Nikon F3AF User manual Part IV Autofocus Operation

Focus The Nikon F3AF features a through-the-lens autofocus system which takes the guesswork out of focusing: just point the camera at what you want to photograph, depress the shutter release button halfway, and watch the subject literally snap into harp focus...automatically.

The system consists of three parts : the special F3AF camera body, the AF Finder DX-1, and an AF-Nikkor lens, either the 80mm f/2.8 or the 200mm f/3.5 IF-ED. The Finder DX-1 is interchangeable and covers approx. 92% of the image area of the actual photograph, meaning that the final photograph will be larger than the image seen in the viewfinder. The focusing screen is built into the bottom of the viewfinder and cannot be interchanged. However, when other Nikon F3 interchangeable viewfinders are used with the F3AF, you have a choice of 20 interchangeable focusing system in unique in that it features exceptionally quick response, allowing you to keep up with active, fast moving subjects.

1) autofocus; 2) focus-aid operation (using the focus indicators inside the finder), or; 3) manual focus (using the matte portion of the focusing screen). As shown in the following table, however, only AF-Nikkor lenses are usable for autofocus. With other lenses having maximum apertures of f/3.5 and faster, you can use the focus indicators as a guide in focusing as you manually rotate the lens focusing ring (49).

Note: Because of the cropping which occurs in the case of mounted slides or regular snapshot-size prints, the actual picture might come out slightly smaller than the image seen in the viewfinder.

Usable Lenses

Focusing method	Lens
Autofocus	AF-Nikkor 80mm f/2.8, AF-Nikkor 200mm f/3.5 IF-ED
Focus-aid operation	Nikkor (Including AF-Nikkor) and Nikon Series E lenses with a maximum aperture of f/3.5 or faster.
Manual focus	Nikkor (including AF-Nikkor) and Nikon Series E lenses

(1) LCD exposure information;
(2) ADR f-number;
(3) Flash ready - light;
(4) Focus-impossible warning;
(5) Focus indicators: near-focus arrow; far - focus arrow;
(6) Central focusing frame;
(7) Half - mirror;
(8) Fine matte/Fresnel field

	Subject in focus
	Far focus (the lens is focused behind the subject)
	Near focus (the lens is focused in front of the subject)
	Autofocus or focus-aid operation is impossible. (This warning also lights up momentarily at the start of autofocus or focus-aid operation, if there is a big difference between the actual camera-to-subject distance and the lens distance setting.)

With the lens A-M switch set at A, depressing the shutter release button halfway turns on the camera's autofocus control (as well as the exposure meter).

At the same time, either the focus indicator(s) or the focus-impossible warning in the viewfinder light up and the lens begins to focus automatically.Note that the main subject (if possible, a subject's vertical line) should be centered inside the central focusing frame in the viewfinder. Autofocus continues for 16 sec. even after you remove your finger from the button. When the subject is in focus, focusing stops and both red arrows light up.

If there is a big difference between the actual camera-to-subject distance and setting on the lens distance scale, the red X lights up momentarily but disappears as soon as focusing begins. If the subject is closer than the closest distance to which the lens can focus, either the far-focus arrow (<) or the red X lights up continuously. However, when the red X blinks or lights up continuously, this indicates that the autofocus system does not function well with the particular subject or shooting situation
(please refer to page 26 for further details).

Notes: 1) After taking a picture during autofocus operation, the lens will continue to focus for 16 sec. after you remove pressure from the shutter release button. To stop the lens movement at any time to conserve battery power slide the A-M switch to M. Immediately lens movement stops, but the red arrow(s) or red X remain on for 16 sec. until switched off automatically 2) While shooting fast-moving subjects, one or both of the red arrows may blink to show that the image is quite close to the In-focus zone; for ordinary snapshots, taking the shot even In this situation can produce satisfactory results. However, if sharp focus is mandatory wait until both red arrows light up condonously 3) When the batteries In the viewfinder are nearly exhausted, autofocus becomes slow or may even stop, even though the red arrow(s) or red X remain lit. In this case, replace the batteries In the finder at your earliest convenience, or set the A-M switch to M and turn the focusing ring manually using the red arrows as a guide.

Focus lock The AF-Nikkor lens has two focus lock buttons on the lens barrel, one on the side and the other on the A-M switch. You can use either of these buttons, depending on your choice of horizontal- or vertical-format shooting. During autofocus operation, depressing the focus lock button allows you to lock in the autofocus distance setting on the lens.

To take pictures with the main subject off-center, first center the main subject within the focusing frame in the viewfinder, depress the shutter release button halfway and make sure both focus indicators light up; then depress the focus lock button and, while holding it in, recompose and shoot.

Notes: 1) With the focus lock button held down, the in-focus indication (> <) may change in the following two cases: l) when you once again depress the shutter release button halfway after the camera's automatic 16-sec. switch has fumed off the indication, or 2) just after you have taken a picture. However, regardless of the focus indication change, the distance set on the lens is Sun the same as when you depressed the focus lock button. 2) When taking pictures in the automatic exposure mode with the main subject off-center, you must a/so depress the memory lock button to get the correct exposure.

Focus Aid Operation (Using the Focus Indicators) With the AF-Nikkor's A-M switch set at M, or with other Nikkor or Nikon Series E lenses having a maximum aperture of f/3.5 or faster, you can use the focus indicators as a guide as you rotate the lens focusing ring. First, center the main subject (if possible, a subject's vertical line) within the focusing frame; then depress the shutter release button halfway to make the red arrows light up (focus information stays on for 16 sec. after removing your finger) If only the far-focus arrow (< ) lights up, this indicates that the lens is focused behind the subject, whereas the near-focus arrow (>) indicates that the lens is focused in front of the subject. These red arrows are very convenient, because they tell you in which direction to turn the focusing ring: just turn in the direction of the arrow. When the image is in focus, both red arrows light up continuously.

When there is a big difference between the actual camera-to subject distance and distance set on the lens, the focus impossible warning appears. In this case, turn the focusing ring until one of the red arrows lights up; then continue to turn the ring until both arrows are lit, indicating sharp focus. If only the far-focus arrow (<) remains lit after the ring has been rotated fully counterclockwise, this means the subject is closer than the closest focusing distance of the lens. If the subject is much closer than the closest focusing distance of the lens, the red X will light up continuously.

In case the red X blinks or lights up continuously and does not disappear even after the focusing ring is turned, this indicates that the focus-aid indication system does not function well with the particular subject or shooting situation. Note: While shooting fast-moving subjects, one or both of the red arrows may blink to show that the image is quite close to the in-focus zone; for ordinary snapshots, taking the shot even in this situation can produce satisfactory results. However, if sharp focus is mandatory, continue to rotate the focusing ring until both red arrows light up continuously

Manual Focus (Using the Matte Portion of the Focusing Screen)

Manual focus is required in the following cases: 1) when the batteries in the DX-1 finder are exhausted, 2) when you are using a lens which cannot provide autofocus or focus-aid operation;

3) when the focus-impossible warning blinks or lights up continuously, or 4) when you simply want to focus the lens yourself. With an AF-Nikkor lens, set the A-M switch to M; then turn the lens focusing ring until the image on the matte portion of the screen inside the viewfinder looks sharp and clear. With all other lenses, rotate the focusing ring in the normal manner.

Note: With the A-M switch on the AF-Nikkor lens set at A, you cannot shift the lens distance setting by turning the focusing ring.