Sony or canon?

[jr_rodriguez]

sgguys:

It's probably because of a lack of image stabilization on the lens (I believe Tamron calls it Vibration Compensation). You may be shooting in low(er) light, and your hands are not steady (nobody's *really* are). There is probably nothing wrong with the lens. Were you shooting in broad daylight, or at night?

[sparkie1263]

The Tamron 70-300 is a good lens as long as you have light. Most of my bird shots are taken with that lens. You need to check your shutter speed and have a steady hand. Like said post some shots and maybe we can give you some help.

Frank

[Peekayoh]

Get an image stablilised Sony. OOps, too late.
You may need to save $500 for an EF 70-300mm f/4-5.6 IS USM Lens.

******* edit*****
Having written the above, I realise it's flippant and less the helpful.

It's much more difficult to steady the camera at longer focal lengths.
You only have to look through the viewfinder with the lens zoomed to 70mm and then 300 mm to see how much more movement there is at 300mm.

Conventional wisdom says that shutter speed should not be less than the reciprocal of the focal length.
That is to say:
100mm focal length - shutter speed not less than 1/100
300mm focal length - shutter speed not less than 1/300

Sony claims that SteadyShot (image stabilisation built into the body) will give you an extra 2 to 4 stops on the shutter. I don't know about 4 stops but 2 to 3 is definitely in range.
What that means is:
100mm focal length - shutter speed not less than 1/25 (maybe 1/10)
300mm focal length - shutter speed not less than 1/80 (maybe 1/40)

That makes a big difference when you're shooting with a slow lens like the 70-300mm.

Canon have in-lens image stabilisation but only in selected lenses and at a higher price point.