The Villages Loc: The Villages, Florida

I've shot with Nikons for many years, film through digital. As I don't have a large selections of lens, I'm considering moving to Canon to experience the difference, and am thinking about the 7D Mark II....as pricing looks good while awaiting the Mark III.

I'm not one for switching lens, so I'm looking at either the 18-135mm USM or STM system. I've read up on the 2 concepts until I'm blue in the face. The USM's good for quick focus needs (sports), with the STM aimed at video as it is quieter. STM appears to be a newer technology. Have listened to focusing sound differences and the USM lens is louder but hard to really tell due to the amplification used in the demonstration. For my type of general shooting (no video) I am leaning toward USM, but am concerned with the noise factor.

Looking for real world feedback from Canon user. Thanks in advance for your insight.

dsmeltz Loc: Philadelphia

What is your concern with the noise factor, if you are not shooting video?

markngolf Loc: Bridgewater, NJ

The 7D MII is a fabulous camera, particularly for sports or birds. I shoot with Canon L lenses - Canon 24 - 70 f/2.8 II and Canon 70 - 200 f/2.8 II. I'm happy with results. I own the Canon 5D MIII.
Mark

CHG_CANON Loc: the Windy City

This sums it up exactly ...

47greyfox Loc: on the edge of the Colorado front range

I have a number of Canon lenses of varying cost, some USM, some STM. Granted, I'm no where near an expert of any kind. I have noticed a few differences: USM are more expensive (don't know why), USM focus a little faster (might be my imagination or I'm still looking for a reason why they are more expensive than their STM counterpart whether L or not), STM are a little quieter. I don't do video, not even a little bit. If money were no object, I'd own all USM. The two lenses that I have exclusively for my 7d2 are both STM (10-18 & 18-135).

robertjerl Loc: Corona, California

I can't hear the difference unless I pay attention (tinnitus) and I have never gotten close enough to a bird for the noise to make a difference. It doesn't seem to bother insects at all. But on moving subjects the AF speed does make a difference.

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

There are many focusing motor technologies. From Canon, USM is good, STM is very good for video, the new updated Nano USM is both fast and quiet. Choose the tech that matches your usage.

Jrhoffman75 Loc: Conway, New Hampshire

"dsmeltz wrote:
What is your concern with the noise factor, if you are not shooting video?

This sums it up exactly ..."

It's not that simple.

When Canon updated some of the USM lenses to STM they also updated the optical design - the 18-135 and the 55-250 in particular. Thus, STM lens are sharper and would be advantageous even if one is not shooting video.

The Villages Loc: The Villages, Florida

I appreciate the feedback I've received.

As an update, in speaking with Canon Technical Support (and in line with some of the prior above comments), they advised that the newly updated "Nano" USM actually incorporates some of the STM components resulting in the best of both technologies.

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

Since you say that you are not really familiar with Canon technology, you might find this a good backgrounder, it has a section about motors, although may not include the latest nano USM, but you seem to have got the essence of that. http://www.youtube.com/watch?v=fkBOsTVfpdA

Some USM lenses (the older ones) can be a little noisy, newer ones (pre nano-USM) are almost silent. The micro motor lenses (typically the cheapest) are the ones to avoid, they're not bad, but can be fragile. They must be switched to manual focus mode for manual focus or may be damaged. USM lenses do not have that problem. STM lenses are silent, and fast enough for many uses, but manual focus is 'fly by wire', there is no mechanical link for manual focus, so it seems a little different. I would certainly go with nano USM wehre possible, and USM if not. STM really was designed for video, and is good enough - I have the 18-135 STM, but the nano USM wasn't available when I bought it.

Good luck!

amfoto1 Loc: San Jose, Calif. USA

USM or "Ultrasonic Motor" focus drive is faster AND better tracking movement. In the case of the EF-S 18-135mm in particular, Canon claims the USM version is 2X to 4X faster. In the past USM was used pretty exclusively in premium or better mid-grade lenses.

STM or "Stepper Motor" focus drive is a bit quieter and smoother operating, so generally is preferred for video work (if not just using manual focus).

"Micro motor" is the third type of focus drive that Canon uses, which is slower, noisier and sometimes less consistent in accuracy than both STM and USM. It's usually found on the less expensive/more entry-level lenses. Canon autofocus lenses utilizing micro motor are not marked either STM or USM, both of which typically cost a bit more.

The difference between these types of focus drive is less noticeable with short focal length lenses. That's because ultrawide lenses such as the EF-S 10-18mm IS STM or the EF-S 10-22mm USM only need to move their focus group a very short distance to go from closest focus to infinity. In contrast, the focusing group of telephoto lenses have to travel much farther, so the speed advantage of USM is more apparent.

The EF-S 18-135mm is unusual, in that it's made using all three different drive systems there's a micro motor version costing around $350 or for about $50 more an STM or for about $200 more a USM version. Not many lenses have been offered in two, let alone three versions at the same time. The price difference is greater in this case, due to the micro motor being a fairly old design now and the USM version's relatively recent introduction (with the 80D, if memory serves) and it's use of the latest-and-greatest "Nano USM". The EF-S 18-135mm IS USM actually is using a new "Nano USM" focus drive that's BOTH fast and accurate for sports AND quiet and smooth for video work. It was the first of three Canon lenses (so far) to implement this new form of focus drive. (The other lenses now using it are the EF 24-105mm f/4L IS USM "II" and the EF 70-300mm IS USM "II".)

The EF-S 18-135mm IS USM also is unusual in that it's the only Canon lens able to use the new PZ-E1 Power Zoom module. That approx. $100 accessory might be of interest to videoagraphers, probably is less appealing to still photographers.

USM lenses aren't always designed to be fast focusing. Some specialty lenses using it are slower... such as macro lenses and the extra large aperture f/1.2L lenses. On these a "long throw" focus design is used, which emphasizes accuracy over speed. This is due to the extremely shallow depth of field that's possible with these lenses.

In general, STM and USM lenses allow for "Full Time Manual" focusing. In other words, you can manually override their autofocus any time without concern about damaging the AF system. This is not true of micro motor lenses. Those should be turned off at the switch prior to manually focusing them, or the focus drive can be damaged. Full Time Manual can be handy to fine tune focus or to quickly, deliberately de-focus a lens to cause it to re-focus.

But, also in general STM lenses are "fly by wire" and USM lenses are not. This means that the STM lenses must be "powered up" before they can be manually focused. When the camera is not activated with a half-press of the shutter button or pressure on the AF On button, or the lens is off the camera, the STM lens' focusing ring will turn but won't effect anything. The lens must be powered up before the focus ring will have effect. In contrast, most USM lenses are electro-mechanical, with physical linkage between the focus ring and the focus mechanism, so turning the focus ring of a USM lens will move the focus whether there's power to the lens or not. There are a few exceptions... for example the EF 85mm f/1.2L USM is a "fly by wire" design.

In general, if you are purchasing the 7D Mark II for any sort of action photography - sports, wildlife, etc. - then you would be wise to pair it up with USM lenses. The camera has a very high performance AF system and to get the best out of it you will want USM lenses. STM or even micro motor lenses will work fine on the camera too, but overall AF performance will be somewhat slowed. OTOH, if video with AF were important to you, aside from the three lenses (so far) using the new Nano USM drive, you would probably want to stick with STM lenses.

amfoto1 Loc: San Jose, Calif. USA

delete... duplicate post

amfoto1 Loc: San Jose, Calif. USA

Actually, the EF-S 18-135mm USM and STM models are virtually identical optically... Both appear to have gotten the same minor improvements over the first, micro motor version.

All three models use the same or very similar 16 element/12 group optical formula. The USM and STM models use a 7-blade aperture that should give slightly nicer background blur than the 6-blade aperture of the original model. The USM and STM models have the same close focusing ability (15.4", 0.28X), which is a little better than the micro motor model's (19/3", 0.21X). And the latter two models variable aperture transitions occur at exactly same focal lengths, which are all a little "longer" than the transition focal lengths of the first model. Also, the odd number of aperture blades will cause the newer models to make 14-point stars around light sources, which some might find preferable to the 6-point stars produced by the even number of aperture blades in the first version. All this implies very little difference, if any, between the optics of the STM and USM versions, but a number of tweaks to the STM over the earlier micro motor version.

Bryan Carnathan at The-Digital-Picture.com (where you can make side-by-side comparisons of lab test shots made with the lenses, if you wish) noted during his testing that while he didn't see any difference in lab testing, out in the "real world" shooting with the micro motor and STM versions, at some apertures and focal lengths one lens was slightly soft on one side or in one corner, while the other lens was on the opposite. He comments that this variation suggests less than exact assembly and calibration, or perhaps less careful quality control. At the time he compared them with the higher specification and considerably more expensive EF-S 15-85mm IS USM lens, which saw more evenly sharp across the entire frame and little or no variation from copy to copy, perhaps indicating more careful construction and attention to precise calibration. In his review of the latest, USM model he noted that corner/edge sharpness was more evenly similar... again suggesting greater precision, care and calibration of the newest model. (https://www.the-digital-picture.com/Reviews/Canon-EF-S-18-135mm-f-3.5-5.6-IS-USM-Lens.aspx)

Also note that the separately sold (but highly recommended) lens hoods are different. The original micro motor and STM lenses use the EW-73B hood, while the latest USM model uses the EW-73D... I don't know if these hoods are interchangeable. Oh, and if the $30 to $35 price of the Canon hood seems a bit steep, there are considerably lower cost "clones" from Vello and others that probably work just about the same.

The Villages Loc: The Villages, Florida

amphoto1 - Thank you so much for your comprehensive response to my question. Its really appreciated.

The Villages

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

Alan is correct, optics and autofocus motors are independent things. I have two versions of the 18-135 EF-S lens. The first was the original, and while fine developed an internal lens defect. Repairing it would cost more than buying a new lens. I got the STM, the latest at the time. Optically it is superior, and I'm very happy with it, but it is not a lens that I would use on manual focus, I have others for that. If the nano USM was available then that is the one I would have purchased.