Tamron 28-75 f/2.8 Lens Autofocus problems

Hello Everyone,

I have a Tamron 28-75 f/2.8 lens for almost an year now. For the past few months, I have been observing that the camera is not able to focus on the subject correctly (I haven't paid much attention to the autofocus before. I thought it is normal for the camera/lens not to pick the right auto focus point). I use a T1i/500D. I see randomly some of the AF points glow on the view finder, but it does't always be on the subject. I am mostly using this for shooting my 1 year old son. Most of the times I see the focus is at the wrong places and not on his face even though I make sure that his face is in the center of the frame and closest to the camera. I use evaluative metering.

Can someone with this lens comment on the problem I am facing? Is this normal not to get autofocus on the right point? I don't remember having this problem with my canon 18-55 IS.

I would use a single focus point. Letting the camera decide leads to the type of problems you are experiencing.

Hard to be certain, but this does not sound like a lens problem. The lens does not choose the focus point--either your or the camera does. If the lens were malfunctioning, it would not focus properly on the selected point. If you leave all points on, the camera will select one, based in part on where it finds high contrast. I agree with the advice to use the center point only for photographs of this sort. I almost always do that when shooting pictures of people. If you have aperture open wide (small f-stop #), with narrow DOF, it is best to aim that point at the area for which focus is most essential, usually the eyes. You can then either recompose or crop if necessary. (BTW, a Tamron 28-75 is my default lens for candids of people unless they are too far away.)

paddler4 wrote in post #12521346
You can then either recompose or crop if necessary. (

Cropping is the best option. Focusing and recomposing with wide apertures can be problematic.

SAPSTAR wrote in post #12520996
I see randomly some of the AF points glow on the view finder, but it does't always be on the subject. I am mostly using this for shooting my 1 year old son. Most of the times I see the focus is at the wrong places and not on his face even though I make sure that his face is in the center of the frame and closest to the camera. I use evaluative metering.

.

Sound like you are in AUTO shooting mode? If yes, try one of the other modes, such as Av, P, etc. You can even use the Portrait mode and make sure that the red AF point on the face flashes in red. Read Page 50 of your 550D manual.

When the camera is set to use all focus points there is no way for the camera to know what you want it to focus on so it guesses and is almost always wrong. Using one focus point is the only way to go.

SAPSTAR wrote in post #12520996
Hello Everyone,

I have a Tamron 28-75 f/2.8 lens for almost an year now. For the past few months, I have been observing that the camera is not able to focus on the subject correctly (I haven't paid much attention to the autofocus before. I thought it is normal for the camera/lens not to pick the right auto focus point). I use a T1i/500D. I see randomly some of the AF points glow on the view finder, but it does't always be on the subject. I am mostly using this for shooting my 1 year old son. Most of the times I see the focus is at the wrong places and not on his face even though I make sure that his face is in the center of the frame and closest to the camera. I use evaluative metering.

Can someone with this lens comment on the problem I am facing? Is this normal not to get autofocus on the right point? I don't remember having this problem with my canon 18-55 IS.

Switch to AV if you have enough of natural light. Select AF point which is close to eye if at F4 and higher.
Switch to M if you are using flash, something like 1/200 ISO200 F4 works most of the times. Use same method.

If I'm using 2.8 I'll manually focus on person's eye.

Thanks everyone for all the suggestions. I was worried that the lens is malfunctioning. Also I placed an order for one more Tamron lens 18-270 last night. So more worried about any problems particularly with all Tamrons...

I always shoot manual and most of the time wide open. I always end up selecting focus points manually to focus only one point or do manual focus... but thought the camera/lens should be able to do this more accurately. If I have to shoot a series of pictures of anything moving, it will be quite impossible if the camera/lens don't keep up with autofocus.

I think I will have to stick to just having the center focus point selected from now on... or use manual.

SAPSTAR wrote in post #12522793
Thanks everyone for all the suggestions. I was worried that the lens is malfunctioning. Also I placed an order for one more Tamron lens 18-270 last night. So more worried about any problems particularly with all Tamrons...

I always shoot manual and most of the time wide open. I always end up selecting focus points manually to focus only one point or do manual focus... but thought the camera/lens should be able to do this more accurately. If I have to shoot a series of pictures of anything moving, it will be quite impossible if the camera/lens don't keep up with autofocus.

I think I will have to stick to just having the center focus point selected from now on... or use manual.

The camera does keep up with a moving object and AF point, when you choose teh sport mode and use center focus point and track the moving object with that point.

shankarhokie wrote in post #12522895
The camera does keep up with a moving object and AF point, when you choose teh sport mode and use center focus point and track the moving object with that point.

Thanks very much for the tip Shankar. I never had to shoot fast moving objects yet, as my son is still crawling . Will be useful very shortly.

I tried some more shots tonight and tried comparing my Canon 18-55 and Tamron 28-75, Now feel a bit comfortable that it is not a lens issue. But using the center focus point only, seems to be the working solution for me right now. If not, manual focus.

Even with a 2.8 lens, that gives you a narrow DOF, particularly when you are in the long end of the rnage. (Check it out for a few distances and focal lengths using a DOF calculator.) While some people like the effect that creates, it also requires very precise focusing, and in some cases, it won't even give you a kid's whole head in focus. And kids move around a lot, which makes it even trickier. For indoor candids of kids, I usually start with something like f/4.5. Just a thought.

paddler4 wrote in post #12524470
Even with a 2.8 lens, that gives you a narrow DOF, particularly when you are in the long end of the rnage. (Check it out for a few distances and focal lengths using a DOF calculator.) While some people like the effect that creates, it also requires very precise focusing, and in some cases, it won't even give you a kid's whole head in focus. And kids move around a lot, which makes it even trickier. For indoor candids of kids, I usually start with something like f/4.5. Just a thought.

I am shooting from a very close distance and most of the time near the 28mm setting. Most of the times I was getting the whole face in focus. Occasionally I noticed that part of the face was faded.

As you mentioned I googled for DOF calculator and found the below link. I will need to spend some time understanding the calculations and correlating them with my photos .
http://www.dofmaster.c​om/dofjs.html

SAPSTAR wrote in post #12528220
I am shooting from a very close distance and most of the time near the 28mm setting. Most of the times I was getting the whole face in focus. Occasionally I noticed that part of the face was faded.

As you mentioned I googled for DOF calculator and found the below link. I will need to spend some time understanding the calculations and correlating them with my photos .
http://www.dofmaster.c​om/dofjs.html

YOu may also want to red the review here

http://www.slrgear.com …uct.php/product​/49/cat/23

Click on the blur index and you can see the edge blur at F2.8. You can see that at F4, that blur all but goes away.