Is it normal for a 70-300 lens IS USM to do this?

bmx43
I am indeed missing the switches you have on yours.

tekkie
I am using Program mode and the singular AF red flashing thingy in the center/middle of the viewfinder. and No, it wasn't dark or low light conditions when the lens would go bananas and literally freeze up out of focus.

oh yes, and I wasn't very close to the subject I was attempting to shoot....not closer than 8 ft plus away.

the bottom line is this: I am not very satisfied with the Canon 70-300 lens and want to return it. Maybe they'll give me a replacement which will perform better and also take more consistently sharp and detailed shots of birds and small critters.

I am going down to Ding Darling National Wildlife Refuge on Sanibel Island next week and I want to have a lens which will capture outstanding pics of birds, gators, crocs, Nile Monitor Lizards, snakes, turtles, etc.

Need a lens which will capture the fillings in a Gator's teeth.

it soudns like its just hunting because its not gettin somethin to focus on. that happens sometimes, especially in low light or low contrast.

oniOn56
In my inexperienced opinion, it was doing more than just hunting but went into a psycho lock up on its ability to focus.

I brought the lens back to the store and a Geek there went through the motions of checking the focusing. After checking it out, he agreed that it had focusing problems and gave me a brand new Canon 70-300 mm IS lens. we shall see how it performs.

I bet you will be much happier with the new one

I have the 70-300 IS on my 400D and have this issue occasionally. In my experience it is due to low light situations with little or no contrast. I move off, focus and move back in and focus again and I'm all good to go.

Just get it close with manual focus then use the af to get better. Also, try using the af assist and see what happens.

IrishKing wrote in post #3487424
oniOn56
In my inexperienced opinion, it was doing more than just hunting but went into a psycho lock up on its ability to focus.

I brought the lens back to the store and a Geek there went through the motions of checking the focusing. After checking it out, he agreed that it had focusing problems and gave me a brand new Canon 70-300 mm IS lens. we shall see how it performs.

congrats, hope it all works out for you!