Fast AF. STM or 7D ?

Started 7 months ago | Questions
Pap Ingos
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Fast AF. STM or 7D ?
7 months ago

Hello,

I've tried the EOS 7D in a shop with an STM lens, i think it was 18-55mm.

I was shocked by the blazing fast autofocus ! I couldn't believe it.

I haven't been following the new developments much. I know STM lenses offer a quieter AF, useful when recording video.

What i want to know is who is responsible for the super fast Autofocus ? The STM lens ? or the 7D ?

If it is the lens, would there be an noticeable AF speed increase when a STM lens is used with an older body, say 40D ?

Many thanks

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Canon EOS 40D Canon EOS 7D
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Jeff Peterman
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Re: Fast AF. STM or 7D ?
In reply to Pap Ingos, 7 months ago

STM lenses do not focus faster than the best non-USM lenses. Their focus is smoother and quieter, but not faster. STM lenses are optimized for video, where the focusing motions of the standard lenses can be disturbing and the whirring noises picked up by the camera microphone.

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TTMartin
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Re: Fast AF. STM or 7D ?
In reply to Jeff Peterman, 7 months ago

Jeff Peterman wrote:

STM lenses do not focus faster than the best non-USM lenses. Their focus is smoother and quieter, but not faster. STM lenses are optimized for video, where the focusing motions of the standard lenses can be disturbing and the whirring noises picked up by the camera microphone.

It may be that they focus more accurately and don't have to hunt for focus. But, there are several reports that STM lens do focus faster than non-USM lenses.

As for an STM lens on the OPs 40D, it would probably be worth it for image quality alone. Canon really stepped up the optics, when it updated the STM lenses.

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Pacific462
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Re: Fast AF. STM or 7D ?
In reply to Pap Ingos, 7 months ago

I've just started using an 18-135STM with a 70D and I'm very impressed with the speed, even when compared to USM lenses. I'm not stating that it's categorically faster, but very impressive. especially for the price.

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Jeff Peterman
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Re: Fast AF. STM or 7D ?
In reply to TTMartin, 7 months ago

there are several reports that STM lens do focus faster than non-USM lenses

I have no problems believing that. But how do they compare to the USM lenses? I think that USM are still the fastest, but haven't seen any data.

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TTMartin
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Re: Fast AF. STM or 7D ?
In reply to Jeff Peterman, 7 months ago

Jeff Peterman wrote:

there are several reports that STM lens do focus faster than non-USM lenses

I have no problems believing that. But how do they compare to the USM lenses? I think that USM are still the fastest, but haven't seen any data.

I agree that USM lenses are still faster, at least the true ring type USM lenses. I'm guessing STM and the microUSM lenses like the EF 75-300 are probably pretty close.

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Dale Buhanan
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Re: Fast AF. STM or 7D ?
In reply to TTMartin, 7 months ago

TTMartin wrote:

Jeff Peterman wrote:

there are several reports that STM lens do focus faster than non-USM lenses

I have no problems believing that. But how do they compare to the USM lenses? I think that USM are still the fastest, but haven't seen any data.

I agree that USM lenses are still faster, at least the true ring type USM lenses. I'm guessing STM and the microUSM lenses like the EF 75-300 are probably pretty close.

I don't really have hard data on that either... but apparently the STM lenses are blazingly fast.  I am sure that part of the speed is due to the short throw required to focus from one end to the other, and that it is an internal focus design.  So while linear movement of the STM action may not actually be faster than the USM action, the distance it has to travel to focus is so much less that to achieve focus it is blazingly fast and silent.

I remember C.hammett commenting when she got her SL1 with both the 18-55 STM and 18-135 STM how extremely fast to focus they were.  She said that the camera with those lenses could focus faster than her 7D with 24-105L.  So that is a bit of anecdotal  evidence, which is quite tantalizing.

I have been seriously thinking of picking up an 18-135 STM myself -- and since I have a raft of USM lenses, I am looking forward to doing a comparison.  So far, my fastest focusing lens is the Canon 85mm f1.8 USM prime.  To me, that is blazingly fast.  I don't have anything that can beat it on a 7D... And if the new STM lenses can do that... they are very fast indeed.

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R2D2
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Re: Fast AF. STM or 7D ?
In reply to TTMartin, 7 months ago

TTMartin wrote:

It may be that they focus more accurately and don't have to hunt for focus. But, there are several reports that STM lens do focus faster than non-USM lenses.

As for an STM lens on the OPs 40D, it would probably be worth it for image quality alone. Canon really stepped up the optics, when it updated the STM lenses.

Definitely +1 on that.

R2

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Wm. L.
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Re: Fast AF. STM or 7D ?
In reply to Pap Ingos, 7 months ago

I can't speak for the 40D but my STM is great on my older body.

My 18-135 STM has caused me to leave my 70-200 IS USM home if that says anything.

Now I'll really throw a curve. I started thinking I'd be getting a 7D after sharing one with an associate but got the 70D because the live view focus was so impressive and the size and weight were more appealing. So far I have no desire or reason to borrow the associate's 7D in the gear we share over my old Rebel. With that I realize there are still reasons one might want the 7D.

IMO the new STM lenses are really great improvements to what I always considered kit lenses. Add the 70D live view AF and you have match made in heaven as some would say. I'm sure the 7D's replacement will have that or up it.

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Pap Ingos
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Re: Fast AF. STM or 7D ?
In reply to Wm. L., 7 months ago

Thinking about it, it was the close to long distance focusing that impressed me that much. I used the long end, 55m, focusing very close to me, less than a meter, and then at the other end of the store, 10's meters away. The focusing was not fast, it was instant. Been using USM lenses for years, never seen that.

I've found this article:

http://petapixel.com/2013/08/26/video-comparing-canons-usm-and-stm-lenses-using-the-70ds-dual-pixel-af/

it "focuses" on the video focusing performance of STM lenses but concludes that " 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."

Do you think new Canon lenses will all be STM from now on ? Will it replace USM ?

I checked the STM range. All zoom lenses are quite slow/dark, with f/5.6 to f/6.3 at the long end. What about something faster? Focusing speed alone is not enough for someone to switch to STM.

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Thorbard
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Re: Fast AF. STM or 7D ?
In reply to Pap Ingos, 7 months ago

The 7D does focus better than the 40D and is perhaps notably faster to go with that.

The STM lenses are faster than some of the other technologies (micro motor and micro USM for example) but is characterised by being smooth "rack focus" more than the quick snap that you get from a true USM lens.

I use the 85mm f1.8 USM and the 40mm f2.8 STM and the difference in the style of the focus movement is very obvious.

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Wm. L.
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Re: Fast AF. STM or 7D ?
In reply to Pap Ingos, 7 months ago

Pap Ingos wrote:

Thinking about it, it was the close to long distance focusing that impressed me that much. I used the long end, 55m, focusing very close to me, less than a meter, and then at the other end of the store, 10's meters away. The focusing was not fast, it was instant. Been using USM lenses for years, never seen that.

I've found this article:

http://petapixel.com/2013/08/26/video-comparing-canons-usm-and-stm-lenses-using-the-70ds-dual-pixel-af/

it "focuses" on the video focusing performance of STM lenses but concludes that " 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."

Do you think new Canon lenses will all be STM from now on ? Will it replace USM ?

I checked the STM range. All zoom lenses are quite slow/dark, with f/5.6 to f/6.3 at the long end. What about something faster? Focusing speed alone is not enough for someone to switch to STM.

I'm not going to be an arm chair director and predict what new products might be.

My lenses include a fast prime, L and kit. My 18-135 STM can't be called a replacement for all of them but I'm happy enough where I'm going to take just it and the relatively small fast prime for my next oversea trip.

It is the video performance that took me over the edge to get the 70D and STM combo, but I find I like the live view and articulating display more than I expected.

The noise from my non-STM is not a problem if there's music sound track but it just does a nice job with auto focus in video.

I'm not a pixel peeper and wanted a lot of capability in a most portable package so why I value the 70D and the particular STM I have could be very different than others.

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ZiggyDeath
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Re: Fast AF. STM or 7D ?
In reply to Dale Buhanan, 7 months ago

Dale Buhanan wrote:

I remember C.hammett commenting when she got her SL1 with both the 18-55 STM and 18-135 STM how extremely fast to focus they were. She said that the camera with those lenses could focus faster than her 7D with 24-105L. So that is a bit of anecdotal evidence, which is quite tantalizing.

Personally, I find my 100L focuses faster than any of my STM lenses - the only one I've never owned (or tested) is the 55-250. 24-70F4L also feels faster. However where I notice STM being more reliable is when focus hunting occurs, it tends not to overshoot as much. This is more apparent in LV in bad conditions. It could be that STM technology is capable of finer control, and more importantly increments, when movement is required - it's certainly marketed that way.

I don't have a 7D nor a 24-105 (the latter, from what I've read has led me to believe it was never a particularly fast focusing lens anyways).

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Dale Buhanan
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Re: Fast AF. STM or 7D ?
In reply to ZiggyDeath, 7 months ago

ZiggyDeath wrote:

Dale Buhanan wrote:

I remember C.hammett commenting when she got her SL1 with both the 18-55 STM and 18-135 STM how extremely fast to focus they were. She said that the camera with those lenses could focus faster than her 7D with 24-105L. So that is a bit of anecdotal evidence, which is quite tantalizing.

Personally, I find my 100L focuses faster than any of my STM lenses - the only one I've never owned (or tested) is the 55-250. 24-70F4L also feels faster. However where I notice STM being more reliable is when focus hunting occurs, it tends not to overshoot as much. This is more apparent in LV in bad conditions. It could be that STM technology is capable of finer control, and more importantly increments, when movement is required - it's certainly marketed that way.

I don't have a 7D nor a 24-105 (the latter, from what I've read has led me to believe it was never a particularly fast focusing lens anyways).

Good input.  From what you have said, it appears that there is a  range of speeds that various USM and STM lenses can focus.  Those with internal focusing designs seem to be faster than those that are not, in both technologies. But given that the designs are the same -- both internal focusing designs - That the new USM designs can be faster than the STM designs.  However, STM gives greater absolute focus control with less hunting.

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WilbaW
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Re: Fast AF. STM or 7D ?
In reply to ZiggyDeath, 7 months ago

ZiggyDeath wrote:

where I notice STM being more reliable is when focus hunting occurs, it tends not to overshoot as much. This is more apparent in LV in bad conditions.

In LV using CD, hybrid, or dual-pixel PD?

It could be that STM technology is capable of finer control, and more importantly increments, when movement is required - it's certainly marketed that way.

I don't believe finer control is needed. For instance, the "crude" 50/1.8 is capable of positioning focus finer than 0.1mm near MFD. That's 5% of the thinnest DOF, 3% of the zone in which manual focus is confirmed, and 0.02% of the MFD. I think their main benefit for camera lenses is in how good they are for controlling speed of focus motion (and quiet operation, though not all are).

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