Learning DOF

[crotonmark]

Please tell me what i am doing wrong - there is very little apparent difference between these two pictures
The settings are F/22 and F4.5
I expected the larger aperture to show an image with more blurring of the bottles

Canon T4i

thanks - Mark

View attachment 25987View attachment 25988

 

[invisible]

Please tell me what i am doing wrong - there is very little apparent difference between these two pictures
The settings are F/22 and F4.5
I expected the larger aperture to show an image with more blurring of the bottles

You're not doing anything wrong, but it looks like you got things a little bit confused. A larger f/stop number (in this case, f/22) means a smaller aperture – this allows for deeper DOF, thus most of your first image is in focus. Conversely, a smaller f/stop number (here f/4.5) means a wider aperture – as a result you get a shallower DOF.

Hope this helps.

 

[MLeeK]

The larger aperture is f/4.5
The smaller aperture is f/22

 

[crotonmark]

yes thank you
But there is not MUCH difference between the two photos even tho the F stops are widely different
that is what I was asking about
According to Peterson there should be a very crisp photo and one that has a shallow blurred DOF
that I didnt get and was wondering why

Mark

 

[Tee]

I can see a difference but I'm guessing the difference isn't as dramatic enough for you? Don't forget the relationship of distance between you and the subject and the subject to the background.

 

[invisible]

Aperture is not the only variable that determines depth of field. The other two are focal length and distance from the lens to the subject. The longer the focal length, the shallower the DOF. The shorter the distance from lens to the subject, the shallower the DOF.

 

[sm4him]

yes thank you
But there is not MUCH difference between the two photos even tho the F stops are widely different
that is what I was asking about
According to Peterson there should be a very crisp photo and one that has a shallow blurred DOF
that I didnt get and was wondering why

Mark

Sure you did. Looks like your focus was on that third bottle from the front. Look at the first bottle; in the first picture, it's also fairly "in focus" and easy to read. In the bottom photo, it's so blurred and oof that you can barely read it at all (well, *I* can't, but granted, I have vision issues).

Also, look BEHIND that third bottle. Not at the other bottles, but directly behind it at the concrete. Again, in the first picture, the concrete is still reasonably sharp, but in the bottom picture it is considerably more oof.

 

[crotonmark]

yes thank you
But there is not MUCH difference between the two photos even tho the F stops are widely different
that is what I was asking about
According to Peterson there should be a very crisp photo and one that has a shallow blurred DOF
that I didnt get and was wondering why

Mark

Sure you did. Looks like your focus was on that third bottle from the front. Look at the first bottle; in the first picture, it's also fairly "in focus" and easy to read. In the bottom photo, it's so blurred and oof that you can barely read it at all (well, *I* can't, but granted, I have vision issues).

Also, look BEHIND that third bottle. Not at the other bottles, but directly behind it at the concrete. Again, in the first picture, the concrete is still reasonably sharp, but in the bottom picture it is considerably more oof.

Yes. Thanks. It's just Peterson's examples are so dramatic I'm disappointed.

 

[sm4him]

yes thank you
But there is not MUCH difference between the two photos even tho the F stops are widely different
that is what I was asking about
According to Peterson there should be a very crisp photo and one that has a shallow blurred DOF
that I didnt get and was wondering why

Mark

Sure you did. Looks like your focus was on that third bottle from the front. Look at the first bottle; in the first picture, it's also fairly "in focus" and easy to read. In the bottom photo, it's so blurred and oof that you can barely read it at all (well, *I* can't, but granted, I have vision issues).

Also, look BEHIND that third bottle. Not at the other bottles, but directly behind it at the concrete. Again, in the first picture, the concrete is still reasonably sharp, but in the bottom picture it is considerably more oof.

Yes. Thanks. It's just Peterson's examples are so dramatic I'm disappointed.

What are you shooting with--what lens? And what were the examples shot at that are so "dramatic?"
If you have a lens that can get wider, you'll notice much more difference at 2.8 than at 4.5--but also, as has been mentioned already by several others, it's not JUST about aperture. Your focal length, AND the distance from lens to subject also factor in.
Unless you are keeping all the other variables exactly the same as in his examples, you aren't necessarily going to get the same dramatic results. But what you've GOT should be enough to get the point across.

 

[crotonmark]

Canon T4i
shooting on a tripod
Aperture priority
Canon 35-105 mm lens F3.5/4.5

Peterson says with large aperture everything but the focused image will blur out - this didnt happen to me
What do I need to do to get a dramatic change?
I was about 4-5 ft from the bottles

 

[invisible]

Canon T4i
shooting on a tripod
Aperture priority
Canon 35-105 mm lens F3.5/4.5

Peterson says with large aperture everything but the focused image will blur out - this didnt happen to me
What do I need to do to get a dramatic change?
I was about 4-5 ft from the bottles

Get closer to the subject, shoot at 135mm at the largest aperture your lens allows.

EDIT: also, for a more dramatic effect, focus on the first bottle and see how this effects the others.

 

[Overread]

Use a longer focal length and shoot from further away.

Distance greatly affects the depth of field just as the aperture does. So if you want to frame a shot like the ones above and have reduced depth of field you've got to shoot from further away. And if you're further away you'll need a longer focal length to be able to frame the same content.

Try comparing the same aperture (say f4) at 35mm and at 105mm

Also note that its not just your distance but your subjects as well. If you want a more dramatic falloff of sharpness having a greater distance between your subject and the background areas helps a lot. In your photos there is a general soft gradient between the bottles and the background, so the depth of field falls off more slowly, if you want that sharper change you've got to have a background that is a lot further away.

 

[invisible]

Use a longer focal length and shoot from further away.

Distance greatly affects the depth of field just as the aperture does. So if you want to frame a shot like the ones above and have reduced depth of field you've got to shoot from further away. And if you're further away you'll need a longer focal length to be able to frame the same content.

Try comparing the same aperture (say f4) at 35mm and at 105mm

Also note that its not just your distance but your subjects as well. If you want a more dramatic falloff of sharpness having a greater distance between your subject and the background areas helps a lot. In your photos there is a general soft gradient between the bottles and the background, so the depth of field falls off more slowly, if you want that sharper change you've got to have a background that is a lot further away.

I think that s/he wanted to see only the subject in focus and the rest of the frame blurred. What you're suggesting will produce the opposite result

 

[crotonmark]

Use a longer focal length and shoot from further away.

Distance greatly affects the depth of field just as the aperture does. So if you want to frame a shot like the ones above and have reduced depth of field you've got to shoot from further away. And if you're further away you'll need a longer focal length to be able to frame the same content.

Try comparing the same aperture (say f4) at 35mm and at 105mm

Also note that its not just your distance but your subjects as well. If you want a more dramatic falloff of sharpness having a greater distance between your subject and the background areas helps a lot. In your photos there is a general soft gradient between the bottles and the background, so the depth of field falls off more slowly, if you want that sharper change you've got to have a background that is a lot further away.

Overread. Thanks. How far away from the fort bottle hold I put the camera? Alo if I move away and shoot at 35mm won't the entire shot be out of focus??


Thanks

 

[crotonmark]

Use a longer focal length and shoot from further away.

Distance greatly affects the depth of field just as the aperture does. So if you want to frame a shot like the ones above and have reduced depth of field you've got to shoot from further away. And if you're further away you'll need a longer focal length to be able to frame the same content.

Try comparing the same aperture (say f4) at 35mm and at 105mm

Also note that its not just your distance but your subjects as well. If you want a more dramatic falloff of sharpness having a greater distance between your subject and the background areas helps a lot. In your photos there is a general soft gradient between the bottles and the background, so the depth of field falls off more slowly, if you want that sharper change you've got to have a background that is a lot further away.

I think that s/he wanted to see only the subject in focus and the rest of the frame blurred. What you're suggesting will produce the opposite result

Invisible. You are right. How o I get only the subject in focus?