What is the focal length multiplier for the Tamron 18-270 mm Di-II PZD VC lens on a Canon XSi digital camera?

Does live view work with other lenses? if so you may just have a dirty or faulty connection re the Tamron 70-200.

I know this is a shot in the dark, but have you cleaned the afore-mentioned contacts, both on the lens and the camera, using s clean dry lint-free cloth ?

A 35-80 mm lens is 2.3X zoom. Divide 80 by 35 and you'll get the result.

It is usually better to know what the focal length of a lens in "35 mm equivalent" is and judge by that, rather than relying on the "X" power of the lens. For instance, most point and shoot cameras start at about 35 mm and have either a 3X or 4X zoom. This would make it a 35-105 or a 35-140. I've seen some that start at 28 mm, though. A 3X starting at 28 mm is 28-84 and a 4X is 28-112. Neither one is a particularly strong telephoto lens and the 4X is just about the same as the 3X that starts out at 35 mm.

It's also important to realize that tradition dictates that lens focal lengths are usually expressed in terms of "35 mm equivalent," where "35 mm" refers to a 35 mm film camera. This is because of the relation between the sensor size and the actual focal length of the lens and the resultant angle of view of the lens.

I have one point & shoot that is actually a 5.8-24 mm zoom. This is a 4X zoom. The 35 mm equivalent is 28-116 mm. The sensor is 7.2x5.3 mm. (1/1.8") (And I wish I knew someone who could explain how the heck they came up with sensor size terminology!)

I have another point & shoot that is actually a 5.7-17.1 mm zoom. This is a 3X zoom. The 35 mm equivalent is 34-102 mm. "How could a shorter focal length give a longer 35 mm equivalent?" you might ask. It's because the sensor is only about 5x4 mm. (1/2.5")

I have a few Nikon DSLR's and - thankfully - they all have the same size sensor. They all have a "lens factor" of 1.5. This means that you just multiply the actual focal length of the lens to get the 35 mm equivalent and then you can make comparisons accurately from camera-to-camera. Most Canon's, for instance, have a lens factor of 1.6. On a Nikon DSLR, a 28 mm lens is the "35 mm equivalent" of a 42 mm lens. On most Canon DSLR's, the same 28 mm lens is the equivalent of a 45 mm lens.

These example are just to show you how freaking confusing it can all become if you try to make sense of the "X" power of a zoom lens.

Bottom line...

Check the 35 mm equivalent specifications for the lens. This way, you will be leveling the field and comparing apples to apples. More or less.

So, have you cleaned the contacts as you were advised? You do this by removing the lens and cleaning the contacts on the camera body and on the lens where they meet with a cotton swab lightly dampened with rubbing alcohol.

hi, clean the camera contacts also , change the firm ware of the lens , hope this helps

Error 01 means that communication between camera and lens is faulty. Try to clean lens contacts.

If it has the correct Canon mount then it will fit, but is still unsuitable.

The lens is designed for APS-C sized sensors, so the image it produces will not be big enough for the full-frame sensor on the EOS 5D. If you use it then there will be unacceptable vignetting in the corners of the images.

The angle of view of the lens will also be different to what you may expect: although it is an 18-270mm focal length it will have the same angle of view as a 28-420mm on a 35mm full frame equivalent camera.

I hope that my posting has helped you and only ask in return that you take a moment to rate my answer.

All canon EF and EF-S lenses work with 500D /T1i model.(yes all)
If your lens is removed from old 500N body and if it has EF marked it will work for every Digital camera model of canon.
Note: its focal length will be multiplied by 1.6 X factor.
(mean 18 mm lens will become 29mm approx.)
If you find this of help rate me.

Nothing you can do. The Tamron is not compatable with your camera. So the focus will be slower

Many zoom lenses of this length, and even shorter have the problem whereby the lens either extends or retracts under its own weight depending on whether the camera is pointing up or down. I had a Canon 28-105mm lens with this problem. More expensive lenses have zoom locks to prevent this from happening. $225 sound like a good price to me!