DOF question/help

I have a question about depth of field. How do you get the whole subject 'in focus'? I'm assuming I'm using the wrong lens for the job (as with the ants pic a while back), but how do you 'know' you're going to have a focusing issue? This pic was shot with my 18-55 from a tripod, IS turned off, and a 2 second timer. What am I doing wrong? I can understand the background being blurred, which is cool, but how do you go about getting the whole object in focus?

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Up your AV setting to at least 11, set your ISO accordingly and set the shutter setting to its appropriate value. It's your aperture setting that you want to increase (decrease in size) to get more DOF.

Basically, a wider aperture.

This will help:

http://www.dofmaster.c​om/dofjs.html

Thanks. That's kind of what I was thinking, but controlling the light was getting to be an issue for me. I took some at 7.1 and 1/320, but had to raise my ISO to 3200, and they still seemed a bit dark to me. To raise my AV to 11, I would need my shutter around 1/50, correct (while running ISO 3200)?

If you're on a tripod, there's no reason to raise your ISO. Simply lengthen your shutter speed.

But in your example you stated you were using a tripod, so absolutely no need for high iso.

Smaller aperture (Larger number) and more space between you and the target.

Ahhh, damn!! I was more worried about sharpness from the tripod and IS and never even thought about a longer shutter speed. Thanks bigtime guys! Trying to learn/remember one thing and I forgot about another, this gets confusing to me at times Unfortunately I'm all out of daylight, but I'm off tomorrow, so I'll have all day to play around.

Thanks again!!

kjonnnn wrote in post #14152426
One thing you might want to consider in this case with the item sitting in the window is that it might be backlit in daylight, and be underexposed. Experiment, and use the manual setting instead of AV. Set the aperture and shutter according to the meter, and then adjust to shutter to OVER expose a bit so that the subject item isn't underexposed.

I was in manual mode...actually, I've yet to experiment with AV & TV mode.

Ace and Deuce wrote in post #14152326
To raise my AV to 11, I would need my shutter around 1/50, correct (while running ISO 3200)?

Correct. That's the "exposure triangle". Closing your lens down from f/5.6 to f/8, you're letting in half the light. So either the shutter speed has to be lowered by half, i.e., 1/25, or the ISO has to be doubled to 1600. Going to f/11, half the light again, the shutter speed would be 1/13, or the ISO would be 3200 (at 1/50).

oldvultureface wrote in post #14152465
Correct. That's the "exposure triangle". Closing your lens down from f/5.6 to f/8, you're letting in half the light. So either the shutter speed has to be lowered by half, i.e., 1/25, or the ISO has to be doubled to 1600. Going to f/11, half the light again, the shutter speed would be 1/13, or the ISO would be 3200 (at 1/50).

This stuff is amazing (and fun) to learn! Thanks!

If you back up and use a longer lens, you can get a nicely blurred background while still keeping your entire subject in focus.

One other note. If you like that blurred background but want more DOF on the subject this is possible also. This is usually more applicable to portraiture, but here goes.

You can back up further from the subject and then use a longer focal length. If you stop down (use a smaller aperture) the DOF on the subject will increase, but the longer focal length with make the background blurrier.

So for example, 50mm and f/2 would give about the same background blur as 200mm and f/4 if you kept the framing the same (by moving back). But the longer lens would give more DOF due to using the smaller aperture.

And see what focal length does to your background. Shoot the subject at 55mm. Then frame the subject at 18mm keeping its size the same in the viewfinder (hint: move closer). Note how the view of the background changes. Nice for including/excluding background details.