Sigma apo what does it mean

Reading mode: Light Dark. Login Register. Best cameras and lenses. Brand index Sigma Sigma Lenses. Add this product to your shortlist for comparison. User reviews. See all user reviews. Gear list. Product description. Discuss in the Third Party Lens Talk forum. Product timeline. Sigma When this window is wide open, something changes in the depth of field… it gets more shallow. Depth of field is how much of your image is in focus. A deep depth of field indicates that both the foreground, subject, and background are in focus and not blurred.

A shallow depth of field is when just the subject is in focus and everything else blurs away. On a lens, aperture is denoted with an F-stop really just another name for aperture.

This may also be denoted by an If you look at a lens, the number that follows the F tells you the widest point that the aperture can go. Although it may seem counterintuitive, the smaller the number following the F, the wider the aperture!

Name Variations: mm F When there are two apertures given, this is a variable-aperture zoom lens showing the maximum aperture at the widest and longest focal lengths. That funky symbol denotes the filter thread. A filter thread expresses the diameter of the front lens element so that you can add, well, a filter to it! Filters are additional panes of glass that you screw or attach on to the front of your lens. However, there are also filters that serve a purpose other than protection, such as Neutral Density filters and Polarizing filters.

If a lens does not offer a filter thread radius, is genereally does not accept front filters. The frame size on a lens tells you what kind of camera the lens was intended for. And DN denotes mirrorless camera format. Lenses are made to fit the sensors they are designed for. Because a crop camera sensor is smaller than a full frame sensor, crop cameras have a smaller area to capture a scene.

With a crop sensor, the angle of view is narrower. Crop specific lenses are made to be perfectly compatible with these sensors, so what you see is what you get. This is true for full frame lenses that are intended for a full frame sensor, what you see with a full frame lens on a full frame sensor is what you get.

Crop sensor cameras are able to utilize both crop lenses and full frame lenses. You see, the lens will reduce in the angle of viewing but still be very effective. Here is an example to explain what I am talking about:. Say you are using a mm full frame lens on a crop size sensor camera. The mm lens you now put on will give you an image equivalent to mm 1. See how it all works here. Lens abbreviations are very important. They tell you what your lens can do.

Since so many lenses have many features, it is beneficial to have them all there, giving you the information you need. This stops you from having to go through lens or camera manuals to find out what you can achieve from each scene. These tell us that the lens is of a professional standard, is designed for an APS-C camera and has optical image stabilization. On top of these, it tells us that the lens has a hypersonic motor while employing a fluorite low dispersion lens element.

A — Art. These lenses place its importance on optical performance and power. Expect these to have very wide apertures across fisheye , wide-angle, zoom and macro lenses. APO — Apochromatic. These lens elements reduce chromatic and other aberrations.

They also bring a stronger contrast, color definition, and sharpness to the image. ASP — Aspherical. These lens elements are shaped in a way to reduce aspherical aberrations. C — Contemporary. These lenses feature variable apertures along its zoom focal lengths. These are what you would expect from budget lenses designed for APS-C camera models.

CONV — Teleconverter compatible. These allow for a longer focal length while allowing the user to retain Automatic Exposure. They will not work on full-frame camera models.