Ok, I was playing around for the still life challenge, and I liked the condensation on the wine bottle. I can't seem to get a picture with enough depth of field when I shoot indoors. I'm using my 100mm macro lens, but using it as a regular lens. I was about 6-8 ft away, and this was shot at f32. The glass was right next to the wine bottle. When shooting indoor table shots, what lens/distance do you use to get a greater depth of field?
Ok, I was playing around for the still life challenge, and I liked the condensation on the wine bottle. I can't seem to get a picture with enough depth of field when I shoot indoors. I'm using my 100mm macro lens, but using it as a regular lens. I was about 6-8 ft away, and this was shot at f32. The glass was right next to the wine bottle. When shooting indoor table shots, what lens/distance do you use to get a greater depth of field?
f/32, 100mm lens, focused at 7 feet, should give you a couple FEET of DOF, kiddo. Something's not computing here.
You might try the same shot at f/16 or f/18. Even though a 100mm macro lens will stop down to f/32, the lens will lose sharpness at that setting due to technical reasons that I can't quote at the moment. Most technical articles I've seen on the subject recommend not going smaller than f/22.
A quick calculation using 100mm, 10 foot subject distance and f/16 gives 1.1 feet (13.2 inches) of DoF. I'm using 0.012mm as the circle of confusion, and this is approximately correct for the 40D.
You should not have to stop down further than f/16, and in fact doing so will give softer results because of diffraction. Make sure your focus distance is correct. Try setting focus manually, and tweaking slightly, taking test shots at each setting.
Maybe camera shake had more to do with the softness than the aperture setting. With a 100mm lens, it's pretty easy to have vibration, even with a tripod in some situations.
Maybe camera shake had more to do with the softness than the aperture setting. With a 100mm lens, it's pretty easy to have vibration, even with a tripod in some situations.
I don't shoot with mirror lock up--does that make a big difference?
Maybe camera shake had more to do with the softness than the aperture setting. With a 100mm lens, it's pretty easy to have vibration, even with a tripod in some situations.
I don't shoot with mirror lock up--does that make a big difference?
Tripod and mirror lockup make a BIG difference yes. Here's a brief statement re: relationship of DOF and Circle of Confusion:
The depth of field is the region where the size of the circle of confusion is less than the resolution of the human eye (or of the display medium). Circles with a diameter less than the circle of confusion will appear to be in focus.
It's a complex topic. In any case, stopping down beyond f/16, say, on a 100mm, is to be avoided. ON my 10mm, f/8 is about as far as I like to go, and no further than f/11... Generally, it looks to me like you're having issues that have little, if anything, to do with DOF and are related to other factors. I'd suggest making a bright, crisp setup for practice purposes, one with a lot of contrast where you can really nail the focus, and try shooting that at different f/stops.
Incidentally, as a rule of thumb, the DOF extends 1/3 in front of the point of focus and 2/3 behind it. So if you have 12 inches of DOF when focused on your wine bottle, say, then 4 inches of it is in front of the wine bottle and 8 inches of it behind the wine bottle. You have to choose where to focus to maximize DOF over the area where you want it. In a studio setup, we'd frame up the image, then use a tape to measure precisely the near and far limits we needed to have on focus, then we'd use a DOF calculator to derive from that the f/stop needed and the precise distance at which to focus. Then we'd use a focusing marker inserted into the scene to attain that focus. This was primarily when photographing architectural models, which we did a lot of, but it's a general rule for all sorts of commercials setups.
Thanks all!
I'll play around with this. It's been a frustration in a couple of different challenges--I'm usually shooting from much farther away or larger things close up. Miniatures, especially were a problem. When everything's so tiny, it's really obvious when it's out of focus!
When you stop the aperture down, the open shutter time has to be doubled for each stop to get the same exposure value or "EV". For instance, if the correct EV at f5.6 is 1/125 sec, you would be shooting at 1/15 sec at f16 to get the same EV.
For subjects that don't change much while you are shooting, you may also want to use a remote shutter release, or the self timer in the camera to remove the hand shake from the equation. Try looking through the viewfinder with the 100 mm lens, and with the camera turned off, and you can see the motion caused by pressing the shutter button. If you want to see how much vibration and hand shake you are getting, strap a small laser pointer to the side of your lens with rubber bands, and watch the spot on the far wall of the room. I use the self timer set at 2 sec quite often for hand holding shots, and the difference in the sharpness of hand held images is quite noticeable.
ETA, I always thought that "circle of confusion" was a reference to forum threads discussing challenge descriptions.
I tried to input a typical shot that I've been doing lately in which my goal is to achieve what appears to be 100% depth of field throughout my image.
Here's my input data:
focal length: 13 mm
f-number: 4.5
focused distance: 5 m (I also tried spelling out 'meters')
circle of confusion: .25 mm
Here are the results:
The near and far limits shown are closer to me than the focused distance that I entered.
Am I reading and/or doing this wrong?
I am wondering if I can use my Tokina 12-24 at about 13mm and get 100% dof throughout my image from about 6 feet to infinity without having to use anything other than the largest aperture. I am shooting in dark and stormy conditions from a kayak and need to maintain enough shutter speed to keep the image sharp.
Did you use a halogen light for the lighting and then color correct? I've seen image degradation from this before as camera sensors don't deal with reds as well as other ranges and the halogens give off a very red light.
It should be 0.025??? I thought the circle of confusion was a variable that I determined based on what I considered acceptable. Otherwise it wouldn't be changeable. I chose .25 mm because of the greater distance from my subject (the foreground) which means that I wouldn't be able to discern anything 0.025 mm in diameter anyway.
But maybe I'm totally confused about it. I don't understand how the circle of confusion factors into the equation anyway and how it would affect the final determination of dof.
Whatever value is used for the circle of confusion, the dof should at least be before and after the chosen focus distance. It didn't compute that way however.
Yep, it seems the Wolfram calculator is giving erroneous results, which is odd, because it seems to be fine for longer focal lengths, and seems reasonable for small focal lengths when the focus distance is short. But it should *never* report a negative DoF. Something is amiss. I'll test this a little further when I get home.
But maybe I'm totally confused about it. I don't understand how the circle of confusion factors into the equation anyway and how it would affect the final determination of dof.=
And thus it's name ;-)
Actually, you will hear different opinions about what the Circle of Confusion *should* be set to, and yoiu can make a good, logical case for very different values, especially if you are talking about viewing prints made from the images. For judging whether you will make an image *on the sensor* that is less blurry than the sensor can detect, set your Circle of Confusion value to twice your camera's pixel pitch. For instance, for the OP's Canon 40D, the pitch is 5.7µm, or 0.0057mm, so setting CoC to 0.011mm is optimal under the conditions I cited.
OK, the Wolfram calculator seems to puke whenever the far limit of focus is at infinity. The denominator in the equation goes negative, driving the far limit negative, and invalidating the result. The near limit seems fine and correlates well to DoFMaster, which is the one I've always used.
OK, the Wolfram calculator seems to puke whenever the far limit of focus is at infinity. The denominator in the equation goes negative, driving the far limit negative, and invalidating the result. The near limit seems fine and correlates well to DoFMaster, which is the one I've always used.
OK, the Wolfram calculator seems to puke whenever the far limit of focus is at infinity. The denominator in the equation goes negative, driving the far limit negative, and invalidating the result. The near limit seems fine and correlates well to DoFMaster, which is the one I've always used.
Now that one seems to work, or at least confirm what I've been thinking.
Again, I was trying to confirm that I could use my Tokina 12-24 at 13mm (to avoid vignetting with polarizer) to get 100% dof from the ground (or water) just in front of me to infinity without stopping the lens down. I need to keep a decently fast shutter speed since I'm shooting from a kayak and although I sometimes stick a tripod into the sand/muck, it's a hassle.
This DoFMaster calculates that I can focus on a point 8 feet away and have acceptable dof from 3.5 feet in front of me to infinity without stopping down the aperture.
This DoFMaster calculates that I can focus on a point 8 feet away and have acceptable dof from 3.5 feet in front of me to infinity without stopping down the aperture.
Yep, should be possible... do be very careful with the focus setting. If you are set even a little bit (less than a foot) inside the hyperfocal distance, your far distance will get blurry. Best practice is to test, find the critical focus setting, set it just a foot or so longer and mark or lock it.
