ETX 90 has a built-in flip mirror, which allows you to attach a DSLR camera whenever you want to the optical tube. The problem is, the mount is not an “Equatorial” version, which means you can forget about long-exposure imaging. Deep space astrophotography is impossible with this telescope.
Planetary imaging abilities are better than nothing, and Terrestrial imaging is definitely better than anything that is not attached to a telescope.
Overall, the mount is not designed for astrophotography; therefore, you are limited to short-exposure, 30-40 second images.