Focus issue on 70-200 is f4

I sold a copy of this lens on CL to a guy a couple of weeks ago. It was excellent in every respect and just out of warranty. The buyer just contacted me and said it wouldn't focus when held straight up or straight down. I never tried to focus it straight up or down so I was unaware of the issue. All my shots were generally horizontal and it works fine. The buyer tested it b/f buying and agreed it was very sharp. Anybody else ever have an issue with focus when aiming the lens high up or down?

I'm not sure what to do. I didn't sell the lens with a warranty, but selling a lens that doesn't work right is not a reputation I want to have.

I don't often shoot that way either. If it is strait down perhaps it was too close to the subject to focus. Not sure about strait up. What would you be shooting? The buyer did test it so it was up to him to do a complete set of tests. Kinda odd that he OK's it and then does not like it. I might call Canon support and just as a few questions about this just to see what they say.

I can try mine out later today. I guess for up I'll have to go and stand under a tree and focus on a branch.

That's weird... If it's focusing fine in other orientations I can't for the life of me think of any mechanical reason a lens wouldn't be able to focus when pointed straight up or straight down. (But I also can't think of many times one would want to shoot straight up or straight down, either.)

About the only thing I can think of is maybe a loose ribbon cable that provides connectivity between the contacts on the back of the lens and the electronics inside the lens... Maybe it's loose and connectivity is lost when the lens is held in certain orientations. But that seems pretty unlikely, too.

Good point though... straight down at the ground might be within the minimum focus distance of the lens (on both the IS and non-IS versions f4 lens, it's just under 4 feet/1.2m).

And, if pointed straight up toward a plain sky, there might not be anything to lock onto. AF requires some detail and contrast, to be able to work. It might vary from camera model to camera model.

It also might be the buyer's camera at fault. Cameras do have orientation sensors in them (so do IS lenses, but non-IS lenses don't). However, I'm again at a loss as to what might cause such a specific problem.

Of it might be that the buyer's wife said, "No way!"

I'd offer to meet with the buyer and test the lens with them. Take a camera of your own along, to test it. It might be a problem with is camera (which do have orientation sensors, as do IS lenses... non-IS lenses don't).

Look for looseness at the bayonet mount on lens or camera... or damage, looseness, dirt or obstructions on the electronic contacts between lens and camera.

Do you have record of the lens you sold somewhere? The serial number? Distinctive marks on the lens that you'd recognize? I'd just be cautious, don't know the buyer and there have been instances of people returning broken gear for a refund, that wasn't the same item as what they bought. Someone here even got a 70-200/4 inside a 70-200/2.8 box off Amazon sometime... no doubt a "return" item that Amazon refunded and put back on the shelf without checking what was inside.

Also "a couple weeks" is plenty of time to do damage to a lens...

So just be very careful and not too quick to take the lens back and give a refund!

Here is what he said: "I just noticed this phenomenon as I was playing around with the focus ring. It does not do it holding the lens horizontally, but holding it up or down, the auto focus and manual focus does not work.

Usually I do not make a big deal out of things like this, but this was a lot of money for me."

Indeed, it was a lot of money and I want him to be happy. I called tech support and the guy was extremely nice. He suggested clearing camera settings, clearing custom settings, selected center focus and trying it again. However, this wouldn't explain the manual focus ring not working. It sounds like the lens is slipping inside. But if that is happening, would the auto focus motor be able to achieve sharp focus? It's a sharp lens. Tech support said a focus issue repair would be a ball park $160.

I asked the buyer to call tech support and see if he could get it resolved. If not, I told him to bring it by and let me look at it. Then I can try it on my camera. But if the manual focus ring is slipping, it won't matter what camera it is on. I think the guy is honest. I know I am. I want to do the right thing. If the repair will be around $160, I think I will offer to split it with him. Does that sound reasonable? He did test it and it has been about 2 weeks.

What a strange objection on a lens' focus ability. I mean how many times is the user going to be shooting exactly straight up or straight down? Honestly, I have NEVER taken a shot with a camera oriented that way.

But I'm going to check right now to see if the lens (135L) currently on my camera will focus with straight up or down orientation.

dave

Dunno, sounds to me like some form of zoom creep to me, gravity is pushing or pulling the lens just enough to effect focus. I seriously doubt it's an issue with the lens and more of just any big lens will behave in unusual circumstances like that.

Just tested my dropped and abused copy on an equally abused A2 film camera, works fine.

Buyer called tech support and the tech said send it in. I have to agree. IMO, an L lens should focus manually or auto no matter what the orientation. There must be a clutch or something that is slipping. I' will look at the lens and if it doesn't have any appearance of abuse, like it was dropped or something, and it still focuses properly at the horizonal, I will offer to pay 1/2 the fixing fee. I sure wish he had discovered this much earlier, like when he was in my office.

My 70-200 f4 IS is actually at Midwest camera for this exact same issue.

Shooting level it will focus fine (AF and MF). If I angle it up more then about 30* then it will go to infinity but not back. If I angle it down more then about 30* it will go to near focus but not back.

This issue just wasn't with AF. Switching to manual focus does the same thing. Angle it up I can rotate the ring and it will go to infinity but it will not go back to near and vice versa with angling it down.

Midwest camera repair said it was a "major focus issue" and cost was about $180. Mind you my lens is just a little over a year old and I babied the hell out of it so no clue how or why the focus mechanism would crap out like that. Quality or design flaw maybe?

Gremlin, this seems to be the exact same issue on a babied lens that is about 15 months old.

It's not unheard of on Canon USM lenses. I've had to send a 400 F/5.6 in for a similar but less extreme problem (AF still worked fine, but there was slip when pointed up). For me it was VERY annoying as I was using it for astro shots.

I just received my new 70-200 f4.Looks like anymore than about 30-35 degrees upward and it wont focus .I need to experiment some more,but looks like I'm gonna have to send it in.

dandai wrote in post #14152416
I just received my new 70-200 f4.Looks like anymore than about 30-35 degrees upward and it wont focus .I need to experiment some more,but looks like I'm gonna have to send it in.

$180, at least that's thy mine cost to fix for the same issue. If it is "new" I'd sugget sending it back for a replacement as this is not something you can fix by yourself.

Must have just been me, its working fine this AM.Hopefully it will continue.

I definitely experience the "too close to subject" issue whereby mine refuses to focus ... Not sure what is the "expected" distance that I must be away from subject - but it seems to be around 8-10 feet ... Anything closer and it refuses to Focus.