Can I shoot Orion with a focal length of 50?

You can't shoot Orion at 50 times the focal length.

The standard lens of 50mm can only capture the Big Dipper at most. It is impossible for a wide-angle lens to capture Orion, Auriga, Gemini, Taurus and Sirius in one picture, and a super wide-angle lens can only capture part of the Milky Way. It is even more difficult to fit the starry sky and the earth into a picture. The simplest and most effective solution at this time is to use fisheye lens.

Shooting Orion skills:

The number of stars photographed by the same lens depends on the physical aperture of the lens. Physical aperture is equal to the ratio of focal length to aperture when shooting. For example, when the focal length is 8mm and the aperture is f/4, more dark stars are photographed than when f/5.6 is used.

But doubling the exposure time can only make the stars visible in the photo brighter, and the invisible dark stars can't be photographed. This phenomenon is called "extreme magnitude" in star field photography. Therefore, under the premise of a certain focal length, the larger the aperture, the more stars are photographed, so a lens with good imaging quality at the maximum aperture is essential.

The same aperture, the same focal length, the higher the ISO, the more stars can be photographed. But too high ISO will reduce the image quality, so you should find out the "highest common sensitivity" of the camera before shooting.

For example, the highest common sensitivity of Canon EOS 350D is ISO800. Quan Huafu Canon EOS 5D Mark II can reach ISO3200, which means EOS 5D Mark II can capture more stars.