ynot said:here's a lens review
http://www.the-digital-picture.com/Reviews/Canon-EF-70-300mm-f-4.5-5.6-DO-IS-USM-Lens-Review.aspx
"The Canon EF 70-300mm f/4.5-5.6 DO IS USM Lens is not a fast lens to begin with, but stopping down to f/8 or so makes it very slow. Image Stabilization helps greatly, but not if you want to stop non-panning action. "
hope it helps
n0d3 said:I don't think its the "true" ring type USM, should be the inferior micro USM.
I dont think it his version of the lens.:think: coz this one has the Ring-USM.I think what the author meant with his 'very slow' is the apperture, and not focussing speed.ynot said:here's a lens review
http://www.the-digital-picture.com/Reviews/Canon-EF-70-300mm-f-4.5-5.6-DO-IS-USM-Lens-Review.aspx
"The Canon EF 70-300mm f/4.5-5.6 DO IS USM Lens is not a fast lens to begin with, but stopping down to f/8 or so makes it very slow. Image Stabilization helps greatly, but not if you want to stop non-panning action. "
hope it helps
wong1979 said:I think true ring or false ring, as long as is USM, ultra sonic, should be ultra focussing speed right? And not take 1.5 second to focus from 1 end to another?
wong1979 said:Hi, I have just gotten a 70-300 lens. From the 70mm, and tried to zoom on a contrasty object, quite ok. But once I up to 300mm, it keeps on focussing. Is this normal?
TIA, wong
benedium said:Do you mean the focussing is slow as in it 'hunts' back and forth, or u mean it moves really slow like a toy car with weak batteries? You may want to take it to the shop to test another copy of the same lens. If shop don't let you change then worst case, bring to canon for checking/servicing.
n0d3 said:Only the true ring type USM will give you that silent/fast focusing speed.
But, Ring USM (Ultrasonic Motor) is not part of the package. Improvements in the CPU and AF routines help in the focus performance increase according to Canon. Accuracy is often more important than speed. Good thing as actual performance of the Micro USM shows accuracy to be very good but speed is just OK - not as good as I had hoped.