1. There are two types of aperture: linked and non linked, which have an effect on metering for some models; If the original leather cavity can be used for aperture linkage, but the price is too high; 2. For AF body and AF lens, when the magnification is relatively high, due to insufficient light intake, even with AF mission mechanism, AF is often sluggish and ineffective; 3. When focusing, if the magnification is determined, coarse focusing can be achieved by moving the body, and fine adjustment can be made to the focusing ring; When focusing, the aperture should be fully opened, and when , the aperture should be manually adjusted; 4. The magnification can be adjusted to achieve a ratio of 1:1 or higher; Adjustable within a certain range; 5. There is a significant field curvature phenomenon when using a large aperture, and the effect of shrinking the aperture is not very obvious; If there is no metering, exposure compensation should be applied, and the compensation coefficient should be calculated according to (1+M) 2; The imaging quality is only related to the lens. For FX lens or body Cameras Telescopic size (mm): 20~140mm Focusing method: built-in ruler on the moving track Other features: remake stand jack, 1/4inch tripod hole Volume (mm) : WxHxL 70 x 110 x 160 Weight (g) : about 224.9g Specifications: A: Compatible with for F-mount Color: Black Material: Plastic+Aluminum Alloy Package Contents: 1 * Macro lens adapter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.