Modern Classic SLRs Series :
Canon T-90 - TTL Flash Exposure Control
With Dedicated Speedlite 300TL.

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We don't go through the detail of why Canon had changed its mind to utilize the mainstream TTL flash technology. This has already been explained in the Canon F-1n site already online.


Instruction manual for 300TL Flash (new)
Two views of the SPC that handle the TTL flash at the mirror box. - Tom Scott -

Canon certainly did its job well by studying the available options in the market on those that have already offered the TTL flash capability before incorporating its own version for the T90. But since TTL flash must relocate the meter sensor back to underneath the main mirror box (Another will perform the required metering function near the eyepiece, you can
take a look at this illustration), facing the curtain and measure the reflected light back from the film during a pre flash for optimum exposure recommendation (so the flash can cut off the power output), a new dedicated flash unit with enhanced capabilities was launched together with the T90.

300TL detail view.jpg (18k) Speedlite 300TL.jpg (9k)
External Resources created by Mr. Christian Rollinger: Macrolite ML-1(HTML); Macrolite ML-2; Macrolite ML-3; Speedlite 133a; Speedlite 155a(HTML); Speedlite 177a; Speedlite 188a(HTML); Speedlite 199a; Speedlite 244t; Speedlite 277t(HTML); Speedlite 533; Speedlite 577 - Cool ...I'd really like this guy..

But first, let us list down what the camera has to
offer within its core feature and how well does it perform with the 300TL Speedlite. Usually, when mentioning flash photography, we talk very much about flash synchronization. And it is relative to the camera's shutter mechanism. The T90's vertically traveled duralumin shutter blades were designed to achieve its top speed of 1/4000 sec at stable and reliable capacity. Another side feature it has was - its top sync speed was also raised to a new height. Thus, for the first time, Canon has a model to provide a 1/250 second X-sync speed with A-TTL facilities.(Horizontal traveled shutter curtain believed to be more durable and trouble free but since it takes longer time to traveled across the 36mm picture frame than the vertical traveled curtain of 24mm, its main draw back was the lower sync speed. Among the Pentax LX, Nikon F3 and Canon New F-1 pro level cameras (ALL were employed with Horizontal traveled shutter curtains), the highest was the LX (1/100 sec), with the New F-1 second with its 1/90 sec and the Nikon F3 the slowest at 1/80 sec.).

The 300TL was a dedicated flash unit was created to be the ideal match for the T90. A selection of five modes (Full Auto, A-TTL, FEL, Manual Hi and Manual Low) lets you meet every photographic situation with total control. We have go through the 300TL' s features one by one below.

Program A-TTL Mode

ATTL Program Chart.jpg (18k)
This mode automatically responds to a wide range of illuminations, from dark surroundings to bright, so automatic fill-in flash is possible. The shutter speed is automatically set between 1/60 sec. and 1/250 sec. Using the A-TTL control system, this mode measures the light reflected from the film surface directly by a sensor inside the camera. When being used for fill-in flash photography, the A-TTL mode automatically reduces flash emission to balance the exposure level between the main subjects and the background. This prevents unnatural lighting of the subject while accurately exposing the background.

High-speed flash sync opens up a new world of faster flash photography. The T90's shutter speed can be set anywhere between 30 sec. to 1/250 sec., giving the photographer great control over subject movement, depth of field and ambient light. In addition to the slower shutter speeds, the T90 when fitted with the 300TL flash unit can operate at the faster shutter speeds needed for daylight photography. The T9O switches to the center-weighted average metering mode automatically to select the correct aperture. if the subject is too far away, both the shutter speed and aperture will blink in the viewfinder as a warning.

Flashbuttons.jpg (12k)
The 300TL flash unit was designed to specifically take advantage of the advanced electronics and superior operation ease of the T90. The combination of the T90 and 300TL makes possible some creative applications in the dark and brighter ambiance light conditions. All operations on the 300TL are fully automatic, even when shooting in broad daylight.

New features like Advanced Through-The-Lens (A-TTL) metering, Flash Exposure Lock (FE Lock), and second-curtain sync combined with the T90's 1/250 sec. flash sync speed to make a great variety of complex flash effects as simple as ordinary available light photography and the aperture-priority A-TTL Support the entire range of aperture values.

speedlite300TL8mdm.jpg Speedlite277T1mdm.jpg 199Aflashbmdm.jpg

Various Canon
Speeedlite models.


Using this mode, the photographer selects the appropriate aperture depending on distance from the subject. Thus, when the background is as important as the main subject, you can choose the correct aperture from among the entire available range and the appropriate shutter speed will be set automatically between 30 sec. and 1/250 sec. If the subject is too far away, the viewfinder shutter speed and aperture indicators start blinking as a warning.

By memorizing the correct exposure setting, the FE (Flash Exposure) Lock mode lets you position the main subject anywhere in the frame while still getting proper exposures automatically.

The 300TL's FE Lock mode employs spot metering and the principle of AE lock to provide accurate flash exposure of the subject in any situation. The subject is initially spot metered by means of a 1/20th strength pre-flash that locks in the correct exposure setting. The photographer is then free to recompose the shot. The resulting exposure is not affected by the position of the subject or the reflectivity of the background. The FE Lock mode can also let the photographer place the subject wherever he wants in the frame while shooting at night. Shooting a non-centered subject in darker conditions without the FE Lock would result in an overexposed picture as the flash attempts to illuminate the background. But we have seen too much of this kind of total black out in the background when dealing with automatic flash. It works like slowing down the shutter speed to absorb more ambiance light from the background to show more 'natural' effect. But this also may take in excessive artificial light (subjective, some may like and some don't).

H/S Control * Note: The T90's H/S Control allows compensation for very white or very black subjects. "H" is used when the subject is white. While "S" is used when the subject is black. The H/S Control functions with either one-point spot metering or multi spot metering.

| Click here for master map for control |

Either shutter-priority FE Lock or aperture priority FE Lock can be selected depending upon the shooting situation. Moreover, because of H/S control operation, the T90 can independently control the exposure level of the main subject with the flash and the exposure level for the background with ambient light. Once the subject is metered and locked in with the AE Lock, the viewfinder display shows how bright or dark the background is in relation to the correctly exposed subject.

FE Lock Chart.jpg (18k)
The H/S controls can thus be used to bring the background into balance with the main subject for a more dramatic shot. For night flash photography, with no H/S controls used, the background will be underexposed. Since the H/S control is variable, the photographer can choose the degree of exposure he wants for the background, making possible a variety of effects from the same situation. And this operation also prevents the background from being overexposed when using the flash for fill-in.

Second-Curtain Sync

All SLR cameras during the sixties up to the mid-eighties came with flash synchronization has always been timed for when the first shutter curtain is fully open, which was common on the camera models from all manufacturers. Actually, I was first caught by this feature when the T90 was launched and thought this is a good one, of which I can imagine a fascinating effect that was never before possible with the conventional First-Curtain Sync. The T90 and Speedlite 300TL offer the alternative of flash output just before the second shutter curtain begins to operate. This is particularly useful for capturing a sense of motion when shooting at a slow shutter speed. The flash discharge comes at the very end of a rather long exposure so that the scene can be naturally seen with the light flowing from it. Strangely enough, not many people took notice of this unique feature pioneered by the T90 but they seemed to be very excited about it when Nikon had this feature available for the first time with it AF 35mm SLR camera, the F801/N8008.

Bulb Mode You can also use the T90 for shooting in bulb mode for a variety of expressive effects. The bulb mode is used for very long exposures, such as for night scenes or even astronomical photography. When using the bulb mode, the aperture is set manually and the shutter remains open as long as the shutter button is pressed down. When making long exposures, the camera should or suggested to be mounted on a tripod and a cable release should be used in order to avoid camera shake during the lengthy exposure time. The T90's bulb mode is specially designed to be highly energy efficient. Battery life is maintained even during very long exposures.

Ring Flash Its dedicated TTL Macro Ring Flash can work from as close as 1 m. (0.4 in.) away. Another flash designed for the T90 to utilize its TTL flash capabilities was a ring light! This completed the T90 extension into the area of macro photography. There are times where correct exposures are particularly difficult when doing super close-up photography. But with the Macro Ring Lite ML-2, you can maintain precise control over flash photography even at exceptionally close distances. Moreover, since accurate focusing becomes critical when doing ultra close-up photography, the ML-2 features a focusing lamp to clearly illuminate the subject. You can also check where shadows will fall by using the ML-2's modeling light.

The ML-2 has two separate flash tubes arranged on the right and left sides of the ring unit. Both can be fired together, or for more versatility, either can be fired alone, creating a slight shadow on the subject and thus adding a quality of depth. The Macro Ring Lite ML-3 designed for the Canon EOS System can also be used with the T90.

Even in macro photography, sometimes the composition of the background is critically important. The ML-2's TTL automatic mode makes it easy to bring out a feeling of solidity in backgrounds with no complex compensation calculations. More depth of field means a greater sense of actuality. Thus, you can shoot extreme close-ups that still gives a sense of presence to your photos.

The Canon's Macro Ring Lite as they called it can work with unmanned photography in close up. Check the accessories available for the T90's remote photography.

Note: PLEASE USE the MAIN MAP for the viewfinder and LCD display for cross reference in this site. Another page is also equally helpful for its layout of controls and buttons.

Concept | Capabilities

Its Metering, Exposure control, Flash photography, Viewfinder display, Film Backs, Built-in Motor Drive, the brains, Focusing Screens Other capabilities and the eyes of Canon; Full specifications with details illustrations of its various controls, available in HTML / PDF (184K) format.

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Instruction manuals for
300TL Flash & Canon T90
Canon A & T series SLR Models

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Credit: Pawel Nabe for his image on the Data Memory Back. EEwyn Foo, my nephew, who has spent quite a number of nights converting the original manual in HTML format. Mr. Richard Yeow, General Manager -Optical Division of Canon Marketing for granting special permission to reproduce this manual into HTML format in his site as a form of obligation to all the T90 users worldwide. Maintainders of the T90 Message Board: Kaipin, Terry Carraway & Dr Strangelove; Tom Scott, for his images of the SPD cell, Chris Tutti for his initial effort to scan and prepared the T90 manual in PDF format. My staffs Miss Wati and Mirza for helping the basic setup work. * Canon, T90, FD Lenses, Canon Marketing are registered trade names or trademarks of Canon Inc. Japan.