Ask for help. When taking a SLR photo, the light is too dim but I don't want to flash. How to fill the light? Can professionals help? Thank you very much This group of photography scum ...

If you really don't want to use flash, in order to ensure the shutter speed, you can only use a large aperture and improve iso.

If your lens is a telescope, there is nothing you can do. You need to change a lens with a large aperture and raise the iso to 1600. Although it is increased earlier and the image quality is reduced, it is better than not shooting at all.