Do you need to buy a set of GND lenses? Same question, where is the ND mirror?

Gnd gradient mirror is used to solve the problem of large light ratio; Nd reducing mirror is used to solve the problem that the shutter speed cannot be slowed down when the light is strong.

Personally, I don't think it is necessary to buy a set. You can decide which model to buy for each filter according to the light environment you often shoot.

Gnd is which gear to use for calculation. There are soft gradient, hard gradient and inverse gradient, which are all used in different occasions.

The same is true for neodymium mirrors. Which file to buy depends on your usual shooting environment.

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In short, I suggest that you don't have to buy a whole set at once, you can buy it separately according to your own situation, and then you can buy it after you figure out what kind of filter you really need. In addition, cheap filters have problems such as color cast, especially when superimposed. If you use it, buy a few brands, otherwise it will be very troublesome to deal with the color cast in the later stage.