Do I understand focus breathing?
Apr 7, 2017 21:28:32 #
Here's how I understand it: when you focus, it looks as if you are also turning the zoom ring. Do I have it, or if not, would you please correct me?
Thanks!
Thanks!
Apr 7, 2017 21:36:04 #
Ben,
http://www.imaging-resource.com/news/2014/12/17/what-is-focus-breathing-and-how-does-it-affect-your-images
--Bob
http://www.imaging-resource.com/news/2014/12/17/what-is-focus-breathing-and-how-does-it-affect-your-images
--Bob
Rab-Eye wrote:
Here's how I understand it: when you focus, it looks as if you are also turning the zoom ring. Do I have it, or if not, would you please correct me?
Thanks!
Thanks!
Apr 7, 2017 23:08:33 #
Apr 8, 2017 01:17:32 #
bclaff
Loc: Sherborn, MA (18mi SW of Boston)
Rab-Eye wrote:
Here's how I understand it: when you focus, it looks as if you are also turning the zoom ring. Do I have it, or if not, would you please correct me?
Thanks!
Thanks!
The focal length of a lens is determined at infinity focus.
As you focus closer the only way to maintain that infinity focal length is to focus by extending the entire lens away from the sensor plane.
(One common current example is the 50mm f/1.8D AF-Nikkor (D not G) )
But that would mean that lenses could extend very far out on a long helicoid.
So quite some time ago lens designers started making the lenses extend less but decrease in focal length as you focus closer.
For most lenses that also meant the air would move in/out of the lens; hence the term "focus breathing".
But it's a misnomer because even internal focus lenses that don't "breath" almost certainly decrease in focal length as you focus closer.
Because the focal length decreases as you focus closer you get a larger Field Of View (FOV) so yes, it might appear that you are zooming.
Apr 8, 2017 04:06:20 #
Pablo8
Loc: Nottingham UK.
It happens!!! Get over it. If you were a working 'Sports Press Photographer', your subject would be long-gone, while you were worrying over the 'Breathing' element of your lens.
Apr 8, 2017 08:33:06 #
Pablo8 wrote:
It happens!!! Get over it. If you were a working 'Sports Press Photographer', your subject would be long-gone, while you were worrying over the 'Breathing' element of your lens.
For goodness sake, I'm just trying to understand a concept! Who are you to tell me to "get over it" or assume that I'm thinking about it and letting it interfere with my photography? Some people here are so helpful. Others...well, that's why there is a Blocked list. Thanks for nothing, Pablo.
Apr 8, 2017 08:37:09 #
Rab-Eye wrote:
For goodness sake, I'm just trying to understand a concept! Who are you to tell me to "get over it" or assume that I'm thinking about it and letting it interfere with my photography? Some people here are so helpful. Others...well, that's why there is a Blocked list. Thanks for nothing, Pablo.
Some people just don't understand that a lot of time we want to know about something it's just for fun.
Apr 8, 2017 08:59:12 #
Apr 8, 2017 09:18:42 #
catchlight..
Loc: Wisconsin USA- Halden Norway
Telephotos will have less focus breathing because your breath is that much further from the lens...
a pancake lens can be a real bitch!
But...
https://www.youtube.com/watch?v=tz8lbCrLBEs
a pancake lens can be a real bitch!
But...
https://www.youtube.com/watch?v=tz8lbCrLBEs
Apr 8, 2017 09:18:47 #
Most zoom lenses exhibit focus breathing.
A 70-200mm lens only zooms to 200mm when it’s focused at a distant subject. When focused on something close, the maximum focal length is typically closer to 150mm, even though the zoom ring still says 200mm, this occurs because the small elements have to shift inside the lens to maintain focus. You can test this yourself by focusing close in front of you and then at a distant objective that is at infinity, the image will shift slightly. Now I could start an argument here but canons control this better in the L line, alas Sigma and Tamron shift to about 150 mm when not at infinity. I think Nikon has fixed this somewhat in the new 70-200. But at 2800 dollars who cares.
Ok I shoot in both systems and so far this hasn’t caused me any grief.
This is a forum and people ask questions. Chill out everyone is in a different place.
The 24-70 lenses do this to.
Cheers Ron
A 70-200mm lens only zooms to 200mm when it’s focused at a distant subject. When focused on something close, the maximum focal length is typically closer to 150mm, even though the zoom ring still says 200mm, this occurs because the small elements have to shift inside the lens to maintain focus. You can test this yourself by focusing close in front of you and then at a distant objective that is at infinity, the image will shift slightly. Now I could start an argument here but canons control this better in the L line, alas Sigma and Tamron shift to about 150 mm when not at infinity. I think Nikon has fixed this somewhat in the new 70-200. But at 2800 dollars who cares.
Ok I shoot in both systems and so far this hasn’t caused me any grief.
This is a forum and people ask questions. Chill out everyone is in a different place.
The 24-70 lenses do this to.
Cheers Ron
Apr 8, 2017 09:21:07 #
Rab-Eye wrote:
Here's how I understand it: when you focus, it looks as if you are also turning the zoom ring. Do I have it, or if not, would you please correct me?
Thanks!
Thanks!
Yes. The focal length changes slightly as the focus is changed, some lens designs exhibit this effect more than others. About the only time I would worry about it is when focus stacking or maybe when doing 1:1 Macro.
Apr 8, 2017 09:28:33 #
bclaff wrote:
The focal length of a lens is determined at infini... (show quote)
I do not beleive that the term "breathing" has anything what-so-ever to do with moving air in or out of the lens. That is something you just came up with on your own to explain the term.
"Breathing" is a term that has been used forever by Engineers and Mechanics and others to describe the effect of one thing changing when another is adjusted.
Apr 8, 2017 09:31:15 #
Apr 8, 2017 09:43:20 #
Apr 8, 2017 10:20:02 #
Videographers worry about it because the lens will "breath" and change a composition when they are using focus to change the point of interest (focus pulling). Videographers will sometimes spend a lot of money for special lenses that won't breath (and have other traits not needed in still photography).
If you want to reply, then register here. Registration is free and your account is created instantly, so you can post right away.