The end user can download the updated firmware from the manufacturer and then use the USB dock to install it on their lens. All of the Sigma Global Vision lenses, including the 18-35mm f/1.8, are compatible with the very affordable Sigma dock. One thing that has made this risk more acceptable is the development of USB docks that allow the end user to update the lens' firmware themselves without needed to send to the lens off to a factory service center. In the past this meant the hassle (and cost) of shipping the lens back to the maker or an authorized service center to have the updated firmware installed in the lens. They usually will modify the lens at no charge, at least until the lens has been discontinued for a while. Companies such as Sigma and Tamron will often release an updated firmware for the lens(es) in question to resolve the issue. This is because third party lenses are reverse engineered and then tested with existing bodies available at the time they are developed. The reason we still use PDAF many times is because it is fast, it works with a TTL optical viewfinder, and usually it gets 'close enough' for most purposes.Īnytime you buy a 'third party' lens, you risk incompatibilities with newer camera models released after the lens was made. So will careful manual focusing using magnified Live View. A well implemented contrast detection autofocus (CDAF) system will almost always be more accurate. Again, the variations will probably be greater on different lens models, but there will be some variation between different copies of the same lens model.īut here's the thing about phase detection autofocus (PDAF): no matter what camera body and what lens you have mounted on it PDAF is never 'perfect'. Different lenses will perform differently on the same exact camera. The variations will probably be greater on different models, but there will be some variation between different copies of the same model. The same exact lens will perform differently on different camera bodies. The question really is, "How well will it AF with your camera?" By all accounts it will AF with your camera. ![]() By all accounts it will communicate with your camera regarding the electronically controlled aperture. In fact, there is no other zoom lens in any focal length range with a maximum aperture larger than f/2.8 offered in the Canon EF mount. That is, there is no other zoom lens in that focal length range with a maximum aperture larger than f/2.8 that is offered in the Canon EF mount. ![]() There's no other lens comparable to the Sigma 18-35mm f/1.8 Art currently on the market.
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