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The light returning through the lens is measured and this value is used to calculate the amount of light necessary for the actual exposure. Multiple pre-flashes can be used to improve the flash output. Canon referred to this as Evaluative TTL (E-TTL) and later improved the system with E-TTL II. The first form of digital TTL by Nikon, called "D ...
Time to live (TTL) or hop limit is a mechanism which limits the lifespan or lifetime of data in a computer or network. TTL may be implemented as a counter or timestamp attached to or embedded in the data. Once the prescribed event count or timespan has elapsed, data is discarded or revalidated.
Asahi Pentax Auto 110. The Pentax Auto 110 features fully automatic exposure, with no user-settable exposure compensation or adjustments. Metering is TTL (through-the-lens) and center-weighted. Unlike 35 mm SLRs, the system's lenses do not have a built-in iris to control the aperture. Instead, an iris is mounted inside the camera body, and ...
The output of a delay generator can gate a digital-to-analog converter and so pulses of a variable height can be generated. This allows matching to low levels needed by analog electronics, higher levels for ECL and even higher levels for TTL. If a series of DACs is gated in sequence, variable pulse shapes can be generated to account for any ...
A digital use of a push–pull configuration is the output of TTL and related families. The upper transistor is functioning as an active pull-up, in linear mode, while the lower transistor works digitally. For this reason they are not capable of sourcing as much current as they can sink (typically 20 times less).
Generally, a TTL output does not rise high enough to be reliably recognized as a logic 1 by a CMOS input, especially if it is only connected to a high-input-impedance CMOS input that does not source significant current. This problem was solved by the invention of the 74HCT family of devices that uses CMOS technology but TTL input logic levels.
The Autoreflex T was the first focal plane shutter 35mm SLR with auto-exposure and TTL metering combined in one body. In Japan it was sold as FTA, in Germany as Revue Autoreflex TTL. It is fully mechanical with shutter-priority auto exposure. The batteries (two PX 675 type mercury cells) were only needed for the CdS light meter.
The 74181 is a 7400 series medium-scale integration (MSI) TTL integrated circuit, containing the equivalent of 75 logic gates [3] and most commonly packaged as a 24-pin DIP. The 4-bit wide ALU can perform all the traditional add / subtract / decrement operations with or without carry, as well as AND / NAND, OR / NOR, XOR, and shift. Many ...