One of the optical issues photographers often have to deal with has to do with focus breathing. It commonly occurs on many modern lenses, making it difficult to understand their true optical properties. In this article, we will take a closer look at focus breathing, how it affects images and what you can do to minimize its impact.
What is Focus Breathing?
Focus breathing is a term that describes the change in focal length that occurs as a result of adjusting the focusing distance of a lens. It is a common issue that occurs on many photographic lenses. As focus is adjusted from close focus to infinity, focus breathing causes noticeable changes in both angle of view and magnification.
These changes are often clearly visible to the photographer during the process of focusing, with different lenses exhibiting varying levels of focal length changes. Focus breathing issues can occur on both prime and zoom lenses.
There are typically two scenarios when photographers notice focus breathing. The first is fairly common, because it has to do with the magnification or “reach” of a lens at close distances. Some lenses, such as the Nikon 70-200mm f/2.8G VR II, exhibit so much of it, that at 200mm and focused on a close subject, it makes the lens look more like a 120mm lens. This catches many photographers by surprise, because they do not expect to see such odd behavior – they expect their lens to magnify the subject as a “real” 200mm lens does at any distance.
Take a look at the above two images. The “before” image on the left part of the slider shows the Nikon 50mm f/1.4G at its closest focusing distance (focused on BB-8 on the bottom right), while the “after” image shows the same lens focused at the white figure in the back (First Order Stormtrooper). Pay attention to how much the framing changes between the two shots – the “after” image looks zoomed out, as if it was shot with a shorter focal length lens. This is the effect of focus breathing on the 50mm f/1.4G lens. The Nikon 70-200mm f/2.8G VR II lens mentioned above shows even more significant levels at 200mm.
The second scenario involves focus stacking when shooting macro, landscape or architecture photography. Photographers notice visible changes in angle of view at close vs farther focus distances (especially infinity), which can make it difficult to merge all images into a single stack successfully during post-processing.
Unfortunately, aside from some high-end (and very expensive) cine lenses, most modern lenses exhibit some form of focus breathing. Why does this happen and is it a big problem?
Why Lenses “Breathe”
Most modern lenses today feature “internal focus” design, which basically moves a group of internal lens elements instead of the whole lens barrel when focus is adjusted. This makes it convenient to use filters on lenses, because the front element does not rotate while focusing. Another benefit of internal focus, is that it does not affect the overall size of the lens – it stays the same at any focus distance. Lastly, it is faster to move a small and lightweight group of lenses instead of the lens barrel when focusing, which increases autofocus speed and makes the autofocus motor less noisy. Because of these and other advantages, lens manufacturers have been mostly releasing lenses with internal focus designs.
Unfortunately, such lenses also come with one big disadvantage – they often exhibit focus breathing. As the group of internal focus lens elements are moved during focusing, others stay in place, which can affect the optical characteristics of the lens, including focal length. Depending on the size of the internal focus group and the overall optical design, the change in focal length can vary, from small to large.
So why don’t manufacturers reflect this in their lens specifications? Why is a 70-200mm f/2.8 lens that has a similar angle of view as a 120mm lens at 200mm still referred to as a 70-200mm lens? Because it only happens at close focusing distances. Since the focal length of a lens is measured at infinity, a 70-200mm lens is going to have proper focal lengths of 70 and 200mm at both ends of the zoom range when focused at infinity. Manufacturers often do provide information in their specifications to be able to identify lenses with focus breathing properties, and we will go through that further down in the article.
Note:It is important to note that focus breathing in lenses always causes a decrease in focal length, not an increase.
Lens designers sometimes take this into account by specifically designing lenses that exhibit minimal amount of focus breathing. After many complaints from photographers, Nikon’s engineers updated the aforementioned 70-200mm f/2.8G VR II lens with a completely new optical formula that minimized focus breathing. The result of this effort was the Nikon AF-S NIKKOR 70-200mm f/2.8E FL ED VR, which showed a drastic improvement in focus breathing compared to its predecessor, as we detailed in our review.
With the release of the new Nikon S-series lenses for the Z mount, Nikon’s engineers are now specifically designing each lens to exhibit a minimal amount of focus breathing as part of their lens design.
Compare these two images from the Nikon Z 50mm f/1.8 S to the ones from the Nikon 50mm f/1.4G provided earlier. You will notice that the new Z mount 50mm f/1.8 S shows very little focus breathing compared to its f/1.4G counterpart.
Other manufacturers are following suit because they understand how frustrating it can be for photographers to encounter such lenses.
How to Find Out If a Lens Has Issues
The easiest way to find out of a lens has focus breathing issues is to take a look at its specifications, specifically at its maximum magnification, which is also known as “maximum reproduction ratio” or just “reproduction ratio”. Simply put, maximum magnification is the ratio of the size of the image on the image sensor relative to the actual size of the subject. This information can be easily used to determine how much focus breathing a lens exhibits when compared to other similar lenses.
Let’s take a look at the last three 70-200mm f/2.8 lenses produced by Nikon and compare them side-by-side, along with the 70-200mm f/4G VR:
|Nikon Lens||Maximum Magnification|
|Nikon AF-S NIKKOR 70-200mm f/2.8G IF-ED VR||0.25x|
|Nikon AF-S NIKKOR 70-200mm f/2.8G ED VR II||0.12x|
|Nikon AF-S NIKKOR 70-200mm f/2.8E FL ED VR||0.21x|
|Nikon AF-S NIKKOR 70-200mm f/4G ED VR||0.274x|
As you can see, the Nikon 70-200mm f/2.8G ED VR II has the lowest maximum magnification / reproduction ratio of 0.12x in the group, so it is no surprise that it is the worst offender in terms of focus breathing. The first 70-200mm had a respectable maximum magnification of 0.25x, which is why photographers quickly noticed how bad focus breathing on the newer VR II version was when compared to its predecessor. Nikon’s latest 70-200mm f/2.8E FL VR is much better at 0.21x, but the best performer here is clearly the Nikon 70-200mm f/4G VR, which has a maximum magnification of 0.274x – the best in the group.
So if I were looking for a lens that shows the least amount of focus breathing among Nikon’s 70-200mm lenses, I would be picking the f/4 version. It is cheaper and lighter than the rest, and it would make an excellent candidate for focus stacking.
However, that is not why we buy 70-200mm f/2.8 lenses, is it? Portrait photographers desire 70-200mm f/2.8 lenses because of their optical qualities and they rarely ever pay attention to focus breathing, as explained further down below.
Now if you don’t have lens specifications in front of you, you can also do a quick test on your lens to see if it suffers from focus breathing. The test is quite simple – set your camera on a tripod, then rotate the focus ring from close focus to infinity and see if the image seems to “zoom out” as you focus. If it does (which it most likely will), your lens has focus breathing. If you see big changes in angle of view as you focus, it means that your lens has a lot of focus breathing.
How to Eliminate Focus Breathing
Since we know that focus breathing is only a major problem at close focusing distances and never at infinity, the solution would be to force the lens to focus at infinity, even when focusing on close subjects. The only way to be able to achieve that is to use extension tubes.
By using one or more extension tubes, you would be moving the lens further away from the camera (since it is just a hollow spacer) and allowing it to focus at infinity at much closer distances, which in turn, would reduce or potentially even eliminate focus breathing.
While on one hand using extension tubes sounds like a great idea, they unfortunately bring a slew of problems with them. First of all, you would lose autofocus capabilities of the lens with most extension tubes. Second, you would lose some light, which would require using faster shutter speeds / increased ISO. Third, you would lose the ability to focus at subjects far away. And lastly, using an extension tube can deteriorate image quality and add more lens aberrations to your images.
Honestly, considering all the disadvantages listed above, using an extension tube just to be able to get rid of focus breathing is a bad idea for most photographers…
Is Focus Breathing a Big Problem?
Is focus breathing a big problem that every photographer needs to be aware of? Not really. Most photographers aren’t even going to notice any differences in angle of view and magnification when using most lenses at close distances. Those who do, are likely comparing different lenses, and just want to find out why they see such differences. So if you are a stills photographer, you should probably ignore the focus breathing issue altogether.
I personally owned the Nikon 70-200mm f/2.8G VR II for many years, despite its heavy focus breathing issues. I shot many events, portraits and weddings with that lens and it paid for itself many times over. That lens had a ton of focus breathing, but I didn’t care, as it didn’t affect my images.
However, if you are a landscape, architecture or macro photographer who wants to be able to focus stack images successfully, especially when shooting subjects from close focus all the way to infinity, then you should pay close attention to the types of lenses you pick. You want to pick lenses that exhibit the least amount of focus breathing so that there are minimal shot-to-shot differences in angle of view when adjusting focus.
Focus breathing is also a pretty big problem for cinematographers, because they do not want to see changes in angle of view when moving focus from one subject to another. Cinematographers specifically pick expensive cine lenses for their work, because they exhibit little to no focus breathing, and have other important optical properties that are critical when shooting videos.
In summary, unless you have these very specific shooting conditions, do not worry about focus breathing, as it probably will not affect your photography in any way.
Thanks for the good review and practical tips. I would however question your assertion that this is not a real problem. I purchased a Tamron 18-400 mm zoom for birding, and the focus breathing was severe. At “feeder distance” (say 20 feet), the field of view was roughly that of a 250 mm prime, which I already owned. For birds and wildlife, that’s not a small difference. So I traded it in for the Tamron 100-400 mm zoom, which exhibited little focus breathing.
I think there is lot of confusion about the term “focus” or “lens breathing”. I’ll try to clear things up a bit:
1. The term “focus breathing” or “lens breathing” describes the changing angle of view while focusing. See e.g. the definition here: en.wikipedia.org/wiki/…ing_(lens). It is not necessarily associated with a change of focal length.
2. There are different methods of a) focusing lenses (e.g. internal and external, but it’s more complicated than that – let’s not delve into that here) and b) to correct for near distance focusing (e.g. with floating elements). All have an influence on how focus breathing shows itself.
3. As stated correctly in this article a lens with minimum or eliminated focus breathing is desirable for cinematography, because it avoids shifting the angle of view (too much) while changing the focal plane. For still photography such a specific behavior is of no particular importance, with the one exception mentioned here: it makes stacking a bit easier. But see also #6 on this.
4. There is negative focus breathing – angle of view widens (“zooming out”) while focusing closer and positive focus breathing – angle of view narrows (“zooming in”) while focusing closer.
5. Negative focus breathing is frowned upon if noticed because people feel “cheated” of a “promised” magnification (= deemed adequate to the indicated focal length) at closer focusing distances. Especially travel zooms with a large focal range can show quite an extreme amount of it. And most discussions evolve around this kind of negative focus breathing – since the massive loss of magnification (= reach) at closer distances is clearly visible when compared to other lens designs with the same indicated focal length(s). On the other hand those kind of lens constructions offer many advantages, among them portability, light weight, great range of focal length at infinity and affordability. Even the most extreme “negative focus breathing” zoom lens can be very useful and adequate in lots of situations.
6. Positive focus breathing is a quite normal behavior for a lot of lens designs and really not a problem for photographers – it’s even a good thing if your main concern is “reach”, because magnification is higher compared to a lens with no or negative breathing when focusing closer. It’s also not that big a problem for stacking purposes – just frame the closest focusing shot first and work backwards from that, than you’ll lose no relevant image elements. Good stacking software can work with the different magnifications of the single shots to produce very good results. They should be even better when done with a non-focus breathing lens, of course.
7. Using extensions tubes introduces positive focus breathing – field of view narrows. As said in the last paragraph: Not really a problem.
8. Maximum magnification at a given focal length is not only influenced by focus breathing but also by minimum focusing distance of the lens.
Several of these points have already mentioned by others in this comment section here,
I hope this clarifies things a bit.
Dear Nasim, sorry to say so, but your article is mostly bogus because you didn’t catch the main point.
A lens which does not change it’s focal length when focusing (focusing by changing the distance to the sensor, as you also do when using extension tubes) has a lot of focus breathing.
If you want to avoid focus breathing, then you have to reduce the focal length when focusing towards close distances.
The focal point of a lens is the point where parallel rays (i. e. coming from infinity) cross after passing the lens. The focal length of a lens is defined by the distance of the lens to the focal point. This means the focal length of a lens is independent of it’s distance to the sensor, and there don’t need to be a sensor at all. As a consequence a photo lens which only focuses by changing the distance to the sensor never changes the focal length.
Now if you draw a sketch, to the right a stroke for the sensor, to the left you draw the lens, and then you draw the rays from the edge of the sensor through the center of the lens, as shown here digicam-experts.de/faqfo…kus_1a.jpg (“Brennweite” means focal length), then you have the angle of view. If you now focus to closer objects by changing the distance of the lens to the sensor (as you would do with extension tubes), then on the sketch you move the lens to the left, and when you draw the rays from the sensor edges through the center of the lens anew, then you have a smaller angle of view, see here digicam-experts.de/faqfo…kus_1b.jpg. I. e. with the same lens and that implies same focal length you have strong focus breathing.
If you want to focus without moving the lens to the left, then you can exchange the lens by another lens which bends the rays stronger. Then the angle of view stays the same, see here digicam-experts.de/faqfo…kus_2b.jpg so no focus breathing, but you’ve reduced the focal length because stronger lenses have shorter focal lengths.
(Here is the complete article digicam-experts.de/faq/12 – in German, but I took out the main parts and explained them for you.)
This means the reduced focal length of the 70-200 VR at close focus probably is not a bug, it is a feature. But a feature which not every photographer welcomes.
Why not digitally correct this?
It mostly affects video, and video is already oversampled.
It’s no wonder Nikon is going the way of the Dodo bird. Consumers don’t like it when they’re cheated after paying a lot of money for a product.
>The easiest way to find out of a lens has focus breathing issues is to take a look at its specifications, specifically at its maximum magnification, which is also known as “maximum reproduction ratio” or just “reproduction ratio”.
i think we should look at both maximum magnification and minimum focus distance to find out focus breathing issues.
In your Informative article on Focus Breathing there is a great photo under focus stacking. It has
beautiful layers in columns of geologic time. I tried to find the location in your photo spot section but it was not listed. Could you tell me if the area where this was taken has a name or where the photo was taken?
Google search says those are from caves in Petra, Jordan
I think that this article could benefit from a bit more thought and clarity.
The focusing behavior of the Nikon 50mm f/1.4G, as I understand it, is pretty much the same as a lens with a single optical element. To focus nearer, you move the lens elements further away from the sensor, which decreases the angle of view. As an extreme example, if you wanted to use this lens as a macro lens you could use an extension tube to double the distance between the optical center of the lens and the sensor. This would cut the angle of view in half. Or to put it another way, it would give you the same angle of view as a 100mm lens focused at infinity.
Focusing works differently on cinema lenses than it does on photographic lenses. On a cinema lens, changing the focus changes the focal length of the lens while keeping the optical center (and thus the field of view) constant. If there is a 50mm macro cinema lens out there, it will have a focal length of 50mm when focused at infinity and a focal length of 25mm when focused an at object close enough to get a 1:1 reproduction ratio.
“Focus breathing,” as I understand the term, refers to a phenomenon where the focal length of a lens changes when you change the focus. Based on that definition, the images you show with the 50mm Nikon don’t show focus breathing, because the field of view changes but the focal length of the lens does not.
It would be useful to have a term that refers to the change in field of view that occurs when you change the focus of a lens, but using the term “focus breathing” for this purpose seems like a poor choice because most photography sites use the term to refer to a change in focal length.
If you are a photographer rather than a cinematographer, the changes in the field of view of the Nikon 50mm are probably too small for you to even notice, much less worry about. When photographers complain about focus breathing, they aren’t complaining that their field of view gets slightly narrower when they focus close up, as occurs on a lens where changing the focus doesn’t change the focal length. They also aren’t complaining that the focal length of the lens gets slightly shorter, as happens on a cinema lens. They are complaining that the focal length gets dramatically shorter, resulting in a much wider field of view.
For example, the Nikon 70-200mm f/2.8G VR II mentioned in the article has a minimum focusing distance of 1.4 meters. If you have have a 200m lens that doesn’t change focal length when changing focus, changing the focus from infinity to 1.4 meters will reduce the field of view by about 12.5%. A 200mm cinema lens will compensate for this by reducing the focal length to 175mm, keeping the field of view constant. But the Nikon reportedly reduces the focal length to 120mm, increasing the field of view by about 46%.
People complain about this for two reasons. First, the change in focal length is huge. A 46% change in the field of view is a lot more noticeable than a 12% change. Second, the change in field of view is in the wrong direction. If you are using a telephoto lens to shoot something at a distance of 1.4 meters, it’s because you are shooting something small. If you do notice that the field of view is 12% smaller, you are likely to be pleased, not disapppointed. And if you don’t want the narrower field of view, you can always zoom out to 175mm.
This means that the images from the Nikon 50mm f/1.4G are not an ideal illustration of a change of field of view with focus because the changes that photographers complain about are both larger and in the opposite direction.
I have no idea why we see drastic changes in focal length on some lenses. The article points to internal focusing, which I believe is part of the answer but it can’t be the complete answer. There are plenty of cinema lenses with internal focusing. The Nikon Z 50mm f/1.8 S has internal focusing, but the article shows that the field of view still gets narrower when the lens focuses closer. So using internal focusing may mean that the focal length is going to decrease when focusing closer, but it doesn’t mean that the focal length has to decrease drasticly, or even decrease enough to cause the field of view to increase.
“Since we know that focus breathing is only a major problem at close focusing distances and never at infinity, the solution would be to force the lens to focus at infinity, even when focusing on close subjects. The only way to be able to achieve that is to use extension tubes.”
How very wrong, Nasim.
First, I’m sure you’re aware of macro bellows.
Second, I’m nearly sure you’re aware of the possibility to use a bellows with a mirrorless Z-body and a G-lens, so you can maintain focus at infinity.
Third, standard manual focus lenses from the 60’s or 70′ moved the whole lens package and are doing waht you say is only possible with extension tubes. Later lens companies went on with “floating elements” to improve close focus. That is that two or more lens groups were moving differently and could cause “focus breathing” which was an unknown word at the time.
Fourth, even with extension tubes or bellows one runs into complications when trying to do a focus stack by using a wider angle than the 70-200 or 50 mm has. Depending on the perspective and the distance, elements in your composition can blurr out that much that in-focus elements are covered by blurr in fore- and background and it is merely impossible to resolve the perspective contradictions. And there’s no solution because you cannot switch off the foreground. Luckily, this problem only appears when trying to focusstack. But it also shows the limitations to counter focus breathing – it can be minimized but not fully avoided.
“Third, standard manual focus lenses from the 60’s or 70′ moved the whole lens package and are doing waht you say is only possible with extension tubes.”
I beg to differ, I tested it quickly: All my old Nikon / Nikkor lenses from 20mm to 180mm do focus breathing. The Q.C. Auto 3.5 f=135mm and the Q Auto 2.8 f=24mm do, both are from the sixties. The others are from the seventies or later, though most of them having much older lens design. (Reusing a lens design over a long period time is something Nikon is well known for. That changed drastically with the Z-lenses.)
(And please do not nitpick, e.g. about extension tubes or bellows. I think we all got what was the message here, don’t we?)
Well, my nitpicking was about the fact that bellows allow continuous adjustments (without moving the tripod) and could include focusing at infinity whereas extension tubes are rather impractical. And the statement of Nasim “The only way to be able to achieve that…” is excluding everything else.
Now, I only have one old Nikkor, a 35/2.8 from 1969. That one is moving the whole lens system as one pack. I think, it will also do focus breathing, same as yours also do, if I understood you correctly.
But moving the whole lens as one single group is nothing else than adding an extension tube between body and lens. If Nasim’s statement would be correct, there should not be any focus breathing. But I do believe, it’s not correct.
Avoiding focus breathing means, while adjusting the distance, the focal length also has to be adjusted as the magnification of the objects should remain the same. However, I don’t think it is that big of a problem for photographers anyway. And for serious cinematographers there are a lot of reasons to grap a ciné-lens anyway.
It might be true that the Nikkor S show less focus breathing – but they also don’t have a proper focus scale, they are focused by wire and I don’t consider them as very useful for accurate focus pulling at different pulling speeds. If I were more into video, I would not see them as first choice .
In addition: Any lens, if not specially designed, does focus breathing, since the movement of the lens to achieve a different focus shortens or lengthens the focal length.
The article points out that zoom lenses with internal focusing suffer more then fixed focus lenses.
PS: I’m wondering if there is ever a lens that no focus breathing at all.
“…more than fixed focal lenses”, of course. Sorry. To add some information:
The Zeiss 100mm f/2 Makro-Planar is said to be one of those lenses which have almost no focus breathing (FB). Cine lenses do also FB, generally less, but some of them are specially designed to minimize it. Tokina claims to have lenses without FB. But upon checking it: they still do. I read some articles about cine lenses regarding FB and stumbled upon the cine Zeiss/Arri Master primes. But even they do a little FB even if they are designed to minimize it. They cost a fortune.
There is no lens without focus breathing, I conclude. I just give some information away I found and am in no way a lens expert.
I’m glad my type of photography is not affected by FB. Cheers! -jan
I think, cine zoom lenses are optimized to not loose focus when zooming (which is usually no problem for photographic zooms). I’m also really happy to not care about focus breathing. It’s between very difficult and impossible to get a lens without FB, I think a bit of FB is usually no problem and if a movie has the only weakness to be filmed with a lens which shows a bit of FB, I will gladly buy a ticket for it :)
I read an article recently about the very expensive lenses for professional TV. Very little focus breathing and parfocal (no focus shift during zooming)
The truth is most still photographers can tolerate this because their setting up the shot before they take it. Video/TV shooters, however face a much bigger problem.
Robin it took me a minute to figure out I could touch the arrow and swipe back and forth to reveal the entire before and after frames. If you don’t have a touch screen a mouse will work.
Nasium, thank you for that easy to understand article explaining focus breathing. The subject has been confusing to me and I understand it now.
You are most welcome JD! Glad you liked the article.