70-200 F4 Sharpness

haven't tested for back focus yet - but seen the results above (and the comment that the pole is more in focus) makes me think I should. Sounds like a project for tomorrow for me...

10megapixel wrote in post #11882567
It's a 70-200 f/4. That lens is super sharp.

I know--just saying it's not horrible by comparison

It's a shame the OP can't provide a couple crops of the same target at 4, 4.5, 5, 5.6... I'd like to see the effect when he stops down. I had one of these myself, and unless the lens is badly miscalibrated, stopping down slightly shouldn't provide a world of difference--these puppies are supposed to be nearly sharp as can be wide open.

rounder_09 wrote in post #11882614
haven't tested for back focus yet - but seen the results above (and the comment that the pole is more in focus) makes me think I should. Sounds like a project for tomorrow for me...

It's not as bad as it seems. You don't really even need one of those focus charts printed out. A printed sheet hung on a wall about 20 feet away should be good, along with a tripod. If your body allows microadjustments, it should only take 5 minutes to take care of.

MOkoFOko wrote in post #11882625
I know--just saying it's not horrible by comparison

It's a shame the OP can't provide a couple crops of the same target at 4, 4.5, 5, 5.6... I'd like to see the effect when he stops down. I had one of these myself, and unless the lens is badly miscalibrated, stopping down slightly shouldn't provide a world of difference--these puppies are supposed to be nearly sharp as can be wide open.

I haven't noticed a big difference, but will run some tests and watch for it. I didn't realize this could be a possibility.

rounder_09 wrote in post #11882824
I haven't noticed a big difference, but will run some tests and watch for it. I didn't realize this could be a possibility.

All lens models can come soft from the factory... Sometimes extended use can cause inner elements to misalign. Even hard falls can do it--which can result from poor shipping and packing too...

I've tested a lot of lenses, and I've run into quite a few soft copies. The worst of the worst are just plain bad through f/11... but most often, I see lenses that are only softer than they should be at wide-open through one stop down... And I know for a fact that your model should be near razor sharp at f/4.

MOkoFOko wrote in post #11883032
All lens models can come soft from the factory... Sometimes extended use can cause inner elements to misalign. Even hard falls can do it--which can result from poor shipping and packing too...

I've tested a lot of lenses, and I've run into quite a few soft copies. The worst of the worst are just plain bad through f/11... but most often, I see lenses that are only softer than they should be at wide-open through one stop down... And I know for a fact that your model should be near razor sharp at f/4.

Hmmmm interesting info. Makes me think that I should get it looked at. Then every now and again I get an image like below (F5 here - perhaps you are on to something with the wide open thing above), which I'm very happy with (looks pretty good to me)... and it makes me think that my issues are user error. These are few and far between though it seems

HTTP response: NOT FOUND | MIME changed to 'image/gif' | Redirected to error image by FLICKR

HTTP response: NOT FOUND | MIME changed to 'image/gif' | Redirected to error image by FLICKR

^^^ that's darn sharp. Much more in line with what you should be expecting. You want to really compare against 4, 4.5, 5... see how they compare, with the same conditions/target.

If the lens is under warranty, it wouldn't cost you anything but your time and shipping to have it sent to Canon for testing and calibration.

MOkoFOko wrote in post #11883085
^^^ that's darn sharp. Much more in line with what you should be expecting. You want to really compare against 4, 4.5, 5... see how they compare, with the same conditions/target.

If the lens is under warranty, it wouldn't cost you anything but your time and shipping to have it sent to Canon for testing and calibration.

Thanks for the help! I'll give that a go.

I'm guessing it isn't under warranty, I believe it is about 4 years old. I'll try some tests at those settings, and see if I can get a handle on it...