What is meant by a telephoto lens "breathing"?

I know it means something along the lines of the zoom not being exactly what the zoom says. For instance, it means a 70-200 mm lens is really only zoomed to 130 or so. So a 70-200 is really a 70-130 mm lens. How would you be able to calculate what the breathing would be for different lenses?

re: What is meant by a telephoto lens "breathing"?

Think it also has to do with how close your subject is,but could be wrong

re: What is meant by a telephoto lens "breathing"?

sonicbuffalo said:

I know it means something along the lines of the zoom not being exactly what the zoom says. For instance, it means a 70-200 mm lens is really only zoomed to 130 or so. So a 70-200 is really a 70-130 mm lens. How would you be able to calculate what the breathing would be for different lenses?

Click to expand...

No, a 70-200 is absolutely fabulous, and is NOT just a 70-130 mm lens. Nobody doesnt like the 70-200.

The effect you describe is only seen at very close focus distances, which is NOT normally how a telephoto is used. Most internal focus zooms do this in some degree.

See 70-200mm AF-S VR II Lens Review by Thom Hogan about more specific numbers and distances.

Edit: Better link explaining Focus Breathing.

....

how I have always understood it, is that the maximum focal length will only give you the maximum multiplication factor at INFINITY. As soon as you try to zoom in on a subject closer than infinity the magnification factor reduces. This is most noticable and frustrating when you buy for example a 18-200 zoom lens thinking you will be able to zoom it on a flower at the minimal focal distance of the lens and expect the same magnication factor as at infinity. I once saw a test online somewhere, where a ?-200mm zoom gave about an 11x magnification at infinity, however when focused in on something at a few meters away the magnification factor was reduced to about 5.

Englischdude said:

how I have always understood it, is that the maximum focal length will only give you the maximum multiplication factor at INFINITY. As soon as you try to zoom in on a subject closer than infinity the magnification factor reduces.

Click to expand...

Right, the Marked focal length only applies to infinity focus (and it is only nominal then, rounded off a bit).
If you focus closer than infinity, the lens lengthens to do that, and the focal length always changes a bit, on any lens, zoom, prime, whatever. The marked focus length number only applies to infinity focus.

This breathing effect is speaking of zooming. Focused at the same close point (where it is no longer precise anyway), zooming can change it again, a little.

Come on guys, we use DSLR, and the viewfinder shows exactly what we are getting. Adjust for that. The exact specific number is not important to us, has no real meaning to us.

WayneF said:

Right, the Marked focal length only applies to infinity focus (and it is only nominal then, rounded off a bit).
If you focus closer than infinity, the lens lengthens to do that, and the focal length always changes a bit, on any lens, zoom, prime, whatever. The marked focus length number only applies to infinity focus.

This breathing effect is speaking of zooming. Focused at the same close point (where it is no longer precise anyway), zooming can change it again, a little.

Come on guys, we use DSLR, and the viewfinder shows exactly what we are getting. Adjust for that. The exact specific number is not important to us, has no real meaning to us.

Click to expand...

I totally agree Wayne. I never give any thought to focal length when I use my Nikkor 70-200 vrii, I just zoom in and then move if it's a problem. Allegedly it's only 135mm close up but who gives a #%^*. I've never been aware of it in practical use and it takes fantastic photos.


Sent from my iPad using Tapatalk HD