EF 100-400mm f/4.5-5.6L IS II USM Lens won’t autofocus

[ryanh]

Hello, I have a 100-400 5.6 ii, it worked fine 2 days ago but now all of a sudden it won’t autofocus.  I can still manually focus but with autofocus I hear the motor and it searches for focus but nothing.  I tried it on my 5d4 and 7d with same results.  Other lenses work fine.  I tried wiping the contacts but that didn’t help.  It looks like over $500 to send in for repairs.  Is there anything else I could try before sending it in?

[Tronhard]

Hi Ryan and welcome to the forum:
Given what you say, it would appear this is a lens-specific issue.
Is this lens a recent acquisition?  In other words, does it have a history of being reliable in focusing?
To help you before you incur costs:
Has anything changed as regards the use of the lens, in the last few days?
Have you checked the positions of the switches for AF-ON and switched them back and forth?
What position is the Mode switch on?
You might want to look at the screws for mounting the rear plate on the lens to see if they have protruded and caused a contact issue that way.

[Waddizzle]

Welcome to the Canon Forums.  

Sorry to hear that you are having issues with your gear.  It sounds like you have been served a boiler plate, cost to repair estimate.  People want to know how much it will cost before they pack up the gear and ship it to a repair center.

Estimates from Canon are free.  You only need to pay for shipping it to them.  They will evaluate your lens and contact you for authorization to begin any repairs.

Is this a new lens that you have recently purchased?  A new lens would a one year warranty.  An older lens would not.  

If you are using any UV, CPL, or ND filters, then I strongly recommend that you remove it.  If you feel the need to have a filter to protect the front element, then I recommend a high quality CLEAR filter.  I use the B+W Nano Clear series of filters.

Check the Focus Range Limiter Switch on the lens.  The lens is capable of focusing on objects at just over a meter away to infinity.  Limiting the focus range can help speed up auto focusing at the cost that the lens will only focus on objects at a certain range of distances away from the camera.

[jrhoffman75]

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@ryanh wrote:

Hello, I have a 100-400 5.6 ii, it worked fine 2 days ago but now all of a sudden it won’t autofocus.  I can still manually focus but with autofocus I hear the motor and it searches for focus but nothing.  I tried it on my 5d4 and 7d with same results.  Other lenses work fine.  I tried wiping the contacts but that didn’t help.  It looks like over $500 to send in for repairs.  Is there anything else I could try before sending it in?

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Canon has a implemented a tiered repair cost system; I believe there are three, but not sure.

When you describe your problem the repair estimate is computer-generated.

Actual cost would be what the actual repair requires. I have always been consulted before the repair to confirm what I want. If you are sending to canon just note that you want a verbal contact before any repairs.