I have a P&S but it is fancier so I can still change shutter speed etc. I've seen so many nice photos where the BG is blurred. the one time I get this effect is when I'm doing a macro shot or if I go ply with my photoshop. How do you get this effect straight from the camera? Use layman’s terms please otherwise you might lose me.
Thanks!
Posted by Wim Reyns on February 25, 2008 at 4:47 AM
The most easy way is to get your subject as close to you as possible and your background as far behind that as possible. Then use a small aperture value and you should be ok.
Wim
Posted by Ed Cordes on February 25, 2008 at 7:39 AM
Wim is correct. Just remember that a small aperture value is a small f stop number, like f 2.8, but it is actually a larger diameter opening of the aperture blades. So, f 2.8 will give you a much shallower depth of field (DOF) than f 16.
Posted by David Bostedo on February 25, 2008 at 9:35 AM
Unfortunately, sensor size also affects this, and with a P&S's small sensor, for a given aperture you get a MUCH larger depth of field. So more of the scene is always in focus, even if you use an aperture like f/2.8. It is possible to get nicely blurred backgrounds with a P&S, but the subject needs to be fairly close, and the background needs to be well behind the subject (like hundreds of feet sometimes). Even then, it may not be as smooth as you'd get with a larger sensor. Apertures would need to be much larger (a lower number) than is possible, to get the same result as a larger sensor.
You can also go to work in Photoshop and add blur to the background. We have to do this any time a background is too close to subjects in our commercial and portrait shooting. Slow and tedious but effective is using the blur tool. Fast and more controllable is using a Gaussian Blur filter on a layer mask.
Hi, Jen - if you're interested in more serious photography, you really need to do more with photoshop. Every digital picture, imo, needs sharpenbing, at the very least. Then, other simple-to-learn things will also be a great benefit.
Then, if you're interested, you can learn as much more in Photoshop aas you want.
If you'd email me with your email address, i'll be happy to share some tips.
Sandy r
Portland, OR
MoonshadowRN@yahoo.com
Posted by Lon Overacker on February 25, 2008 at 2:38 PM
Hi Jen,
Hopefully what has already been said was helpful. In general, the wider the aperture (f2.8,f4,f5.6) the less depth of field. The smaller the number the bigger the lense opening. But just as important is the lens to subject distance and distance to background. As has been mentioned, the farther away the background is, the more likely it will be out of focus (assuming the wide aperture (f2.8) AND you're focused on the foreground object.
Practice, practice, practice... It's pretty easy to experiment and for most of us, a much better way to learn than reading a book. Find a tree or something you can get close to, say less than 10ft and make sure there is something in the background that's at least a 100ft or more away. Take some images with various settings and watch what happens. Focus on the foreground, change the settings. Then try focusing way in the background and watch what happens to the foreground.
Hope this helps,
Lon
Posted by Basil Greber on February 25, 2008 at 7:21 PM
All the things that have been said are correct. Bigger magnification ratio (macro & close-up) reduces depth of field (= blurry backgrounds), bigger foreground/background separation does it, too. But in the end, the conclusion is frustratingly simple: If you want clean backgrounds also in non-ideal situations, you need a DSLR with a fast lens. I'm not saying you need a DSLR to take good images, even though it certainly helps with some aspects, but the bigger sensor is really essential to obtain that typical shallow DoF look.
On the other hand, obtaining a lot of DoF is more easily achieved with small sensor cameras (such as P&S cameras) - something I'm often envious of when taking macro shots, where DoF gets insanely shallow (so shallow that almost nothing is in focus) with a DSLR unless you're stopping down a lot.
Basil
Posted by Dan Borzynski on February 26, 2008 at 2:11 AM
Depth of field is depth of field is depth of field. The sensor size has NOTHING directly to do with depth of field. It is a function of magnification and f-stop, nothing more.
For for cameras with small sensors, to obtain the equivalent of 50mm on 35 mm, or any other focal length, a lens of focal length 8-15 mm is used (or some significantly smaller focal length). The net result is that you get a picture which has all of the properties of a 35mm lens of focal length 8-15 mm (or some significantly smaller focal length).
So why does it look like there is more depth of field? Because so much more of the background is taken in and is smaller. This means that to your eye, those trees in back are sharper looking.
With a longer focal length, say a *real* 100mm, or a *real* 200 mm, not an effective 100 or 200 mm with sensor cropping, there is far less of the background to spread across the frame of the image. A background tree that would be 1 mm across in the frame on a 15 mm lens is now 10 mm across on a 150 mm lens, but just as out of focus, giventhe same f-stop, subject distance and focal distance.
The difference in apparent depth of field in a small point and shoot and a larger dSLR is exclusively due to the ability to control the background with a *real* longer focal length, not an effective longer focal length. It is for this same reason that you can get those nice, smooth backgrounds you see in macro shots.
Beyond that, everything is good advice.
Posted by Benjamin Glatt on February 26, 2008 at 4:55 AM
Wim and Ed are mistaken. You want to use a large aperture (small F-stop) to achieve your desired depth of field. The smaller the aperture, the larger the F-stop.
Posted by Basil Greber on February 27, 2008 at 7:12 PM
Dan, you're wrong. Sorry to be so blunt, but this is it. DoF is related to reproduction ratio (combining focal length and focus distance into one variable) and f-stop. And for a smaller sensor, the reproduction ratio is of course smaller for the same composition.
What you say about the longer lenses is correct, that's why a long tele is so nice for insect macros - you can chose the background more precisely. But as you said, DoF is DoF is DoF, and is not the same as cleaner background.
Basil
Posted by Benjamin Glatt on February 27, 2008 at 8:49 PM
Posted by David Bostedo on February 27, 2008 at 10:48 PM
Ben - Basil is correct, and while the article you posted isn't wrong, it's making a correlation that doesn't really have anything to do with optics or the equations that determine DoF. That's one of the problems with the topic - there are lots of practical ways to think about it, many of which don't get at the underlying reasons. You can correlate sensor size to DoF because of the other factors mentioned. The actual sensor size doesn't really affect DoF. Rather the lens used, and focus distance, combined with aperture tend to be different for a smaller sensor, and create a different DoF.
Look at it this way - if you took a full frame DSLR, like a 1DsIII, and inserted a P&S sensor, you'd get the same DoF, and just a much smaller part of the image. The sensor size wouldn't change the DoF.
Here's a good article showing how angle of view and focal length don't affect DoF - just the size of the object in the image (which affects focus distance) and the aperture. Only those two things.
As Dan stated and the article shows, you may appear to get more DoF with a wider angle simply because you shrink all the objects in the BG to the point at which they may seem more in focus. (And Dan, the shorter lenses used with a P&S don't take in more BG - they have the same field of view as the 35mm lenses after the sensor multiplication factor is taken into account.)
(Finally, sorry to the original poster if they are getting emailed all of my edits...there were several as I read and re-read.)
Discussion
12 repliesThanks!
Wim
Then, if you're interested, you can learn as much more in Photoshop aas you want.
If you'd email me with your email address, i'll be happy to share some tips.
Sandy r
Portland, OR
MoonshadowRN@yahoo.com
Hopefully what has already been said was helpful. In general, the wider the aperture (f2.8,f4,f5.6) the less depth of field. The smaller the number the bigger the lense opening. But just as important is the lens to subject distance and distance to background. As has been mentioned, the farther away the background is, the more likely it will be out of focus (assuming the wide aperture (f2.8) AND you're focused on the foreground object.
Practice, practice, practice... It's pretty easy to experiment and for most of us, a much better way to learn than reading a book. Find a tree or something you can get close to, say less than 10ft and make sure there is something in the background that's at least a 100ft or more away. Take some images with various settings and watch what happens. Focus on the foreground, change the settings. Then try focusing way in the background and watch what happens to the foreground.
Hope this helps,
Lon
On the other hand, obtaining a lot of DoF is more easily achieved with small sensor cameras (such as P&S cameras) - something I'm often envious of when taking macro shots, where DoF gets insanely shallow (so shallow that almost nothing is in focus) with a DSLR unless you're stopping down a lot.
Basil
For for cameras with small sensors, to obtain the equivalent of 50mm on 35 mm, or any other focal length, a lens of focal length 8-15 mm is used (or some significantly smaller focal length). The net result is that you get a picture which has all of the properties of a 35mm lens of focal length 8-15 mm (or some significantly smaller focal length).
So why does it look like there is more depth of field? Because so much more of the background is taken in and is smaller. This means that to your eye, those trees in back are sharper looking.
With a longer focal length, say a *real* 100mm, or a *real* 200 mm, not an effective 100 or 200 mm with sensor cropping, there is far less of the background to spread across the frame of the image. A background tree that would be 1 mm across in the frame on a 15 mm lens is now 10 mm across on a 150 mm lens, but just as out of focus, giventhe same f-stop, subject distance and focal distance.
The difference in apparent depth of field in a small point and shoot and a larger dSLR is exclusively due to the ability to control the background with a *real* longer focal length, not an effective longer focal length. It is for this same reason that you can get those nice, smooth backgrounds you see in macro shots.
Beyond that, everything is good advice.
What you say about the longer lenses is correct, that's why a long tele is so nice for insect macros - you can chose the background more precisely. But as you said, DoF is DoF is DoF, and is not the same as cleaner background.
Basil
Look at it this way - if you took a full frame DSLR, like a 1DsIII, and inserted a P&S sensor, you'd get the same DoF, and just a much smaller part of the image. The sensor size wouldn't change the DoF.
Here's a good article showing how angle of view and focal length don't affect DoF - just the size of the object in the image (which affects focus distance) and the aperture. Only those two things.
As Dan stated and the article shows, you may appear to get more DoF with a wider angle simply because you shrink all the objects in the BG to the point at which they may seem more in focus. (And Dan, the shorter lenses used with a P&S don't take in more BG - they have the same field of view as the 35mm lenses after the sensor multiplication factor is taken into account.)
(Finally, sorry to the original poster if they are getting emailed all of my edits...there were several as I read and re-read.)