Modern Classic SLR Series
Contax RTS II - Other Issues - Part III


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Auto Exposure (AE) Mode

Once the Shutter Speed Dial is locked into the "A" setting, the Contax RTS II Quartz is set in the AE Mode for completely automatic exposure, where it has proven to be more responsive than manual control in many situation. The photographer merely chooses an aperture setting, and the camera will automatically set the proper shutter speed for an optimum exposure.

<<<<<<<----- Illustrating the pathway to the metering system in a modern SLR camera. There are two locations where the SPD metering cells locate. The one at the eyepiece is for counterweighted ambient light measurement while the SPD at the base of the camera, facing backward toward the film plane is for measuring light real-time reflects off the film plane when the shutter opens during a TTL flash exposure.



Comparing technologies used in the metering system for a two decades old CONTAX RTS II QUARTZ with any of a Y2K's Autofocus SLR such as one of those top of the line AF models from Canon, Nikon or Minolta, you will find great similarity among them.

In a automatic exposure operation (when the shutter speed dial is set to lock at "A" position or If the photographer wishes an indication of the approximate shutter speed the camera has selected, this is provided by the Viewfinder Data Display at a single touch of the Exposure Check Button, which turns the display on for 16 seconds. The auto-selected shutter speed will be displayed by a digital LED steadily lit, to the right of the finder frame.

AE SetDial.jpg
If two adjacent LEDs are lit, this indicates that the camera has selected a shutter speed which is in between the standard settings. (Both "500" and "250" lit would perhaps indicate a speed of 1/350 sec.). In case the ambient light is too intense to provide a correct exposure at the working aperture, the display will signal the need for selection of a smaller aperture by lighting the "OVER" LED indicator. If the "B" indicator lights, the exposure will fall between 4 and 16 seconds, or the scene is in danger of under exposure.

Manual Exposure Mode

Although in auto exposure is sufficiently good to cover most photographic situations, however, there may be time where the surrounding lighting condition is changing too rapidly to call for manual mode operation for consistent exposure control or for any reason If the photographer wishes to use the RTS II Quartz in Manual mode, setting shutter speed/aperture combination himself, the Shutter Speed Dial should first be unlocked from the "A" setting and set to any desired shutter speed.

After pressing the Exposure Check Button to activate the Viewfinder Display, the photographer will see two of the shutter speed LEDs lit up. One of these will be lit steadily, indicated the proper shutter speed as determined by the camera's own SPD metering; the other will flash at regular intervals to indicate the actual speed at which the shutter dial is set.

To achieve a correct exposure, the photographer should adjust shutter and/or aperture settings until only one shutter speed LED is flashing steadily. At this point, the photographer may release the shutter, or may make fine adjustments of the aperture ring to achieve slight over or under exposure.

EV based AE Lock Function

When operating in AUTO mode, there are still a few ways to manipulate exposure the camera has set. First is by means of an AE (auto-exposure) lock, the next is via the exposure compensation dial and lastly, a more primitive way is to alter exposure by changing the ASA film speed.

AE Lock lever.jpg
One of the main feature found in the Contax RTS II Quartz during the '80 was a feature called AE Lock (Auto-exposure Lock) function which has facilitates faster operational sequences handling a SLR camera during shooting. Although its is easy to operate but it is also good to understand how it works. This is closely associate with the term Exposure Value (EV).

Exposure Value is actually a range of light intensity which depends on various factors. EV capabilities indicate the range of ambient light within which the exposure system is designed to work, and are usually provided according to standards which include ASA 100 film and a 50mm lens with a maximum aperture of f/1.4. Under these conditions, for example, the RTS II Quartz is capable of metering accurately the range from -1 to + 19 EV - one of the widest sensitivity ranges of any 35mm SLR camera, a figure ranked quite highly among comparing professional class SLRs, the more popular Nikon F3 has EV1~ EV18, just for an example. The major advance in the AE Lock function of the RTS II Quartz is that it locks the camera's exposure system according to an EV setting, rather than merely freezing a shutter speed as other similar functions do. Thus, if the aperture setting is changed after the AE Lock function is activated, the camera will automatically change shutter speed to maintain proper exposure at that EV level. This allows the photographer to expose a series of photographs at a consistent EV, for example, even while varying aperture settings in order to obtain different depth-of-field effects.

Exposure Compensation Function

In order to overcome backlighting, or to enhance mood or highlight details in a photograph, the Contax RTS II Quartz provides a +2-stop Exposure Compensation adjustment. This is used to increase or decrease the overall exposure of the photo, and operation is indicated in the viewfinder.

For cases of extreme backlighting, where a factor of greater than two aperture settings is involved, the AE Lock function can be used to lock in the proper exposure setting for the main subject. In order to maintain least disturbance of auto exposure reading, especially in unmanned situation such as self-timer operation, there is also a conveniently placed but highly functional view finder eyepiece blind that can be used to shut off any stray light into the eyepiece that might affect metering accuracy.

Viewfinder Eyepiece-Blind Lever: A feature first saw in the Canon AE-1 in 1976 but proved to be a very useful feature for all auto exposure camera which has metering cells near the eyepiece. This lever closes a special curtain over the camera's eyepiece, in order to prevent extraneous light from interfering with the sensitive exposure metering system, when the camera is being operated by remote control.

Metering Pattern for auto/manual and flash photography

Metering patterns control the functions of the photocell. The same lighting conditions measured with the same metering system will result in different readings (and consequently different exposure values), depending on how the photocell "senses" the light. The ability of the photocell to determine actual lighting conditions is controlled in large part by the metering sensitivity pattern. <<<<<<<---- A computer simulated image of a typical center weighted average metering pattern.

This pattern tells the photocell just how much light is falling on which areas of the image. Generally, the applications for which the camera was intended determine which metering sensitivity pattern is to be used. Metering sensitivity patterns an important issue but Contax adopted a more conservative approach as opposed to other such as Canon New F-1 (1981) way of using focusing screen to alter the metering sensitivity patterns or the Olympus OM3/OM4 (1983) way of providing multi-spots metering on top of their counterweighted average metering system.

Center-weighted metering pattern for auto/manual exposure. For normal shooting in either AE or manual mode. The sensitivity de creases progressively from the center to the edges. The pattern remains unchanged regardless of the lens focal length, and center-weighting in the horizontal direction is greatly accentuated to minimize difference in exposure between horizontal and vertical positions.
Center-weighted metering pattern for flash photography. More incline towards the center with emphasize on the lower half portion in the picture frame as most flash applications are presumably concentrate at the middle.

The macrophotography and photomicrography segment demands higher magnifications and precise framing and composition. The 97% field view is a welcoming improvement.

<<-- Both images from my Copyright ©-Free image collection, 2000 leofoo® Malaysian Internet Resources.

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The immediate obvious difference is the large viewfinder image projects inside, which means, in fact, that this small camera actually has a larger-than-normal viewfinder screen combined with wide-angle viewfinder optics. The result is an image about 30 per cent greater than in most other 35 mm SLRs and that includes the previous original RTS's poor 92 % picture angle. Although the finder magnification ratio of 0.87X at infinity when used with a 50 mm lens, the image project inside the viewfinder is comfortably big for easy picture composition.

97% Field-of-View A major improvement in the RTS II Quartz is its expanded field-of-view to fully 97% of the actual film frame from a below average 92% presented in the original CONTAX RTS. This is a distinct advantage in providing the photographer with a view that incorporates enough of the frame to insure that composition will be precise, and that unwanted or distracting elements will not be included in the actual scene.

LED Data Display

Basically, there are a few popular methods used by camera manufacturers to display exposure data in the viewfinder. Most have selected match needle which has a clear dominate during the seventies. The late seventies saw the creative use of LEDs (light Emitting Diodes) as alternative as the property has a far superior positive visual identification in many situations especially unfavorable lowly lit or even in high contrasty situation. However, the Nikon F3 started the LCD (Liquid Crystal Display) in 1980 and tends to become a mainstream display method in all modern cameras.

However, that was mainly due to its energy saving property as LCD consumes only 1/10 of power of comparing LEDs. But the superior characteristic of LEDs is still unchallenged by neither LCD nor the old fashion match needle system.

The LED display was chosen for the RTS II Quartz viewfinder which offers one of the world's most sophisticated Viewfinder Data Display systems for manual focus 35mm photography.

A quick outline of the data available to the photographer in the viewfinder includes: Shutter Speed, Aperture Setting, Exposure Compensation Indication, AE/Manual Mode Indication, AE Lock Use, overexposure Warning, TLA Flash Data and Battery Check.

16-Second Auto cutoff:
The LED Data Display is activated for 16 seconds by pressing the Exposure Check Button (located on the front of the camera body). After 16 seconds, the display will automatically cut off, in order to prevent unnecessary battery power drainage. The display can be activate again simply by pressing the button once more. Even with the display off, the LEDs will briefly light to provide exposure data to the photographer when the shutter is released in the AE Mode. In addition, the LED Data Display has an automatic two-stage brightness control, which brightens or dims the intensity of the LEDs depending on ambient light conditions. This makes the display particularly easy to read under extremely dim ambient lighting.

Brightest SLR Viewfinder: The Contax RTS II Quartz features the consistently brightest viewfinder available on any 35mm SLR camera. Viewfinder brightness is an extremely difficult factor to quantify, depending greatly on what section(s) of the viewfinder are measured, and at what aperture values. However, no other 35mm SLR can match the consistent brightness, corner-to-corner and at all aperture values, of the RTS II Quartz. This means faster, easier, more accurate focusing under any conditions, with any lens or optical-path accessory.

<<<<<<........ LiJiang, Yunan Province. Copyright © 2000 MCLau ®

Battery Check: Advance warning of reduced battery power is provided by the LED system. When the LEDs light steadily, or flash at regular intervals, battery power is sufficient. Should the LED display begin to blink rapidly, battery power is declining, and the battery should be replaced. However, as a emergency measure, there are two mechanical shutter speeds of 1/50sec and "B" which are battery independent should the battery fails or depleted.

Over Exposure Warning: Should the "OVER" LED light when the camera is in AE mode, a smaller aperture must be selected in order to properly expose the film. (This indication also operates with TLA Flash equipment.)

AE Lock Use: When the camera is in the AE mode, the indicated shutter speed LED will flash at regular intervals when the AE Lock function is activated.

meterbar500.gif metrbarmanual.gif
AE/Manual Mode Indication: Indication as to whether the RTS II Quartz in operating in AE or Manual exposure mode is provided by the Shutter Speed LED Display. In AE mode (Aperture Priority AE), the shutter speed will display and supplemented by other icons or indicators when operating in assisted mode such as activating exposure compensation, AE Lock etc.

Exposure Compensation Indication: Use of the camera's exposure compensation function is indicated by the lighting of a ( + ) or (-) LED at the bottom of the frame.

Aperture Setting: The aperture setting of the lens is displayed by a seven-segment digital LED at the bottom of the finder frame.

Shutter Speed Setting: Shutter speeds are displayed by digital LEDs situated to the right of the finder frame. There are 16 digital LEDs to indicate the operating speed, from 1/2,000 sec. to 4 seconds and "B". In addition, the "OVER" LED indicator and the TLA Flash " " indicator are located just above the shutter speeds. This has facilitated a more responsive photographic experience even if it demands instinctive response to sudden action or events.

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1975: RTS
1979: 139Q
1980: 137MD
1982: 137MA
1982: RTS II
1985: 159MM
1987: 167MT
1990: RTS III
1992: S2
1992: S2b
1992: ST
1994: RX
1996: AX
1998: Aria
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Credit: MClau, joint maintainer of the Contax RTS MB. Some of the content are extracts from: Cees De Groot, who maintains a Contax FAQ site and Tim Roger website on Contax SLR cameras, A few of the images on Zeiss lenses were downloaded from Contax US website. My buddy, Yeak & Rizal Yahya, for their cool programming with Contax RTS's Message Board, Note:certain contents and images appeared in this site were either scanned from official marketing leaflets, brochures, sales manuals or publications published by Kyocera over the years and/or contributions from surfers who claimed originality of their own work solely for educational purposes. The creator of the site will not be responsible for any discrepancies that may arise from such possible disputes except rectifying them after verification."Kyocera", "Yashica", "Contax" & "Carl Zeiss T*" are registered trade names of Kyocera Corporation Inc., Japan. A site made with an Apple IMac, dedicated to all fans of Contax cameras and Zeiss Optics.