Teleconverter is an extreme example, tripling the focal length of any lens over 50mm. The tube manages the massive 3x magnification through a series of built-in optics, and includes all the electronics required to keep your camera’s aperture and metering features working properly. Autofocus is not generally supported due to the 3 stops loss of light, athough it does autofocus with lenses that have a maximum aperture of f/2.8 or faster. Don’t expect miracles though – it’s very sluggish, making it difficult to capture the high-speed sports or active wildlife that it brings you so close to.
Once fitted, the difference through the viewfinder is immediately apparent, with a 75-300mm lens instantly becoming 225-900mm. As a side effect of this extreme extension, though, less light travels through the lens – ultimately increasing exposure times and making the image look darker through the viewfinder than you would expect.
Longer shutter speeds make a tripod essential, and when it comes to image quality, you need to be realistic. While you’re getting longer focal lengths at a budget price, less detail is captured and there’s noticeable grain. Images tend to look dull and grey unless they’re properly compensated for. But so long as you’re aware of these downsides, this teleconverter is a much cheaper alternative to buying an extra lens.