Problem with Zoom on Sigma EF 610 DG Super Flash

I just bought a Sigma EF 610 DG Super flash. I am using it with on my Canon EOS T1i with Tamron 18-270 and 28-75 lenses. The flash always shows a incorrect zoom when used with these lenses. When I am at 28 mm, it shows 35. at 70mm on the lens, it shows 105, at 50mm it shows 70.... etc.

Any one else have the same problem? Did I receive a defective flash? . This flash is £240 in UK. So I asked a friend to get it for me from the US for $240. I can't even return it now .

Without going into the technical ... I's say, if the flash is giving even coverage at whatever lens/flash reading regardless of what you see, I'll be happy. But then again, where hotshot flash is concerned, I'm quiet forgiving on the whole.

Since you're using the flash with a 1.6x camera, you can zoom it to 1.6 times your focal length and still get complete coverage. The zoom settings on the flash are based on a 35mm (full frame) field of view.

This is just a guess, but it could be Sigma's way of doing what the Canon flash units have done for a few years now - compensate for the camera format. This is a good thing, because it wastes less light and gives you more range, shorter recycle times and extended battery life.

Thanks for clarifying Curtis. Now I am less worried .

I agree with Curtis. This is normal.