Why did sony omit oss image stability on this lens? with oss the speed can be reduced on a kit lenses to accomplish 20mm @ f2.8.

I think you may be misunderstanding the benefits of OSS on a wide-angle prime lens. The wider the angle, the less the effect of camera shake on the image. OSS (and other stabilizing hardware/software) are most beneficial for long and/or zoom lenses. So, in other words, adding the cost, size, weight and complexity of the OSS hardware to the 20mm lens is not needed and thus adding it would far outweigh any advantages. I've taken hundreds of pictures with my 20mm (and the two adapters which make its field of view even wider) in all kinds of lighting (bright to dim) and I've never had reason to worry about camera shake. There's a technical reason why which I'll try to explain below. I have to ask...do you own a Sony camera that uses E-mount lenses? Do you own this lens? Have you ever taken photos with it? And finally, why do you ask the question? Your comment that "with oss the speed can be reduced on a kit lenses to accomplish 20mm @ f2.8" really makes no sense at all. The 20mm is not a "kit lens" and reducing the shutter speed (longer exposure) does not "accomplish" an aperture of f2.8. The bigger the aperture, the more the shutter speed can be increased (for a shorter exposure to allow the same amount of light to reach the sensor). I'm pointing out all this information because I felt the need to illustrate that your original question, and BoJo's answer, are both misleading. I hope the time I've taken to make these comments is useful to you or someone else. The SEL-20F28 is a fine prime wide-angle lens and due to that wide angle, it doesn't need OSS. There was no "omission" of a feature due to cost; there was no need for the feature. Perhaps that's the simplest answer to your question.If you look at the full line of Sony E-mount lenses, you'll see that the OSS feature is not included in the two primes below 30mm (the SEL-20F2.8 and the macro lens SEL-30M35); above that prime range and in ALL zoom lenses (which have much longer reach and narrower field of view the OSS feature is included. For example, in the prime lenses, the SEL-50F18 and SEL-35F1.8 have OSS, All the zoom lenses (e.g., SEL-18105GPZ, the SEL-1650PZ the kit lens, the SEL-55-210, etc.) have OSS because the longer the lens (i.e.., the narrower the field of view and the more magnification, the more camera shake becomes an issue). The issue is whether a lens needs the OSS at its focal range, not whether Sony decided to save money (i.e., make the lens cost less to buy--which does not necessarily equate to saving money for the manufacturer). I hope this extra bit of technical explanation helps. By the way, I think the ideas in the answer you got from "BoJo" to your question are both true and misleading because they omit the issue of field of view and its effect on camera shake. In other words, the comments are not "educated" in the sense of understanding photographic concepts and technology. BoJo's comments all relate to cost, profit margins and referring to competing camera models/makes that incorporate an anti-shake feature into the camera bodies (perhaps like Sony's Alpha line that are not "mirrorless" such as the A58 and A77II). In the "mirrorless" line of Sony Alpha cameras (with the exception of the new, bigger Full Frame A7II line) there's no room for OSS hardware in the camera body (hence the addition of OSS to the lenses), There's really no need to "ask Sony" this question; you just need to know something about lens technology that applies to all lenses regardless of their manufacturer.BoJo remarks that "(in-camera stabilization is) one of the clever advantages that camera makers who incorporate OSS into their camera bodies." That's true (and why the FE A7II line now has in-camera OSS), but the issue of the necessary increase in size of the camera body was not mentioned by BoJo. As another example, the Nikon 1 line of mirrorless cameras (a really small line of cameras with a 1-inch sensor) also use in-lens stabilization (Nikon calls it "VR" for vibration reduction) for exactly the reason I've explained...adding stabilization to the camera body makes the body much bigger, more expensive and more complex. Good luck.

What's the equivalent focus length in APS-C frame?

Sony NEX/alpha cameras are 1.5x crop factor so you multiply 20mm x 1.5 factor to get a 30mm full frame (35mm film) equivalent lens which is a medium wife angle lens. Good for general street photography.

SEL-20F28 E-Mount 20mm F2.8 Prime Fixed Lens

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