Depth of Field Calculator-

Not sure if you would be interested, but I just found this pretty cool DOF calculator:

www.dofmaster.com/dofjs.html

Good find. Thanks.

Just saved that one

I don't recommend them to my students. You need a "feel" for DOF with all your lenses at different distances and aperture settings. A landscape photographer knows to stop down the lens (and use a tripod) to get the DOF he needs. And most portrait photographers like a shallow DOF, so use a larger ap.

If you have to pull out a calculator before you take a shot, you probably missed it.

Matthew

BTW while it may give you a "ballpark" figure, they are calculated for an 8x10 print. Any other print size, it has no real meaning.

MLKstudios wrote: I don't recommend them to my students. You need a "feel" for DOF with all your lenses at different distances and aperture settings. Even a landscape photographer knows to stop down the lens (and use a tripod) to get the DOF he needs. And most portrait photographers like a shallow DOF, so use a larger ap.

If you have to pull out a calculator before you take a shot, you probably missed it.

Matthew

BTW while it may give you a "ballpark" figure, they are calculated for an 8x10 print. Any other print size, it has no real meaning.

I bet this BTW may be puzzling to some. Perhaps you can expand a bit??

I found the DOF scales on my old, mechanical, film cameras very useful, and it's something I miss. I like zone focusing, and I also think they helped me get a feel for the DOF of a lens faster.

As long as it requires an extra device, and requires me to input the settings I probably wouldn't use a DOF calculator like the one above before a shot when working. I have used the one linked above when just contemplating shots sitting at home. I installed CHDK (<-makes my compact digital almost tolerable to use, IMO) on my Powershot, and it has a built in DOF calculator that works like a scale. It inputs the settings as the camera is operated and it displays DOF info on the LCD. I love it! I don't understand why my fancy DSLR doesn't have something like it. It seems like it would be simple enough.

Of course all DOF calculators and scales must be tested to see how they stack up to an individual photographer's opinion of what is sharply in focus or not, but this has always been an issue. Early advice I heard was to consider the DOF scale exaggerated by an f/stop until personal testing showed otherwise.

While more common years ago with MF lenses, there are still DOF scales on some lenses. Look for matching numbers on either side of the true focus point. Your DOF reaches from the number on the left to the same number on the right -- the chosen f/stop number.

If your lens doesn't have a scale (not all do) then your camera may have a DOF preview button, that stops the lens down to the chosen aperture and lets you SEE the DOF on the viewfinder screen. They work well in bright light, but so not so well in low light with a small chosen ap -- it simply gets too dark to see.

As for a better explanation of what I said above. DOF has three factors. In order they are distance, focal length and lastly the chosen ap. If you use a 50mm, then you only have two factors -- distance and aperture as the focal length is a constant. In my course (week 1) I have my students use reciprocity and f/4, f/8 and f/16 so they get a feel for how much DOF those apertures make.

It takes some experience, but as long as you are aware of what affects the DOF, you can get to where you have a sense of how much "apparent" focus to expect at different distances and settings, without a "calculator".

Matthew

To add, the DOF calculators were calculated long ago for acceptable resolution (lines per inch) for an 8x10 enlargement. If you print larger than that, you need more DOF to look as sharp, and smaller, you can use a larger ap.

MLKstudios wrote: While more common years ago with MF lenses, there are still DOF scales on some lenses.

They are there, but the scale is so small it's almost useless. On my Canon primes the only marks are for f/22, and those are just a few millimeters apart. I don't need to know the DOF for f/22. I want to know it for f/5.6.

EDIT (way later): I'm comparing a modern Canon 50mm f/1.4 to an assortment (Nikon, Pentax, Olympus, Canon FD...) of older, manual focus 50mm lenses. They've got nice, big DOF scales. For instance on the Pentax (K) 50mm f/2, which would have been a pretty cheap lens in it's day, the area between the f/4 marks on the DOF scale is similar to the area between the f/22 marks on the EOS lens. Maybe it has something to do with the design requirements for AF. I still think it would be an easy feature to include in the operating software.

HP, I'm sure you know this already, but for others who may not know...

A telephoto lens is going to have both 22's close together since focal length is factor #2 and long lenses have less DOF than short lenses. On a wide lens, the 22's are going to be far apart, since you get much more DOF at the same aperture (f/stop).

There is also something called "hyperfocal" distance, once used by landscape photographers, where you put the right number on infinity. You now have the maximum DOF possible for that lens (at that ap).

But again, that's based on an 8x10 print. Like Henry (Matt) noted above, stop down one more full stop to get what you need to look truly sharp.

Matthew

What a good thread, and good information. This was a good read!