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Difficulties isolating subjects with my Canon 50mm f/1.4 lens
I'm still very much new to photography, but I'm having trouble isolating subjects even with an aperture of f/2. I can't prove it, but while I was playing with my camera earlier today, I notice in the playback that the farther I am from the subject the less bokeh I get and the closer I get to the subject the more bokeh I get...

Comments (22)

Bokeh is not a "more or less" effect. It is a "smoother" or not so smooth, concept..

I.e., what's the nature of the blur or fuzziness, not how much blur or fuzziness is there..

Depth of field is the concept that defines how much of the depth of a picture is sharp. Are the fence, five feet away, and the tree, ten feet away, or is just the kid's wagon, half way between the fence and the tree, in focus..

Bokeh is the nature of the blur of the out of focus flowerbeds against the house..

The closer you are to something, the less the depth of field..

In our fence / tree example, there's five feet between them, and five feet from you to the fence..

Back up twenty feet from the fence, focus on the wagon inbetween the tree and fence, and you'll find lots of additional depth of field... more stuff behind the tree and more stuff n front of the fence will be sharp..

YOUR 50mm at f2 if you want the background fuzzier, increase the distance from the subject to the background, and aim the camera so that the background objects lend themselves to looking good while fuzzy. Big round flowers look a lot better in the background than an 1989 Plymouth Voyageur.

BAK..

Comment #1

BAK wrote:.

Bokeh is not a "more or less" effect. It is a "smoother" or not sosmooth, concept..

I.e., what's the nature of the blur or fuzziness, not how much bluror fuzziness is there..

Depth of field is the concept that defines how much of the depth of apicture is sharp. Are the fence, five feet away, and the tree, tenfeet away, or is just the kid's wagon, half way between the fence andthe tree, in focus..

Bokeh is the nature of the blur of the out of focus flowerbedsagainst the house..

The closer you are to something, the less the depth of field..

In our fence / tree example, there's five feet between them, and fivefeet from you to the fence..

Back up twenty feet from the fence, focus on the wagon inbetween thetree and fence, and you'll find lots of additional depth of field...more stuff behind the tree and more stuff n front of the fence willbe sharp..

YOUR 50mm at f2 if you want the background fuzzier, increase thedistance from the subject to the background, and aim the camera sothat the background objects lend themselves to looking good whilefuzzy. Big round flowers look a lot better in the background than an1989 Plymouth Voyageur.

BAK.

Okay, I think I get it...

Comment #2

You need to go online and find a DOF calculator and play with it; experimenting with different settings for each of your lenses. That way you can get a better feel for the DOF for each lens you use..

Johnny.

Http://www.flickr.com/photos/latitudes/..

Comment #3

JohnnyBlood wrote:.

You need to go online and find a DOF calculator and play with it;experimenting with different settings for each of your lenses. Thatway you can get a better feel for the DOF for each lens you use..

Johnny.

Http://www.flickr.com/photos/latitudes/.

Please excuse for this stupid question, but why do I need a Depth of Field calculator? To calculate the distance that I need to be in order to "force" bokeh?..

Comment #4

Sgt_Strider wrote:.

JohnnyBlood wrote:.

You need to go online and find a DOF calculator and play with it;experimenting with different settings for each of your lenses. Thatway you can get a better feel for the DOF for each lens you use..

Please excuse for this stupid question, but why do I need a Depth ofField calculator? To calculate the distance that I need to be inorder to "force" bokeh?.

To force "out of focus", yes. As has been mentioned, "bokeh" is a subjective quality, some lenses have inherently "good" bokeh, with others the bokeh is harsh..

The DOF calculator cannot tell you anything about bokeh, but it can guide you in finding the right conditions for achieving out-of focus background (and foreground as appropriate).As to the suggestion:.

You need to go online and find a DOF calculator and play with it;.

That is one approach. Personally, even though I understand numbers pretty well, I prefer to go out and shoot some pictures while varying the distances: camera to subject, subject to background as well as lens aperture. They say a picture says a thousand words. Well, just my opinion, the theoretical knowledge is useful too, try this:http://www.dofmaster.com/dofjs.html.

Regards,Peter..

Comment #5

Sherwoodpete wrote:.

Sgt_Strider wrote:.

JohnnyBlood wrote:.

You need to go online and find a DOF calculator and play with it;experimenting with different settings for each of your lenses. Thatway you can get a better feel for the DOF for each lens you use..

Please excuse for this stupid question, but why do I need a Depth ofField calculator? To calculate the distance that I need to be inorder to "force" bokeh?.

To force "out of focus", yes. As has been mentioned, "bokeh" is asubjective quality, some lenses have inherently "good" bokeh, withothers the bokeh is harsh.The DOF calculator cannot tell you anything about bokeh, but it canguide you in finding the right conditions for achieving out-of focusbackground (and foreground as appropriate).As to the suggestion:.

You need to go online and find a DOF calculator and play with it;.

That is one approach. Personally, even though I understand numberspretty well, I prefer to go out and shoot some pictures while varyingthe distances: camera to subject, subject to background as well aslens aperture. They say a picture says a thousand words. Well, justmy opinion, the theoretical knowledge is useful too, try this:http://www.dofmaster.com/dofjs.html.

Regards,Peter.

Thanks for the link, but how can I interpret those numbers? I know this may be asking too much, but do you think you can provide me with an example such as your focal length and aperture and then explain to me what all those numbers on that site mean? Such as the near limit, far limit, and total limit for depth of field...

Comment #6

Sgt_Strider wrote:.

Thanks for the link, but how can I interpret those numbers? I knowthis may be asking too much, but do you think you can provide me withan example such as your focal length and aperture and then explain tome what all those numbers on that site mean? Such as the near limit,far limit, and total limit for depth of field..

Just look at the diagrams underneath the Depth of Field Calculator.Chris R..

Comment #7

But do you think you can provide me with an example such as yourfocal length and aperture and then explain to me what all thosenumbers on that site mean..

If you do not get a 'feel' for the settings of your lenses and the corresponding DOF you will continue to have trouble perfectly isolating your subjects and creating the best possible blur/bokeh. The numbers do not need to be memorized, but getting a feel for how your lens works at different apertures and distances from your subject is essential. Otherwise you're just making stabs in the dark or just taking snapshots..

Johnny.

Http://www.flickr.com/photos/latitudes/..

Comment #8

Sgt_Strider wrote:.

.... I notice in theplayback that the farther I am from the subject the less bokeh I getand the closer I get to the subject the more bokeh I get..

Exactly right..

Depth_of_field/Width_of_field = constant*F-stop*Distance_to_subject.

For small depth of field (compared to field width), move closer and/or open the lens..

Dave.

PS for the same image composition wide angle lenses have smaller DOF because you've got to move closer to the subject to keep the same composition...

Comment #9

Dave Martin wrote:.

Sgt_Strider wrote:.

.... I notice in theplayback that the farther I am from the subject the less bokeh I getand the closer I get to the subject the more bokeh I get..

Exactly right..

Depth_of_field/Width_of_field = constant*F-stop*Distance_to_subject.

For small depth of field (compared to field width), move closerand/or open the lens..

Dave.

PS for the same image composition wide angle lenses have smaller DOFbecause you've got to move closer to the subject to keep the samecomposition..

Don't get me started .

If I was to comment, I might say that moving the camera closer alters the composition.But I won't say anything this time Regards,Peter..

Comment #10

What I wrote earlier was wrong. Moving closer while keeping the same magnification* by adjusting focal length does NOT change DOF..

The relationship is:.

DoF/WoF=constant*F-Stop*(1+1/magnfication).

So for a particular camera and size of the subject in the frame, depth of field does not depend on distance to the subject - however, perspective does depend on distance to the subject..

Sorry,.

Dave.

*magnification is image_size/object_size...

Comment #11

Here's a DOF comparison site from Tamron for seeing how their various lenses compare..

Link goes to the explanation page, click on the little orange square on the right side to actually start the demonstrator..

Adjust the aperture on the vertical scale/axis, adjust the focal length on the horizontal scale/axis, and the Tamron lens(es) that meet the criteria (if Tamron makes one) will be highlighted in orange on the right hand side in the lens list..

Http://www.tamroneurope.com/...fentiefenvergleich.289.0.html?&L=0&L=2.

Good Day,Roonal.

'Money doesn't buy happiness, but it makes for an extravagant depression' by golf tournament sportscaster..

Comment #12

Sgt_Strider wrote:.

I'm still very much new to photography, but I'm having troubleisolating subjects even with an aperture of f/2. I can't prove it,but while I was playing with my camera earlier today, I notice in theplayback that the farther I am from the subject the less bokeh I getand the closer I get to the subject the more bokeh I get..

I've noticed that too. .

As you were scolded, "bokeh" is not the amount of OOF, but rather a "feeling" when you view an OOF object. If the OOF object is smooth and doesn't show any iris artifacts, then the "bokeh" is said to give a good "feeling"....

But I think you want MORE OOF objects in the background, so to INCREASE the blur (decrease the sharpness):.

1. Use a wider aperture2. Get the camera closer to the subject (that you want sharp).

3. Get the subject (that you want sharp) farther from the background (that you want blurry).

After you achieve a blurry background, then you can go to the next step, which is to become sensitive to poor "bokeh"....

Charlie DavisNikon 5700, Sony R1, Nikon D300HomePage: http://www.1derful.infoBridge Blog: http://www.here-ugo.com/BridgeBlog/..

Comment #13

Bokeh is the smoothness of the out of focus (OOF) areas, not how much is OOF as such. You're talking about how much is blurry due to being OOF..

The amount of OOF stuff you get depends on how much is in focus, ie depth of field (DOF) about the focus point..

DOF is proportional to focus distance. Close items have a small DOF. Far items have a larger DOF..

Wider apertures result in a smaller DOF. Narrower apertures result in a larger DOF..

For a constant lens focal length, DOF decreases as you decrease the f-stop number to open the aperture, and DOF increases as you increase the f-stop number to make the aperture smaller..

For a constant f-stop number, DOF decreases as you increase the lens focal length as that increases the size of the aperture opening, and DOF increases as you decrease the lens focal length as that decreases the size of the aperture opening..

This is because the f-stop is a ratio; f/n = focal length / aperture diameter..

Cheers from John from Adelaide, South AustraliaJohn Harvey Photography http://johnharvey.com.auCanon 40D, Canon 20D & Fuji F10..

Comment #14

Chuxter wrote:.

Sgt_Strider wrote:.

I'm still very much new to photography, but I'm having troubleisolating subjects even with an aperture of f/2. I can't prove it,but while I was playing with my camera earlier today, I notice in theplayback that the farther I am from the subject the less bokeh I getand the closer I get to the subject the more bokeh I get..

I've noticed that too. .

As you were scolded, "bokeh" is not the amount of OOF, but rather a"feeling" when you view an OOF object. If the OOF object is smoothand doesn't show any iris artifacts, then the "bokeh" is said to givea good "feeling"....

But I think you want MORE OOF objects in the background, so toINCREASE the blur (decrease the sharpness):.

1. Use a wider aperture2. Get the camera closer to the subject (that you want sharp)3. Get the subject (that you want sharp) farther from the background(that you want blurry).

After you achieve a blurry background, then you can go to the nextstep, which is to become sensitive to poor "bokeh"....

Charlie DavisNikon 5700, Sony R1, Nikon D300HomePage: http://www.1derful.infoBridge Blog: http://www.here-ugo.com/BridgeBlog/.

I'm not going to take some of the firm responses here personally. This is the beginners forum and I think my question is completely legit to ask. I appreciate the explanation that you made as it really helped..

I don't know if you have the time to help, but if you or someone else can explain to me what some of the numbers on the DOF calculator site means then that would be great. The site doesn't appear to explain what some of those values mean and I think if I understand them then it'll help me "master" this skill..

Http://www.dofmaster.com/dofjs.html..

Comment #15

Ok...here goes an example, hope it helps..

Go to the calculator and choose the Canon Camera (top drop down list)Go to the lens and choose 50 mm for your lens.Pick the f-stop from the drop down to be f/2.Let choose the distance of the lens to the object to be 10 ft..

When you are done, you will see the following numbers:.

Near limit = 9.56 feetFar limit = 10.5 feet.

Since you subject is at 10 feet, your subject should be sharp. The near limit of 9.56 feet means that if your subject was to stand about .44 feet (10-9.56) in front of where he/she was, the subject should still be in sharp focus. If the subject starts to get closer to you from the near limit, then the subject will start to be out of focus, blurred, hence the bokeh. Likewise for the far limit, if the subject move back from where he/she was by .5 feet (10.5-10), the subject should still be in focus. Anywhere beyond the far limit, and the subject will start to be out of focus..

Did that help??..

Comment #16

If your subject is at or beyond the hyperfocal distance you have no OOF behind the subject. If it's closer than the hyperfocal distance you have some OOF behind the subject that is more and more blurry as the subject is closer to you and farther of the hyperfocal distance.VictorBucuresti, Romaniahttp://s106.photobucket.com/albums/m268/victor_petcu/http://picasaweb.google.com/teodor.nitica/..

Comment #17

I don't know if you have the time to help, but if you or someone elsecan explain to me what some of the numbers on the DOF calculator sitemeans then that would be great. The site doesn't appear to explainwhat some of those values mean and I think if I understand them thenit'll help me "master" this skill..

Read this. It should help a lot:.

Http://www.luminous-landscape.com/...tutorials/understanding-series/dof.shtml.

Http://www.dofmaster.com/dofjs.html..

Comment #18

In additon to what the DOF calculator tells you, if you're using a longer lens, the background will appear to be more blurry than if you use a shorter lens that theoretically gives you the same DOF value (from a different distance and with different f-stop). With the longer lens, the perceived DOF is less as the background appears bigger than with the shorter lens, even though the amount of detail is no different from using a shorter lens if the DOF is the same in each case..

Numbers spat out of a DOF calculator don't always explain the whole impression that you gain when looking at an image..

As for bokeh, another easy way to describe it would be the quality of the blur in the OOF areas. Smoother is better. More choppy is not so good. For example, you can use a Canon 50/1.4 lens at f/1.4 and a Canon 50/1.2L at f/1.2 on the same body from the same place and the 50/1.2L will produce better bokeh, ie the 50/1.2L OOF result will be smoother and seemingly blurrier than with the 5/1.4..

Cheers from John from Adelaide, South AustraliaJohn Harvey Photography http://johnharvey.com.auCanon 40D, Canon 20D & Fuji F10..

Comment #19

Devnull wrote:.

I don't know if you have the time to help, but if you or someone elsecan explain to me what some of the numbers on the DOF calculator sitemeans then that would be great. The site doesn't appear to explainwhat some of those values mean and I think if I understand them thenit'll help me "master" this skill..

Read this. It should help a lot:.

Http://www.luminous-landscape.com/...tutorials/understanding-series/dof.shtml.

Http://www.dofmaster.com/dofjs.html.

So I finally got around to reading that article and it does address a lot of my questions and confusion. However, one thing that I still don't understand is what if I stand away from the near and far limit of the DOF calculations? Meaning, what if I'm using a Canon 17-40mm f/4 L lens at 17mm on a crop body, but standing about 20 feet away from the subject and using f/4, will most of the picture appear somewhat sharp? Or that only the center will be sharp while the corners will be a bit soft and I won't get much OOF?..

Comment #20

Sgt_Strider wrote:.

Devnull wrote:.

I don't know if you have the time to help, but if you or someone elsecan explain to me what some of the numbers on the DOF calculator sitemeans then that would be great. The site doesn't appear to explainwhat some of those values mean and I think if I understand them thenit'll help me "master" this skill..

Read this. It should help a lot:.

Http://www.luminous-landscape.com/...tutorials/understanding-series/dof.shtml.

Http://www.dofmaster.com/dofjs.html.

So I finally got around to reading that article and it does address alot of my questions and confusion. However, one thing that I stilldon't understand is what if I stand away from the near and far limitof the DOF calculations?.

I'm not sure what you mean by "stand away from" above..

Meaning, what if I'm using a Canon 17-40mmf/4 L lens at 17mm on a crop body, but standing about 20 feet awayfrom the subject and using f/4, will most of the picture appearsomewhat sharp? Or that only the center will be sharp while thecorners will be a bit soft and I won't get much OOF?.

Time to try the Depth of Field calculator you quoted above..

Using the scenario you described the calculator produces the result that everything will be acceptably sharp from 7.7 feet to infinity. There will be very little out of focus given this situation..

Now you are asking about the difference between the centre and the corners. That is a separate issue, and concerns lens quality, not depth of field. Generally when a lens is working about two to three stops smaller than the maximum aperture, the lens gives best results and the centre and edges will be about the same..

The effects of corner softness would normally be much less significant than the depth of field effects.Regards,Peter..

Comment #21

Sgt_Strider wrote:.

Devnull wrote:.

I don't know if you have the time to help, but if you or someone elsecan explain to me what some of the numbers on the DOF calculator sitemeans then that would be great. The site doesn't appear to explainwhat some of those values mean and I think if I understand them thenit'll help me "master" this skill..

Read this. It should help a lot:.

Http://www.luminous-landscape.com/...tutorials/understanding-series/dof.shtml.

Http://www.dofmaster.com/dofjs.html.

So I finally got around to reading that article and it does address alot of my questions and confusion. However, one thing that I stilldon't understand is what if I stand away from the near and far limitof the DOF calculations?.

What do you mean? You're 20 feet from your subject, you focus on your subject and DOF covers from some way in front of the subject to some way behind it. If you move and refocus on the subject, then the DOF range changes..

Meaning, what if I'm using a Canon 17-40mmf/4 L lens at 17mm on a crop body, but standing about 20 feet awayfrom the subject and using f/4, will most of the picture appearsomewhat sharp? Or that only the center will be sharp while thecorners will be a bit soft and I won't get much OOF?.

Cheers from John from Adelaide, South AustraliaJohn Harvey Photography http://johnharvey.com.auCanon 40D, Canon 20D & Fuji F10..

Comment #22

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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