Tamron 28-300mm Autofocus issues... 20D

Started Jul 19, 2005 | Discussions thread
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TobyG Regular Member • Posts: 142
Tamron 28-300mm Autofocus issues... 20D

I recently purchased a 20d and bought this lense. The only other lense I have besides the kit lense is the 50mm 1.8.

Well for the past week I thought I was having autofocus issues with the 20d that so many other people claim. I went back to best buy and swapped it for a new camera, sure it was a problem with the camera. Well, it doesn't appear that it was the camera as it does the same thing on my new camera. Almost every picture at 300mm are out of focus. Been reading a lot, finding out that autofocus may not function any smaller than 5.6.

I found some posts saying the lense will lie to the camera and tell the camera that it's a 5.6, even at 300mm. This doesn't seem to be true on the 20D. The 20D states it's 6.3. And the camera does still attempt to autofocus even with the lense at 6.3...

So I borrowed a friends 300D. Same thing, 6.3. Same focus issues.

Oh and I read all the issues about the autofocus, using the center point only and so on. That doesn't help. Same issues. So I took a different approach and turned on all autofocus points on both cameras. I then checked the pictures (just took many random pictures around my room) in EOS Viewer and checked the focus points the camera picked and checked if the photos were in focus in the area they said they focused on. They were not. At least half were out of focus. I tried the lense again on both cameras but this time just short of 200mm, right at F5.6 (before it flips to F6.3). Much better! But, this is not an option for me. This lense has got to go back I think.

Anyone else have similar issues?

Oh and because of all of the issues I was having, I decided to pick up a used D60 off eBay last night. Picked it up today and was playing with it. Great camera, at ISO 400 and below. But anyway, with the Tamron 28-300mm mounted on the D60, it DOES tell the camera f5.6 even at 300mm. The D60 seems to autofocus much better with this lense than the 300d or the 20d.

It's a shame. The lense actually takes pretty good pictures. But I can't use the lense and keep myself to F5.6 or under by not zooming all of the way. That would be too hard to manage. I ordered the 28-135 IS and then I'll pick up the 70-200mm F4 or something for my zoom.

also... (sorry, been playing with this for the past week or so)...

I did borrow my friends 28-135 IS lense and it autofocuses just fine on all 3 cameras. The 50mm seems to have a bit of front focus so I wasn't using that as much in my testing, since it's been somewhat unreliable for me.

Anyone else using this Tamron 28-300mm F3.5-6.3 on their 20D?

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