Say the aperture diameter is untouched and the focal length doubled the projected image dims to 25% of its original brightness (2 f-stops). Conversely, if the focal length cut in half, the image brightens 2 f-stops. The Math: 50mm lens 12.5mm aperture = f/4 --- 100mm lens 12.5mm aperture = f/8 --- 25mm 12.5mm aperture = f/2
This 12mm extension tube fits between camera body and the lens, providing a brighter image that the Extension Tube EF 25 II. Compact and portable- a great accessory to take when shooting wildlife. Maintains electronic contact between lens and body. AED 388.50. Out of stock online.
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