# What is significance of gold or silver markings on EF-S lenses?



## fotoray (Jun 13, 2011)

What is significance of gold versus silver rings on EF-S lens barrel? 

The new EF-S 55-250 lens appears to have silver ring (if it is a color photo). The older 17-85 has gold, the newer 15-85 has silver, while the 10-22 has gold. There seems to be a random mixture - or is it really random?

Does this have a meaning - like the red ring is for L lenses, and the green ring for DO lenses? ???


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## neuroanatomist (Jun 14, 2011)

The gold 'ring' (not a solid plastic ring like the red and green rings, but just a dashed, painted line) signifies the lens uses an ultrasonic motor (USM) for autofocus. 

However, on one new EF-S lens with USM (the EF-S 15-85mm f/3.5-5.6 IS USM), Canon has eliminated the gold ring. 

That 'inconsistency' in the use of the gold ring actually goes back to 1999 and the EF 75-300mm f/4-5.6 III USM, about which which Canon stated, "_The front part of the zoom ring now sports a silver ring for a luxury touch,_" despite the lens having USM (it still has the Ultrasonic symbol painted in gold on the barrel). That may be the earliest use of the silver ring, I'm not sure.

So, currently, you can't tell at a glance whether a lens has USM. Put another way, if a lens has a gold ring (or a red or green ring), it has USM; if it has a silver ring, it might or might not have USM (but probably it doesn't, based on the small fraction of silver-ringed lenses which have USM).


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## Chewy734 (Jun 14, 2011)

Thanks for the explanation neuroanatomist.

Out of curiosity, are you in the neuro field with photography being your hobby or something?


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## fotoray (Jun 14, 2011)

neuroanatomist said:


> The gold 'ring' (not a solid plastic ring like the red and green rings, but just a dashed, painted line) signifies the lens uses an ultrasonic motor (USM) for autofocus.
> 
> However, on one new EF-S lens with USM (the EF-S 15-85mm f/3.5-5.6 IS USM), Canon has eliminated the gold ring.
> 
> ...



Thanks for the info. Very interesting. I read the Canon release on the new EF-S 55-250 zoom and there is no mention of USM, so it has the painted silver ring. From now on I'll be more conscious of gold vs sliver....


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## neuroanatomist (Jun 14, 2011)

Chewy734 said:


> Out of curiosity, are you in the neuro field with photography being your hobby or something?



Yes and yes. 



fotoray said:


> I read the Canon release on the new EF-S 55-250 zoom and there is no mention of USM, so it has the painted silver ring.



If a lens has USM, it will always be in the full name of the lens (for an overview, see the EF Lens Lineup page). 

But, even that doesn't tell the whole story. Ultrasonic means the AF motor is silent (from a human hearing perspective, at any rate), but there are two kinds of USM - micromotor USM and ring USM. Of the two, ring USM is superior, and is what's found in L-series lenses, DO lenses, and the better quality non-L lenses. Ring USM is faster than micromotor USM, and often more accurate. Micromotor lenses focus more slowly, and usually do not offer full-time manual focusing (meaning you need to switch the lens to MF before moving the focus ring, else you may damage the lens). 

To find out which type of USM a particular lens has, you usually need to dig into reviews (e.g. TDP) or specs page (e.g. PhotoNotes). For a few examples, the 28-135mm f/3.5-5.6 IS USM lens has ring USM, whereas the 70-300mm f/4-5.6 IS USM has micromotor USM. All five of the EF-S lenses with USM have the ring-type USM. The 85mm f/1.8 USM has ring USM, whereas the 50mm f/1.4 USM has micromotor USM (although it has a unique clutch mechanism to allow full time manual focusing, which is probably one of the reasons the lens' AF system is reportedly prone to breaking).


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## Chewy734 (Jun 14, 2011)

neuroanatomist said:


> Chewy734 said:
> 
> 
> > Out of curiosity, are you in the neuro field with photography being your hobby or something?
> ...



Cool! What's your profession exactly?


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## neuroanatomist (Jun 14, 2011)

Chewy734 said:


> [Cool! What's your profession exactly?




I work for a large pharmaceutical company, doing biomarker research in neuroscience, oncology, and immunology. I don't get into the lab all that often (one of the big downsides to being a director) - but I do have a very nice Zeiss microscope in my office, and a large stack of slide boxes awaiting my attention...


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