That is normal for lenses with aperture rings for Nikon, you must close down the aperture on the lens and then you can adjust the aperture through the camera.

Yes, Samyang and Rokinon are the same company. Samyang lenses are meant for the EU market and Rokinon is meant for the U.S. market. Samyang is typically less expensive but the same quality and warranty.

Yes, its compatible. The UMC is for multiple lens coatings for less light scattering as it enters the lens to produce a better quality image.

This lens works well wit the FTP adaptor. No problems.

Both lenses would be good options for astrophotography usage needs. That being said, the new Rokinon 14mm f/2.8 Series II Lens for Nikon F does have some impressive improvements, such as better optical performance, a focus lock mechanism that allows you to lock the position of the focus ring (beneficial for crucial focus with astrophotography), the ability to declick the aperture ring, and weather-sealing. Overall, the newer Rokinon 14mm f/2.8 Series II Lens for Nikon F would be recommended, but if you are on a budget, the Rokinon 14mm f/2.8 IF ED UMC Lens For Nikon with AE Chip is still a good option and would be recommended.

You can contact our customer service department for a return and then order the correct lens. The link below will take you to the lens with the AE chip; https://bhpho.to/2WSDKfF

No, manual focus only.

I have both the EOS R and the Canon Mount Adapter EF-EOS R and although it will attach, it will not capture photo or video.