Let's talk about STM motors that Nikon is now exclusively using while everyone else is embracing linear motors. This is probably one of the main concerns other than the cost of entry to the whole new system.
I have experience of 2 STM lenses from Canon and Sigma, namely 50mm f/1.8 and 70mm ART and I have to say while they eventually get "there", there are much slower, noisier and even less precise than Sigma's and Canon's ultrasonic motors.
Recently Sigma released II version of their E-mount 24-70mm. While the optical formula received only minor changes, they notably switched from STM to HLA linear motor. All reviews claim that the new lens is focusing faster. This is the most like for like comparison I can think of. I have personally not tested either version.
My big question is whether Nikon uses some different STM that is much better than the above, and how do staple Nikon lenses compare with HLA equipped Sigma ART, Sony GM II or even Tamron G2 lenses? I know many of you dabble in E-mount eco-system so should hopefully have some experience.
Where possible I would like to avoid Sony body prices (A1!) and ergonomics!
tomasr wrote:
Let's talk about STM motors that Nikon is now exclusively using while everyone else is embracing linear motors. This is probably one of the main concerns other than the cost of entry to the whole new system.
I have experience of 2 STM lenses from Canon and Sigma, namely 50mm f/1.8 and 70mm ART and I have to say while they eventually get "there", there are much slower, noisier and even less precise than Sigma's and Canon's ultrasonic motors.
Recently Sigma released II version of their E-mount 24-70mm. While the optical formula received only minor changes, they notably switched from STM to HLA linear motor. All reviews claim that the new lens is focusing faster. This is the most like for like comparison I can think of. I have personally not tested either version.
My big question is whether Nikon uses some different STM that is much better than the above, and how do staple Nikon lenses compare with HLA equipped Sigma ART, Sony GM II or even Tamron G2 lenses? I know many of you dabble in E-mount eco-system so should hopefully have some experience.
Where possible I would like to avoid Sony body prices (A1!) and ergonomics!...Show more →
I don't have any real experience with Nikon but consider that Sony may well have developed their XD linear motors with the A9/A1 bodies in mind and that their newest lenses are capable of shooting up to 120fps.
Is the entire Z mount lens range able to shoot the the max fps of the Z9/Z8? genuine question as I don't know.
I have a Z-mount Tamron 28-75mm G2 that I have used extensively. Compared to Nikon’s Z lenses, it’s more or less identical in focus speed. The Nikon f/2.8 trio may focus just slightly faster, but they are all extremely close.
I have used most of the Z mount lenses and don’t feel that Nikon is giving up any AF speed by using STM motors. Why would Nikon choose an interior technology for AF drive? I know it’s trendy to hate on Nikon, but they aren’t inept despite what many try to claim…
I suppose it’s all in how the STM drive is designed and implemented. I have tried a couple of Viltrox Z-mount lenses with STM motors that were noticeably (but not massively) slower than Nikon and Tamron lenses. I have not tried any Sigma Z-mount lenses so don’t know how they compare.
tomasr wrote:
Let's talk about STM motors …
My big question is whether Nikon uses some different STM that is much better than the above, and how do staple Nikon lenses compare with HLA equipped Sigma ART, Sony GM II or even Tamron G2 lenses?
The only possible exception may be the 26mm pancake, but Nikon doesn’t say that it has any limitations on the Z8/Z9.
Even Nikon’s cheapest Z lenses (28mm and 40mm) focus lightning fast on my Z9.
In my experience, it’s only older F-mount glass on the FTZ that can’t keep up in all situations.
SNJOps wrote:
I don't have any real experience with Nikon but consider that Sony may well have developed their XD linear motors with the A9/A1 bodies in mind and that their newest lenses are capable of shooting up to 120fps.
Is the entire Z mount lens range able to shoot the the max fps of the Z9/Z8? genuine question as I don't know.
STM vs linear conveys nothing useful about the actual focusing performance.
1. Not all of these motors have the same performance. Just like some Diesel engines driven cars are must faster/faster accelerating than gasoline engine cars although most people would think that gasoline cares are much faster.
2. The construction of the lens, the number of moving groups and inertia of those, have just as much impact as the motors
3. The ability of the body to deliver the right amount of current is also key
But some Sony fanboys have been insistently using this argument to convey a false sense of intrinsic superiority of Sony. Un-surprisingly...
It seems to me that these different focus motor technologies have all advanced to the point that they are plenty fast enough to get an accurate shot even at the very high frame rates that modern mirrorless/shutterless cameras are capable of. I would not choose my system based on this.
I would like to see which of these technologies are able to perform at this level, have the potential to be the smallest, lightest, most energy efficient technology. Anyone have good information on this?
As Bernard said motor technology on its own is irrelevant to speed or quietness. Naturally marketing departments like to find ways to distinguish their products from others and make claims that those differences somehow make their product superior. They have varying degrees of success at doing that, but their motivation is never anything to do with informing their customers or conveying actually relevant engineering information.
Steve Spencer made a great summary post on this topic a few years ago, worth a read:
I don't have much experience with Canon or Sony lenses, but have sometimes tested them a bit. I have a lot of experience on Nikon lenses for both F and Z mounts. The Z mount lenses that I have are all S-line and they focus almost silently. From what I've played with Canon's basic lenses for RF mount, the relatively inexpensive primes seem to be produce more noise when focusing than the Nikon Z S-line primes (such as 35/1.8, 50/1.8 etc.)
In lenses that have bigger optics, Nikon typically use two focus motors and the focus speed has not been an issue for me. Sony's linear motors may be faster but a lot of the time I get something like 99% of shots in focus with my Z8 and perhaps 90-95% with the Zf (which is a more consumer grade body). I photograph portraits, weddings, academic events such as PhD defences and dinner parties, outdoor events, concerts, street, some wildlife, landscape and nature-close-ups, so quite varied subject matter. I find that the focus issues that I've experienced with Nikon Z have not so much to do with lens focus speed but the logic that the AF system uses (i.e. if a person turns away from the camera such as in figure skating, it sometimes happens that the camera identifies a spectator's face and focuses on that instead of the subject.) Another example is when vertical brightly lit reeds are lit from behind and I am shooting into the light, with the subject in the foreground. In that case the camera sometimes focuses on the reeds rather than the subject. But mostly I find the AF in the Nikon Z8 excellent and Zf very good.
Lenses that I use are relatively fast (f/1.8 S-line primes, f/2.8 zooms) and those are all particularly good. I also use a slower telephoto lens (100-400/4.5-5.6) and that can have a bit of trouble in very dim light (after sunset, when exposures are like 1/250s, f/5.6, ISO 25600) and in that situation the AF can be erratic. But mostly I've had very little trouble with AF. The earlier Z6 II which I had did have AF issues, on static subjects it was good but it couldn't reliable focus on an approaching subject to my satisfaction (maybe only 70% of shots in focus when a person walks briskly towards the camera).
I have heard that some of the non-S-line, less expensive, lenses have extending inner barrels when focusing and they can be a bit more loud when autofocusing, but I haven't purchased those lenses so I don't really know for sure. I can say that there is barely any sound coming from the S-line lenses when focusing or vibration reduction operating.
I think Sony marketing makes a big deal about linear motors, of course they have to talk about what they have, and they did produce the first dual-focus motor lenses which Nikon likely took the idea from. But for me this is not an issue at all. For the record, Nikon does use linear motors in the 400/2.8 and 600/4.
SNJOps wrote:
I don't have any real experience with Nikon but consider that Sony may well have developed their XD linear motors with the A9/A1 bodies in mind and that their newest lenses are capable of shooting up to 120fps.
Is the entire Z mount lens range able to shoot the the max fps of the Z9/Z8? genuine question as I don't know.
Most F-mount AF-S lenses also can use those modes. I've seen a video of owl flying and it was shot at 120 fps (not absolutely sure if it was a video or a 120 fps stills sequence) and seemed all to be throughout in focus, it was shot with the Z9 and PF 500mm f/5.6 with the FTZ or FTZ-II adapter.
I think when this was asked of Nikon, they said lenses for F mount which were still in production when the Z9 was launched would work fine at the high fps modes but there may be some earlier lenses which had been discontinued that they couldn't say if they could keep up at the highest fps rates.
I would think there is no issue with Z mount autofocus lenses with respect to high fps AF tracking. Of course this doesn't mean that all shots will always be in focus, but I haven't seen any complaints with regards to this issue specficially. I guess the best way to find out is to do your own testing in your own applications.
I'm not a frequent user of ultra high fps but have occasionally used those modes. When shooting figure skating at 20 fps, I've noticed that sometimes the camera will focus on spectators when the skater is turned face away from the camera and the camera seems satisfied with the focus on spectators and doesn't immediately return to the main subject. At 10 fps it seems the camera more reliably returns to the subject when the face has turned back towards the camera. So basically shooting at 20 fps requires more care (narrower focus area selection) to get consistent results in such cases. At 10 fps it's close to 100% correct focus even with a wide focus area bar. For ease of shooting and composition, I frequently use a custom AF area which is about 1/2 of the frame wide, and 3 rows tall, and this is so that I can have the subject on the left, center or right side of the frame without moving the focus area around, but this means the focus area usually includes some spectators. For higher reliability I use the wide-area S focus area mode which is about square or slightly narrower than it is tall; this allows precise focusing on s a specific person but then if I change the position of the skater in the frame, I have to move the focus area to that position. With Nikon you have to make these adjustments to achieve the highest reliability of focusing. But at single shot mode, or e.g., at 10 fps, this is less necessary than when shooting e.g., at 20 fps.
I'm quite happy with the Z8 AF and this includes many adapted lenses such as 105/1.4 and 200/2 II, but as I said I don't really need the ultra-high-fps all that often and so probably someone else can give more insight as to performance at those rates.
Eco-Scott wrote:
Mechanically, what is the difference between STM, Linear Motors, Canon's USM and Fuji's DC Motor?
I am not an expert on motors but put together some information from various sources.
STM = stepping motor, this is a technology where the rotating part moves relative to a static part, and the movement happens in steps. The rotation controlled electromagnetically and the motor has the ability to actively stay in a fixed position (at any of a discrete set of rotational steps). The motor is typically on a side of the lens and rotates a lead screw and a follower is used to convert the rotation into linear movement of the focus group.
DC motors have a coil in a permanent magnetic field. The current in the coil causes a force to be applied to the coil, leading to its rotation. There is a commutator which switches the direction of current through the coil to keep the rotation going.
Ring-type USM (or SWM in Nikon terminology) has two parts, one rotating the other static. The rotation is caused by ultrasonic vibration created by applying an electrical signal to a piezoelectric material and is converted into linear movement via studs rotating in a thread around the lens. Other types of USM exist which have some differences in principle. Nano USMs are linear motors powered by ultrasonic vibration.
Linear motors move the focus group directly without there being rotating elements present. The movement is typically caused again by electromagnetism, via voice coils e.g. in Nikon's SSVCM but may alternatively be ultrasonic. Nikon uses optical measurement of the position of the focus group in conjunction with the voice coil motor.
I guess one could say that a huge variety of different technologies have been developed / utilized for lens autofocusing. I believe Nikon chose stepping motors for the majority of lenses because they wanted the lenses to be really video friendly, i.e. precise and silent. I guess having one motor type (sometimes two units) across different lenses has the advantage that spare parts are not likely to run out any time soon. Ring SWM (USM in Canon terminology) can fail if stored without used for a long time, and since many ring SWM lenses have motors specific to the lens type, they may not have made enough spares to cover the lifetime of the lenses. Early USM and SWM lenses have had motors die. I'm not sure if this is still happening on newer lenses that don't use the first-generation ring motors. Anyway Nikon doesn't seem to use SWM in Z lenses at least not at the moment. They just have stepping motors or the SSVCM linear motors.
