Foot zoom vs. lens change: not the same

It seems like this comes up over and over again in lots of threads. Here's the best way to visualize the difference:

1. Put a zoom lens on your camera.
2. Stand back from the subject and zoom in.
3. Walk toward the subject while zooming out to maintain the framing.

You'll see how the perspective changes, although the subject stays framed the same. This same effect is used often in video to achieve a the dramatic feeling of zooming in on a subject without compromising the framing.

Logan7 wrote in post #11965391
It seems like this comes up over and over again in lots of threads. Here's the best way to visualize the difference:

1. Put a zoom lens on your camera.
2. Stand back from the subject and zoom in.
3. Walk toward the subject while zooming out to maintain the framing.

You'll see how the perspective changes, although the subject stays framed the same. This same effect is used often in video to achieve a the dramatic feeling of zooming in on a subject without compromising the framing.

The above is 100% correct.

For more information on perspective and how to control it, please read our "sticky" (now found in the General Photography Talk forum) tutorial titled Perspective Control in Images - Focal Length or Distance?.

Yes, that's the right response to "foot zoom" — I've been running around for days, but couldn't get my prime to change its angle of view even by a single degree!

(Of course, at least as I see it, this doesn't mean that using a prime, and running around a bit more, is "better" or "worse;" it's a _different_ thing to zooming.)

This video gives a good explanation of the perspective change.

http://www.thecamerast​ore.com …length-matter-perspective

Gerhard

Great video link. Enjoyed it and learned from it. Thanks.

Agree. Zooms open up a world of dual control of both framing and perspective that you often cannot achieve with primes. Ironically, primes are often useful precisely because they tend to "force" a certain perspective. For example, if you're shooting tight head shots with a 100mm prime, you will find it difficult to get the camera "too close" to the subject (which would cause negative perspective effects) because the framing is too tight.

..... on the other side of the mountain there is also probably a very nice view too ... ..
In other words, just take the picture where you are, and try to find the right angle, height, light and if something disturbing is in the frame, just move your feet to avoid the disturbing object.
Actually, you rarely need to move to replace a zoom.

Then zooms mostly have a huge DOF, so you need to tight much more your subject if you you want to avoid unpleasant background -> with a fast prime @F1.4 or@F1.2 background will magically disappear in an ultra smooth bokeh. It Also means that with slow zooms, you must be in macro mode to get something like bokeh ..

twotimer wrote in post #11965484
This video gives a good explanation of the perspective change.

http://www.thecamerast​ore.com …length-matter-perspective

Gerhard

Wow! Great video. As a camera noob it's great to see examples like that, puts it into perspective more than just reading it. Now time to try it!

I laugh every time some goon mentions "be a man like Ansel Adams and use footzoom" (this happens about once every 6 hours on here).

I took this (nothing more than a quick snapshot) yesterday @ 16mm...if I had a longer lens and had to footzoom I would have been in the water (was standing on a relatively narrow dock)

IMAGE LINK: http://www.flickr.com/​photos/tamasv/55012347​73/

newworld666 wrote in post #11966299
..... on the other side of the mountain there is also probably a very nice view too ... ..
In other words, just take the picture where you are, and try to find the right angle, height, light and if something disturbing is in the frame, just move your feet to avoid the disturbing object.
Actually, you rarely need to move to replace a zoom.

Then zooms mostly have a huge DOF, so you need to tight much more your subject if you you want to avoid unpleasant background -> with a fast prime @F1.4 or@F1.2 background will magically disappear in an ultra smooth bokeh. It Also means that with slow zooms, you must be in macro mode to get something like bokeh ..

Huge DOF? Meh, none of my zooms have a "huge" depth of field unless I choose to stop them down, with the exception of the UWA lenses which will by their very nature have a large DOF.

LowriderS10 wrote in post #11966409
I laugh every time some goon mentions "be a man like Ansel Adams and use footzoom" (this happens about once every 6 hours on here).

I took this (nothing more than a quick snapshot) yesterday @ 16mm...if I had a longer lens and had to footzoom I would have been in the water (was standing on a relatively narrow dock)

I agree; or how about being eaten by a lion when you climbed into the exhibit to get a closer view? A zoom doesn't change the perspective relative to a prime, a prime at the same focal length will give the same perspective. What a zoom does is give you more versatility. Some call laziness, I call it opportunistic. With the exception of "chart" shooters and pixel peepers, most people would be hard pressed to tell the difference between a prime and a quality zoom at the same focal length and aperture.

No Adams didn't foot zoom, he could see at different F/Ls, big diff. Foot zooming is a myth.

Learning to see at different focal lengths?
priceless.

And yes this topic comes up about every month or so,

newworld666 wrote in post #11966299
Then zooms mostly have a huge DOF, so you need to tight much more your subject if you you want to avoid unpleasant background -> with a fast prime @F1.4 or@F1.2 background will magically disappear in an ultra smooth bokeh. It Also means that with slow zooms, you must be in macro mode to get something like bokeh ..

A 50mm lens mounted on APS-C camera, when focused at something 10' away and shot at f/1.8 has DOF zone of 8.1 inches, while at f/4 has DOF zone of 18.1 inches...hardly a 'huge DOF'. There is no difference per se in 'prime' vs. 'zoom' DOF. The background is more recognizeable, but DOF itself is not the issue at play.

f/4

Scatterbrained wrote in post #11966495
I agree; or how about being eaten by a lion when you climbed into the exhibit to get a closer view? A zoom doesn't change the perspective relative to a prime, a prime at the same focal length will give the same perspective. What a zoom does is give you more versatility. Some call laziness, I call it opportunistic. With the exception of "chart" shooters and pixel peepers, most people would be hard pressed to tell the difference between a prime and a quality zoom at the same focal length and aperture.

Exactly...not to mention, it varies from lens to lens...I've owned some zooms that have been sharper than some primes...

And I agree, I don't think of it as lazy at all...that's like an accountant saying he wants to keep it real by doing all the math by hand. If the right tool is available, use it!

airfrogusmc wrote in post #11966514
No Adams didn't foot zoom, he could see at different F/Ls, big diff. Foot zooming is a myth.

Learning to see at different focal lengths?
priceless.

And yes this topic comes up about every month or so,

While learning to see at different FLs may be priceless, so is the fact that I have 16-35 covered at f2.8 with ONE lens. Less money, less stuff to carry and less changing lenses in the middle of shooting because I just realized that my 35 prime was too long and my 17 prime was too short, so let me dig out my 24 prime...or should I go with my 28 prime?

The concept of "foot zooming" is not about whats in the image, but about what is in your head.