What is the difference between usm and hsm

I've never found myself thinking that any of my HSM lenses were focusing too slowly when using them under normal shooting conditions.

Mark-B msbphoto. I realized my error after I hit send. Here in the east we just had a mild earthquake. I was a little distracted. AF speed doesn't just depend on the type of the motor, but also on how much glass it has to move, and how far.

I am sure the weight of the glass to move, and the travel distance are not identical in the two lenses in question Canon and Sigma I haven't owned the Canon, only the Sigma. For me, it focuses fast enough much better than my previous zoom, Tamron I was dissapointed with HSM at all, specially with the price difference. Both are terrific. Approve the Cookies This website uses cookies to improve your user experience.

By using this site, you agree to our use of cookies and our Privacy Policy. Register to forums Log in. Aug 23, 1. LIKES 0. Just bought a 20D and need a wide angle lens pretty badly but I can't bring myself to buy a too damn big :P This Sigma is quite tempting though if the HSM is half-decent. Both are adequately quiet, with USM bordering on absolutely silent. While both are quick, USM is markedly faster.

And from what I hear, the is only mediocre. The is excellent, even wide open. Basically, you get what you pay for. I have the older version, which doesn't have full-time manual focusing and has the bigger 82mm filter threads. The lens is OK. Mine is a little soft on the right side wide open. Stopped down, it is clear and sharp.

You might want to look at the newer version. The old version that I have has gotten a bad rap here. I believe the newer verison has been improved in a lot of ways. I use this lens mainly for architecture. That said, I will be trading this lens in for the Sigma in a few months. I need the wider angle and straighter lines.

I think it's marketing hooplah. They are both equally fast and quiet. If you truly compare the same kind of lenses you won't notice a difference. Not USM vs.

Hardly noticeable in my opinion. Jamie H. Never argue with an idiot. I find the HSM in my Sigma to focus at one speed - fast and jerky. It is quick - but all at one speed and it jumps around and it does make a little bit of noise doing it My Canon USM lenses focus very fast too, but they seem to focus at varying speeds. They even seem to accelerate and deccelerate to the focus point. Then stop when focus is reached and don't jerk around as much.

The jumping around with the Sigma may be partly the result of the wide angle and large DOF. Don't have any experience with the Sigma , but I have been very pleased with the L -- Good luck and good shooting. Thanks for the comments. Think about a tamron instead. The sigma HSM is not a very good performer. My sample was pathetically soft wide open and when stopped down it was still softer than the cheaper canon USM. Many people have reported the same.

I hear a lot of conflicting reports about the because people get confused about the old and the new DG VincentJ wrote: Think about a tamron instead. Inner focusing old one has a ring at the end of the barrel that moves and makes noise Full-time manual focusing old one you have to flip a switch 77mm filter size old one is a heafty 82mm and filters are expensive Optics 1. Optical image stabilization uses gyroscopic sensors to detect the vibrations of the camera.

The lens adjusts the optical path accordingly, ensuring that any type of motion blur is corrected before the sensor captures the image. The zoom range is the ratio between the longest and shortest focal lengths. A higher zoom range means that the lens is more versatile. At the shorter end of the lens you get the widest angle of view. This allows you to fit more of the scene into the photograph based on APS-C format.

At the longest end of the lens you get the narrowest angle of view. This allows you to fit a small portion of the scene into the photograph, such as when you are zooming in on a subject based on APS-C format. A true macro lens has a magnification of This means that the image produced is a life-size representation of the subject being photographed.

Aperture 1. With a wider aperture the sensor can capture more light, helping to avoid blur by enabling a faster shutter speed. It also provides a shallow depth of field, allowing you to blur the background to focus attention on the subject. Similar to the number of aperture blades, rounded blades affect the way the light gets through to the sensor.

Rounded blades, often only found on more expensive lenses, improve the appearance of the out-of-focus areas. This allows you to attain better, softer looking bokeh in your photos. More blades is often an indicator of a better quality lens.