Yes, the Sigma 30mm f/1.4 lens can focus to infinity. This means that it can focus on objects that are at a great distance, allowing for sharp and clear images of faraway subjects. The ability to focus to infinity is important for landscape, astrophotography, and other types of photography where distant subjects are the main focus. **

The Sigma 30mm f/1.4 DC DN is a prime lens designed for mirrorless cameras with APS-C or Micro Four Thirds sensors. It has a fast maximum aperture of f/1.4, allowing for excellent low-light performance and shallow depth of field. The lens is compact and lightweight, making it a great choice for street photography, portraits, and everyday use. It also features a stepping motor for smooth and quiet autofocus, making it suitable for both photo and video applications. **

The main difference between the Sigma 30mm 1.4 DC HSM and the Sigma 30mm 1.4 DC HSM Art is that the Art version is part of Sigma's high-end Art series, known for its superior optical performance and build quality. The Art lens typically features better image quality, sharper details, and improved color rendition compared to the non-Art version. Additionally, the Art series lenses often have a more robust construction and enhanced features, making them a preferred choice for professional photographers or enthusiasts looking for top-notch performance. **

AF-S (Autofocus Single) mode is used for still subjects, where the camera focuses once and then locks the focus until the shutter button is released. AF-F (Autofocus Flexible) mode is used for moving subjects, where the camera continuously adjusts focus as the subject moves. Pre-AF is a feature that allows the camera to continuously focus on a subject even when the shutter button is not pressed halfway, which can help reduce the time it takes to focus when the shutter button is pressed. **

To use the Sigma 30mm f/1.4 DC HSM Art lens on the EOS 650D, you will need to ensure that the lens is compatible with the Canon EF mount. You can attach the lens to the camera body by aligning the red dot on the lens with the red dot on the camera mount and then twisting the lens clockwise until it locks into place. Once the lens is securely attached, you can start shooting with your EOS 650D using the Sigma 30mm f/1.4 DC HSM Art lens. **

The choice between the Sigma 18-35mm f/1.8 and the Sigma 24mm f/1.4 depends on your specific needs and shooting style. If you require a versatile zoom range and the flexibility to shoot at different focal lengths, the 18-35mm f/1.8 would be a better option. On the other hand, if you prefer a wider aperture for better low-light performance and more background blur, the 24mm f/1.4 would be a great choice. Consider your shooting preferences and the type of photography you do to make the best decision for your needs. **

No, the Sigma 30mm 1.4 DC lens is designed specifically for use with APS-C sensor cameras, not full-frame cameras. Using this lens on a full-frame camera may result in vignetting and image quality issues, as the lens does not cover the entire sensor area of a full-frame camera. It is important to use lenses that are compatible with the specific sensor size of your camera to ensure optimal performance and image quality. **

Yes, the Sigma 16mm f/1.4 is known for its fast and accurate autofocus performance. It has a high-speed autofocus motor that allows for quick and precise focusing, making it ideal for capturing fast-moving subjects or shooting in low-light conditions. Overall, users have reported that the focus performance of this lens is excellent, resulting in sharp and clear images. **