55-250mm STM Lens goes to Sleep

[Calsal]

FYI...

While recently shooting a bicycle race with a 70D and 55-250mm STM, I noticed that when switching the lens to manual focus, pre-focusing at a specific place on the course, and waiting for a cyclist to pop into my composition... apparently this lens (not the camera) goes into a “sleep mode" after 1 minute and it then takes 1-2 secs to wake.

When the shutter is pressed to take the shot, the lens performs a refocus exercise and then settles on the focus mark previously set manually. All well and good except in those 2 secs... I miss the shot.

I’ve since read Canon’s IB for the lens, the problem related to sleep mode and delayed focusing is described under “Shooting Precautions.” 

In all other respects this cheapie lens is surprisingly sharp, has good range, and easy on the neck-and-shoulder, but not well-suited for this type of shooting. There is an awkward workaround, but safer to carry along trusted pro gear and get the job done. Lesson learned.

[TTMartin]

Thanks for the heads up.

Does a half press of the shutter button wake the lens back up?

[Calsal]

Yes, indeed. When the shutter is pressed half-way, the lens does waken by performing its 1-2 second "check." One can still take pics during that brief interlude, but everything is out-of-focus. The camera is fully awake (metering and display) and ready, just not this particular lens. 

[TTMartin]

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@Calsal wrote:

Yes, indeed. When the shutter is pressed half-way, the lens does waken by performing its 1-2 second "check." One can still take pics during that brief interlude, but everything is out-of-focus. The camera is fully awake (metering and display) and ready, just not this particular lens. 

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Then it would seem your last line about needing pro gear to get the job done is more a reaction to your not understanding how your gear worked than the gear not being suitable. Had you realized in advance how the lens would behave a simple half shutter press would have readied it for when the cyclist got to the proper location in your composition. Not exactly what I would call an awkward work around. 

Again thanks you for the heads up on the lens behavior, so I don't go through the same frustration you did. But, I wont be because I wont use the EF-S 55-250 IS STM lens, but, because I know what to expect from it.

[Waddizzle]

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@Calsal wrote:

Yes, indeed. When the shutter is pressed half-way, the lens does waken by performing its 1-2 second "check." One can still take pics during that brief interlude, but everything is out-of-focus. The camera is fully awake (metering and display) and ready, just not this particular lens. 

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Standards Operating Procedure.  Keep the DSLR ready to shoot.  

[RobertTheFat]

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@Calsal wrote:

Yes, indeed. When the shutter is pressed half-way, the lens does waken by performing its 1-2 second "check." One can still take pics during that brief interlude, but everything is out-of-focus. The camera is fully awake (metering and display) and ready, just not this particular lens. 

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What I think I heard you say in your original post is that the lens does correctly reset the focus, just that it takes too long to do it. This implies that the lens is listening to the camera, even though it maintains its own knowledge of where the intended focus point is. So it you set the camera to one of its continuous-focusing modes and used back-button focus to keep sending a signal to the lens, would that keep the lens from going into its sleep mode?

[RobertTheFat]

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@Calsal wrote:

FYI...

While recently shooting a bicycle race with a 70D and 55-250mm STM, I noticed that when switching the lens to manual focus, pre-focusing at a specific place on the course, and waiting for a cyclist to pop into my composition... apparently this lens (not the camera) goes into a “sleep mode" after 1 minute and it then takes 1-2 secs to wake.

When the shutter is pressed to take the shot, the lens performs a refocus exercise and then settles on the focus mark previously set manually. All well and good except in those 2 secs... I miss the shot.

I’ve since read Canon’s IB for the lens, the problem related to sleep mode and delayed focusing is described under “Shooting Precautions.” 

In all other respects this cheapie lens is surprisingly sharp, has good range, and easy on the neck-and-shoulder, but not well-suited for this type of shooting. There is an awkward workaround, but safer to carry along trusted pro gear and get the job done. Lesson learned.

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I think what you're seeing may be the unavoidable downside of Canon's otherwise very good STM ("STepping Motor") lenses. An STM lens uses its focusing motor for even manual focus, which puts a greater load on the camera's battery. The "sleep mode" that you describe is undoubtedly intended to spare the battery to allow more time between charges and would therefore be considered a feature, not a bug. STM lenses are favored by those shooting video, because they're unusually quiet. They may also give a smoother transition when you have to refocus.

Some of those in this forum are quite partial to STM lenses for their unusually good optics, and often recommend them to users looking for a good, reasonably priced lens. But a caution about the sleep mode should probably be included in such recommendations.