DOF Factors... Visual Examples For Beginners

[Stradawhovious]

I did this a few years ago to give myself a visual example of the 3 main factors that influence DOF... Focal length, Distance from Subject and Aperture. I did not include sensor size, as I only have crop sensor bodies. Depth of Field (referred to from now on as DOF) is the measure of what part of the photograph is in focus. The shallower the DOF, the less of the frame that is in focus. In all the photos, the plant is about 18" behind the "subject". I vaguely remember posting this here a while ago, but was unable to find it. THere are a multitude of folks new to photography that ask about this concept on a pretty regular basis... I thought that visual examples would be helpful.

Lets go to the examples. First one I'd like to address is Aperture. It's probably the easiest to do since you don't need to switch lenses, shift your feet or recompose due to a shift in FL. Simply put, the wider the aperture (smaller the F/number) the shallower the DOF.

Both of these photos were taken at the same distance from the subject with a 50mm 1.8 lens. The first was taken at f/8, and the second was taken at f/1.8.

Next, let's move on to distance from the subject. These next two photos were both taken with the 50mm 1.8, f/8. but the second I (obviously) moved the camera much much closer to the subject.

(I love this picture.)

And last, is Focal Length. For the first shot, I used the 50mm 1.8 at f/5.6 and the second I left the camera in the same spot and replace the 50mm 1.8 with a 185mm 2.8 shot at f/5.6

I used some pretty extreme examples here, but hopefully you can see how those three different factors will affect DOF.

 

[mikoh4792]

Very helpful. Thanks for sharing.

 

[Overread]

You missed out one example - the mind bending using two different focal lengths - same apertures - at different distances (ergo same frame coverage).

 

[Stradawhovious]

You missed out one example - the mind bending using two different focal lengths - same apertures - at different distances (ergo same frame coverage).

I still have the items... maybe I can hit that one soon. Didn't want to confuse the noobs too much!

 

[ByronBrant]

You missed out one example - the mind bending using two different focal lengths - same apertures - at different distances (ergo same frame coverage).

Please explain what the difference would be in the photos?

 

[Ysarex]

You missed out one example - the mind bending using two different focal lengths - same apertures - at different distances (ergo same frame coverage).

Please explain what the difference would be in the photos?

The DOF would be the same but the front back distribution would be a little different.

Joe

edit: Here we go again......

 

[ByronBrant]

You missed out one example - the mind bending using two different focal lengths - same apertures - at different distances (ergo same frame coverage).

Please explain what the difference would be in the photos?

The DOF would be the same but the front back distribution would be a little different.

Joe

edit: Here we go again......

Thanks. Looks like I need to try this for myself

 

[Stradawhovious]

Thanks. Looks like I need to try this for myself

Best way to learn almost everything.

 

[ByronBrant]

Thanks. Looks like I need to try this for myself

Best way to learn almost everything.

Very true. But this internet is a fascinating place

 

[pgriz]

I'll characterize myself as a slow learner. Book learning gets me to the point that I'm aware of the "theory" of what the elements are (vocabulary, how they relate to each other, and sometimes, how to use them). Then some awkward period of trial and error to see if I can relate what I learned to actual use. Then comes a period of more or less focused experimentation where I explore variations of what I've kinda figured out, and discover the boundaries (this works ok, but don't try to do THAT as it doesn't work). Then I go back to the "book" and reread everything again, noticing many of the things I skipped/skimmed over because at the time they didn't make any sense, or I didn't know what to do with them. Another period of experimentation follows, in which things start to become clearer in terms of how the various variables relate to each other. At some point, I'll go through a structured routine in which I try to test out all the stuff I supposedly learned. And eventually, this segues into a series of practice sessions in which I try to move the knowledge down to the subconscious level. If you go back to the "book", you are now at the level where you can find the places where THEY made mistakes or didn't explain a concept very well, or just plain gave you wrong information.

I go through what Stradahovious described in his original post, pretty much every time I try and learn something (it's at the "structured routine" level of figuring things out). That is how I have learned about what my abilities are at hand-held shooting, where and when I can use IS/VR, what the dynamic range of my camera is, how diffraction blurs detail at higer f/stops, etc. I can set the exposure without taking a light-meter reading, and have it come out within 1/2 stop of the correct exposure. I know how much noise I'm going to have at each ISO level (important stuff to know when you have an obsolete camera). This is stuff that you can internalize and it becomes part of your "software" that guides your actions photographically. Once you have the technicals out of the way, you can concentrate on meaning and feeling, and stuff that allows images to communicate. And THERE, I'm still at the awkward fumbling stage. But just as with sex, it is a lot of fun, while you're figuring things out.