STOP using Focus & Recompose

[khunpapa]

When your subject is to the right of the frame and you acquire focus it is a certain distance from your lens. when you recompose the focus distance on your lens hasnt changed but the rotation shifts the plane of focus behind where it originally was.

in this diagram the blue line and black line are same length (focus distance)

when recomposed the focus plan shifts back (indicated by pink horizontal line)

this example shows 20 degree rotation

Nice & clear illustration. At 6 feet away, focus at right then recompose at middle would cause focal distant change 6.62 inches. But ..

The 20 degree rotation means that your right subject is 2.2 feet away from the middle.

BUT ..

The 85mm lens on FF sensor have only h24 x v16 degree of Angle of View; or 12 degree keft + 12 degree right. That 20 degree rotation means that you are focusing on the subject which is completely outside your wanted frame.

To keep the right focusing point with in the frame, you have to rotate less than 12 degree. If it's 10 degree, the displacement now would be less than a foot.

Now I wonder why this imaginary beginner would decide to focus on something only a foot away from the desire point.

Another wonder is : at f1.2, the,DoF is less than 1.5" inches. If he focuses at the 20 degree right, once he rotates his camera back at the center, he will clearly see that the object is out of focus as the distant discrepency is 6.6". Why he keep on pressing the shutter despite the OVF clearly shows the blur object?

...

But when think of today more and more beginners buy FF camera plus 85mm f1.2 lens from the start, your suggestion is very reasonable.

--
Flashes of my Memory.

 

[tcg550]

It just occurred to me, are beginners using f1.2, 1.4 lenses?

If they are they are probablly still struggling with getting the eyes and nose in focus without recomposing.

If they're using their kit lens around 3.5 and smaller then focus and recompose probablly works well.

Just yesterday I took a photo of my wife standing on the rivers edge in Downtown Detroit. I focused on her face and then recomposed with her to the right of the frame in order to get a nice shot of the river running past.

I could have used the pad to move the focus point but that would have taken a little extra time (negligible) but the bigger problem for me is remembering to put the focus point back to the center or move it to the desired focus point for the next shot.

Just easier to leave it in the center and recompose.

 

[Jonsi]

I am not saying never use it..

Your title literally says "STOP using" it.

 

[j tokarz]

I've always focused then recomposed, never never disappointed yet. And i have been taking photos for donkeys years. I don't seem to have the time to faff about changing pointd then shooting.

 

[j tokarz]

besides never moving the focusing point (have always used centre ), i don't pixel peep and don't always follow the rules, in fact rarely. Content is all i want. I have some great photos over the years.

 

[Steve Bingham]

I've been focusing and recomposing for all of my photography life which goes back to film, pretty sure I won't be stopping.

Yeah me too - and I made a damn good living both as a pro and photo teacher.. What a dumb post.

 

[mamallama]

Not to worry. The flexibility of modern cameras is such that you can compose first and autofocus on whatever you want by simply pointing to it. Focus and recompose will soon be a thing of the past that only the old timers do. :-D

 

[BrownieVet]

I have used Focus and recompose for many years and have many great photos but also many out of focus images that if i had know the issue, I could have tried a different technique and perhaps had even more great photos.

Is it fair to say your camera has multi-point selectable focus and you know how to set your camera to Back Button Focus? If that is the case, perhaps giving that alternative would be better than your "Thou Shall Not Focus and Recompose".

Of course that may not be appropriate in Beginner's Forum, however, the "Rule" you presented and your explanation to the focus plain, etc. is not necessaily accurate. I'll let you analyze what I meant.

 

[BrownieVet]

Pending the OP's explanation to the contrary we can only assume that this is what shall be known as Trumpian agreement to future generations.

--
Most of my images are here:
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[BrownieVet]

When your subject is to the right of the frame and you acquire focus it is a certain distance from your lens. when you recompose the focus distance on your lens hasnt changed but the rotation shifts the plane of focus behind where it originally was.

in this diagram the blue line and black line are same length (focus distance)

when recomposed the focus plan shifts back (indicated by pink horizontal line)

this example shows 20 degree rotation

 

[tamaraw35]

Not to worry. The flexibility of modern cameras is such that you can compose first and autofocus on whatever you want by simply pointing to it. Focus and recompose will soon be a thing of the past that only the old timers do. :-D

I'm not so sure about that. Prefocus can be better for some moving subjects, depending upon your environment, lighting, and af speed. Pointing the camera is also considerably simpler and faster than messing with a d-pad, joystick or touchpad to select different af points. I have found only touchscreen focus to equal it in simplicity, but that prevents viewfinder usage.

This is not to say that other techniques can't be more effective in different situations, just that focus & recompose is not as obsolete as you may think. Different techniques for different situations and different strokes for different folks!

 

[MikeC-1961]

STOP USING Focus and Recompose. When you focus using centre AF point and then recompose your shot, you tend to shift the focus plane behind the persons head and eyes are out of focus, So intead compose and then select an AF point thats closest to the eyes.

this is more and more important the faster the lens is. 1.2, 1.4, 2.8 with a shallow depth of field. if you are stopped down and have alot of focus depth then continue to use Focus and Recompose.

See this illustration.

See how recomposing shifts the focus plane!

See title above!

 

[scokill]

Pending the OP's explanation to the contrary we can only assume that this is what shall be known as Trumpian agreement to future generations.

 

[mamallama]

Not to worry. The flexibility of modern cameras is such that you can compose first and autofocus on whatever you want by simply pointing to it. Focus and recompose will soon be a thing of the past that only the old timers do. :-D

I'm not so sure about that. Prefocus can be better for some moving subjects, depending upon your environment, lighting, and af speed. Pointing the camera is also considerably simpler and faster than messing with a d-pad, joystick or touchpad to select different af points. I have found only touchscreen focus to equal it in simplicity, but that prevents viewfinder usage.

This is not to say that other techniques can't be more effective in different situations, just that focus & recompose is not as obsolete as you may think. Different techniques for different situations and different strokes for different folks!

It used to be about all you had. Now there are many choices. And you don't need to fuss with touchpad.

 

[rurikw]

tamaraw35 wrote

I'm not so sure about that. Prefocus can be better for some moving subjects, depending upon your environment, lighting, and af speed. Pointing the camera is also considerably simpler and faster than messing with a d-pad, joystick or touchpad to select different af points. I have found only touchscreen focus to equal it in simplicity, but that prevents viewfinder usage.

Depends on camera. At least on my Pana GX7 you can touch focus with the viewfinder active. Feels a tad cramped but works.

 

[tko]

Not to worry. The flexibility of modern cameras is such that you can compose first and autofocus on whatever you want by simply pointing to it. Focus and recompose will soon be a thing of the past that only the old timers do. :-D

So you hold the camera out with both hands, compose on the back LCD, slide your finger over the viewfinder to the focus spot, remove your finger, hope the model didn't move, hope your thumb (because that's the only digit free and on the back) isn't bigger than the eye you're trying to focus on, and take the photo? And you can accomplish this in direct sunlight as the subject is moving with a heavy lens attached?

Modern technology must be very impressive indeed

 

[mamallama]

Not to worry. The flexibility of modern cameras is such that you can compose first and autofocus on whatever you want by simply pointing to it. Focus and recompose will soon be a thing of the past that only the old timers do. :-D

So you hold the camera out with both hands, compose on the back LCD, slide your finger over the viewfinder to the focus spot, remove your finger, hope the model didn't move, hope your thumb (because that's the only digit free and on the back) isn't bigger than the eye you're trying to focus on, and take the photo? And you can accomplish this in direct sunlight as the subject is moving with a heavy lens attached?

Correct. You don't get it. You are assuming too much. You can preset the options if you know how you want to take the pictures. It's easy. Read your options in your camera manual.

Modern technology must be very impressive indeed

--
no, I won't return to read your witty reply!
professional cynic and contrarian: don't take it personally
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[skyglider]

STOP USING Focus and Recompose. When you focus using centre AF point and then recompose your shot, you tend to shift the focus plane behind the persons head and eyes are out of focus, So intead compose and then select an AF point thats closest to the eyes.

this is more and more important the faster the lens is. 1.2, 1.4, 2.8 with a shallow depth of field. if you are stopped down and have alot of focus depth then continue to use Focus and Recompose.

See this illustration.

See how recomposing shifts the focus plane!

.... image deleted to save bandwidth ....

Here is why I totally disagree with your statement to "STOP using Focus & Recompose".

First, I'm going to assume that the average distance that photos are taken of people is about 6 feet (72 inches). The distance may vary but say 6 feet is an average distance.

Second, assume that the focus point is the closest eye of a person.

Third, the distance of recompose is 26 inches as shown in the figures below. My experimentation has shown that 26 inches recompose is pretty much on the high end of recomposing at a subject to sensor distance of 6 feet.

Forth, the camera used is a Canon 7D DSLR.

(Note that the drawing below was done via computer so the measurements are accurate.)



FIGURE-A:
Figure-A shows the sensor to focus point distance of 6 feet (72 inches). The shooter half presses the shutter and locks focus. Then the camera is pivoted on the axis of the sensor to position the the subject on the left side of the frame. The recompose amount is 26 inches as shown. ---- In this ideal recompose where the axis of rotation is at the sensor, the distance from the subject's eye to the sensor remains at 72 inches so focus on the eye remains perfect.

FIGURE-B:
Figure-B shows a worse case recompose where the shooter held the camera steady and pivoted at his neck, which moves the sensor toward the right. The distance from the focus point (subject's eye) to the sensor is now 72-1/4". This is a change of 1/4" in distance.

Here are the depth of field calculations for two scenarios.


DOF calculator at: http://www.dofmaster.com/dofjs.html

The first is a worse case of using a focal length of 70mm and a large aperture of F/2.4 shooting at a distance of 6 feet (72 inches). (One would not normally be using a focal length of 70mm at a distance of 6 feet but I used 70mm as worse case.) Note that the depth of field is 2.34 inches. Note that the eye to sensor distance increase of 1/4 inch (0.25) in this unrealistic worse case is well within the DOF of 2.34 inches. The eye is still in sharp focus.



The second scenario is a more normal case of using a focal length of 24mm and the same aperture of F/2.4 at a subject to sensor distance of 6 feet. Note that the DOF is now a whopping 19.1 inches. A HUGE amount more than the 1/4" increase in eye to sensor distance.

At either a focal length of 70mm or 24mm, the eye remains in sharp focus for all practical purposes. Also note that the large aperture of F/2.4 that I used is a "typical" worse case since using smaller apertures would INCREASE the depth of field even more.

THE REAL WAY TO FOCUS & RECOMPOSE:
Rather than holding the camera in the same position and pivoting the body or at the neck to recompose, the better technique is to recompose the camera by using the wrists. Like this youtube video shows at 4:37 in the video:

Focus & recompose technique by Vail Fucci

A practical method would be to recompose using mostly the wrists but with some pivoting at the neck. This would probably result in about half of the distance change that is shown in Figure-B above. So the eye to sensor distance change might be 1/8 inch which is even less than the 1/4" shown in Figure-B.

SUMMARY:
So frankly, I think you are doing beginner shooters a big disservice by telling them in your title and first post to "STOP using focus & recompose" or their subjects will not be in focus.

If shooting at very close subject to sensor distances, like close ups of flowers or insects, then yes, focus & recompose can lose subject focus. In those scenarios, it's best to keep the camera still and select the focus point. But those are specific situations. Not the approximate 6 feet distance shown in the image you posted.

Similar to some other shooters who have posted in this thread, I've also been using focus and recompose for my normal shooting for umpteen years and my subjects have been in sharp focus.

So my suggestion to beginner shooters is "DO USE focus & recompose" for normal shooting distances! It's a LOT, LOT faster to focus & recompose, than to manually select focus points by using navigation buttons or even touch screen.

My $.02 anyway,
Sky

 

[rurikw]

I think your error is that you are looking at distances rather than the focal plane (Which you left out of your chart). The focal distance is different in different parts of the frame, increasing toward the edges. In your example according to my calculations the focus point in the direction of the subject will be a bit over 9" further away so quite out of focus except maybe with very small apertures/sensors. Your example is rather extreme though so would normally be less but still easily several inches so certainly not much hope of getting sharp eyelashes with any reasonably large apertures and sensors.

Tan19.9~0.36

0.36x26"~9.4".

I think the OP's heading is unfortunate as FARC is quite handy and useful in many situations but for shallow depth of field cases he has an important point that can save many beginners from unnecessary disappointments and headscratching. And not only beginners. I for one was surprised at the magnitude of the effect.

 

[tamaraw35]

tamaraw35 wrote

I'm not so sure about that. Prefocus can be better for some moving subjects, depending upon your environment, lighting, and af speed. Pointing the camera is also considerably simpler and faster than messing with a d-pad, joystick or touchpad to select different af points. I have found only touchscreen focus to equal it in simplicity, but that prevents viewfinder usage.

Depends on camera. At least on my Pana GX7 you can touch focus with the viewfinder active. Feels a tad cramped but works.

That's using it like a touchpad/trackpad on a laptop. My Canon m50 does that too. Since you aren't looking at the screen, you don't know exactly where that first touch input will put the focus point until you actually select one; then you have to drag it to your desired location. It's great for tracking or moving the focus point in a fixed scene, but it's not optimal for instantly selecting where you want the focus point to be. I consider it to be a different technique than touching an exact location on an image once to focus, thus why I mentioned touchpad and touchscreen focus separately.