Focus/Recompose Rule Of Thumb

[Rosshole]

Why Focus-Recompose Sucks

The Problem With The Focus-Recompose Method - Digital Photography School

For Sharp Photos, Should You Be Using the Focus-Recompose Method? at PhotoWhoa Blog | Discover how you can be a better photographer

I am confused... do people actually focus, lock, walk around, and then shoot?

because the links supplied show straight lines for the focus point... that can't be right. Once you set the focus @ 6' from the lens, no matter what direction you point the camera, 6' from the lens will always be in focus. I will almost always pick my focus point (like the eyes), focus on that, then do a slight recompose, and shoot. how is this wrong?

so modern cameras broke physics?

 

[Josh66]

Why Focus-Recompose Sucks

The Problem With The Focus-Recompose Method - Digital Photography School

For Sharp Photos, Should You Be Using the Focus-Recompose Method? at PhotoWhoa Blog | Discover how you can be a better photographer

I am confused... do people actually focus, lock, walk around, and then shoot?

because the links supplied show straight lines for the focus point... that can't be right. Once you set the focus @ 6' from the lens, no matter what direction you point the camera, 6' from the lens will always be in focus. I will almost always pick my focus point (like the eyes), focus on that, then do a slight recompose, and shoot. how is this wrong?

so modern cameras broke physics?

Did you even read the links?


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First of all, the distance is measured from the film/sensor plane, not the lens. And it's a plane, not a sphere, so "everything 6' away" will NOT be in focus. This is all covered in those links...

 

[Rosshole]

Did you even read the links?


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First of all, the distance is measured from the film/sensor plane, not the lens. And it's a plane, not a sphere, so "everything 6' away" will NOT be in focus. This is all covered in those links...

Yes, I did read the links... and I am confued because I have NEVER experienced this in any practical application...

It must be because I don't take portraits of people looking up at them... I shoot from eye level to my subject...

 

[Josh66]

Did you even read the links?


---

First of all, the distance is measured from the film/sensor plane, not the lens. And it's a plane, not a sphere, so "everything 6' away" will NOT be in focus. This is all covered in those links...

Yes, I did read the links... and I am confued because I have NEVER experienced this in any practical application...

I think it will really only be an issue at larger apertures, like f/2.8 and larger. The larger the aperture, and the closer you are, the more noticeable it is. It would also be more noticeable in larger formats, so it would be harder to see on a crop sensor than full frame.

At, say, headshot distances around f/2, it's enough to notice.

 

[table1349]

It is basic Geometry 101. Straight lines do not equate to equal distance. Thin DOF leaves little or no room for error.

 

[Derrel]

It is basic Geometry 101. Straight lines do not equate to equal distance. Thin DOF leaves little or no room for error.

A few keys in gryponslair99's brief post. "Geometry". "thin DOF". "Little or no" room for error.

Working backward, let's say we are close to our subject; that means the depth of field is MUCH more-limited than if we were say, five to 20 meters distant.

Let's say we have a 100mm lens, and the aperture value is f/3.2, for super-sharp optical performance and also for wonderfully soft background blurring.

The depth of field from 1) close-range and 2) long focal length lens and 3) wide aperture means that there is little to no room for error in placement of the focus.

Focus and recompose does not work very well in situations like that. But even #2 is not without a caveat; if you're at 10 feet and using a SHORT focal length lens, the edges of the frame are VERY MUCH FARTHER away than the center of the frame!!! it's actually very easy to envision the geometry...the wide-angle lens's field of view is wide, so you have a very much longer diagonally-oriented line of sight out to the edges of the frame. At f/stops where the DOF is shallow, the margin of error EXCEEDS the depth of field...and blows the shot...

A telephoto lens, since it has a narrower angle of view, is actually an EASIER tool to use focus and recompose on than is say, a 35mm f/1.4 lens, buuuut....when the magnification is very high, even slight focusing errors become apparent at wider f/stops.

Where the problems start to creep in in my experience are when using fast lenses, like 50/1.4 or 85mm f/1.4, at close ranges, at wide apertures...there's just soooooo little room for error when the actual DOF band is like 1.5 to 2 inches deep...either you hit focus, or you miss it. For that reason, I usually prefer to shoot stopped down somewhat, to cover my proverbial ass. You see, the real world also has issues like focusing accuracy, subject movement, and so on. There's often a compounding of issues principle at work in real shooting scenarios...I often want to give myself a little of what I call "DOF cushion", so I can come back with usable shots, not excuses. There are situations where focus and recompose will work, sure. LOTS of them! And there are also situations in which it will ***k you up.