Technique for focusing "into your scene"
Hi all,
Question about 4x5 focusing. But first, to set the stage, let's talk digital for a moment.
When learning about focusing a digital camera I have read many times and in many places, to maximize overall image sharpness and depth of field, focus 1/3 of the way "into" your scene.
By all accounts this works pretty well and reliable.
Now, let's shift gears to 4x5. Here, I have learned from others and have read, basically do the following:
- Focus on the near/far
- Tilt for the near/far
- Note the standard position on the metric scale
- Then hunt around the scene and find the most out of focus area, focus on that area, then note that position of the standard on the metric scale
- Then, here's the catch....place the standard at the mid-point of the near and far focus points
The last step is the one I want to talk about. Positioning the standard on the mid-point....doesn't that equate to focusing 50% "into" the scene? Shouldn't we be focusing at the 1/3 point "into" the scene? I know the math is harder, but, thoughts on that?
Thanks!!
Re: Technique for focusing "into your scene"
Re: Technique for focusing "into your scene"
Quote:
Originally Posted by
Richard Wasserman
Which essentially says the same thing..."Focusing at the median of (A,B) will make the closest point and the furthest point equally sharp." which is essentially the 50% mark. How you get there will vary depending on your camera, but in essence, the instructions (which btw, I have read and re-read many times) gets you to a point where your min/max focus extension determines where we split the difference.
Why is that when the strategy for a non-movement camera is to focus 1/3 of the way into the scene? Shouldn't this hold true when using a camera with movements? Why would it be different?
When you think about it, the max extension focus point in many cases will be your most important subject material. Further, if using tilt, the max extension point establishes the plane of focus which, to me is a pretty darn important aspect of the photo, right? So, if you focus 50% into the scene or focus at the "median of (A,B)" you are in effect moving the plane of focus further away from the initial focal plane.
I guess forget all that noise....why "median of (A,B)" and not 1/3 towards the minimum extension or 1/3 of (A,B)?
Re: Technique for focusing "into your scene"
Put aside all of the math and theory and consider that there is truly only one slice of "focus" for a given focus distance. The "depth of field" is merely the area which appears, at a given print size, to be "in focus" or in other words, not obviously out of focus.
The closer you get to the edge of that depth of field, the less in focus it is. And if you print to a different size, it may become obviously out of focus once inspected.
In my opinion, it's much better to maximize the usage of your depth of field by putting what is most important in the image as close to the actual focus "slice" than do the whole "into the scene" focusing technique. This is made even easier with LF and movements, where often I would choose to focus on a foreground subject, and using tilt, make sure it and the horizon at infinity are both in reasonable focus. Then, stop down to get more perceived DOF. And when it doubt, stop down a little more. The perceived sharpness of your negative will really not be much different at f/22 or f/45, but having 1/3 of your negative clearly out of focus will definitely be obvious to a viewer. Don't worry about diffraction - that is mostly an overblown issue.
For small formats, using hyperfocal focusing makes a bit more sense to me - mostly for speed of shooting. But I'd still rather have a sharp subject with a slightly out of focus background than a kinda-sorta in focus subject with slightly sharper background, with the sharpest focus in the image somewhere behind the subject.
Re: Technique for focusing "into your scene"
Not the same maths at all (if indeed the 1/3 "rule" for digital photography is actually based on maths). From the little I know on the subject (haven't done much digital photography), it's stated as 1/3 from the lower part of your image, not 1/3 of the actual scene.
In other words, it has nothing to do with the distance between lens and subject as well as between lens and film plane, on which much of the DOF maths is based on a large-format camera.
Re: Technique for focusing "into your scene"
From a compositional standpoint, there is no rule of thumb. The nice thing about large format is that you have a big viewing screen. You can take your time and study your composition from an esthetic rather than just technical standpoint. The best way to learn is to ignore everything you've been taught before or have inferred before. Learn with your eyes, assisted by a good focus loupe, instead of a calculator. Damn the math.
Re: Technique for focusing "into your scene"
Quote:
Originally Posted by
Drew Wiley
Damn the math.
I need a t-shirt with this printed on it. :)
Re: Technique for focusing "into your scene"
I have found moving the back standard, focusing on the nearest and then farthest parts of the scene I want to be in sharp focus, and moving the standard halfway between to be very handy when the scene is too dark over the 11x14 GG when trying to get the focus exactly where it needs to be. And it can give someone a place to start from...along with leveling the camera and movements zeroed out.
Most of the time I have already translated what is in front of my eyes into a working model of what will go on the GG as I am setting up the camera...but still watching for surprises around me and on the GG. Such as, "Why was I thinking horizontal here...this is a vertical all day long!" But like Drew said -- it all happens on the ground glass. Do it enough times and one finds the quickest route for how one creates the image on the GG.
Re: Technique for focusing "into your scene"
Quote:
Originally Posted by
AdamD
When learning about focusing a digital camera I have read many times and in many places, to maximize overall image sharpness and depth of field, focus 1/3 of the way "into" your scene.
By all accounts this works pretty well and reliable.
It's not correct and it's not reliable.
Quote:
Originally Posted by
AdamD
Why is that when the strategy for a non-movement camera is to focus 1/3 of the way into the scene? Shouldn't this hold true when using a camera with movements? Why would it be different?
It doesn't hold true for any camera.
Re: Technique for focusing "into your scene"
Quote:
Originally Posted by
Corran
In my opinion, it's much better to maximize the usage of your depth of field by putting what is most important in the image as close to the actual focus "slice" than do the whole "into the scene" focusing technique.... I'd still rather have a sharp subject with a slightly out of focus background than a kinda-sorta in focus subject with slightly sharper background, with the sharpest focus in the image somewhere behind the subject.
That's how I approach it as well.