What is focus breathing?

There are a lot of new lenses being introduced right now, and many in the 200mm range.  One topic that is being mentioned in reviews is focus breathing.  Many of you might be saying what is focus breathing, and does it really matter.  Focus breathing is a lens aspect worth knowing about, and depending on what lens you use, might affect your end result.  I’m going to focus on zoom lenses going out to 200mm.  Currently I have a DSLR 70-200mm E FL F2.8 and just recently picked up the 24-200mm F4-6.3 S lens for the Z system.

What is focus breathing?  When you zoom your 70-200mm out to 200mm and focus on something distant, you expect to get a 200mm angle of view.  Chances are at infinity at 200mm you are getting that angle of view.  But now imagine still shooting at 200mm, but you have to focus on something 8 feet away.  To focus on this close subject the lens elements must move in the lens which adjusts how close they are to the sensor.  What can happen with this shift in focus is that instead of getting a true 200mm at 8 feet, the angle of view might be closer to 180mm or even 150mm.  Focus breathing varies from lens to lens.  Many earlier 70-200mm were notorious for focus breathing, which causes issues for a lot of photographers.  If I am a portrait shooter, the 70-200mm F2.8 is a staple lens, something you use on every shoot.  But if I am shooting tight 200mm headshots close up, I’m going to be seriously disappointed if the angle of view is 150mm.  In other words, I am not getting as tight of a headshot as I would like.

I went out and shot my house address from about 10 feet using the lenses mentioned earlier.  Here is the 70-200mm E FL F2.8.

And from the same distance, here is the 24-200mm F4-6.3.

Here is the good news.  Both of these lenses have very little focus breathing.  Comparing the images, both look about the same size.  Thankfully many new lenses are producing less focus breathing than in the past.  If you are wondering about your specific lens, just google it along with focus breathing in the search.  Or if you have two lenses with the same focal length, try focusing on something close at the long zoom range and see if the image size is similar.

Can you correct focus breathing?  Yes, but it really isn’t practical in everyday shooting.  You could attach an extension tube which would counter focus breathing, but you loose a stop of light and add another piece to your setup.  Focus breathing is worth knowing about, especially if you are buying a new lens.  But I wouldn’t worry too much about it unless you are shooting close up at the long range of your zoom lens all the time.  Happy shooting!