I bought a lens reversal ring to try macro photography on my 50mm f/1.8 prime lens. But when I tried it, I couldn't control the aperture as my lens doesn't have manual aperture control. I attached the lens normally and changed the aperture and again detached it to use it reversed. But still, the aperture hole was the smallest. How can I overcome this problem? And if not possible, what equipment should I buy to make this work?
For Nikon F-mount lenses with mechanical aperture control, you can use the Nikon BR-6 Auto Diaphragm Ring.
For Canon EF lenses, which have electronic only camera/lens communication, you can use an "Automatic" Macro reverse mount adapter.
There are also other "DIY" ways to set the aperture to a desired setting.
For Nikon F-mount lenses they usually involve fixing the aperture control lever at a specific position. For Canon EF lenses, one can dismount the lens from a powered up body set to the desired aperture while holding down the 'Depth of Field Preview'.