Modern Classic SLRs Series :
Pentax LX - TTL / OTF Flash Metering

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The AF400T was a guide number of 40 (ASA100) is the most powerful unit among the few original TTL options for Pentax Flash Units.

Some of the very versatile, dedicated TTL Auto Flash Units option available for the Pentax LX

Automatic Switching between Auto Flash and Auto Exposure With the AF400T,
AF280T, AF200T (See bottom of the page) or AF080C attached and the shutter dial set at "AUTOMATIC", the LX automatically sets the shutter speed at 1/50 second when the flash is recharged if the exposure measurement requires a shutter speed slower than 1/30 second. For shutter speeds faster than 1/60 second, the LX automatically switches to the IDM-controlled automatic exposure mode. The LX's automatic flash system automatically chooses between the Auto Flash and automatic exposure modes, depending on light conditions and the degree of flash recharge.

Accurate TTL Auto Flash Controlled by IDM Combine the LX's IDM System with Pentax dedicated flash units AF400T, AF280T, AF200T or AF080C Ring Light Set, and discover the sophisticated convenience of fully automatic TTL flash photography.

With this system, flash output is controlled not by the flash unit, but by the camera's own metering system. Incoming light—both flash and ambient light—is measured as it reaches the film plane, and the automatically terminated the instant sufficient light has reached the film. TTL Auto Flash allows flash photography at any aperture, and makes complicated flash setups simple. The LX system guarantees the accuracy and versatility a professional requires.

"Fail-safe" Dedicated Flash Features Since the TTL Auto Flash system measures the light actually reaching the film plane, the photographer can select any aperture, allowing precise control over depth of field. And the flash output is controlled accurately regardless of where the flash is placed, what other light sources are being used, or what filters or close-up accessories are being used.

The Fully Professional AF400T The AF400T offers full system flash capabilities for the most exacting professional flash applications. This high-performance grip type flash unit has a guide number of 40 (at ISO 100/m). Used with the LX, the AF400T permits the versatile TTL Auto Flash as well as three settings for Auto Flash, four settings for Dedicated Manual Flash and four settings for Manual Flash—a total of 12 different flash settings.
* Note: Actual view of the AF400, please refer to top of the page.

The flash head can be adjusted 270° horizontally, 90' vertically and -15° vertically for bounce and close-up photography. The flash covers an angle of view equal to that of a 35mm lens. With a wide-angle adapter AFW2, which covers the angle of view for a 24mm lens, or a telephoto adapter AFT2 (both optional), the AF400T can be used in wide variety of flash applications. The AF400T connects to the LX via a 4P Sync Socket with a 4P Sync Cord A, or via the hotshoe of finders like the FA-1 with a 4P Sync Cord B. The AF400T System Kit includes a 4P Sync Cord B, a bracket, a clamp, and a battery pack for "AA" batteries. (670g for AF400T main unit.)

4P Sync Cord A.jpg 4P Sync Cord B.jpg
4P Sync Cord A 4P Sync Cord B
Power Sources for AF400T and AF080C The AF400T has four different power sources for maximum versatility: a handy battery pack with six "AA" Ni-Cd batteries, AC Adapter II for AC outlet, TR Power Pack with six "C" batteries, or a Power Pack 510V with a high-power battery for extended use. With AC Adapter II and the smaller battery packs, flash recharge time is approximately seven seconds at full flash output. In the Auto Flash mode, even faster recharge is possible. The Power Pack 510V is a powerful power source for heavy-duty professional use and has a very short recharge time of approximately two seconds even at full output. AC Adapter II, TR Power Pack and Power Pack 510V can also be used as a power source for the AF080C Ring Light Set.

AF080C Ring Light Set The Pentax AF080C Ring Light Set consists of a Ring Light that screws onto the front of the camera lens and a Control Pack which clips onto the camera's hotshoe. Used with the LX system in the TTL Auto Flash mode, it provides direct, shadowless lighting to within centimeters of the subject, an impossible task with regular flash units.
AF080C Ring Flash.jpg (13k)

With a guide number of 8 (at ISO 100/m), the unit is powered by 4 "AA" batteries housed inside the control unit. For added versatility, three optional power sources are available including the transistorized TR Power Pack to boost operation with 6 "C" batteries, the high-voltage Power Pack 510V for fast recycles, and the AC Adapter II for operation on AC current. The Ring Light also offers two-way manual override with dedicated flash features for convenient close-up work.

af280.jpg (13k)
The Versatile AF280T The handy and easy-to-use AF280T clips directly onto the LX's hotshoe and offers full TTL Auto Flash control plus other benefits, including two-way manual override, horizontal and vertical bounce flash, accessory telephoto and wide-angle lens adapters, and dedicated flash operation in all operating modes.

The AF280T features a top guide number of 28 (at ISO 100/m) and power-saving thyristorized circuitry for maximum performance from its 4 "AA" batteries. Alkaline and rechargeable Ni-Cd batteries may be used. The Compact AF200T with Confirmation Beep Tone This compact and versatile flash unit, powered by 4 "AA" batteries, has a guide number of 20 (at ISO 100/m) and clips directly onto the hotshoe of any LX finder. It has settings for both TTL and Auto Flash, and gives you a choice of flash levels. In addition to fully automatic operation, it offers a flash-ready indication in the viewfinder and an audible signal to confirm proper flash exposure.


AFW2 Wide-Angle/AFT2 Telephoto Adapters
(For AF 400T)

Both AF280T and AF200T cover an angle of view equal to a 28mm lens. However, with the wide-angle adapter AFW1 (optional), they can cover the angle of a 24mm lens. Telephoto adapter AFT1 (optional) extends flash range.


AF160 F, the most compact in size among them - but came with some compromise on features.

Auto Flash Exposure Check

When using both the AF-280T and AF-400T in the Auto or TTL Auto Flash modes, you can check whether your subject is within flash range before releasing the shutter by pressing the TEST button on the back of the flash unit. If the Auto Check Lamp next to the TEST button lights up, the subject is within the auto flash range. If the lamp does not light, use a more powerful flash setting or move closer to the subject. With TTL Auto, you also have the option of using a larger aperture (e.g. f/2.8 instead of f/5.6).

Multiple Flash Photography with TTL Complex multiple flash situations are simple with the LX TTL Auto Flash system. For example, attach three AF400T flash units to the LX 4P sync terminal via a distributor, and clip a AF280T or AF200T unit to the camera's hotshoe. To the IDM System, this four-way flash setup is as easy as a single flash. Light from all four flashes is measured by the SPD cell in the LX body and output from all units controlled accordingly. Even the most difficult professional lighting problems are solved simply and accurately in the LX's TTL Auto Flash mode.


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