C100: C100MKII: Big autofocus difference between STM and L glass?

G

George Loch

Well-known member
Is there a large performance difference between an STM lens and an L lens? I have yet to get an STM lens to test it with, but I am thinking about getting one for some event work (Comic Con).

-gl
 
George Loch said:
Is there a large performance difference between an STM lens and an L lens? I have yet to get an STM lens to test it with, but I am thinking about getting one for some event work (Comic Con).

-gl
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There's no inherent difference beyond what the specs showcase. "L" is a branding device. "STM" is a description of a focusing mechanism used in lower end lenses. That' about it. Compare specs, MTF charts, etc.

That said, of course STM focuses better for video than USM and of course the L lenses have better built quality and generally are sharp/fast/etc.
 
Something else to consider. I did a shoot at Warner Bros yesterday with a rented C300. I was going to use my 18-135 STM IS but realized the C300 didn't have DPAF. This meant I was going to have to manually focus using only the C300s screen and EVF. The 18-135 STM IS is focus by wire. Meaning that pulling precise focus quickly and accurately is difficult as is doing rack focuses. I was following a conversation all around a room from person to person so I was zooming and framing quickly. Thankfully my client had their 24-105 F4 L IS available so I used it. While I don't like the 24-105 lens, it is much better at manual focus than my 18-135 STM IS. My C100 MKI does a good job with the DPAF and the 18-135 SMT IS, but I was glad to have access to a better manual focus lens for that particular shoot.

I did a shoot last month and tried to do some rack focusing with my 18-135 STM IS and discovered that it is almost impossible to hit any marks with the lens. Great run and gun lens with DPAF but for more cinematic shooting, I would get an L lens personally.
 
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I have a 40mm STM pancake, it is slower to focus when DPAFing, compared to my Ls.

But it is absolutely silent, whereas the Ls are not.
You cannot use the internal audio when DPAFing with Ls.

And as puredrifting pointed out, if you want to switch to manual focusing it is much better using an L.

As a micro shooting setup it's pretty awesome, the new 50mm STM looks pretty cool for this kind of micro run and gun DPAF setup.
 
Earlier this summer, I took my C100 into a local camera store and tested the DPAF with an STM lens, several USM lenses, a Sigma, a Tamron, and an older non-USM Canon lens. Focus-wise, the STM seemed quieter and just a little smoother than the USM lenses. But as long as I wasn't racking between something close and something near infinity, I couldn't really tell the difference in terms of a smooth pull. That's not to say that all USM lenses will the same result. The system has been around for a long time, and I wouldn't be surprised if the more recent USM models were smoother.

The Sigma and Tamron lenses that I tried were giving me very jerky and uneven pulls... as bad or even worse than the old non-USM.

Wish I'd kept that footage, but I needed the drive space!
 
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Okay. Thanks all. I have a kit full of L glass and wondered if an STM would be worth it. It sounds like it won't be for my uses.

-gl
 
About the only benefit to STM aside from the quieter focus motor is the ability to use face-detect AF on the C100 Mark II. That's the only reason I keep the 18-135 around.
 
Also, the STM zoom lenses appear to be programmed to be parfocal. At least the 18-135 and all of my EOS M lenses work that way.
 
jbregar said:
About the only benefit to STM aside from the quieter focus motor is the ability to use face-detect AF on the C100 Mark II. That's the only reason I keep the 18-135 around.
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Is face detection autofocus enabled only on STM lenses, not on EF ones?
 
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