Canon 100 - 400 Issue

A couple of months ago I bought a new Canon 100-400L. I haven't been able to use it as much as I should, but the images I have taken so far look good to me. However, when cleaning the front and rear lens recently, I looked through the lens from the rear at a light bulb to look for smudges or areas that needed to be cleaned. I noticed what looked like a lot of "pits" on the inside of the front element. There were a lot of them, and they were scattered over the whole lens area.

I don't think this should be normal, but I wanted to see if anyone here has noticed something like this before.

Thanks for your help.
Ken

Can you better describe what the "pits" look like? The 100-400 is famous for ingesting dust, but dust specks don't look like pits. On the other other hand, I bought a brand new Canon 600 IS in 2000 that arrived with numerous small, white, fibrous specks inside the front element that proved to be fungus. Canon's service department did a quick cleaning for me that completely solved the problem (I'm still using the lens today). Assuming your problem is not some kind of optical illusion, Canon can very likely fix it under warranty.

Cliff,
To me, the "pits" look like the element was hit by a blast of sand under high pressure. I suppose they could be tiny pockets that developed during the grinding or polishing or however they manufacture the element.

Thanks
Ken

Those should not be there, and that lens should go right back on warranty. It's a one-year warranty. I had issues with my 100-400L when I bought it (bad contacts causing error 99 messages) and Canon replaced several parts of the lens and had it back in my hands within two weeks at no cost, all warranty covered. It's been a star in the two years since then.

Yes, send it back. In addition to correcting the problem you see, ask them to make sure it meets all factory specs. Specimens of this lens seem to vary far more than other Canon lenses, and many people have reported great improvement following factory servicing.

I figured this was not a normal thing, but I wanted to make sure since I have never heard of the issue before. I am going to send it back to Canon.

Thanks for you advice.
Ken