"Zoom with Feet" using zoom lens

krb wrote in post #6400936
Okay, granted that high level decisions of "long vs short" happen first.

Working in a controlled environment gives you that luxury.


Now take sports as an example. You "move your feet" to select the perspective. Field level or up in the stands. Visitor's goal vs home goal vs somewhere along the sidelines. Then during the game you use the zoom to frame players to get the shots you want.

I seldom actually work in controlled environments but I still know what focal length I want and why. It's the first decision to make when you put your camera together.

cdifoto wrote in post #6400968
Yeah I should have gotten into it a little deeper than that but...eh. I figured it's kind of a given. You're using a longer lens (focal length) because you want to be further away from the subject (distance) and still have tight framing (feet).

cdifoto wrote in post #6400971
I seldom actually work in controlled environments but I still know what focal length I want and why. It's the first decision to make when you put your camera together.

This is experience taking over, of course.

For the newbies, we need to teach them the real basics and how to think through the process of setting up good composition.

Once the newbies gain the experience, they too can take the shortcuts we old farts often do.

Oh yeah that's true. I'll never be a teacher. I suck at it.

I just want to say *cough*

stephen_g wrote in post #6400459
I have a question that sorta relates to this, too, if you shot a pic with say, a 20mm lens, then one with a 200mm, but way way way further back, so you got the same amount in the pic, would the image look the same?

I hope you realize that the answer is no.

By changing the distance between the camera and subject, you will change the perspective in the image. By that, I mean that the size comparisons between elements of the image that are closer to and further from the camera would be quite different in the two shots you describe.

Krypty wrote in post #6401274

Krypty - the diagram with no comments seems to be rather meaningless in the context of stephen_g's question. Can you fill us in as to what you were trying to get across?

First of all (for the newbies looking at the diagram) could you answer a couple of questions:

What format camera are the angles of view supposed to be for?

Are the angles of view in the horizontal plane, vertical plane, or diagonal across the view?

I was shooting a wedding earlier this summer, using mostly my 24-60 lens. When we got outside to the park, with good light I whipped out the 70-200 f/2.8 to do some portraits. I had to stand maybe 15-20ft from the subject, shooting around 100mm or just over, and got nice blurred background.

I'm glad we finally got that straightened out.

And don't forget the details in the image:
MOVE YOUR FEET! A <rant> of sorts.

This has a great animation / explanation for framing and perspective :
http://www.canon.co.jp …g/enjoydslr/par​t3/3C.html

An example of change in perspective caused by altering the camera-to-subject distance to hold the subject at a given size, so the background changes size relative to the main subject (touch up paint bottle in center), and even the other parts of the subject (the ruler and the things placed at the ends of the ruler) is altered in perspective....

70mm

Wilt wrote in post #6407310
An example of change in perspective caused by altering the camera-to-subject distance to hold the subject at a given size, so the background changes size relative to the main subject (touch up paint bottle in center), and even the other parts of the subject (the ruler and the things placed at the ends of the ruler) is altered in perspective....

Wilt - if you added the camera-to-paint bottle distances for each of the images, it might help some folks understand a little better.

SkipD wrote in post #6408533
Wilt - if you added the camera-to-paint bottle distances for each of the images, it might help some folks understand a little better.

I would if I could, but I can't -- so I won't

The two photos were shot quite a while ago (months/year) and I do not recall. I can tell you that I adjusted camera position for each lens FL (70mm, 200mm) used so that the center paint bottle was constant size in the frame. In view of the FL used, the shooting distances expressed in relative terms would have been N' for 200mm, and (N'/2.86) for 70mm. Instread of actual distances that were used to make the shots, I will use a realistic portrayal of what was involved...

By moving the camera closer, the paint bottle was relatively close to the lens for the 70mm shot, and the blinds in the backround would be relatively far away, so the blinds look farther and narrower. (For example, 5' to bottle vs 25' to blinds or ratio of 1:5) For the 200mm shot, the relative distance between the camera and bottle is a smaller (for example, 14' to bottle, 34' to blinds or ratio of 7:17).

Also by moving the camera position, the apparent depth of the ruler is altered as a relationship to the shooting distance. Because I had stretched a string along the floor to align my tripod to that line, I was assured of a fixed angular perspective to all the objects in the scene. And the items at the tip of the ruler, which identical in actual height, appear to recede more in the shorter FL shot and the front one is relatively taller than the back one. With the longer FL shot, both are more similar in height.

EOSBoy wrote in post #6400517
Longer focal lengths exaggerate depth of field creating more diffused bokeh. For portraiture and shooting more definitive subjects they require longer focal lengths to isolate themselves from the background, obviously. As for using shortest focal lengths to pull off the same look, you'd have to get very close and the subject would become distorted due to the wide field of view.

Just wanted to add that DOF does NOT increase with wider lenses. It's a common misconception. See Luminous Landscape's article here. What really changes is the proportion of the OOF to the subject when using telephoto lenses, since longer lenses compress the image, and thus "exaggerating DOF" as EOSboy mentions, making DOF seem thinner.

stephen_g wrote in post #6400459
I have a question that sorta relates to this, too, if you shot a pic with say, a 20mm lens, then one with a 200mm, but way way way further back, so you got the same amount in the pic, would the image look the same?

No, and it's quite easy to convince yourself with a thought experiment.

You're shooting a house with a fir tree in the front garden. With your 20mm lens your positioning to get all the house in the frame means that the tree is just 1 foot from your lens - your viewfinder is almost filled with tree trunk.

But with the 200mm lens you're standing much further back and the tree trunk hardly obscures any of the house.