Canon 24mm f/1.4L softness - and a clue!

I have one of these and have never been happy with its lack of sharpness, especially at low f/stop numbers.

Someone on another forum passed on a clue that frankly amazed me and might be the answer to my issue. He said that not infrequently, the rear element of this lens is full of tiny air bubbles that would obviously affect sharpness, no matter what they do to "calibrate" it.

Somewhat dubious, this morning I held my lens up to a light looking through the rear element - and there there were! Thousands of tiny bubbles acting like a diffusion filter. Its not subtle at all - the bubbles (or whatever they are) are easily seen.

Of course it will be on its way back to Canon shortly, but I'm still shaking my head over how this defect could have passed even the most rudimentary QC inspection process.

John Maio said:

........I held my lens up to a light looking through the rear element - and there there were! Thousands of tiny bubbles acting like a diffusion filter. Its not subtle at all - the bubbles (or whatever they are) are easily seen.
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Al lenses should be inspected. This could be done automatically! I wonder whether they use some optical bench to do this? It would be straightforward to design!

Thanks for bringing this to our attention! One small bubble will not do any harm. What you found is bad!

I'm now going to check all my lenses!

Asher

Asher Kelman said:

Al lenses should be inspected. This could be done automatically! I wonder whether they use some optical bench to do this? It would be straightforward to design!

Thanks for bringing this to our attention! One small bubble will not do any harm. What you found is bad!

I'm now going to check all my lenses!

Asher

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It does seem strange that a lens this expensive would have such a glaring defect.

I checked mine - no bubbles.

The 24 1.4L was delevered to Canon service. I'll let you know what they say and do to improve it when it returns.

What was the outcome, John? A happy one, I hope.

My wife has a 10-22 with an obvious bubble in a forward lens element, and it produces dual blemishes on images. We sent it back (twice) to Canon, neither time was it fixed. Now we have to send it back a third time. Deep sigh.

When I spoke with customer service in California (the second time it came back unrepaired), the representative said, "I don't know what to tell you, but according to my computer, that lens was fixed." According to his computer. I didn' t know whether to laugh or cry!

Hope your lens comes back repaired. I'm sure my experience was an anomaly.

This is an interesting revelation, I wonder how how many people have had this issue of the micro-bubbles in the rear element? I love Canon (Love 'em!), but I have serious questions about their QC sometimes. Not to start a complaint thread.