How To Convert the AF NIKKOR 20mm f/2.8 to a Macro Lens

With a few accessories, you can turn any prime or zoom lens into a powerful macro lens by simply reverse mounting it to the camera.

Lenses gather the image in front of the camera and reduce it to fit on the sensor or film frame. Telephoto lenses also reduce the image, simply by a lesser degree. But the greatest amount of reduction occurs with a wide angle lens. By reversing the lens, it magnifies the image it projects onto the sensor or film frame larger than life size. And the wider the field of view, the greater the magnification.

The AF NIKKOR 20mm f/2.8 is a particularly good candidate for reversal, as its additional width offers a higher degree of magnification, and its speed makes it easy to work with, as does its aperture ring.

Here’s what you’ll need:

Fotodiox 62mm Macro Reverse Ring
Nikon BR-6 Auto Diaphragm Adapter

or

Nikon BR-2A 52mm Macro Reverse Ring (see note below for advantages to using this)
Fotodiox 62-52mm step-down ring
Nikon BR-6 Auto Diaphragm Adapter

Setup:

1. Attach the reverse lens mount adapter to the filter threads of the lens. Do not over-tighten. (If using the BR-2A, first attach the 62-52mm step down ring to the lens.
2. Attach the Nikon BR-6 to the mount end of the lens.
3. Turn the lens around and screw its front filter threads into the adapter.

Operation:

1. Set the camera to exposure mode.
2. Set the focus ring of the lens to the infinity mark.
3. Be sure the aperture lever on the BR-6 is pulled out, and allow it to return to its normal position.
4. Set the aperture as desired; wide open gives the least depth of field, fully stopped down introduces the softening effects of diffraction. f/11 is a good starting point.
5. Set the shutter speed to 1/60 sec.
6. Move the camera closer to or farther away from the subject to focus.
7. Slide the aperture lever on the BR-6 to stop down to the selected aperture.
8. Take a test shot, and chimp (CHeck IMage Preview).
9. Adjust exposure if necessary, and take the shot.

The fast f/2.8 aperture of the AF NIKKOR 20mm makes handheld shots possible, but using a tripod will make focusing easier, and allow slower shutter speeds for wider apertures and thus greater depth of field.

When using a tripod, you may find focusing easier if you use a Macro Focusing Rail. This is an accessory which mounts between the camera and the tripod to allow precise movement in and out to assist in focusing, rather than repositioning the tripod each time. Some tripods may include a similar feature built in.

The BR-2A Advantage
The advantage to using Nikon’s Macro Reverse ring is that it has three mounting positions, which make it easier to position the index mark closer to the top for ease of use. It’s also made of chrome-plated brass as opposed to the black anodized aluminum of the Fotodiox. It’s considerably more expensive than the Fotodiox, but keep in mind that you only need one, it uses the most popular thread size, and you only need to purchase an inexpensive step-up or step-down ring to make it work with another lens.

The BR-6 Advantage
You can use a reverse-mounted lens without the BR-6, but there is no aperture control (other than stopping down fully by sliding the aperture control lever), and the mount size of the lens is left exposed. With the BR-6, you can protect the lens with a 52mm filter, and have full aperture control.

Using Other Lenses
Normal (50mm) lenses also work well, but keep in mind that the wider the lens, the greater the magnification. Longer lenses work better by mounting them conventionally with an extension tube.
Standard and wide-angle zoom lenses work well too, where the zoom will let you dial in the degree of magnification and aid in focusing.

Operation with G Lenses
With the addition of a locking cable release, you can also use G lenses which do not have aperture rings.

1. Be sure the aperture lever on the BR-6 is pulled out, and allow it to return to its normal position.
2. Attach the cable release to the BR-6.
3. Focus with the aperture wide open as normal.
4. Stop down to the desired taking aperture by pushing in the plunger and locking the cable release.
5. Take a test shot, and chimp (CHeck IMage Preview).
6. Adjust exposure if necessary, and take the shot.