Infrared Index Of The Zoom Lens - Pentax smc -FA Operating Manual

Infrared Index of the Zoom Lens

When taking infrared photographs with the
zoom lens, compensation in focus is neces-
sary depending upon the focal length. The
distance scale of the zoom lens has infrared
indexes for each focal length.
Compensate for the focus according to the
focal length in use (see page 9.).
2 0
15
7
200
With lenses having indexes only for the
longest and shortest focal length, such as FA
Zoom 70-200mm, obtain the compensation
value for intermediate focal length by using
the scale as a guide.
28 -105
ft 15 8 5 3 2 1.6
∞
m 5 3 2 1.2 0.7 0.5
The red line on the lens barrel of the FA28-
105mm f/4-5.6 (IF) is the infrared index line.
Compensate for focus according to the focal
length in use. See more details on page 9.
The following lenses have no infrared index
line.
FA Zoom 28-90mm f/3.5-5.6
FA Zoom 28-200mm f/3.8-5.6
21