Is my 70-200mm F2.8 L back focusing?

I did some tests. The focus chart and real world ones. Can you help me check?

Center crops:

1. Focus on the guy's head. Camera focuses on the tree on the right

Did you use a tripod? (I somehow doubt it) - When holding a lens at a wide aperture it is quite easy to move a fraction after locking focus, you have a very limited DOF.

You really need to do something more controlled using a tripod IMO.

You may be right, it may be in need of adjustment, but using fast lenses wide open at long focal lengths does take a bit of practice.

I don't know ,it is not looking good to me.

to ensure if the camera was focused on the items you mentioned, look at the pics using Canon's Zoombrowser EX. There is a view that you can use to see what the camera focused on, similar to the AF points in the viewfinder. That way you can confirm that you focused on exactly what you wanted.

rodal126 wrote in post #4206555
to ensure if the camera was focused on the items you mentioned, look at the pics using Canon's Zoombrowser EX. There is a view that you can use to see what the camera focused on, similar to the AF points in the viewfinder. That way you can confirm that you focused on exactly what you wanted.

If he focused and recomposed or moved slightly, this will do him no good. It only shows which focal point was activated at the time of the shot. If he locked focus elsewhere, then it is useless.

transcend wrote in post #4206821
If he focused and recomposed or moved slightly, this will do him no good. It only shows which focal point was activated at the time of the shot. If he locked focus elsewhere, then it is useless.

True. Let me add that this method would be more accurate if used with a tripod (and the shot was not recomposed)

Without a controlled test, it's a waste of time:

1. Tripod is essential,

2. For longer focal length, mirror lockup and remote release essential,

3. Use the standard chart (with horizontal lines perpendicular to line of site) shot at 45 degree angle.

4. Focus/recompose is looking for trouble and can be misleading.

Thanks for the replies. I used a tripod on the 2nd and 3rd pic. Mirror lockup and remote shutter. As for the focus points, I used the center focus point and remember very well which point I aimed at.

However, this morning I tried again. I don't know what I did other than switch the focus distance switch on the lens. Forgive me if I seem dumb. I haven't read the manual yet because I left the box at a friend's house.

F/4, iso400, 1/25 sec, tripod, mirror lockup, remote

was it at 70? 200? try about 10ft away and put the batteries appart about 2ft-3ft. I use hard cover books for my "in-house" focusing tests.

Another one:

Circled area is the point of focus. Though this doesn't show much, it just seems to me that the focused area is sharp.

silvex wrote in post #4207806
was it at 70? 200? try about 10ft away and put the batteries appart about 2ft-3ft. I use hard cover books for my "in-house" focusing tests.

200mm. I was 7 feet away. Ok, I'll try your method now. Got no books here though.

MannP wrote in post #4207845
200mm. I was 7 feet away. Ok, I'll try your method now. Got no books here though.

Shoot two shots f2.8 iso100 the f4 iso100 on a tripod as perpendicular and level a s possible to the subject. Like put objects on a dining table one on each end staggered. then put the lens height about 3'6" (on tripod ) 10feet way and shoot on the fist object at f2.8 the at f4 Av mode on tripod an remote switch or cameras timer.

then open it and sharpen both shots ONLY no noise or levels etc etc.

How about this? 10 ft away, camera raised to your specified height. But iso is at 200 and F/4.

Looking good...at F4, but try BOTH f2.8 and f4 at 70 then at 200. four shots. BTW the camera does not look THAT level with the surface the batteries are at. check this thread...

https://photography-on-the.net/forum/showthre​ad.php?t=398587

see how my camera was "kind of level with kitchen counter...

try like three boxes with letters on ( cereal, sugar, bounty etc etc)

I forgot about this link...

http://www.pbase.com/i​mage/40706398