How to eliminate cross black phenomenon in subtractive lens photography?

The adjustable pressure reducer also has the most serious problem, that is, the "cross pattern".

The so-called cross-shaped mirror means that when the adjustable antireflection mirror is selected at a higher level and used with a short focal length lens, the following effects are likely to appear:

These two puzzling cross dark fields are cross stripes. Even if there is no cross pattern, there will be obvious uneven dimming phenomenon.

This is a common problem of all adjustable reducers, which has nothing to do with high-end and low-end. Even high-end adjustable reducers can only "alleviate" but not "eliminate" this drawback.

Of course, you can also use a lower-grade lens or a lens with a longer focal length to eliminate the cross pattern and reduce the dark field effect.