Additional information on Canon T70 Camera, 1984
Part II - The Dual metering system, the AE, Manual and Stop Down AE modes

 
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The triple Programmed AUTO modes

During the early part of the '80s, with the numerous models available from the various manufacturers which offered Programmed AE, helped made the acceptance by users towards this mode that was once considered as a very amateuristic feature for SLR camera. The world's first SLR model featuring the Program AE mode was the evergreen
Canon A-1- widely regarded as a modern classic SLR. The T70's Programmed AE was a quantum leap in versatility and improvement over the A-1's. Within the Programmed AE feature, which also extended to flash photography - has three programmed AE variations.

PGRM Chart.jpg


T70 Front.jpg (13k)

Note
: Horizontal lines indicate operation of safety shift.

Graph of Shutter Priority AE (with shuttor speed set to 1/125 see)

STANDARD PROGRAM - Just leave everything to the camera.

It offers with focus-and-shoot ease. Standard Program is designed for moments when sudden shifts in light can transform highlights into shadows and vice versa. This program is balanced to take such various into account. The result is a perfect exposure every time you press the shutter button.

LCD PGRM.gif
Standard Program takes a middle path in choosing the shutter speed and aperture.

The program is therefore best suited for lenses from wide-angle to short telephoto. In low light, the viewfinder's "P" symbol flashes to warn that the camera is going to select a shutter speed below 1/60.

WIDE-PROGRAM - For a deeper photographic experience

PGRM Wide.gif
Depth of field is a term that refers to the area in focus in front of and behind the subject. The Wide Program in the T70 emphasizes depth of field and is especially effective with wide-angle lenses.

Landscapes group shots and crowded interiors are just some of the many situations where it comes in handy. The T70 increases depth of field by selecting smaller apertures at the expense of faster shutter speeds. The "P" mark flashes at speeds below 1/30sec.

TELE-PROGRAM -Programmed for action

PGRM-tele.gif
In the Tele Program mode, the T70 uses the fastest shutter speed that the light will allow.

Depth of field here is a secondary consideration, so the aperture remains wide open until about 1/250 sec. If camera movement is likely to be a problem (at speeds under 1/125 see) the "P" mark will blink. Tele Program isn't confined to use with telephoto lenses; it is equally effective with standard and wide angle optics.

SHUTTER-PRIORITY AE - Speed dictates

Despit it being one of the most versatile multi-mode SLR camera around, there was something strange when the Aperture-priority AE was omitted from the T70, although Canon is fully capable of incorporating the Aperture-priority AE mode into the T70. Canon must have realised the weaknesses of their competitors' models because when you mentioned Shutter-priority AE, the brand that came to mind is often Canon's SLRs. However, Canon did produced quite a number of Aperture Priority AE SLRs, in the A series, other than A-1, you have the AV-1 and a very surprising AL-1 QF (Quick Focus) as the AE mode of choice. The T series, has a narrower option in the top-of-the-line
T90 and the entry level T60. However, the flagship model, the New Canon F-1 will transform into an aperture priority AE camera when you replace the standard eyelevel finder with the AE Finder. Other T series models has the WIDE PROGRAM (referred above) as an alternative.

LCD Tv.gif
Control of the shutter speed is a decided advantage when you want to arrest the action or intentionally blur the subject to convey the sensation of movement.


Shutter-priority AE is the mode for this. With the lens at "A", press the mode selector and the shift button until Tv appears on the display. Then select the required shutter speed using either of the shift buttons.

CanonT70claudio8.jpg
The T70 automatically chooses the right f/stop. You can check in the finder what aperture the camera has selected by pressing the shutter button halfway or by pressing the exposure preview button.

Credit: Images courtesy of Mr. Claudio®. who is a collector for Canon photo gear, he also has an Ebay Section as well as maintaining a website on his own where occasionally trading some photo equipment. Image(s) copyright © 2003. All rights reserved. Please respect the visual property of the contributing photographer.


What if the light grows too bright or too dark for the selected shutter speed? This is where previous "automatic" cameras showed that they weren't so automatic after all. They would simply give either a washed out or underexposed picture. The T70 is more resourceful. When the light level exceeds the minimum or maximum lens aperture, the camera switches automatically to a higher or lower shutter speed. At the same time the aperture number in the finder blinks as a warning. For reference, the LCD panel displays the new shutter speed.


MANUAL MODE - Back to user control, do it everything yourself

LCD manual.gif
When your mind's eye tells you that a particular scene requires the human touch, switch over to Manual.


Now you are in full control. You set your own shutter speed and aperture to create the mood and tone. Experiment.
The T70, for its part, is ready to help you by providing a full aperture reading in the finder. And like every other mode, it'll issue exposure warnings when necessary.

T70 200mm.jpg
LCD Bulb.gif

Stopwatch Time Exposure

Digital quartz technology replaces the rule of thumb method of mentally counting of the seconds during time exposure photography. With the shutter speed at "bulb", release the shutter. The frame counter converts to a stopwatch and counts to 30 seconds repeatedly. Dashes mark the 30 sec increments to give an accurate record of timed exposures up to 2 minutes.

New perspectives with ease and precision STOPPED-DOWN AE

LCD stopdown.gif
Stopped down AE enables you to use close-up accessories. The T70 can take you on journeys to miniature worlds of indescribable beauty.

With a few simple accessories and the camera in Stopped-down AE mode, you can observe insects and plant life from a completely fresh vantage point.

Bellow.jpg
Earlier owners of Canon may have invested into some system accessories such as for macro photography. That will not be going to waste, even if you have older optic such as FL lenses. This is one area where the T70 has a broader scope of compatibility * than the T50 with older accessories and lenses.

From macro and macrophoto lenses to auto bellows units and extension tubes, the Canon close-up system has everything you need in closeup photography. Other equipment is available for applications as esoteric as copying and slide duplication. Double Cable Release operation is possible with an adapter. Stopped-down AE is set with the same handy buttons as the other modes. An aperture symbol on the LCD display signifies the mode. All you have to do is choose the aperture, focus and shoot.

* T50 has no provision for stopped down AE and thus cannot used with older FL lenses.

Viewfinder.jpg
Two Metering Options

Science fiction movies notwithstanding, the computer has yet to be invented that can match the human brain's powers of deductive reasoning.


Nor can computers simulate or anticipate our feelings and emotions. They can only assist us in achieving our goals.

Canon's engineers recognized this. They decided that it was high time the photographer was given more control over one of the key elements in photography: exposure. So, whereas otha electronic cameras feature just one metering system as a compromise solution for multiple situations, the T70 has two metering systems.

Sensor.jpg
Two Metering Options at Your Fingertips

Science fiction movies notwithstanding, the computer has yet to be invented that can match the human brain's powers of deductive reasoning. Nor can computers simulate or anticipate our feelings and emotions. They can only assist us in achieving our goals.
Metercell.jpg

meterswitch.jpg
Center-weighted average metering is available for scenes with unfform lighting, free of harsh contrasting tones and highlights. To cope with strongly backlit subjects and when using long focal length lenses, there's Selective Area (Partial) metering. Metering mode selection is made by a simple slide switch.

Average.jpg
Center-weighted average metering Light coming throug,h the lens is refocused by an aspherical metering element and prism onto a highly sensitive SPC located above the eyepiece.
Averagegraph.jpg

Partial.jpg
Selecthe Area metering Overreliance on one metering system can result in disappointment. An extremely bright background, for example, will fool an average type exposure meter, causing the subject to come out too dark. The T70 solves the problem with the addition of Selective Area metering.
Partialgraph.jpg

This restricts metering sensitivity to the frame's central portion, or 11% of the image area.

The output from two independent photosensitive areas of the SPC is switched electronically to change the metering pattern. The patterns themselves, depicted above and on the facmg page by a three-dimensional computer graphics model and chart, are based on an exhaustive analysis of thousands of photographicc situations. In Center-weighted average metering, sensitivity is concentrated on the central picture area - the normal subject positlon and diminishes toward the edges. A backlit subject positioned off-center presents no difficulty, either. In the Selective Area mode, pressing the shutter button halfway or pressing the exposure preview button locks the exposure. Simply take a reading of the subject close up, then recompose the picture and release the shutter. The AE lock works with both Shutter-priority AE and the program modes.

LCD Illustrate.jpg (13k) Flowchart.jpg.jpg

LCD battery.gif
3-Level battery check The battery check doesn't just inform ffthe batteries are dead or okay.

It also tells you their strength. Three dashes indicate fully charged condition, two dashes satisfactory level. Change the batteries when only one dash appears.

LCD ASA.gif
Film speed button Film speeds from ISO 12 to 1600 can be set.

Keeping the film speed button depressed, tap the UP or DOWN shfft button to select the speed. Press the shfft button continuously and the speeds advance automatically pausing briefly at the most commonly used film speeds of ISO 25, 100 and 400).

LCD Mode Selector.gif
AE Mode Selector Mode selection is a simple, two button operation.

While pressing the AE mode selector, set the desired mode with either shfft button. The modes advance in the sequence of Tv (time value) for Shutter-priority AE, Wide Program, Standard Program and Tele Program.

LCD AE.gif
Shutter speed selection

Set the mode to Tv first and shutter speeds from 1/1000 sec down to 2 sees and bulb can be keyed in with the shfft buttons.

LCD ShutterSpeed.gif

Self-timer operation


The self-timer provides a l second digital countdown as well as the usual audible warning. The beep tone increases in tempo two seconds before shutter release. To cancel the self-timer, press the battery check button.

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