What lens do you need to shoot the flat details of clothes?

I'm not sure what you mean by "unclear details". My understanding is that when you want to shoot details, the camera can't focus when it is close to the object. If it's Canon's 50 1.8, its closest focus distance is 0.45m, which means that the lens can't focus when the focal plane is less than 0.45 m away from the object ... The focal plane is the position of your sensor, which means that there is a horizontal line pattern in the middle of the circle next to the viewfinder or flash.

As for the 85mm lens you mentioned, the closest focus distance of 85 1.8 is 0.85m, and that of 85 1.2 is 0.95m, which I think is even less in line with your requirements.

In fact, the effect you want is already in the category of macro photography, and you should also consider the magnification. On the premise of not using special macro lens, there is a simple way to use close-up lens, which can enlarge the magnification and effectively shorten the focusing distance. The disadvantage is that you will lose some image quality. In addition, most close-up rings don't have electronic contacts, which means that you have to focus manually and the aperture will be locked at the maximum (the close-up ring will lose some aperture). If you want to use any aperture, you need to adjust the aperture to the required value first, then unscrew the lens while holding down the preview of depth of field, and then install the close-up circle.

A simpler and more economical way is to take close-ups, but this thing has a great loss of image quality and will distort dark corners. If you specialize in the details of this kind of clothing, a close-up is better.

Finally, the comparison before and after installing the close-up ring is attached. The picture was not taken by myself, but reprinted elsewhere.