:2/3 DoF ratio at distant focus). Some macro-photographers attempt to capitalize on this optical phenomenon by slightly "back-focusing" on subject (such as eyes), and allowing DoF to pull foreground (nose) into focus as well. Quite tricky, and best accomplished by focus bracketing to find the most pleasing single image. This is also the basis for focus-stacking image captures.

purplesquid Loc: Vancouver, British Columbia

Thanks very much Nikonian72 for all the info. I too would really like to see a focal length-DoF comparison.

Screamin Scott Loc: Marshfield Wi, Baltimore Md, now Dallas Ga

Go to this link for a number of different macro calculators including one for DOF.
http://www.cambridgeincolour.com/tutorials/macro-lenses.htm

forjava Loc: Half Moon Bay, CA

Informative remarks all around, esp. the DoF ratio point of Nikonian72.

purplequid, the questioner, asked about variability across lens makers. I'll try to feed in some marginal points, about manufacturers' specification fuzziness as it applies to (1) flatness of field, (2) angle of view, and (3) maximum aperture. Then I'll offer a way not mentioned here to lessen the need for focus stacking, in response to purple's question about avoiding stacking.

Flatness of field is an unstated assumption of the DoF-ratio equation mentioned by Nikonian72. The focal plane is generally bowl-shaped, from the vantage point of the subject; ideally this plane is flat in macro lenses. The versions of both the Nikkor 55mm (1:2) micro (macro) and 60mm (1:1) micro are noteworthy for their fidelity to flatness. Not all so-called macro lenses have flat fields but flatness is generally seen as a fundamental attribute of macro.

So, per purple's second question, does the manufacturer make a difference? At the margins due to flatness. Also for lenses generally, angle of view can be slightly mis-stated, another minor thing. Finally, the maximum aperture is sometimes slightly understated, as, I am told is true of a Voigtlander 58mm f/1.4.

As to purple's last question, "if there was anything (short of stacking) i can to improve the DoF of my images": Just got a Nikkor 85mm tilt-shift lens, which lets us re-orient the plane of focus to cover more of, say, a lizard that is not conveniently perpendicular. That is, the rectangular plane of focus can be moved away from perpendicular to the sensor plane. This can make it unnecessary for the photographer to coax the lizard into the plane of focus.

purplesquid Loc: Vancouver, British Columbia

Thanks much for all the great info. Always fantastic to learn as much as possible.