Wide Aperture - Need a little help with focus

[cleanpig]

Okay, that I shall do.

 

[hydroshock]

thats too much math, if you're on a tripod anyway, move it up to 5.6 or 8 even, make more distance from your subject to the background and use a longer shutter speed. if you spend all your time fretting about numbers you'll stop seeing your subject the way you want to see it, imo.

 

[pgriz]

When dealing with a thin DOF, it usually helps turning off the auto-focus, and doing it manually. If you have live-view on your camera, you can get very precise focus doing it manually, expecially if you have your camera on a tripod. The workflow that I would use for closeup shots like yours, is to put the camera on a tripod, place it approximately at the right distance to get the framing you want, turn the lens AF off. Now depending on how much DOF you want, you should use the DOF calculator, at the distance you have, and determine at which aperture you will have enough DOF to include all of the subject that you want to have sharp. Next, set the aperture accordingly, focus on the right spot, and take the shot. If done correctly, there will be enough DOF in front and behind your point of focus to get the entire subject in focus.

 

[cgipson1]

thats too much math, if you're on a tripod anyway, move it up to 5.6 or 8 even, make more distance from your subject to the background and use a longer shutter speed. if you spend all your time fretting about numbers you'll stop seeing your subject the way you want to see it, imo.

What has shutter speed to do with the DOF issue he describes, and wants to learn more about ?

 

[cgipson1]

When dealing with a thin DOF, it usually helps turning off the auto-focus, and doing it manually. If you have live-view on your camera, you can get very precise focus doing it manually, expecially if you have your camera on a tripod. The workflow that I would use for closeup shots like yours, is to put the camera on a tripod, place it approximately at the right distance to get the framing you want, turn the lens AF off. Now depending on how much DOF you want, you should use the DOF calculator, at the distance you have, and determine at which aperture you will have enough DOF to include all of the subject that you want to have sharp. Next, set the aperture accordingly, focus on the right spot, and take the shot. If done correctly, there will be enough DOF in front and behind your point of focus to get the entire subject in focus.

Exactly!

 

[hydroshock]

when you change the stop, you need more time for light, it's simple compensation for a still subject. shutter speed has nothing to do with DOF. Never said it did. You can get just as sharp an image. It's patience, not arithmetic.

 

[cgipson1]

when you change the stop, you need more time for light, it's simple compensation for a still subject. shutter speed has nothing to do with DOF. Never said it did. You can get just as sharp an image. It's patience, not arithmetic.

Yes... I agree, when you close down the aperture... it requires either a longer exposure, or increased ISO. And for a still subject, a longer shutter speed is not an issue.

BUT The OP indicated something you seemed to have missed. He wants a blurry background AKA Bokeh. And he wants the entire subject in focus also.

The blurry background means that he needs a larger aperture... so just closing down the aperture to increase DOF will not solve his issue as that will make for a larger DOF AKA sharp, in focus background. What Shutter speed is required by closing down the aperture is meaningless in this situation, he just needs a fast enough shutter speed to prevent motion blur.

What he needs is to be able to calculate precisely what DOF he needs using MATH... and then fine tune his focusing to make optimal use of that DOF.

 

[weepete]

There's no maths involved if you use a dof calculator, it's all done for you!

 

[cgipson1]

There's no maths involved if you use a dof calculator, it's all done for you!

Very True.. but there is still math, you just aren't doing it yourself! lol!

 

[hydroshock]

I'm not arguing with you, and I saw the OP, by keeping the widest aperture to get that same bokeh he could pull the camera back from the subject which will proportionally increase the dof to get the figure in focus. Then you can crop. That limitation is the lens really. And the very lowest iso would ensure a clean snap. Motion blur is completely irrelevant, still subject + tripod. so what you are advising isn't wrong, like i said not arguing with you, just simplifying it because this is a beginner's thread and the technical stuff is great and all but isn't exactly necessary to practice what he's trying to get at first. I've found it more confusing to more beginners than not.

On a side note, I wasn't entirely impressed with the af on those entry level dslrs. I would shoot all mf too since there's no moving subject.

I'll shut up now, it's been overthought.

 

[cgipson1]

I'm not arguing with you, and I saw the OP, by keeping the widest aperture to get that same bokeh he could pull the camera back from the subject which will proportionally increase the dof to get the figure in focus. Then you can crop. That limitation is the lens really. And the very lowest iso would ensure a clean snap. Motion blur is completely irrelevant, still subject + tripod. so what you are advising isn't wrong, like i said not arguing with you, just simplifying it because this is a beginner's thread and the technical stuff is great and all but isn't exactly necessary to practice what he's trying to get at first. I've found it more confusing to more beginners than not.

On a side note, I wasn't entirely impressed with the af on those entry level dslrs. I would shoot all mf too since there's no moving subject.

I'll shut up now, it's been overthought.

No problem.... we were both trying to help the OP.. that is what counts!

 

[cleanpig]

I love you guys. :3

Hahaha. XD

 

[KmH]

A blurry background is not bokeh.

Bokeh is not adjustable, but a blurry background is.

Bokeh is the subjective visual quality of blurred image elements.
Lens construction, the number and shape of the lens aperture blades, the quality of the glass lens elements, all determine the bokeh quality a lens will produce.

The only way to change the bokeh is to use a different make/model of lens.

 

[Designer]

cleanpig; after you're finished fooling around trying to find the optimum plane of focus for this shot, you might consider finding a better background and get some light on the front.

 

[o hey tyler]

thats too much math, if you're on a tripod anyway, move it up to 5.6 or 8 even, make more distance from your subject to the background and use a longer shutter speed. if you spend all your time fretting about numbers you'll stop seeing your subject the way you want to see it, imo.

You do realize that if you need a certain area of DOF, that using a DOF calculator is the fastest and easiest way to establish your camera distance and aperture to set up a particular shot, right?

It's not even math. You just plug in numbers and it does the calculations for you. You know, like one of those calculator things?

If they're shooting at f/2, and then they move their camera back 5 feet, their DoF will still be larger. Moving 3 stops down to f/5.6 would likely be overkill.