Sony FE 2x Teleconverter (SEL20TC)

These teleconverters are designed to work with compatible Sony lenses to extend their focal length range while maintaining optical quality to a reasonable degree. Let’s delve into the general features and functionality of a typical FE 2x teleconverter:

1. Focal Length Extension: A 2x teleconverter doubles the effective focal length of the lens it’s attached to. For example, if you attach a 2x teleconverter to a 100mm lens, it effectively becomes a 200mm lens.
2. Compatibility: Teleconverters are typically designed to work with specific lenses. In Sony’s case, the FE 2x Teleconverter is designed to be compatible with a range of Sony FE lenses, including telephoto primes and zooms.
3. Optical Quality: While teleconverters extend the reach of a lens, they also introduce additional optical elements into the light path, which can impact image quality. High-quality teleconverters, like those produced by Sony, aim to minimize any degradation in image quality, but some loss of sharpness, contrast, and maximum aperture is common, particularly with a 2x teleconverter.
4. Autofocus Performance: Teleconverters can affect autofocus performance to varying degrees depending on the lens they’re paired with and the camera’s autofocus system. Some combinations may experience slower autofocus or reduced accuracy, particularly in low-light conditions or with subjects that lack contrast.
5. Aperture Adjustment: When using a teleconverter, the effective maximum aperture of the lens is reduced. For example, a lens with a maximum aperture of f/2.8 may become effectively f/5.6 with a 2x teleconverter attached. This reduction in aperture affects both exposure and depth of field.
6. Physical Design: Teleconverters are typically designed to be compact and lightweight, allowing for easy attachment and removal from the lens. They usually feature weather sealing to protect against dust and moisture, ensuring durability in various shooting conditions.
7. Limitations: While teleconverters are useful for extending focal lengths, they also have limitations. They may not be compatible with all lenses, particularly those with large front elements or certain optical designs. Additionally, using a teleconverter can amplify any existing optical flaws in the lens.

Overall, a 2x teleconverter like the Sony FE 2x Teleconverter (SEL20TC) can be a valuable accessory for photographers looking to extend the reach of their lenses without the need to invest in additional, longer focal length lenses. However, it’s essential to understand the potential trade-offs in image quality, autofocus performance, and maximum aperture when using a teleconverter.