p.1 #1 · Focus Breathing on Sony FE Lenses - share your tests
I didn't find a thread where we could share info on focus breathing on Sony FE mount lenses, so thought I'd start one. I have been doing a bunch of video interviews with the A7RIII on a tripod and using various FE autofocus lenses in AF w/ face detect. I noticed a lot of annoying focus breathing with the Batis 40 even with a largely static interview subject, so I tested a few lenses and settings and thought I'd share what I found.
Please add your own data so we have a comprehensive list of focus breathing by FE mount lenses. Hopefully this is of general interest to those doing video or focus stacking.
Here are some results from perspective of someone doing video interviews using AF face detect with a largely static subject at 5-10 feet.
Sony FE 24-105 - very little to no focus breathing at 24, 50, and 85mm with AF on, face detection, AF drive speed normal and AF tracking sensitivity at normal or responsive. Very good focus breathing performance while tracking an interviewee (minimal movement). Very little to no focus breathing even with bigger focus changes (like changing from background at a distance to interview subject at 5', or as interview subject moves from 5' towards MFD. I'm sure a real cinema lens is better but for my amateur video projects, I think focus breathing is a non issue with this lens.
Sony FE 35/2.8 - focus breathing present at same settings with static interview subject with AF tracking sensitivity at responsive. enough to be visible. Less at AF tracking sensitivity standard but still there slightly (you have to look for it)
Sony FE 85/1.8 - Same as FE 35/2.8... OK for video interviews with AF tracking sensitivity at standard.
Sony FE 50/1.4 - none to minimal visible focus breathing with AF tracking sensitivity at either standard or responsive. About as good as the FE 24-105... unlike that lens, I did detect focus breathing on larger changes in focus (e.g. background at 20' moving to subject at 5').
Batis 40 - focus breathing noticeable with static interview subject with AF tracking sensitivity at responsive. Still visible but acceptable to me at AF tracking sensitivity set to standard. About the same as the FE 35, performance not as good as FE 50 or FE 85, and 24-105 is much better. I think with the Batis 40 and FE 35, if the background has elements that will emphasize the focus breathing (e.g. straight lines or edges of objects near the edges of the frame) then it could be a concern.
Result: FE 24-105 and FE 50/1.4 are great... use AF tracking sensitivity at standard (not responsive) with the other lenses and expect some minimal focus breathing. Was disappointed with the Batis 40, focus breathing really bad with AF tracking sensitivity at responsive. much more than I recall with the FE 55 for talking head interviews - will have to test that lens next.
p.1 #3 · Focus Breathing on Sony FE Lenses - share your tests
Tested Batis 40 with updated firmware. AF in stills works great post firmware update. But the small focus movements while tracking the subject in video with AF-C and face detect induce visible focus breathing. It is very noticeable w/ AF tracking sensitivity on responsive (more focus changes as the subject moves slightly), less so at standard (fewer focus changes). It is about the same as the FE 35, so I think it has to do with the focus breathing characteristics of the lens, not the AF performance/firmware.
Most of my video in last ten years has been family and travel stuff with lots of camera movement, so focus breathing hasn't really been an issue. I really noticed it with these video interviews - and that is with minimal focus changes as an interview subject moved fore and aft. I now see why real (expensive) cinema lenses eliminate focus breathing, it would be really annoying filming while shifting focus between subjects at various distances on a camera locked down on a tripod.
p.1 #4 · Focus Breathing on Sony FE Lenses - share your tests
Significant focus breathing can be a nuisance when focus stacking as well because you have to compose more carefully keeping the narrowest FOV in your stack in mind, and also because aligning images becomes more error prone.
Interestingly, what I consider my best IQ lenses Loxia 21,25 and Sigma 14/1.8, all breathe a lot with the Loxias approaching 10% for near-far shots. A bit annoyingly, the Loxias are narrowest when close focused, whereas the Sigma is narrowest at infinity (more things to remember when swapping lenses).
In the wide to ultrawide range I've found the Sony 12-24 noticeably better behaved wrt focus breathing (maybe half as much as the Loxias) and the CV12 even better (minimal FOV change).
