My struggle with Depth of Field

[owura]

I started shooting with DSLR just 24hrs ago. One aspect of SLR photography that I have always admired is the manipulation of depth. As a beginner,I realized that achieving a desired depth is not an easy feat. I played around with my camera for hours trying to get that effect in some of my pics and be able to replicate it whenever I desire, but that was remotely the result. I am not sure if I am at fault or my equipment is. From my understanding, the smaller the f value (my camera's lens is f/3.5 -22) the more blurred the background. I was wondering if there's any accessory that I can add to further lower the f number on my lens.

If anyone has any advice regarding how to practice achieving desired depth of field, I will really appreciate it. BTW,I have done a lot of reading regarding this, however, as the saying goes:experience is the best teacher. As such, I will be hoping to hear from some seasoned photographers. Here some shots I made. In #2 my intention was to keep on the third swing in focus but that didn't work out.

#1

Conifers time by owura02, on Flickr


#2

swings in the park by owura02, on Flickr


#3


IMG_6334 by owura02, on Flickr

 

[dxqcanada]

So explain the three images ...

 

[Jcampbelll]

Your background will be more out of focus when there is a greater distance between the subject and the background.

 

[Edsport]

You can't change the f values of the lens. A cheap canon 50 1.8 is about a hundred bucks on ebay and the 1.8 will give lots of blur to your backgrounds. To get more blur with the lens you have keep the background far away from the subject and getting closer to your subject if possible...

 

[white]

Camera depth of field works a lot like your eye. The closer the focus, the more pronounced the blur is.

Also, achieving narrow depth of field is not done just by selecting a large aperture. Several other factors come into play: lens focal length, distance of camera to subject, and distance of subject to background.

For clarity, depth of field means range of sharpness. All of your photos have sharp areas and blurry areas. But for a more pronounced effect, you are either going to need to get closer, shoot at a larger aperture (f/2.8 or larger), and invest in lenses in the 80mm - 135mm (and beyond) range.

 

[ann]

the first one shows some blur in the background, and not all the swings are sharp; however the flash fired on the 3rd so all bets are off.

 

[owura]

So explain the three images ...

Explain the images? How? All i was trying to do was to isolate subjects, which i think I did in #1 and #3 after several shots. In #2, as mentioned earlier, my goal was to isolate the third swing but I wasn't able to achieve that. As far as having themes for the pics, I didn't have any. I just went to the park just to practice. As I said earlier, that was my first time using a SLR.

 

[owura]

You can't change the f values of the lens. A cheap canon 50 1.8 is about a hundred bucks on ebay and the 1.8 will give lots of blur to your backgrounds. To get more blur with the lens you have keep the background far away from the subject and getting closer to your subject if possible...

Camera depth of field works a lot like your eye. The closer the focus, the more pronounced the blur is.

Also, achieving narrow depth of field is not done just by selecting a large aperture. Several other factors come into play: lens focal length, distance of camera to subject, and distance of subject to background.

For clarity, depth of field means range of sharpness. All of your photos have sharp areas and blurry areas. But for a more pronounced effect, you are either going to need to get closer, shoot at a larger aperture (f/2.8 or larger), and invest in lenses in the 80mm - 135mm (and beyond) range.

I have a 70 - 300mm zoom/macro lens. The issue is that, when in AF and I am too close the the subject, the shutter doesn't fire. So I am doing something wrong.

Your background will be more out of focus when there is a greater distance between the subject and the background.

Thank you all for responding. All of you mention that the background needs to be further away in order to be blurred. So, for instance, in #2, if I want to isolate the the third swing, how do I blur-out the first two swings and the others? Do I just move closer to the third? If I do that, I assume I will be cutting the first two from view.

 

[HikinMike]

I have a 70 - 300mm zoom/macro lens. The issue is that, when in AF and I am too close the the subject, the shutter doesn't fire. So I am doing something wrong.

No, that just means that you are too close. There is a minimum focus.

 

[clanthar]

Thank you all for responding. All of you mention that the background needs to be further away in order to be blurred. So, for instance, in #2, if I want to isolate the the third swing, how do I blur-out the first two swings and the others? Do I just move closer to the third? If I do that, I assume I will be cutting the first two from view.

Your swing set is a good exercise subject. You may be wishing for something that you can't have. The control that f/stop exercises over DOF is limited. DOF is a function of f/stop + magnification. Magnification is the dominant determinant of DOF. At a given magnification (lens focal length + distance focused + sensor size = magnification) you will have a working range of DOF possible from the range of available f/stops. That working range may be more or less than you'd like -- increasing the f/stop range may not help. Take the swings: Let's assume you used the 70mm end of your lens and have a camera with an APS sized sensor. Now let's assume you were 20 feet from the 3rd swing and took the shot at f/4.0. You've got 3.6 feet of total DOF -- more than you'd like. If you switch to a faster lens and try again at f/2.0 you'll lose 1/3 that DOF. The only way to lose more DOF without altering the composition of the photo then would be to increase the size of the sensor -- and that means a new camera.

Modern digital cameras have relatively small sensors compared for example with legacy film cameras. A common pro camera back in film days used 70mm film. As a rule modern digital cameras produce more DOF than older film cameras.

Joe

 

[pgriz]

Depth-of-field shrinks as the focal length (all other things being equal=AOTBE) increases.
Depth-of-field shrinks as the aperture becomes larger (AOTBE). [aperture numbers becoming smaller]
Depth-of-field shrinks as the subject becomes closer to the camera (AOTBE).
Depth-of-field shrinks as the sensor size increases (AOTBE).
The corollaries are also true.
So to control your depth of field, you need to think of subject placement relative to the background, the focal length you need to use, and the aperture.

A convenient way to calculate your depth-of-field is found at www.dopmaster.com.

 

[Professional]

Look at those shots, both done at f5.6, 1/30, ISO1600, 70mm, no flash, only the ambient light which was low and not enough, i used 30D as my 350D is with my dad to keep it for my kids, and i used 24-70 as i don't know where is my kit lens and i sold my 28-90, so i didn't have any choice, but at the end using different lenses at same focal length and same f-stop and on same camera will not give big difference in DoF.

 

[Canon AE-1]

You mean Hyperfocal Distance and Depth of Field Calculator - DOFMaster

 

[catrinahampton]

Camera depth of field works a lot like your eye. The closer the focus, the more pronounced the blur is.

Also, achieving narrow depth of field is not done just by selecting a large aperture. Several other factors come into play: lens focal length, distance of camera to subject, and distance of subject to background.

For clarity, depth of field means range of sharpness. All of your photos have sharp areas and blurry areas. But for a more pronounced effect, you are either going to need to get closer, shoot at a larger aperture (f/2.8 or larger), and invest in lenses in the 80mm - 135mm (and beyond) range.

Ditto this! The thing that made it click for me was this explanation.stand at an arms length or more away from a wall and put your hand six inches in front of your face and focus on you fingers. Notice how blurry the wall is? Now focus on the wall and see how blurry your hand looks. Now, put your hand six inches from the wall and focus on your fingers...the wall isn't very blurry anymore. Dof has a lot to do with distance between the subject and its surroundings.