The most important observational device in low-tech societies is the eye. There are no artificial visual sensors, and there’s no way to form images using wavelengths other than visible ones. Optical technologies that aid human vision become theoretically possible with the invention of glass, and the Greeks and Romans had a decent understanding of the optics of mirrors, or catoptrics. However, sophisticated optical devices only appear at TL4.
Unless otherwise stated, TL3-4 optical instruments give -2 to Vision and related rolls; see Defective Vision. As well, vision is limited by the horizon; see Visual Signals (LT pp. 48-49) and the Horizon Table (LT p. 49).
Technologies aiding other senses are largely absent at TL0-4, although TL4 does see the first mention of the ear trumpet (below).
Eyeglasses were invented in Italy around 1285 A.D. Convex lenses corrected farsightedness, including difficulty in reading with increasing age. Nicholas of Cusa described using concave lenses to correct nearsightedness in a treatise written 1453-1458; glasses for the nearsighted are TL4. Treat either sort as a Mitigator (p. B112) for its form of Bad Sight (p. B123). At TL3-4, glasses are held up to the eyes by the frame or a handle (a lorgnette design), occupying a hand, or are clamped to the nose (a pince-nez design). Pince-nez fall off on a roll of 12 or less on 3d if the wearer moves faster than a walk; they’re often attached to a chain. $100, 0.25 lb.
The ear trumpet has a wide, flaring horn at the end of a conical tube. The narrow end is held to the ear. By gathering sound waves over a large area, it amplifies a faint sound for the listener. Originally developed for use at sea, to hear shouts from other ships, it was later adopted by the hard of hearing to mitigate their disability. Creative spies will think of other uses! Increases the range at which a sound can be heard 8x (see Hearing, p. B358). $15, 2 lbs.
In 1609, Dutch lens grinder Hans Lippershey invented the microscope, which used lenses to see nearby small objects. In 1673, Anton van Leeuwenhoek began reporting his biological discoveries, which included microorganisms and human sperm. Early microscopes have 40¥ magnification (eliminating -9 in size penalties for an object on a slide). Chromatic and spherical aberration impose Vision and skill penalties of -2 (quality). $200, 2 lbs.
The first spyglass was invented in 1608 by Hans Lippershey, who received a large bounty from the Dutch government. A spyglass has two concentric tubes, which hold two lenses set fairly close together; sliding them back and forth adjusts the magnification for different ranges. It’s substantial enough to serve as a well-balanced light club, but such abuse means it will never work as a spyglass again!
This model has 4x magnification, allowing the user to ignore -2 in range penalties to Vision rolls while scanning for a particular object. After spotting his target, he can take an Aim maneuver to focus on it; this eliminates -4 in range penalties for that target, but gives no bonus to see other things.
Spyglasses and telescopes also have Bulk scores, like ranged weapons (p. B270); this one has Bulk -2. Bulk penalizes both Holdout rolls and Vision rolls to scan the environment for a particular object. To offset the latter penalty, take extra time to scan (p. B346). $100, 4 lbs.
At TL4, mirrors and lenses distort the images they deliver. Optical instruments therefore penalize Vision and vision-dependent skill rolls. While multiple lenses or mirrors with different properties can cancel out each other’s distortions, this technology isn’t perfected until TL5. Nearly all TL4 instruments give penalties:
for any use of optics with a penalty worse than -2, roll vs. HT after every 5 minutes. Failure means moderate pain (p. B428); if use continues, later failures worsen this to severe pain, then terrible pain, and finally agony. Critical failures cause immediate agony! Pain endures until the sufferer regains positive FP through rest, or a minimum of 10 minutes.