Depth of Field Technique - ultra wide angle photos with closeup objects

[steve1401]

Hi,

I'm sure this has been discussed before, but a quick search didn't answer my questions, so apologies if this is a repeat...

There are a lot of pictures with a relatively small object, say a small tree stump or a puddle, filling the foreground of a picture, with the rest of the picture simply setting the scene. Usually these are taken with a wide angle lens; 15mm for example.

What are the best techniques to make sure that the foreground object (the important item) is sharp, but making sure that the rest of the scene is also sharp - ie an infinite depth of field (DoF). I struggle to achieve this with my Sigma 10-20 attached to a D300. Because of the extreme wide angle, the foreground object is often very close (.5 meters or less).

Using the DoF calculator on this site, if I enter 10mm lens, F8, dist to subject = 0.5 and then calculate, my "Closest distance of acceptable sharpness" is 0.268 m and the "Furthest distance of acceptable sharpness" is 3.634 m.

Thanks
Steve

[atvinnys]

wouldn't that be a case of using the Hyperfocal distance? (just throwing that out w/o much thoughts, I'll leave that to the experts...)

[Dave Humphries]

Hi Steve,

I'm no expert either, but what Vincent is suggesting is to try entering several focus distance numbers into the calculator until 0.5m comes out in the "Closest" box and see if the "Furthest" box is infinity, if it isn't, set the aperture diameter one stop smaller (i.e. if f8 is no good, try f11), then you'll need to try some slightly larger numbers as the focus distance to get back the 0.5 in the "Closest" box again.

It is an iterative process, but one you can get a feel for what's sensible after a little experimentation.

In theory, tables or graphs could be used, but I don't know where you might find those and there are so many variables, maybe it's not as practical as I think.

Time for an expert,

[graynomad]

Hi Steve,

Most of the shots of the type you're talking about (the really sharp ones anyway) have been taken with a camera that allows movements, ie large format or some medium format cameras.

By all means try the abovementioned calculator but I suspect that you still won't have the required DoF, bearing in mind that the image will start to be difraction limited at around f8-16 depending on the camera.

The best way to do what you're after is to buy a T&S (PC in Nikon parlance) lens. These lenses allow the tilting of the plane of focus such that everything from say .5m to infinity is perfectly sharp even wide open. Unfortunately these lenses cost a fortune.

There is a great tutorial on this subject here on the CinC site.

Regards
Rob

[McQ]

Hi Steve. All great advice. You might also want to take a look at this thread from earlier:
Using the Hyperfocal Distance in Practice

The key is to have some objective goals. How close and how far do you want objects to be sharp? What you mean by "sharp"? As Rob mentioned, these goals may or may not be possible with a regular (non tilt/shift) lens. The calculators mentioned in the above thread will help you with that part.

PS: Here's the tutorial that Rob referred to...
Tilt/Shift Lenses: Using Tilt Movements to Control Depth of Field

[steve1401]

Guys, thanks very much for the replies. I think I now understand how best to use the DoF calculator and also (as I kind of expected) understand that there are limitations to the gear I have.

Cheers
Steve