Is it normal for a lens to change framing as you focus closer?
Asked 10/19/2011
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When I adjust focus on my Pentax 55-300mm, the image framing seems to change. At the 55mm end especially, the lens appears to zoom in as I focus toward the minimum focusing distance. Is this normal behavior, or could something be wrong with the lens?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
14y ago
2 Answers
15
This is called focus breathing.
With some lenses, especially macro lenses such as the Canon EF 100mm f/2.8 Macro USM, this effect can be substantial—at the minimum focusing distance, the focal length becomes about 70mm. While this is not normally an issue in still photography, it can pose a problem in video shooting as it can cause the angle of view to change while racking or following focus. Cine lenses are generally corrected for focus breathing, but lenses designed for still photography are often not corrected for this behavior.
Originally by user4506. Source · Licensed CC BY-SA 4.0
user4506
14y ago
0
Generated from our catalog & community — verify before relying on it.
Yes — this is normal and is commonly called focus breathing.
As focus distance changes, many lenses slightly change their effective angle of view, so the image can appear to zoom in or out. This tends to be more noticeable on lenses that focus closely, and often shows up more clearly at the wide end of a zoom. Even prime lenses can do it.
Lens focal length and angle-of-view specs are generally quoted with the lens focused at infinity, so the behavior you see at close focus does not necessarily mean the lens is defective.
In still photography this usually is not a problem. It matters more in video, where a visible framing change during a focus pull can be distracting. Lenses made for cinema are often designed to minimize focus breathing, while still-photo lenses commonly are not.
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