Canon 75-300m Lens not focusing

[Blake1]

I recently bought a new lens, and it doesn’t seem to be focusing. The focus moves when I try to zoom in or out. When I use auto-focus, the lens focuses only when I’m zoomed out. When I'm zoomed in, it will only jitter back and forth.

[deebatman316]

Return the lens for a refund. It shouldn't be broken. That's Canon's worst lens made. It's poor optically, lacks IS and uses slow Micro Motor AF motors l. 

[Blake1]

What about the 70-300

[deebatman316]

From who Canon or 3rd Party. Canon has made 3 different models. One was a professional grade "L" lens. The other 2 are consumer grade. The current version II of the consumer grade lens is good. But what is your budget though.

[Tronhard]

TO DEMETRIUS:

The OP has a 75-300, not the 70-300 to which I think you are referring when you talk about an L lens.  By now I am sure you are aware that I have a very low opinion of the 75-300.  That said, it's still supposed to autofocus.  It may be the lens, or the camera may not be getting sufficient contrast to make that focus, or it may be too close to the subject for the level of zoom.  We need more information.

To BLAKE:

To clarify your situation, can you please advise what types of subjects you are trying to focus on  and

how close you are to them when you have difficulty in getting a focus lock

[deebatman316]

The OP later asked about a 70-300mm lens. So I was not responding to the original 75-300mm lens that they mentioned.

[Tronhard]

OK sorry Demetrius, I was confused - there is no sign of that interchange on the screen I am looking at, just the OP and your two responses before mine.

[deebatman316]

As to the other part AF issues. I'm not on my usual computer where I can see the whole post. I'm currently on vacation so I'm using my phone. So I can only get a limited view of the post.

[Tronhard]

@BLAKE1

Since you have made inquiries about the 70-300 lens, I thought you might find this useful:
70-300 Canon Lenses In-Depth Analysis - Canon Community

However, I think it would be helpful to know what camera you are using, your focus mode (spot, area, etc.) and distance to the subjects you are trying to focus on.  The issue may not lie with the lens.

[Tronhard]

Lucky you to be on vacation!!  Where are you holidaying?