Depth Of Field Scale

[BEEZY]

My friends, "as John McCain would start a sentence" I would like to use the depth of field scale on all my lenses to capture a scene where sharpness is rendered from foreground, to horizon. I always wondered how those media photographers created sharp images without looking through a viewfinder by holding a DSLR above their heads to take shots, until I read that they use the depth of field scale. My aim is to create storytelling compositions, and I have learned that focus is always a factor. My gear consist of the Nikon D80, AF Nikkor 70-300mm 1:4-5.6G, Sigma DG 28-70mm 1:2.8-4, and Nikon 50mm f/1.4D AF Nikkor lenses. Also, is it possible to use this scale on all the lenses I've listed? I have sneaky suspicion that the different focal lengths of all listed lenses, have different dynamics in attaining sharpness from foreground to horizon. By all means, please explain. Thanks

"Truth is the light illuminating my images"

"Better to do something imperfectly than to do nothing flawlessly." - Robert Schuller
"You don't take a photograph, you make it." - Ansel Adams

[vandergus]

Yeah, using depth of field scales can be difficult with modern lenses, especially zooms, since the depth of field changes with focal length. Older lenses typically had depth of field scales printed on the lens so the photographer could do quick calculations in their head. See this image of an old nikon zoom lens. The curved lines on the barrel represent the depth of field scale. The lens is zoomed by moving the collar up and down on the lens barrel, and wherever the collar intersects the depth of field lines is where you make your calculation.

Modern zooms and even many modern primes don't have depth of field scales marked on them, to the chagrin of many a photographer. So if you want to calculate DOF in the field, you'll need some sort of calculator. Check out DOFmaster.com for some good resources.

At the very least, you could memorize some hyperfocal distances for you 50mm f1.8. Pick a common aperture setting, say f/16, and calculate what the hyperfocal distance is (turns out to be 25.8 ft, according to DOFmaster). So manually set your focus to 25.8 ft and everything from 12.4 ft to infinity will be in focus.

Good luck

[Chip]

Maybe this Depth of Field Calculator site will help?

Good luck.

[kencaleno]

Ok, to keep it simple-don't use an aperture (F-stop) smaller than F 11, or you will get diffraction issues,and focus 1/3 of the way into the scene as viewed in viewfinder. This works,there need be no calculations. Just try it. remember that infinity starts at 30 ft. focus will start from halfway between where you focus,and the camera. Regards, Ken

P.S. There is no need to make things complicated - K.I.S.S. (Keep It Simple,Shutterbug)

[OsmosisStudios]

I had a hard time understanding what you were saying there Ken. It's like the sentences arent quite complete or something.

Also, wouldnt "infinity" change depending on the lens used? All lenses have a different minimu focus distance, so wouldnt the infinity point start at varying points as well?

[vandergus]

Also, wouldnt "infinity" change depending on the lens used? All lenses have a different minimu focus distance, so wouldnt the infinity point start at varying points as well?

Indeed. My 100mm has markers all the way out to 50 ft before it reaches infinity. For wider angle lenses though, "infinity" can be pretty short, which, I think, is the point that Ken was trying to make.

[inkista]

Originally Posted by vandergus

Yeah, using depth of field scales can be difficult with modern lenses, especially zooms, since the depth of field changes with focal length. ...

Actually, it's not the focal length that's the problem (you usually only find those scales on primes anyway); it's that the DoF changes with image plane size. All those DoF scales are calibrated for full-frame/35mm film. Using the same lens on a crop body, and the DoF scale becomes inaccurate (link).

I tend to do what Ken's advocating: stop down to the f/8-f/16 range and focus 1/3 of the way into the scene (because DoF is usually 1/3 in front of the focal point, and 2/3 behind it). It does tend to work pretty well. [grin].

The only lens I have where this emphatically DOES NOT work is my Sigma 8mm f/3.5 circular fisheye. For some reason the focus scale on this lens is completely whacked, and it's actually focusing at infinity if you've got it set to somewhere between 1 and 3 ft. Go figure. But this isn't a problem most folks are likely to run into.

[OsmosisStudios]

... mainly because most people have 8mm circular fisheye lenses!

Glad to see that my assumptions werent wrong. I still dont totally understand what ken said, though.

[kencaleno]

what ever point you focus on,1/3 distance in front of subject and 2/3 distance behind subject will be the depth of field. Say,for instance you are set at f11 using a prime 50mm lens, and you focus on a subject 10 feet away: your depth of field will be from 7 feet to infinity andthe part of the scene in acceptable focus will be from 7 feet to 21 feet (1/3 in front; 2/3 behind subject)so if you focused on 30 feet at F22 depth of field will be from 5 feet to 75 feet. If you have a 6mm fisheye lens you could be 1" away from a newspaper page and capture the whole page! Hope this explains all, regards, Ken .(By the way, if you want the math for this):

Hyperfocal distance = F squared/f times d mm

Where F = focal length of lens
f is the aperture #
d = diameter of the circle of confusion (circle of confusion of crop cameras is 0.019mm for Nikon and 0.020mm for Canon- full frame is 0.025mm)