Whats up with my focus?

[SpeedingSphere]

At longer lengths, my 70-200mm F/2.8L IS seems to blur a bit and I'm not sure if its the lens or if its the camera body back/foreground focusing. I was shooting some ducks and when I looked at them enlarged, they seemed a bit soft.. Should I send the body in to Canon to have it looked at? I'm receiving my 40D either tomorrow or the day after. I'll try some shots when I get it.

Here are a few 100% crops at the sharpest focus I could get. What do you guys think?





The only one I am somewhat happy with is the one of the duck drinking at the shoreline. None of them have had PP except for resizing and the overlay of 100%..

IS was on for all of the shots, Flash was used on i believe 3 of them.

**edit** also, no filter was used on the lens

[jorgemonkey]

What were your camera settings? I'm looking at the first one, and it looks like the pigeon on the top lefts leg has some motion blur on it.

[SpeedingSphere]

Focal Length: 140.0mm Exposure Time: 1/125
Aperture: f/7.1 - ISO Equiv.: 200
Whitebalance: Auto - Exposure: aperture priority
and flash used on the first one. The others ranged between 1/200th and 1/500th @ F/2.8-F/7.1

It doesnt seem to be a motion blur issue causing them to go out of focus.. Seems to be something with the lens or body..

[Loupey]

As far as your examples are concerned, I really can't see a thing on my 12.1" laptop screen.

If you really want to test the focusing, zoom to the max, shoot close, and open up your aperture. This will give you the absolute thinnest DOF and you can check critical focusing that way.

Better yet, pick something around the house to shoot with a strong flash (to eliminate the possibility of camera motion blur factoring into the example).


Can you post an uncropped and cropped images at full 640 pixels wide?

[SpeedingSphere]

Seems to have a pre-focus problem? I'd assume its the body as the foreground is pretty sharp

*idk if you meant it in this way or not when you said you couldnt see the examples, so I figured I'd throw this out there, the thumbnails above are click to enlarge. :P

[SpeedingSphere]

after a quick browsing of google, I found that there is an internal focus plane adjustment by allen key. I adjusted it one way and it went further infront of the object and turned it back two times and its spot on!

Heres what the crop looks like now.. seems I figured my own problem out.

[SpeedingSphere]

sorry for the third post.

I tuned it in even finer by going one click of the adjustment at a time and eventually pin pointed it in to the sharpest click. I wish this was user adjustable like the external diopter adjustment! Adjust it to your longest lens and you should have a pin prick of a lens focus on all the rest I would say!

[Jimmy B]

If you could post a link to where you found that info.........
Jimmy B

[SpeedingSphere]

surely!

http://www.google.com/translate?u=ht...&hl=en&ie=UTF8

**I would just manually hold up the mirror flap though to keep dust from the sensor instead of using cleaning mode. You really wont be near the shutter or the sensor during the process unless you have shaky hands. I used the tip my friend showed me for steadying my hands from model building: clap em really hard to get em tingling and they'll be alot more still.

[mikeb380]

At longer lengths, my 70-200mm F/2.8L IS seems to blur a bit and I'm not sure if its the lens or if its the camera body back/foreground focusing. I was shooting some ducks and when I looked at them enlarged, they seemed a bit soft.. Should I send the body in to Canon to have it looked at? I'm receiving my 40D either tomorrow or the day after. I'll try some shots when I get it.

Here are a few 100% crops at the sharpest focus I could get. What do you guys think?





The only one I am somewhat happy with is the one of the duck drinking at the shoreline. None of them have had PP except for resizing and the overlay of 100%..

IS was on for all of the shots, Flash was used on i believe 3 of them.

**edit** also, no filter was used on the lens

It could be a number of things. First I would suspect is auto focus as AF doesn't really know what you want sharpest. try mounting the lens and camera on a tripod and shoot both AF and manual to see if there is any difference. You might need to get an eyepiece correction to see the focus well. Try to reshoot, as close as possible the same scene for the tests. Make several comparison shots to be able to determine what is up. If you have the same problem on Manual Focus then it could be either the lens or the camera. Try the lens on the new camera and see how it works there. If those are sharp, then the problem is probably the camera. If you can borrow another 200 mm lens to try on your camera, do that and see how sharp it is. By doing this you can avoid sending a good camera for repairs and still have a problem with the lens.

Hope this helps
Good luck

Michael

[Jimmy B]

Mike thanks for the link.
JB

[SpeedingSphere]

It could be a number of things. First I would suspect is auto focus as AF doesn't really know what you want sharpest. try mounting the lens and camera on a tripod and shoot both AF and manual to see if there is any difference. You might need to get an eyepiece correction to see the focus well. Try to reshoot, as close as possible the same scene for the tests. Make several comparison shots to be able to determine what is up. If you have the same problem on Manual Focus then it could be either the lens or the camera. Try the lens on the new camera and see how it works there. If those are sharp, then the problem is probably the camera. If you can borrow another 200 mm lens to try on your camera, do that and see how sharp it is. By doing this you can avoid sending a good camera for repairs and still have a problem with the lens.

Hope this helps
Good luck

Michael

-For autofocus, I use the middle focus point, lock it, and then recompose my shots. Correcting the focus plane fixed everything. I got my new body(40D) and the shots are even more in focus, so its definitely the body. I may send it to Canon to get cleaned and adjusted. As of now though, its super sharp and I'm fine with everything.

-JB, youre welcome!

[SmartWombat]

I tuned it in even finer by going one click of the adjustment at a time and eventually pin pointed it in to the sharpest click.

This is user adjustable in software on the 1DmkIII, and it's adjustable on a per-lens basis.
I assume from that ability to have it set per-lens that the focus offset may be different for different lenses and your approach of setting it for the longest focal length lens might not give you the best results.
That's why I sent in all my bodies and lenses at once and had Canon setup the lot to work with each other in any combination.

[livin4lax09]

just for future reference, know that lenses are most of the time softest wide open. If you stop them down a bit they become sharper. Except the 200 f/1.8, which people like to say is sharpest at f/1.8. I don't believe it though.

[morrow47@charter.net]

SmartWombat,

Can you give me an idea what Canon charges for this service?