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DPChallenge Forums >> Photography Discussion >> DOF and Shutter Speed
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 06/16/2007 11:41:14 PM · #1
I'm trying to photograph a structure along a pole, and I need good depth of field from top to bottom. I'm shooting in early evening sun, and my automatic shutter speed settings are between 1/200 and 1/320, but I'm not getting the best focus, and I think it's because of shallow depth of field.

How can I fix this? My thought is to manually set the shutter speed for, say, 1/100 (I'm picking that out of the blue) or something slower. Slower than 1/60 or so, and I think I'll need a tripod. But if I pick something too slow, then I risk overexposure, as part of the structure is in the sun.
 06/16/2007 11:49:36 PM · #2
Shallow DOF - use the largest aperture possible F/1.2 F/1.4 F/1.8 F/2.0 F/2.8 whatever u can do, but the focal length does effect how far or clsoe of a subject u can have in focus.

Good DOF, stop down the aperture to as small as you can go youll have to compromise between aperture and usable shutter speed.

Actually doing the math on a zoom lense u can find a dof calculator.

Message edited by author 2007-06-16 23:51:29.
 06/16/2007 11:52:21 PM · #3
I'm not sure what settings you have with your camera, however you are on the right line for getting a greater depth of field. I assume that your camera will automatically stop down the aperture in response to you forcing a slower shutter speed.
One thing you will need to do to maximize the dof is to focus the camera somewhere closer than infinity. It will likely be necessary to focus bracket (that is take a number of exposures with the focus at different distances) in order to find the optimum range of sharpness.
 06/16/2007 11:54:22 PM · #4
Unfortunately the olympus doesn't have Aperture Priority. Go into manual stop the aperture down. Id just shoot each time changing the shutter speed.

Im guessing the rule of sunny 16 works here?
 06/17/2007 12:07:16 AM · #5
Originally posted by RainMotorsports:
Unfortunately the olympus doesn't have Aperture Priority.

Um, I'd beg to differ. My 3 year old Oly C-740 has Aperture, Shutter and Manual. Manual is a PITA though.
 06/17/2007 12:13:49 AM · #6
Originally posted by _eug:
Originally posted by RainMotorsports:
Unfortunately the olympus doesn't have Aperture Priority.

Um, I'd beg to differ. My 3 year old Oly C-740 has Aperture, Shutter and Manual. Manual is a PITA though.


My 2.5 year old C-500 doesnt.

1 - I was wrong the C-7000 does.

2 - WTF does your olympus have todo with his? I said the Olympus not all Olpympus. LMAO

If it has Aperture priority mode would it not better to use?

Message edited by author 2007-06-17 00:17:12.
 06/17/2007 12:24:03 AM · #7
Bvy:
Depth of field is controlled by aperture, not shutter speed. How that's set depends on your camera's controls.

Look for a mode that lets you choose aperture - typically called aperture priority mode and labeled with an "A" on the selector. Everything I'm going to say depends on finding that mode. If your camera can't do that, I'm not sure what to suggest other than looking for a landscape setting, which will probably have a small aperture.

Set your aperture to something small, remembering that higher numbers mean smaller aperture. Try F/8, for example, as a start.

Your camera will then select a shutter speed that will properly expose at that aperture. If it's not reading right, so shots are over or underexposed, there are two possibilities depending on your camera's controls:
1) Set exposure compensation with the camera still in aperture priority mode. If it's underexposing (shots are too dark), set that above zero. If it's overexposing (shots are too bright) set it below zero.

2) Note the shutter speed the camera chose, switch to manual mode (typically marked "M") and change the shutter speed according to whether it was underexposing (choose a longer shutter) or overexposing (choose a shorter shutter).

I often find that when shooting against a bright background or the sky, I have to experiment to find the right settings, so M mode is handy.

Good luck!
 06/17/2007 12:25:02 AM · #8
There's a little matter of choosing a point of focus also. If the shooter is including the entire structure in the image and it is centered, then most likely the point of focus is in the middle of the structure and the foreground portion of the structure will be OOF. Estimate what point on the structure is 1/3 of the way in, center that point, press shutter button halfway to lock focus, then recompose and depress fully.

R.
 06/17/2007 01:18:03 AM · #9
Originally posted by Bear_Music:
There's a little matter of choosing a point of focus also. If the shooter is including the entire structure in the image and it is centered, then most likely the point of focus is in the middle of the structure and the foreground portion of the structure will be OOF. Estimate what point on the structure is 1/3 of the way in, center that point, press shutter button halfway to lock focus, then recompose and depress fully.

R.


Just a little side note on this one though.... when you do the third of the way in thing it may not look clear through your viewfinder but take the shot anyway and look at it to make sure but it should be right on.

It also sounds like maybe brother dusky blue sky might be your friend. There is a book titled Understanding Exposure by Bryan Peterson that I just finished reading the other day and although I haven't put it all to use yet, at least I think I understand more now. Send me a PM if you'd like me to quote some of the pertinent stuff from it for you with regards to your shooting situation. I'm no expert but I can give some of the info in this book.
 06/17/2007 10:46:21 AM · #10
Originally posted by levyj413:
Bvy:
Depth of field is controlled by aperture, not shutter speed. How that's set depends on your camera's controls.


So good DOF is a matter of adjusting aperture (smaller) versus shutter speed. That is, a smaller aperture will result in a slower shutter, but aperture is the variable to start with. Right? Also, I'm not comfortable with full manual settings, so I think I'll start with adjusting EC once I find an aperture that works.

I was glad to see your reply. It was your photo of the staircase (and the past attempts) that got me thinking about all this. Thanks!
06/17/2007 10:49:40 AM · #11
Easy way to remember how to control DOF is; slow down , close down. Open up, speed up.
 06/17/2007 10:52:40 AM · #12
Originally posted by Bear_Music:
There's a little matter of choosing a point of focus also. If the shooter is including the entire structure in the image and it is centered, then most likely the point of focus is in the middle of the structure and the foreground portion of the structure will be OOF. Estimate what point on the structure is 1/3 of the way in, center that point, press shutter button halfway to lock focus, then recompose and depress fully.

R.


So I think what I'm hearing is that objects beyond my focal point (work with me if I'm bastardizing terminology here) are more likely to be in focus, than objects before. So if I lock focus on an item about a third of the way up the structure (versus halfway or further up) then evething beyond that should stay in focus providing I've chosen a good aperture.
06/17/2007 11:05:14 AM · #13
Originally posted by bvy:
So good DOF is a matter of adjusting aperture (smaller) versus shutter speed.


Bingo!

Now let's discuss this in more depth.

DOF actually depends on four factors: aperture, focal length (which is determined by how much you zoom), distance to the subject, and sensor size (larger sensors mean smaller DOF, so SLRs have smaller DOF than point-and-shoots). So standing in the same spot, keeping your zoom level at the same amount, with the same camera, you change DOF just by changing aperture.

You've got the 1/3 thing right. Basically, some range is in focus - how deep that is in distance from your camera is the depth of field. But it's not centered around the place you focus. Instead, it's about 1/3 closer and 2/3 further away. "About" is important - it's not exact.

For example, if the sharp range is 3 feet, and you focus on a rock, about 1 foot of the ground closer to the camera will also be sharp and about 2 feet of the ground behind the rock will be sharp.

One last concept. For each combination of aperture and focal length, there's one distance that, if you put the subject there, the sharp range stretches to infinity. That's called the hyperfocal distance. Landscape photographers love this, because it lets them have an entire scene sharp. In contrast, portrait photographers usually want to blur the background, so they want to keep their subjects closer than the hyperfocal distance.

Thus, a landscape shooter might find the hyperfocal distance, focus 1/3 of that far away from the camera, and get almost everthing sharp. For example, if the hyperfocal distance is 60 feet, then everything from 20 feet to infinity will be sharp.

Here's a page with some good explanations, including two great diagrams: //photospot2004.blogspot.com/2004/07/depth-of-field-third-dimension.html

Look at the diagrams of the kid being focused on - see how the sharp range isn't centered on the kid?

And here's a depth of field calculator:
//www.dofmaster.com/dofjs.html

Play with it to get a sense of how this works. Be sure to plug in your camera model and the actual focal length, not the 35mm equivalent (PM me if you need that last bit explained). Some folks carry around sheets of info, and some SLR lenses have it marked on the barrel. For now, I just mess around until it looks good.

Thanks for the kind words about my stairs shots. :)

Message edited by author 2007-06-17 11:39:05.
 06/19/2007 07:14:07 AM · #14
Originally posted by levyj413:
Originally posted by bvy:
So good DOF is a matter of adjusting aperture (smaller) versus shutter speed.


Bingo!

Now let's discuss this in more depth.


Excellent stuff. Thanks so much for taking the time to post it. The links were especially helpful. I'm hoping I have time to take these skills back to the structure I originally spoke of before, well, tonight (to make the challlenge). Thanks again!
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