How to choose shop camera lenses without being deceived?

When choosing shop camera lenses, it is necessary to make a comprehensive judgment based on shooting needs, camera model, and budget. To avoid being misled, the following points should be noted:
Clear shooting requirements
Priority should be given to using a large aperture fixed focus lens (such as 50mm f/1.8) for portrait photography, taking into account both background blurring and portability; Recommended for landscape photography is the ultra wide angle zoom lens (such as 14-24mm f/2.8), which can accommodate more visual elements.  ‌
Calculate equivalent focal length
Half frame cameras need to convert equivalent focal length:
The conversion factor for Canon APS-C format is 1.6
Sony/Nikon/Fuji, etc. have a 1.5
For example, a 50mm lens has a viewing angle close to 75mm on a half frame, which is closer to the effect of a portrait golden focal length of 85mm.  ‌
Avoid blindly pursuing a large aperture
Fully opening the f/1.4 aperture can easily lead to insufficient in focus sharpness. It is recommended to use f/1.8 for portrait photography to meet most scenes, and for night photography, it can be paired with supplementary lighting equipment instead of blindly pursuing a larger aperture.  ‌
Pay attention to anti shake and focusing performance
Priority should be given to lenses that support anti shake function, especially in telephoto settings (such as 200mm or above) and low light environments, to reduce image shake and blur.  ‌
Refer to professional reviews and user feedback
Pay close attention to technical parameters such as camera stabilization and focusing speed, and choose based on actual shooting experience to avoid relying solely on the concept of "one camera takes the world" promoted by businesses.  ‌