Is the Canon EOS 850D / Rebel T8i good for beginners?

Yes. It has guided menus, a vari-angle touchscreen and a bright optical viewfinder, and the 45-point autofocus is forgiving for new shooters. It is a solid step up from an entry Rebel without a steep learning curve.

Does the 850D shoot uncropped 4K video?

No. 4K UHD is cropped to roughly the center of the sensor and uses contrast-detect autofocus, so it is better for static or manually focused shots. Full HD uses Dual Pixel autofocus and is the easier choice for handheld video.

How does it compare with the EOS 90D?

The 90D has a higher-resolution 32.5MP sensor, faster 10 fps shooting and uncropped 4K, but it is larger and more expensive. The 850D is lighter and simpler, and both share the EF mount and 45-point AF layout.

What lenses fit the Canon 850D?

It uses the EF and EF-S mount, so any Canon EF or EF-S lens fits, plus third-party EF lenses. EF-S lenses are designed for its APS-C sensor; full-frame EF lenses also work with a 1.6x crop factor.

Does it have image stabilization?

There is no in-body stabilization. Stabilization comes from IS lenses, and the camera also has electronic stabilization for video. For handheld low light, an IS lens helps most.

Can I transfer photos to my phone?

Yes. Built-in Wi-Fi and Bluetooth work with the Canon Camera Connect app for wireless transfer and remote shooting. There is no USB-C charging; the battery charges in an external charger.