Tamron 70-200 F/2.8 lens: What am I doing wrong?

krs · 05-21-2009, 07:47 PM

Not too long ago, I purchased a Tamron 70-200 F/2.8 lens, partly to use at Tae Kwon Do competitions (indoor, low light).

It seems that I am getting a number of pictures turning out like the following:

I am not having this problem with other lenses, like the 50mm F/1.4, or my Sigma 28-70 F/2.8.

I did a focus test (link below) which looks like the lens is focusing correctly...

Thoughts?

Jewelltrail · 05-21-2009, 07:51 PM

Well, the first thing you are doing wrong, is there are no pics showing here--at least I can't see them.

krs · 05-21-2009, 07:55 PM

Sorry - link challenged - should be there now...

*Oldschool* · 05-21-2009, 08:03 PM

Try again.

vizjerei · 05-21-2009, 08:09 PM

Did you select your AF point to upper points instead of using centre point?...

krs · 05-21-2009, 08:20 PM

AF-C (Continuous), Center Point. What is "upper points"?

krs · 05-22-2009, 11:11 AM

Additional insight would be appreciated. I hope this is not a back focus issue (chart test does not indicate that)....

netuser · 05-22-2009, 11:36 AM

Can't see image number one.

*deadwolfbones* · 05-22-2009, 11:46 AM

If it's focusing properly in focus tests, you're likely simply missing focus in the heat of the moment. At f/2.8 the DOF is quite narrow and it's easy to do.

*farfisa* · 05-22-2009, 12:00 PM

The focus sensors are pretty big on the camera, and they love stark horizontal lines (which is why they're always on focus charts)--there are plenty of them in that picture: the line between the mat and the floor, the dark black lines made by the bleachers, etc.

Any possibility you were in AUTO AF point select mode?

AF-C can look around for lost of things. I usually use AF-S, then just keep putting my finger on and off the shutter button until I get the lock I want.

Then again, I miss a lot of shots too!

krs · 05-22-2009, 12:29 PM

Originally Posted by deadwolfbones

If it's focusing properly in focus tests, you're likely simply missing focus in the heat of the moment. At f/2.8 the DOF is quite narrow and it's easy to do.

I have thought about that too, but it was a number of shots, many of which are like the sample picture, and with AF-C, you would think more would come out with reasonable focus?

krs · 05-22-2009, 12:31 PM

Originally Posted by deadwolfbones

If it's focusing properly in focus tests, you're likely simply missing focus in the heat of the moment. At f/2.8 the DOF is quite narrow and it's easy to do.

Originally Posted by farfisa

The focus sensors are pretty big on the camera, and they love stark horizontal lines (which is why they're always on focus charts)--there are plenty of them in that picture: the line between the mat and the floor, the dark black lines made by the bleachers, etc.

Any possibility you were in AUTO AF point select mode?

AF-C can look around for lost of things. I usually use AF-S, then just keep putting my finger on and off the shutter button until I get the lock I want.

Then again, I miss a lot of shots too!

I was definitely on AF - C center focus - picture information supports that...

Your comment about the focus sensors being big, andother things that might have been picked up makes sense.

I have wondered if sometimes I would be better off with manual focus!

What is odd, is as indicated, other lenses like the 50 mm F/1.4, do not give me this problem - even at the same event! Makes me wonder if the lens is playing a role here!

**Marc Sabatella** · 05-22-2009, 04:54 PM

I think it's pure dumb luck as to why you happened to get lucky and achieve focus on your trget with one lens but not with another - it's a situation where it's going to be essentially random what the camera chooses to focus on.

FWIW, in situations like that, I do think MF is often more efficient.

*pbo* · 05-25-2009, 01:35 AM

Hey, just a thought - a 50mm is much wider than a 200mm, and it has a much greater depth of field - even if you misfocus a bit, the kid will still be in focus.

I think smart things for you to do are:
1) mount your camera vertically (portrait) instead of horizontally (landscape) - that is, if you can zoom in more on the kid; this will not only fill the frame with the main kid, but also make him draw more attention in the picture.
2) set AF point away from the center - my favorite is the point below center - so it's either the one right below center if you are shooting horizontal, or the one left from center, if you are shooting vertical. This way, you can focus on the floor under the kid, which is static. Your lens will hunt much less that way, too. One of the reasons you got a blurry shot might be, you clicked the shutter while the lens was still focused on the floor behind him - and hasn't yet recomposed. Or you cropped the picture and tricked us all

By the way, Picasa behaves real weird on this forum, flickr seems to work much better.