Focus on the eyes?!?!

[Scatterbrain]

I also tend to use auto focus, but set my focus point.

The problem with manual focus is that if the subject moves even a tiny bit then your focus is out. A larger AV setting (not so small DOF) also helps as you'll get more in focus. This is particularly useful if the subject might move or if there's more than one person in the frame.

Oh & there's always photoshop to sharpen the eyes if you don't get them as clear as you'd like.

Scatterbrain

[daft_biker]

Originally Posted by Mr Guy

Pivoting the camera creates an arc of focal range exactly that distance.

There is no arc - the plane of focus is flat and parallel to the film plane unless you use a tilt and shift lens. And even when you use a tilt and shift lens (or a camera with movements) the plane of focus is still flat, just you can place it at an angle to the film plane.

I agree with your previous point about focus and recpompose being fine where there's enough DoF to cover focus errors.....I do it regularly on my compact. I did say it had it's uses

[Mr Guy]

Originally Posted by daft_biker

There is no arc - the plane of focus is flat and parallel to the film plane unless you use a tilt and shift lens. And even when you use a tilt and shift lens (or a camera with movements) the plane of focus is still flat, just you can place it at an angle to the film plane.

I agree with your previous point about focus and recpompose being fine where there's enough DoF to cover focus errors.....I do it regularly on my compact. I did say it had it's uses

While that's strictly true (and, in several ways, also not true*), as said in the other thread, it's only relevant for extremely narrow depths of field. It's becoming one of those questions where while what you are saying is mostly accurate, it's misleading for the purposes of answering the question. (And I think you could probably make the argument that my clarifications may be muddling the situation more!) I actually found a website explaining it the way you phrased it that's completely logically incorrect, mostly because he's drawing the wrong triangles.

Basically, what I'm saying is while the kind of composition clashing with depth of field is achievable, I would tend toward saying the first question you should be asking yourself in that situation isn't, "Should I recompose", it's "Do I really need this depth of field to be so narrow".


*The fact it's treated as flat while it isn't always is why you have sharpness fall off at corners.

[gh patriot]

Originally Posted by SandeeWig

Mr. Guy, thanks so much for taking the time to respond and provide so much information. I really need to read and wrap my brain around how depth of field is calculated so I know how to adjust for different apertures and focal lengths.

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

This will help

[SandeeWig]

dhart - thanks so much for your comments and suggestion. I'm going to practice with the off-center focus point selected and see how it goes. I try to remember the rule of thirds, but I have such a habit of centering people in the frame.

Scatterbrain - thank you for your input. I can totally see how manually focusing could easily be thrown off by the subject moving. Though - and correct me if I'm wrong - wouldn't you have to re-auto-focus (by depressing shutter button halfway) if the subject moves after you've auto focused w/ a specific focus point?

daft_biker and Mr. Guy - I'm trying to wrap my brain around the differences of opinion here. If you all have some links to diagrams that may help me visualize what you're saying, I'd appreciate it. For my situation (at least for the week of photos taken thus far), the main question is the aperture setting and the true need for dof to be so narrow. Lighting was an issue, so the lower f-number helped, but created a focus field of about 4 inches (according to the link provided by gh patriot), which made most of my pictures out of focus. Coming from a P&S with the widest aperture setting of f8, I'm not really used to being able to open up to f22. Plus I was using a flash most of the time anyway, so should've known to go to a higher f-number.

gh patriot - thank you for that link. I've seen that site before and not spent any time on it, but now that I understand what I'm testing and reading I think I'll be spending much more time there!!

Thank you all so much!!

[Mr Guy]

Well it's not so much a difference of opinion, it's a matter of whether the difference should change much!

This is a good explanation:

http://visual-vacations.com/Photogra...pose_sucks.htm


The real problem I have with it, is that it takes a very carefully constructed scenario (Unusually close photographer with a wide open lens with a significant recomposition) to construct a scenario that demonstrates the problem. My response is that, well, with that narrow tolerance without putting the critical point right on an AF point, you're likely to screw the pooch anyway, so you have to ask yourself if you really NEED to be in that situation, with such a narrow DOF.


(For example, what he kindly neglects to point out, is that for the scenario he constructed with a 100mm lens from 6 feet on a crop body, your entirely field of view is only a little under a foot and a half across, so if you REALLY did what he described, you'd have a nice slighly out of focus shot of just that girl's bust.)

[SandeeWig]

Originally Posted by Mr Guy

Well it's not so much a difference of opinion, it's a matter of whether the difference should change much!

This is a good explanation:

http://visual-vacations.com/Photogra...pose_sucks.htm


The real problem I have with it, is that it takes a very carefully constructed scenario (Unusually close photographer with a wide open lens with a significant recomposition) to construct a scenario that demonstrates the problem. My response is that, well, with that narrow tolerance without putting the critical point right on an AF point, you're likely to screw the pooch anyway, so you have to ask yourself if you really NEED to be in that situation, with such a narrow DOF.


(For example, what he kindly neglects to point out, is that for the scenario he constructed with a 100mm lens from 6 feet on a crop body, your entirely field of view is only a little under a foot and a half across, so if you REALLY did what he described, you'd have a nice slighly out of focus shot of just that girl's bust.)

Thank you for the link Mr. Guy; it was an interesting, well explained description of what you and d_b are talking about. Is this the site that is completely logically incorrect?!

Either way, it does explain it well enough for me to understand that I need to
a) use the auto-focus points Canon gave me and select the one that is appropriate for my shot; vs. aiming for center and recomposing, and
b) pay close attention to my aperture setting in all situations and play around w/ that dof calculator a little more so I have a better idea of what I'm going to end up with after i press the shutter.

Thanks again! You all have helped me a great deal here. Now to put it into action.

[Mr Guy]

Well see that's the thing I'm having trouble figuring out how to phrase. It's not that they are WRONG so much as the situation just isn't so dire as they imply. You just need to be aware that the situation CAN arise, and account for it properly when you are in that situation, then you're alright. It's just not nearly so easy to wander into as they imply, because the error has to be larger than the depth of field, and as your depth of field shrinks, so does your viewing angle to a certain extent, and it becomes harder to recompose in such a way that your error is larger than your depth of field.

If you HAVE the option of using the correct AF, that's probably better, because it reduces the potential for error. I just think the general principle they should be taking away is not that recomposing sucks, it's that using extremely narrow depths of fields without caution sucks.

[SandeeWig]

Originally Posted by Mr Guy

Well see that's the thing I'm having trouble figuring out how to phrase. It's not that they are WRONG so much as the situation just isn't so dire as they imply. You just need to be aware that the situation CAN arise, and account for it properly when you are in that situation, then you're alright. It's just not nearly so easy to wander into as they imply, because the error has to be larger than the depth of field, and as your depth of field shrinks, so does your viewing angle to a certain extent, and it becomes harder to recompose in such a way that your error is larger than your depth of field.

If you HAVE the option of using the correct AF, that's probably better, because it reduces the potential for error. I just think the general principle they should be taking away is not that recomposing sucks, it's that using extremely narrow depths of fields without caution sucks.

Gotcha! I think just being aware of the potential situation is very good advice. It teaches one (i.e. ME!) to learn how to properly focus, either using autofocus points or manual. I was practicing with the manual focus tips jdepould gave last night, and that seems like it would work really well for portraits, especially for more than one person (provided, of course, they do not move after you get them focused!).

At least now I have some things to keep in mind when composing the shots relative to getting proper focus. I had to get some control; letting the camera decide just wasn't workin out!

[hassson]

Originally Posted by SandeeWig

Also, is there a way to "zoom" in to your focal point w/o actually zooming? That probably makes no sense, but I thought I read in my manual somewhere that you could zoom in to focus and then recompose your shot before taking it...how does that work?!

Hey SandeeWig,

In my canon XSi, I use the live view for tricky focus shots, this is where you can zoom into the scene but not actually zooming in, so yes it make sense

In order to switch to live mode:
- You need to be working in the creative mode: A-Dep, M, AV, TV & P.
- Make sure you have the live view enabled from the setting menu.
- while you are compsing & focusing press the Set button & you will switch from view finder to the LCD live view option where you can find a small box which can be moved around.
- zoom in using the most upper right button, zoom in & more zoom in then back to normal zoom.
- Focus manually - so far i couldn't have the camera's auto focus working in that mode, but I'm so happy with the manual focus.

I hope this is what you meant by zooming in w/o actually zooming.

Good luck