Secondary Procedures for Autofocus Photography

3.When the distance scale of the prime lens is set to minimum or around there, you can focus on your subject even if it is beyond the original closest shoot- ing distance. Note, however, that picture quality may somewhat be impaired.

4.If the prime lens is the 135mm f/2, make sure you set the distance scale between infinity (») and 2m (6.6 ft) in order to obtain precise in-focus indica- tion. You should set it at closer than 2m (6.6 ft), or the precise in-focus indica- tion may not occur.

5.it takes around 0.5 sec. to automatically focus on a subject from the maxi- mum to the minimum shooting distance.

SECONDARY PROCEDURES FOR AUTOFOCUS PHOTOGRAPHY

As shown in the focus detection range chart (p. 17), the longer the focal length of the lens in use, the narrower its focus detection range. To shoot a subject that is in motion, you will need a wide autofocus operation range that covers the distance between you and the moving subject. If you set the prime lens's dis- tance scale at infinity, the approaching subject may fall short of the minimum shooting distance for the focus detection range indicated.

For example, when taking a picture of a subject with a TC-16-mounted 300mm f/2 lens within a range of 70m (229,7 ft) to 10m (32.8 ft), which is the prime lens's minimum focusing distance, you won't be able to shoot the subject if it comes closer than 35m (114.5 ft) if you've set the distance scale to infinity because the minimum shooting distance required for autofocus detection to work at this distance is 35mm (114.5 ft).

It is thus best to reset the prime lens's distance scale by observing the following procedures.

1.Detach the prime lens in use from the TC-16 and attach it to the F3AF/DX-1 assembly.

2.Focus on the subject at its maximum shooting distance; then lock this read- ing on the prime lens's distance scale. (With the 300mm f/2 IF-ED, use the lens's convenient presettable focusing ring locking screw.)

3.Remove the lens in use from the F3AF camera body and insert the TC-16 between the prime lens and the F3AF/DX-1 assembly; then set the TC-16's ON/OFF switch to "ON".

4.Focus on the subject at its minimum shooting distance. If both LED in-focus indicators (X) light up, this means the distance scale preset in Step 2 enables continuous autofocus operation, But if the LED focus-impossible warning indicator (x)* or the LED far-focus indicator (•*) lights up, this means the subject is closer than the preset minimum shooting distance. So, in this case, reset the distance scale by observing the following proce- dures.