by James H Coleman
Australian Photography May 1985
Minolta is the first cameramanufacturer to break the focus barrier with this engineering marvel incorporating into its compact body an automatic focusing mechanism and practically every other current single lens camera operating technique.
As well as a perfectly functioning autofocus, the X7000 provides auto exposure control, auto load, advance and rewind, auto flash exposure control off-the-film, self-timer, and DX film speed setting.
Another important advancement is automatic exposure programme selection coordinated with the focal length of lens in use, which furthermore is continually adjusted as required when a zooming lens is in operation. In addition to this 'adjustable' programmed facility, the X7000 offers aperture-priority, shutter-priority, and metered manual systems. The models sold on the Australian market are called the Minolta X7000, but for North America the cameras are labelled Maxxum, a measure to protect legitimate importers from having to guarantee equipment bought overseas from unknown sources.
The autofocus operation is actuated by pressing the shutter release button halfway down. The image sighted in the focus zone - delineated by a small rectangle in the centre of the viewfinder - passes through the semi-silvered part of the mirror and is protected by dual optics onto charge coupled device (CCD) sensors in the camera base. With reading from these coupled with input from the lens, an eight-bit central processing unit (CPU) determines within milliseconds the exact focusing movement required. Guided by digital signals from the CPU, a four-speed micromotor drives the lens to the focus spot at up to hundreds of revolutions a minute. The moment the subject comes into precise focus, a green LED lights in the viewfinder, accompanied by an audible 'beep' if desired. This dual signal operates even when focusing manually.
Three modes in one
The focus mechanism works in low-light situations down to EV 3 (f2 at ~z sec. ISO 100), and with the addition of the programme flash 2800AF illuminator, provides a focusing light for complete darkness. The programme is actually three modes in one. The shutter speed and aperture are set according to one of three AE programmes with different slopes, according to the focal length in use or variation through zoom. Infinitely-variable combinations are selected to favour greater depth of field for lenses shorter than 35mm, more standard settings for lenses 35mm to 105mm, and tele settings for longer lenses.
In aperture priority, available apertures are selectable in half-stops and stepless shutter speeds are co-ordinated accordingly. In shutter priority, speeds 1/2000 to 30 sec. are selectable in full stops, and the camera selects aperture.
For metered manual, speeds are selected by touch buttonslocated next to top-deck display panel, and the apertures selected by another pair of buttons to the left of the lens, operated by the user's other hand.
The X7000's new 'A' mount incorporates electrical contacts through which focus and exposure-related information is transmitted to body CPUs from the read-only-memory (ROM) integrated circuit built into each lens. There is also a coupler driving the lens' focusing mechanism and simultaneously encoding rotation data for feedback to the focusing CPU. One of the technical firsts involved in the new X7000 system is based on a rear-component movement for focusing, plus a compound aspheric front element.
Another unique aspect is the Quick Programme Shift. A separate key allows the operator by an instant touch to increase or decrease shutterspeed or lens opening by half-stops while in programme mode. Also a separate 'P' touch button instantly switches operation to full programme if required. All information is continuously shown on the digital display panel on the camera's top deck on the viewfinder. Both displays include exposure mode, auto/manual shutter speed and stop number, exposure adjustment, over/under-exposure warning and film speed. In addition, the display read-out shows drive mode (single exposure, sequence or self-timer), manual setting indications, frame count, self-timer countdown and long-exposure duration. Additional signals in the viewfinder are focus signals, flash-ready plus exposure-confirmation signals, and metered-manual indicator. Nearly every other picture-taking situation has been anticipated. Auto exposure hold is arranged by a special button in right-thumb position for making specific measurements in, for instance, backlight situations. Focus-hold is by retaining finger pressure on the release button. Film-load is clearly indicated by a small window in the back of the camera through which the cassette designation is clearly visible.
A range of accessories has been produced to extend the range of the X7000's operation. Among the 12 integrated autofocus lenses available are 35-70mm f4, 28-135mm f4-4.5, 28-85mm f3.5-4.5, 35-105mm f3.5-4.5, and 70-210mm f4 zoom lenses and 24mm f2.8, 28mm f2.8, 28mm f2.8, 50mm f1.4, 50mm f1.7, 50mm 2.8 Macro, 135mm f2.8, 300mm f2.8 Apo fixed focus designs.
Two programme backs are available, the model 70 which controls camera/flash control, data imprinting, long exposures and intervalometer operation with push-button operation, and the model Super 70 which offers a built-in microcomputer allowing operators to select exposure programmes including automatic bracketing and concealed data imprinting.
A control grip CG-1000 attached to the X7000 allows two flash units to be used -- one on the grip and one on the camera. There are also three optional focusing screens, a remote control cord, wireless controller, and external battery pack.
As basic power for the X7000 is provided by four AAA alkaline-manganese batteries, an optional pack utilising four AA A/M or rechargeable batteries can be fitted, though this adds slightly more bulk to the righthand-grip section of the camera body.
1. Exposure modes
2. Film speed indicator
3. Exposure adjustment reminder
4. Frame counter/self-timer countdown/"bulb" elapsed time
5. Shutter speed/lfilm speed
6. Selectable-setting indicators
7. Aperture/exposure adjustment
8. Drive modes/self-timer
1. Focus frame
2. Acute·Matte focusing screen
3. Focus signals
4. Flash signal
5. Exposure modes
6. Shutter speedl film speed
7. Metering indicators
8. Aperturel exposure adjustment
9. Exposure adjustment reminder
As with any new model apparatus, the Minolta X7000 presented a learning challenge that was quickly overcome. In operation, the Minolta X7000 is a delight. As the 'in-house' focusing is so simple it can be found to be slightly sensitive.
The shutter release button is unusually small, so some care is required in carrying out the two functions, (1) slight pressure to focus and check the exposure measurements before (2) final pressure to fire the shutter. In any case, the speed and accuracy of focusing is at first almost too good to be believed. As with most autofocus lenses, it must be remembered that the triangulation system must have an element to 'grab', just like a split-image rangefinder, so there must be an element of high/low contrast to fix on. However the ground glass indication of in-focus is the final proof, and it is very positive.
The ultimate test of this camera's unique brain power in automatically adjusting to picture-taking requirements can be proved by making a test in the programme mode with a zoom lens with exposures at variolls focal lengths, as we did with a 35-70mm zoom lens. From the one fixed position our test pictures were assessed by the variable monitor system as: 5 feet 1/125 at f4, 20 feet -- 1/750 atf15, and 50 feet -- 1/500 at fll. Though this could not have been considered a laboratory test, the results on the negative were absolutely consistent.