Nikon SB-21

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Nikon SB-21 macro ring flash was designed to be used with the legacy OTF TTL flash control system of the Nikon F3 and F4. On a DSLR, it can only be used in manual mode.

The SB-21 is known as both SB-21A and SB-21B, depending on what controller (AS-12 or AS-14) it is packaged with. The SB-21A comes with AS-12. It has a proprietary mounting foot that matching the Nikon F3 hot-shoe. The SB-21B comes with AS-14. It has a standard ISO-type mounting foot that fits on the Nikon F4 and newer models. The mounting foot of the controller is the only difference between SB-21A and SB-21B.

It comes with adapters to fit lenses with 52mm or 62mm filter threads

Nikon warns against using the autofocus when the SB-21 is attached to the camera's lens with other AF lenses that the AF MicroNikkor 60mm f/2.8 and AF Micro-Nikkor 105mm f/2.8. The manual states: “when the SB-21 is used with other AF Nikkor lenses, performing autofocus may damage the camera”. It also say that AF Zoom¬∑Nikkor lenses should not be used with the SB-21 at all.


Generic flash.
Head: Fixed 35mm coverage.
Swivel & tilt: no.
Exposure modes: Varipower, OTF.
Manual settings: 1/1, 1/4 and 1/16 (3 steps).
No built-in wireless modes.
Features: Ext. power.
Trigger voltage: 4.6 volt.
Batteries: 4xAA.
Field upgradable: No.
Dimensions: 130 x 120 x 21 mm, 395 g.
Guide number (ISO 100, meter): 13.

Discontinued: Yes.

For a detailed explanation of the above specifications, see the guide.



Brand profile

Key info

Established: 1917
HQ: Tokyo, Japan
Web: Global, EU, US, man

Nikon is a multinational corporation headquartered in Tokyo, Japan specializing in optics and imaging. Its products include cameras, lenses, flash units, scanners, binoculars, microscopes, measurement instruments, and steppers (used in semiconductor fabrication). The company was founded in 1917 as Nippon Kōgaku Kōgyō Kabushikigaisha (Japan Optical Industries Corporation), and renamed Nikon Corporation, after its cameras, in 1988. Nikon Corporation is one of the companies of the Mitsubishi Group.

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