70-200mm f/4L - focus problem

Hello,
I have had this lens for while now, but never quite satisfied with its sharpness. So recently I did some tests and compared shots with a friend who also has a the same lens. (I'm using a 7d, he has a t1i). The test subject is a paper with 1" squares, with the center square having more lines for detail.

The 1st pic here is a 1:1 crop showing the single AF point.
(AE mode, 4.0, 1/2500, 200mm focal length, standard pic style, sharpness 3, used tripod & 2sec timer)

The 2nd pic was taken by my buddy with his lens & body:
(AE mode, 4.0, 1/3200, 200mm f. len, stand pic style, handheld, oneshot)

You can see that there is a huge difference in sharpness. I've tried the micro-adjustment on the 7d, but cannot get it any sharper.

From what I've read here & else where this lens is highly recommended, and one of its best assets is it's sharpness. But mine sure is not. Any recommendations are appreciated.
thanks.

Just a followup... this is the shot that finally pushed me to do some more critical testing with this lens.

This red-tailed hawk was floating in our front yard, and I had taken some, what I hoped were some decent shots. When you zoom in to 1:1 you can see that it appears to be poorly focused.

Photo details: AE, 1/2500, 200mm f. len, AF:AI Servo, Spot AF, the AF point is on the bird's right wing).

You turned IS off on the tripod right?

That said, Something looks VERY off, Try doing the paper square thing again but this time try using AF microadjust to dial it in... Also perhaps try liveviewing and seeing if you can manually focus the lens and get it perfectly sharp...

If you cant fix it with microadjustment, Then send it to Canon, Because somethings definitely not right... My copy looks better than that with a 1.4x TC attached! Heck, a 55-250 probubly would look better

Sorry, I didn't mention that this is the non-IS version of the F4. So, yes the IS is off

And yes, I have already tried the micro-adjustment. My guess is that the auto-focus is so far out that the micro-adjustment range is not wide enough to bring it back in.

I assume there is no other adjustments that I can do? Including to the lens itself?

jvh003 wrote in post #15096378
Sorry, I didn't mention that this is the non-IS version of the F4. So, yes the IS is off

And yes, I have already tried the micro-adjustment. My guess is that the auto-focus is so far out that the micro-adjustment range is not wide enough to bring it back in.

I assume there is no other adjustments that I can do? Including to the lens itself?

Not really, Not without running the risk of breaking something... lol

Did you buy the lens new or used? do you know if it was ever dropped or knocked or anything?

No matter what Id send it off to Canon, They'll get it back in shape real quick for you.. Its NOT normal and NOT ok..

As the others have said...that looks seriously borked. I'd definitely have Canon take a looksee.

and just to be sure....you have no filter on it, right?

I did buy it used, and I did ask the seller if it was ever dropped (ans: no). It is in mint (physical) condition. So, it doesn't look as it had been dropped. ( I have never dropped it, or knocked it ).

Thank you for the help and confirmation that there is really something wrong with the lens. It sure didn't look normal to me either. But I did want to get some opinions from this forum first.

Do you have any idea how much it might cost to be repaired by Canon?

(and yes... i have tried without a filter).

If the thing was dropped off in the carpet floor, for example, then something internal will go wrong despite perfect outside cosmetics. I believe the internal alignment of the lenses is quite fragile to external shock.

That's being said, it could be a manufacturing defect. In any case, the focus of your lens is way off. I would suggest you use the live view to focus manually first. If the glasses are fine and aligned correctly you should get a tack-sharp image using live view and perhaps you can micro adjust it. If it is not sharp, you need to send it to canon.

I also have a 70-200 F4. It is super sharp, super nice. It is likely there is something wrong with yours internally.

Are you using any sort of filters on the lens?

forgetting the AF for a moment, how sharp can you get a similar test using liveview and manual focussing?

joeseph wrote in post #15096496
forgetting the AF for a moment, how sharp can you get a similar test using liveview and manual focussing?

Try this.

joeseph wrote in post #15096496
Are you using any sort of filters on the lens?

forgetting the AF for a moment, how sharp can you get a similar test using liveview and manual focussing?

This is a good suggestion. I'll try this test with the same test subject.
Thanks

Turns out the problem was a due to my uv-filter. I thought originally that I had tested with out the filter... but after reading that suggestion here several times here... I tried testing without it again.

Turns out the Hoya UV(C) filter was throwing off the AF very badly. So ok... I thought maybe it was a dud (which it is), and I recently bought and tried another. Well the results were better than my original filter, however still not near as sharp as the 'bare' lens itself. (So I took it back... forget the filter... I use the hood all the time anyway).

So... wondering if this is a common experience out there?
Anyone else with bad experience(s) with UV filters on this lens?

Wouldn't know. Have never bought a filter for a lens since I got back into photography with a dSLR. But I have bought lens hoods for every lens I use.

Glad you got your 70-200 figured out. It is my favorite lens and one that I will not sell.

I think if you did a search you would find out that there are more bad experiences with the uv filters than there are good.

Agree with the responses saying UV filter can be causing AF focus issues. Some filters are just made poorly and interfere with the inner lens' optics.