The reducer shortens the focal length of the telescope and is therefore also called a focal reducer. This makes the optics "faster" for photography and the image brighter. It also increases the field of view.
Since a stronger signal is captured in the same exposure time with a reducer, you can expect a higher signal-to-noise ratio and thus better detail in your images.
The reducer is very complex in design, as it contains four elements in four groups, including two ED lenses. By increasing the lens diameter, it offers significantly better image illumination compared to the previous smaller V0.79x reducer, and distortion of the stars at the edge is reduced to an absolute minimum.
The focal length of the VSD90ss telescope is shortened by about 0.71x and the aperture ratio is reduced from 5.5 to 3.9. This gives you a super-fast f3.9 astrograph that also fully illuminates a full-frame DSLR camera.
