Video: Comparing Canon’s USM and STM Lenses Using the 70D’s Dual Pixel AF

As Canon has begun focusing more adamantly on making its DSLRs capable video capture machines, the company has had to adjust its glass to match. The new Dual Pixel AF on the 70D is a great improvement (check out these videos if you doubt that) but if you’re planning on shooting video using the autofocus, you’ll probably get to the point where you have to choose between buying a USM lens and an STM lens.

When that time comes, the video above by YouTube user marconilanna should make that choice a little easier by showing you the differences — in both noise and speed — between one of Canon’s STM lenses and a few older USMs.

First, the technical bit. USM stands for Ultrasonic Motor, while STM stands for Stepper Motor. Both are autofocus motors built into different lenses you’ll find in Canon’s lineup. General opinion seems to be that USM lenses are more professional-grade and better for shooting photos, while STM lenses are geared more towards amateurs and better for video, but why?

A schematic of the different types of USM motors Canon uses in its lenses.

A schematic of the different types of USM motors Canon uses in its lenses.

Take a look at the video at the top and you’ll find out. While USM lenses are lauded as being “almost silent” on Canon’s website, you can still pick up the focusing sound on the camera’s microphone when shooting video. As one Redditor put it “USM lenses sound like they’re possessed by a rodent.”

By comparison, the STM lenses really are almost silent, as they were built with video in mind — rodents need not apply. Their focus speed, while a tiny bit slower, is also better suited for video as it’s smoother and less “jarring.”

Finally, one of the big differentiators is that the STM lenses use a focus-by-wire system, which means that manual focusing will still make noise (albeit not much) and be slightly delayed since you’re not directly moving the focusing element when you turn the focus ring.

The Canon 40mm f/2.8 STM lens used in the video.

The Canon 40mm f/2.8 STM lens used in the video.

For most people, all of this adds up to the same “general opinion” mentioned above. If you’re an amateur who shoots a lot of video without manually pulling focus, you’ll probably go with an STM lens and be very happy. However, if you’re mostly shooting stills, the USM lenses will offer a faster focus with only a little bit of noise that shouldn’t matter even in quiet scenarios.

Of course, it’s up to you to draw your own conclusions once you watch the video above. Keep in mind, it’s not perfect: as one Redditor pointed out, the 40mm f/2.8 STM used in the video has a greater depth of field wide open than the 50mm f/1.4 USM, meaning it needed to focus a lot less. Still, the video gives you a good starting point if you’ve never seen the two technologies compared side-by-side.

(via Reddit)

P.S. We’re sure there are other practical differences between USM and STM lenses that we didn’t get a chance to mention in the post. If anything comes to mind, feel free to drop some knowledge in the comments and help out your fellow photographers.

  • derp

    any idea whether the sound was recorded with the internal microphone or an external mic? i’d have guessed that an external mic would not pick up the USM noises.

  • D.G. Brown

    As a note, not all USM lenses are direct drive. On the 85mm f/1.2L II USM, for instance, focusing is done by wire. Of course this isn’t the case for the majority of USM lenses, but it’s also not a trait inherent to USM (it’s just that most are implemented as direct drive).

  • Carl Meyer

    Canon’s marketing VS Nikon’s incompetence.

    While 70D’s autofocus is hyped to the maximum, two years old Nikon 1’s phase detection autofocus continues being ignored even by Nikon.

  • Ian

    USM first appeared in 1987, back when a video camera consisted of a camera attached to a battery pack and a portable VCR. For still shooters, it’s still amazingly fast and quiet compared to DC motors. It is almost silent to human ears, but obviously not DSLRs (particularly using the internal mics). Makes me wonder what wildlife with sensitive hearing think of USM.

  • Terrance Lam

    The 50 F/1.4 is definitely a micro-motor USM, not sure about the other two USM lenses and so it definitely makes those harsher noises.

    I’ve compared my 70-200 F/2.8 IS USM, 24-70L USM Mark II, 100L Macro USM, 18-55 STM, 50 F/1.4 USM on my SL1 and there is so much variation in performance from the micro motor and ring USM as well. The Ring USM freaks out a lot less, but the STM is still the smoothest and quietest by far. The 24-70L USM Mark II is the quietest of the Ring USM lenses I own.

    The 70D certainly performs really well, but also my little SL1 with the Hybrid II PDAF is pretty good as well, both certainly better than my EOS M for this kind of AF test.

  • Terrance Lam

    Don’t disagree with that sentiment but to be fair, it relies on a much smaller sensor with far deeper depth of field to gain focus. The rather large hyperfocal range makes that system focus extremely fast. Much like AF on a wide angle lens is always much faster than a telephoto lens.

  • russianbox

    was this with an internal mic? maybe its not an issue when you have a røde

  • sam1741

    i have tried STM lens (40mm) before.. and the focus speed is dissapointing
    even slower than non-usm lens.

  • YouTuber

    Especially the VMP with +20db and the levels manually adjusted waaay low. Be gone dSLR hiss!

  • USM4TW

    The USM lens looked much better in every shot. Was that the conclusion I was supposed to reach? Glad all my lenses are USM :)

  • asa

    you spend to much on lenses….

  • Terrance Lam

    LoL you and my wife agree on that point.

  • SJ

    does USM work on canon 70D? or only STM works in it?

    as usm is a little bit cheaper in price……..

  • James

    I have read in product discriptions that the STM feature only works with the Canon EOS Rebel T4i Digital Camera

  • Selwyn Lloyd

    Flip I have an EF-S 18-135 IS STM lens on my 70D and it works wonders, superfast and quite. James the STM works on a 70D. Love the lens.

  • nomadinca

    in your conclusion you have included amateur videographers or stills shooter, but you have excluded videographers who will mostly use the autofocus probably only to help their manual focus occasionally and still rely on manual focus during recordings.

    So, for those type of videographers, would you suggest going for STM or USM?
    How is the sound when you manually focus an STM lens during recording?

  • O.T.O

    I agree ^^^^, got the 18-55 IS STM lens but I think I should have got the 18-135 IS STM lens with my 70d.. or should I just go for the 55-250 IS STM lens?

  • Selwyn Lloyd

    That just depends on what your want to photograph. Seen as though you already have a 18mm range, the better option then is the 55-250mm. Expensive but worth it. And the bigger the aperture 2.8 the better.

  • Gunjan Sahay

    I couldn’t agree more with the “possessed by rodents” comment. Lol

  • dovetail65

    Your 40m STM must have been broken or it did not like the camera you are using. With my 70D all the STM lenses are just as fast as my USM lens and much more quiet! Actually, my STM lens are faster than any lens I have, ZERO hunting, ZERO noise and are fairly decent sharpness to the stills. For video there is no comparison the STM are far better. For stills they are a great value. I just don’t get why your lens would be slow when mine are so very fast. There was a firmware update for the 40MM STM that I had to with my lens, possibly that contributed to your slower speeds.

  • dovetail65

    Yes USM works with 70D, but if you do video at all go wth the STM. The 70D STM combination is fantastic at video and darn good at stills. Unless you are a pixel peeper in the real works the STM lens are your best bet woth a 0D. I hav the 1.4USM and its sharper than any of the STM, still my 18-135 STM is on the camera 80% of the time.

  • dovetail65

    100% you should have got the 18-135 STM.

    In my experience with the 70D, not on paper, but my personal experince the 18-135 STM is a far better lens. I returned the 18-55STM, but kept the 40mm STM, 18-135STM and 55-250 STM. By far the 18-135 STM is the way to go. The 18-55 STM is not very good(well sharp anyhow) at either 18-20mm or 50-55mm, but the 18-135 is great from 20-130mm, noticeably better for me as far as focus speed and sharpness of image.

    You wont want the 55-250STM as your only lens as from 55-70mm its not very good and at 55mm you will miss way to many family type shots. You will be backing way up. Canon is rumored to be coming out with a 18-300 STM and my 55-250STM will be sold asap once that happens. For a family guy thats not a pro like me and as long as the new 18-300 STM is as good as the 18-135STM it will be the best choice.

    If you could only have one lens for the 70D , for me its the 18-135 STM by a huge margin.

  • rottiepaws

    Thanks! I bought my 50D a few years ago and recently upgraded to the 70D body only. I didn’t know there was a difference. I took the 70D body back and bought the kit with the STM lens. I was having issues with the 50D’s lens which is an ultrasonic lens. The 70D kit lens is also 18-135 instead of 28-135 which isn’t a huge difference, but it’s nice. Plus when I tilt the lens forward, it doesn’t extend all the way out like the 50D kit lens did!

  • fgwapo

    never trust your auto focus when recording in video. Always use manual focus.

  • Javed Safdar

    I am an amateur & I have recently bought a Canon D70 with the 18-135 IS STM lens kit + EF 50 mm. I was wondering why the Focus Ring on the 50mm Lens turns when in Auto mode BUT the same does not happen in the STM lens.
    I will be very obliged if someone would tell me if there is a Fault in the Lens OR if the Ring is NOT supposed to turn in the AF mode. The Focus is fine, ONLY the outer Ring does not move as it does in the 50mm Lens.
    Javed Safdar
    [email protected]