Mamiya/Sekor 500 DTL

35mm MF film SLR camera


Production details
Announced:July 1968
System: Mamiya TL/DTL M42 (1966)
Imaging plane
Maximum format:35mm full frame
Mount and Flange focal distance:M42 [45.5mm]
Imaging plane:36 × 24mm film
Speeds:1 - 1/1000 + B
Exposure metering:Through-the-lens (TTL)
Exposure modes:Manual
Physical characteristics

Manufacturer description #1

The Mamiya/Sekor DTL Series 35mm single lens reflex cameras incorporate two separate thru-the-Iens metering systems - one system for "Spot" readings and one system for "Averaging" or integrated readings. This technological breakthrough represents the most significant advance in 35mm Single Lens Reflex picture taking since Mamiya's engineers created the eminently successful TL series.

The Mamiya/Sekor DTL system offers the following advantages: (1) It measures the raw light as it passes through the lens, and this is done at the same aperture as is used in taking the picture. (2) It can be used as either a true spot meter, measuring only that portion of the picture deemed most important by the photographer - or an averaging meter, measuring the entire picture so as to provide an average reading for a subject with a variety of contrasting tones. (3) It does not slow down the picture taking process because Mamiya/Sekor's Human Engineering controls, provide for switching the meter "on" and "off," and the selection of the "Spot" or the "Averaging" mode of light measurement while the camera is in the picture-taking position. (4) There are no complicated mechanical or electronic systems that may go out of adjustment and require expensive repairs. There are no special calculations or compensations to be applied when using non-automatic lenses or lens attachments.

Best of all, Mamiya achieved the incorporation of two separate thru-the-Iens metering systems in a single camera without any compromise whatever in the quick and efficient use of the camera.

With the introduction of the new Mamiya/Sekor DTL Series cameras, it was unnecessary for Mamiya's engineers to sacrifice any of the superb innovations which were characteristic of the TL Series. In retaining and improving upon Mamiya/Sekor's highly acclaimed Human Engineering features, the designers extended and enhanced the efficiency of a system already established as a leader in its field.

[1] The film speed dial incorporates both ASA and DIN scales, with new film speed ratings of from 25 to 3200 ASA and 15 to 36 DIN. All settings are clearly defined by engraved numbers. The electronic flash synchronization speed setting (1/60 sec.) is shown in red.

[2] An exposure meter "off" locking button is conveniently located on the top of the center shaft of the film advance lever. Simply depressing this button locks the meter in the "off" position and retracts the film advance lever.

[3] The large viewfinder on the DTL insures a comfortable and adequate view of the picture area as covered by the lens, even if the photographer wears glasses.

[4] The oversized instant return mirror of the DTL offers protection against a vignetted image when lenses of extremely long focal lengths are used, and distributes the light evenly over the entire viewing screen for effective viewing and accurate meter readings.

[5] Mamiya/ Sekor's Human Engineering design places all the essential controls of the camera so that they may be operated with a minimum of effort on the part of the photographer. An entire roll of film may be correctly exposed in the DTL camera, covering a variety of lighting conditions without ever removing the camera from the picture taking position.

[6] Mamiya/Sekor lenses are characterized by their silky smooth action, functionally located controls and optical excellence. An added advantage of the universal thread lens mount is the availability of thousands of lenses of other manufacturers, all designed to fit this mount. The owner of the new DTL camera may choose 35mm SLR lenses of practically any focal length, mechanical construction or optical design.

[7] Focusing the Mamiya/Sekor DTL is extremely easy, because of the efficient fresnel viewing screen with the micro-diaprism rangefinder center spot and matte ring. This combination provides for a brilliant view of the subject, accurate determination of depth of field, and rapid critical focusing adjustments.

[8] A visual control center keeps the photographer in complete control of all camera operations. All control function indicators, including exposure needIe and reference points, the 6% spot reading area, the "Spot" or "Average" mode indicator and a micro-diaprism focusing spot, are precisely located in the viewfinder of the Mamiya/Sekor DTL, providing continuous visual control of all the camera's functions.

[9] The lens mount with universal thread incorporated in the Mamiya/Sekor DTL Series is precisely machined to insure proper seating and alignment of all compatible lenses and optical attachments. This simple but proven design reduces the risk of costly damage often encountered during the changing of lenses on cameras using other lens mounts.

[10] Full flash synchronization is provided by Mamiya/Sekor's separate "FP" and "X" terminals. A complete range of shutter speed and terminal combinations enable the photographer to choose from an extended variety of flash bulbs and electronic flash equipment.

Manufacturer description #2

To take more exciting and creative pictures, you need more control of your exposures. Regardless of the source or sources of light, you should be able to record the scene exactly as you see it. Only the Creative Switch on the Mamiya/Sekor DTL makes this possible. It even protects your imagination from unthinking automation which can read the scene, but doesn't know what's important in it to you.

For the easy shots with front lighting, set the Creative Switch on the Mamiya/Sekor DTL to "A" for an averaged meter reading. If the subject is back or sidelit, or the lighting gets a little confusing, switch to "S" and take an exact spot reading of the most important element in your scene. Almost all fine focal plane 35mm SLR cameras have one of these metering systems; only the Mamiya/Sekor DTL has both. And you need both to capture every picture that your lively imagination can discover.

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35mm full frame

43.27 24 36
  • Dimensions: 36 × 24mm
  • Aspect ratio: 3:2
  • Diagonal: 43.27mm
  • Area: 864mm2

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Image stabilizer

A technology used for reducing or even eliminating the effects of camera shake. Gyro sensors inside the lens detect camera shake and pass the data to a microcomputer. Then an image stabilization group of elements controlled by the microcomputer moves inside the lens and compensates camera shake in order to keep the image static on the imaging sensor or film.

The technology allows to increase the shutter speed by several stops and shoot handheld in such lighting conditions and at such focal lengths where without image stabilizer you have to use tripod, decrease the shutter speed and/or increase the ISO setting which can lead to blurry and noisy images.

Original name

Lens name as indicated on the lens barrel (usually on the front ring). With lenses from film era, may vary slightly from batch to batch.


Format refers to the shape and size of film or image sensor.

35mm is the common name of the 36x24mm film format or image sensor format. It has an aspect ratio of 3:2, and a diagonal measurement of approximately 43mm. The name originates with the total width of the 135 film which was the primary medium of the format prior to the invention of the full frame digital SLR. Historically the 35mm format was sometimes called small format to distinguish it from the medium and large formats.

APS-C is an image sensor format approximately equivalent in size to the film negatives of 25.1x16.7mm with an aspect ratio of 3:2.

Medium format is a film format or image sensor format larger than 36x24mm (35mm) but smaller than 4x5in (large format).

Angle of view

Angle of view describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term field of view.

As the focal length changes, the angle of view also changes. The shorter the focal length (eg 18mm), the wider the angle of view. Conversely, the longer the focal length (eg 55mm), the smaller the angle of view.

A camera's angle of view depends not only on the lens, but also on the sensor. Imaging sensors are sometimes smaller than 35mm film frame, and this causes the lens to have a narrower angle of view than with 35mm film, by a certain factor for each sensor (called the crop factor).

This website does not use the angles of view provided by lens manufacturers, but calculates them automatically by the following formula: 114.6 * arctan (21.622 / CF * FL),


CF – crop-factor of a sensor,
FL – focal length of a lens.


A lens mount is an interface — mechanical and often also electrical — between a camera body and a lens.

A lens mount may be a screw-threaded type, a bayonet-type, or a breech-lock type. Modern camera lens mounts are of the bayonet type, because the bayonet mechanism precisely aligns mechanical and electrical features between lens and body, unlike screw-threaded mounts.

Lens mounts of competing manufacturers (Canon, Nikon, Pentax, Sony etc.) are always incompatible. In addition to the mechanical and electrical interface variations, the flange focal distance can also be different.

The flange focal distance (FFD) is the distance from the mechanical rear end surface of the lens mount to the focal plane.

Lens construction

Lens construction – a specific arrangement of elements and groups that make up the optical design, including type and size of elements, type of used materials etc.

Element - an individual piece of glass which makes up one component of a photographic lens. Photographic lenses are nearly always built up of multiple such elements.

Group – a cemented together pieces of glass which form a single unit or an individual piece of glass. The advantage is that there is no glass-air surfaces between cemented together pieces of glass, which reduces reflections.

Focal length

The focal length is the factor that determines the size of the image reproduced on the focal plane, picture angle which covers the area of the subject to be photographed, depth of field, etc.


The largest opening or stop at which a lens can be used is referred to as the speed of the lens. The larger the maximum aperture is, the faster the lens is considered to be. Lenses that offer a large maximum aperture are commonly referred to as fast lenses, and lenses with smaller maximum aperture are regarded as slow.

In low-light situations, having a wider maximum aperture means that you can shoot at a faster shutter speed or work at a lower ISO, or both.

Closest focusing distance

The minimum distance from the focal plane (film or sensor) to the subject where the lens is still able to focus.

Closest working distance

The distance from the front edge of the lens to the subject at the maximum magnification.

Magnification ratio

Determines how large the subject will appear in the final image. For example, a magnification ratio of 1:1 means that the image of the subject formed on the film or sensor will be the same size as the subject in real life. For this reason, a 1:1 ratio is often called "life-size".

Manual focus override in autofocus mode

Allows to perform final focusing manually after the camera has locked the focus automatically. Note that you don't have to switch camera and/or lens to manual focus mode.

Manual focus override in autofocus mode

Allows to perform final focusing manually after the camera has locked the focus automatically. Note that you don't have to switch camera and/or lens to manual focus mode.

Electronic manual focus override is performed in the following way: half-press the shutter button, wait until the camera has finished the autofocusing and then focus manually without releasing the shutter button using the focusing ring.

Manual diaphragm

The diaphragm must be stopped down manually by rotating the detent aperture ring.

Preset diaphragm

The lens has two rings, one is for pre-setting, while the other is for normal diaphragm adjustment. The first ring must be set at the desired aperture, the second ring then should be fully opened for focusing, and turned back for stop down to the pre-set value.

Semi-automatic diaphragm

The lens features spring mechanism in the diaphragm, triggered by the shutter release, which stops down the diaphragm to the pre-set value. The spring needs to be reset manually after each exposure to re-open diaphragm to its maximum value.

Automatic diaphragm

The camera automatically closes the diaphragm down during the shutter operation. On completion of the exposure, the diaphragm re-opens to its maximum value.

Fixed diaphragm

The aperture setting is fixed at F/ on this lens, and cannot be adjusted.

Number of blades

As a general rule, the more blades that are used to create the aperture opening in the lens, the rounder the out-of-focus highlights will be.

Some lenses are designed with curved diaphragm blades, so the roundness of the aperture comes not from the number of blades, but from their shape. However, the fewer blades the diaphragm has, the more difficult it is to form a circle, regardless of rounded edges.

At maximum aperture, the opening will be circular regardless of the number of blades.


Excluding case or pouch, caps and other detachable accessories (lens hood, close-up adapter, tripod adapter etc.).

Maximum diameter x Length

Excluding case or pouch, caps and other detachable accessories (lens hood, close-up adapter, tripod adapter etc.).

For lenses with collapsible design, the length is indicated for the working (retracted) state.

Weather sealing

A rubber material which is inserted in between each externally exposed part (manual focus and zoom rings, buttons, switch panels etc.) to ensure it is properly sealed against dust and moisture.

Lenses that accept front mounted filters typically do not have gaskets behind the filter mount. It is recommended to use a filter for complete weather resistance when desired.

Fluorine coating

Helps keep lenses clean by reducing the possibility of dust and dirt adhering to the lens and by facilitating cleaning should the need arise. Applied to the outer surface of the front and/or rear lens elements over multi-coatings.


Lens filters are accessories that can protect lenses from dirt and damage, enhance colors, minimize glare and reflections, and add creative effects to images.

Lens hood

A lens hood or lens shade is a device used on the end of a lens to block the sun or other light source in order to prevent glare and lens flare. Flare occurs when stray light strikes the front element of a lens and then bounces around within the lens. This stray light often comes from very bright light sources, such as the sun, bright studio lights, or a bright white background.

The geometry of the lens hood can vary from a plain cylindrical or conical section to a more complex shape, sometimes called a petal, tulip, or flower hood. This allows the lens hood to block stray light with the higher portions of the lens hood, while allowing more light into the corners of the image through the lowered portions of the hood.

Lens hoods are more prominent in long focus lenses because they have a smaller viewing angle than that of wide-angle lenses. For wide angle lenses, the length of the hood cannot be as long as those for telephoto lenses, as a longer hood would enter the wider field of view of the lens.

Lens hoods are often designed to fit onto the matching lens facing either forward, for normal use, or backwards, so that the hood may be stored with the lens without occupying much additional space. In addition, lens hoods can offer some degree of physical protection for the lens due to the hood extending farther than the lens itself.


Teleconverters increase the effective focal length of lenses. They also usually maintain the closest focusing distance of lenses, thus increasing the magnification significantly. A lens combined with a teleconverter is normally smaller, lighter and cheaper than a "direct" telephoto lens of the same focal length and speed.

Teleconverters are a convenient way of enhancing telephoto capability, but it comes at a cost − reduced maximum aperture. Also, since teleconverters magnify every detail in the image, they logically also magnify residual aberrations of the lens.

Lens caps

Scratched lens surfaces can spoil the definition and contrast of even the finest lenses. Lens covers are the best and most inexpensive protection available against dust, moisture and abrasion. Safeguard lens elements - both front and rear - whenever the lens is not in use.