SRT101

(1966)  Minolta had finally done it.  In 1966, it began production of an SLR with a TTL meter and interchangeable lenses.  It took the industry by storm and blew away the competition. Why?  Because it operated with a fully-automatic aperture!  Sure, there were lots of other German and Japanese 35mm SLR cameras that had auto-diaphragms, interchangeable lenses, and even built-in, TTL meters, but all of them had at least one major drawback.  For example, the other camera companies that were offereing TTL metering at that time were using awkward, stop-down metering systems, such as the Asahi Spotmatic of 1964, the Canon FT of 1966 and the Mamiya 1000TL of 1966.  So even if their camera sported auto-diaphragm lenses, the photographer still had to stop-down the lens in order to take a meter reading. In this metering approach, you press a switch on the camera body  which stops-down the lens and activates the meter. Only at that point can the meter take a reading. Not only is this process awkward, it defeats the whole purpose of having an automatic lens -- to keep the lens open and the viewfinder bright until the instant of the exposure!   Other cameras, such as the Nikon Nikkormat of 1965, whcih had full-aperture metering, required the photographer to match up lugs on the camera and the lens -- before attaching the lens -- for accurate metering. What a pain! But Minolta was able to avoid all of these pitfalls.

The biggest technical obstacle to developing a TTL metering system with fully automatic lenses is that the meter in the camera needs to know the f-stop setting on the lens -- because an automatic lens always stays at it maximum aperture.  The lens and the camera have to be able to "talk" to each another.  For most other camera manufacturers, the f-stop ring had been placed in the middle or at the front of the lens.  This made linking the f-stop ring and the camera's TTL metering system a difficult challenge.  For most companies, this would mean redesigning their entire line of SLR lenses.  Instead, they offered the consumer stop-down metering, and hoped no one would notice.  

Minolta was able to avoid the whole problem of "stop-down" metering because they happened  to design most of their Auto-Rokkor lenses -- from the very beginning -- with the aperture ring next to the camera body.  By placing a small lug on the Auto-Rokkor f-stop ring, and placing a matching spring-loaded pin on the SRT101 camera body, the problem was solved.  The lens conveys the selected f-stop to the camera meter as the aperture ring is turned.  The pin on the camera conveyed the f-stop adjustment to the built-in, TTL meter. A 4mm change in the f-stop ring on the lens changes the TTL meter reading in the camera by one f-stop. The meter is then able to determine the appropriate shutter speed -- for that scene, shutter speed and film speed -- while the lens diaphragm stays open at its maximum setting.  This is just one of the reasons why Minolta was able to keep their lens mount the same over all these years, while nearly every other camera manufacturer has had to make significant changes in their lenses.  

With this modification, the MC Rokkor lenses were born and stop-down metering became a thing of the past -- well,  if you owned a Minolta SRT101!  The "MC" in "MC Rokkor" refers to "meter-coupling" -- not "multi-coating", as some people think. These lenses were double-coated -- the first lenses ever to offer "multi-coating" (more than one layer of coating). At the time, Minolta didn't refer to it as "multi-coating". They called it "Achromatic coating", but "multi-coating" it was! The older Rokkor and Auto-Rokkor lenses will fit on the new SRT camera because the mount is the same, and will operate correctly, but they cannot couple to the TTL metering system of the SRT101.  Metering with non-MC lenses is accomplished in the "stop-down" fashion.

One challenge to the new system was that, since the lenses remain at the maximum aperture regardless of the pre-set f-stop, there is no way for the photographer to view the actual depth-of-field in the viewfinder -- as you could do easily with older lenses by just pressing the built-in DOF button on the lens. While this approach could still be used with lenses sporting a DOF button, Minolta addressed the issue directly by adding a new DOF (depth-of-field) button to their new SRT101 camera.  This was an easy item for Minolta to add since it was a feature that they had already tried out on the Minolta SR777 prototype. In fact, a stop-down button was required on the SR777 since it was designed to use stop-down metering.  Pressing the stop-down button, stops an automatic lens down to the pre-set aperture, so that you can view the actual depth-of-field in the viewfinder. On cameras with stop-down metering, this button is called the stop-down metering button, but on Minolta cameras, because it is primarily used to check depth-of-field, it is referred to as the DOF button.

But the new TTL meter and new meter-coupled lenses were not the end of the new features of the Minolta SRT101.  That would have been enough to set the industry on fire, but Minolta didn't stop there.  Unlike lenses from other companies, the MC Rokkor lenses were a simple bayonet mount. And I mean simple. Just push a button to take the lens off and just insert and twist to put the lens on. With other companies, like Nikon, Canon, etc. the photographer had to set the f-stop on the lens before attaching it (no kidding) or set the shutter speed before attaching the lens (no kidding) or adjust the ASA film speed setting before attaching the lens (no kidding) or cock the shutter before attaching the lens (no kidding) or release the shutter before attaching the lens (no kidding). It's hard to believe the torment that non-Minolta users went through!

In addition, the new Minolta TTL meter readout was moved from the top of the camera, as in the SR-7, and was placed inside the viewfinder -- an incredible innovation in miniaturization and convenience.  Up until now, photographers would compose the scene in the viewfinder and then have to drop the camera to make exposure adjustments -- and then raise the camera again and re-compose.   One word -- S-L-O-W!

In the SRT101, two "needles" were placed on the right-hand side of the viewfinder and connected to the aperture, shutter speed and film speed settings.  By changing any of these factors, the needles would match up when the exposure was correct.  Just get the needle inside the circle and your exposure will be fine.  And to top it off, Minolta added a battery-check tab in the viewfinder, as well as over- and under-metering-range triangles for very bright and very dark situations.  Yet another new feature of the SRT101 is that the complete range of shutter speeds (1 second to 1/1,000, plus B) is visible in the viewfinder, so you no longer needed to remove your eye from the viewfinder to adjust the shutter speed -- and take a picture.   Other new features included a built-in flash shoe and a switch to turn off the meter -- the latter being a lesson Minolta learned from the SR-7.  The other important advances of the SR-7 were retained, such as the mirror lockup for the super-wide 21mm lens, and a self-timer.  

Minolta studied thousands of photographs in order to determine the best way to accomplish accurate TTL metering.  Different companies had different designs, but Minolta noticed that a large proportion of photographs were really two scenes in one: an upper-half which was often a bright sky, and the lower-half which was typically a darker foreground.  Many pictures were incorrectly exposed due to the inclusion of the bright sky which "over-powered" the foreground and caused the meter to underexpose the main subject -- which is usually in the foreground.  Minolta devised an innovative solution, with a simple modification to the typical TTL metering system.  While most TTL manufacturers used one CDS cell affixed inside the pentaprism, Minolta employed two cells pointed in two directions.  This allowed the camera's meter to view, and compare two different areas of the picture.  The Minolta engineers determined that the typical exposure could be dramatically improved if the sky-portion of the scene had less effect on the exposure.  They were able to accomplish this by having one CDS cell reading the sky (or upper portion of the scene), and a second CDS cell reading the lower-portion of the scene.  The brightness of the sky was then easy to control, and no longer overwhelmed the foreground reading.  Minolta dubbed the new system "CLC" which stands for "Contrast Light Compensation".  On SRT series cameras, if the CLC system is used, it is imprinted on the front plate of the camera, just below the "M" in "Minolta".

There were actually three versions of the SRT101, with slight variations over time, however, these model numbers are not inscribed on the cameras.

• SRT101 (model a) -- (1966)
  
  The original SRT101 (model a) is distinquished by having a black, finely-milled, shutter speed dial similar to the earlier SR cameras.  The SRT101 (model a) originally was only available in chrome, but around 1969 a few black models were made. In either instance, the shutter speed dial is always black.

• SRT101 (model b) -- (1969)
  
  On this model, the black, finely-milled, shutter speed dial is replaced with a dial of three rows of large teeth.   The teeth made it much easier to change the shutter speed with one finger, as you view the changes to the shutter speed in the viewfinder.  The camera was available in chrome or black -- and the color of the shutter speed dial matchs the color of the camera.  While the major features of the SRT101 (model b) are the same as the SRT101 (model a), there are some other minor changes that were gradually added over time -- changes that most people will not notice.  For example, the matte focusing screen shows a less obvious fresnel pattern, some of the external, flat-head screws are replaced with Phillips-head screws and some of the screw locations are different, the pressure plate is a little larger; and the take-up spool has been improved. The SRT101 (model b) must not be confused with the later SRT101b which was really a model of the SRT201, and is covered in that section.

• SRT101 (model c) -- (1971)
  
  On this model, the mirror-lockup option was dropped.  By this time, Minolta knew it would never need to develop another recessed wide-angle lens.  They had succeeded in developing super-wideangle lenses using new optical designs that eliminated the need for the recessed lens design.  Minolta knew that their older 21mm recessed wide-angle would not fit on this camera, so they designed a new 21mm that didn't need the mirror lock-up device.  So users of the SRT101 (model c) would still have the option of a super-wide-angle, 21mm optic.  There were other minor changes as well, such as the revolving ISO dial on the camera back no longer revolves -- as it did on earlier models.  Many a shutterbug had used this feature as a film reminder, but it's roating feature was no longer needed as a reminder since the film speed was dialed into the ASA knob.  Otherwise the noticeable features of this version of the SRT101 are the same.  A black version was also available.
  

The SRT101 would have sold much better had there been better marketing by Minolta.  With all of the other camera companies touting their "automatic lenses", "built-in meters", "TTL metering", "professional features", ad nauseum, it was difficult for the average consumer to separte the wheat from the chaff.  Full-aperture metering was a new concept and the typical new camera buyer had no idea how important it was. And Minolta's marketing never told them. Likewise, the other companies never mentioned in their ads that there were serious limitations to their "advanced metering features", like the need to stop-down the lens.  The benefits of full-aperture metering were incomprehensible to someone who had never owned an SLR camera before.  In fact, Nikon, Canon, Pentax, and Olympus were unable to produce any TTL, full-aperture SLR cameras until 1972 -- six years after the SRT101 made its debut!  Still, despite the lackluster marketing, the SRT101 sold well and was manufactured from 1966 until 1975 -- a run of nine years -- when it was replaced by the more fully-featured SRT201.  The SRT101 was one of the most innovative cameras in photographic history. In fact, it is held in such high regard that an SRT101, in like-new condition, will sell for more today that it cost in 1966! 

For a comparative look at the major features of the SRT101 models, check out MINMAN's SLR table -- the world's most complete!

CAMERA SPECIFICATIONS

Camera	SRT-101	SRT-101	SRT-101
Model	a	b	c
Years made	1966-1969	1969-1971	1971-1975
Type	Mechanical 35mm SLR	Mechanical 35mm SLR	Mechanical 35mm SLR
Shutter	Fully mechanical, horizontal, cloth focal plane shutter	Fully mechanical, horizontal, cloth focal plane shutter	Fully mechanical, horizontal, cloth focal plane shutter
Metering	Built-in TTL CDS meter coupled to shutter speed, aperture, and film speed Contrast Light Compensation (CLC) metering method using dual CDS cells in pentaprism	Built-in TTL CDS meter coupled to shutter speed, aperture, and film speed Contrast Light Compensation (CLC) metering method using dual CDS cells in pentaprism	Built-in TTL CDS meter coupled to shutter speed, aperture, and film speed Contrast Light Compensation (CLC) metering method using dual CDS cells in pentaprism
Meter sensitivity	EV 3 to 17	EV 3 to 17	EV 3 to 17
Exposure modes	Unmetered manual Metered manual using matched needle method	Unmetered manual Metered manual using matched needle method	Unmetered manual Metered manual using matched needle method
Automatic exposure adjustment	--	--	--
Viewfinder	Fixed eye-level pentaprism with complete range of manually selected shutter speeds, over- and under-exposure marks, battery check mark, and two manual exposure match needles	Fixed eye-level pentaprism with complete range of manually selected shutter speeds, over- and under-exposure marks, battery check mark, and two manual exposure match needles	Fixed eye-level pentaprism with complete range of manually selected shutter speeds, over- and under-exposure marks, battery check mark, and two manual exposure match needles
Focusing screen	Fresnel-field screen with a micro-prism center	Fresnel-field screen with a micro-prism center	Fresnel-field screen with a micro-prism center
Lens mount	Minolta SLR bayonet	Minolta SLR bayonet	Minolta SLR bayonet
Lenses	Optimum: MC Rokkor Usable: Auto Rokkor, Rokkor, MC Rokkor-X, MC Celtic, MD Rokkor, MD Celtic, MD Minolta	Optimum: MC Rokkor Usable: Auto Rokkor, Rokkor, MC Rokkor-X, MC Celtic, MD Rokkor, MD Celtic, MD Minolta	Optimum: MC Rokkor Usable: Auto Rokkor, Rokkor, MC Rokkor-X, MC Celtic, MD Rokkor, MD Celtic, MD Minolta
Mirror	Instant return, oversized mirror with lock-up	Instant return, oversized mirror with lock-up	Instant return, oversized mirror
Film speeds	ISO 6 - 6400	ISO 6 - 6400	ISO 6 - 6400
Shutter speeds	Mechanical: 1 - 1,000; B Manual: 1 - 1,000; B	Mechanical: 1 - 1,000; B Manual: 1 - 1,000; B	Mechanical: 1 - 1,000; B Manual: 1 - 1,000; B
Flash synch	X: B; 1 - 1/60 FP: B; 1 - 1/1,000 M: B; 1 - 1/15 MF: B; 1 - 1/30	X: B; 1 - 1/60 FP: B; 1 - 1/1,000 M: B; 1 - 1/15 MF: B; 1 - 1/30	X: B; 1 - 1/60 FP: B; 1 - 1/1,000 M: B; 1 - 1/15 MF: B; 1 - 1/30
Flash connection	Built-in, cold shoe X and FP PC contacts	Built-in, cold shoe X and FP PC contacts	Built-in, cold shoe X and FP PC contacts
Film counter	Automatically resetting type counting upward	Automatically resetting type counting upward	Automatically resetting type counting upward
Battery	one 625 mercury battery	one 625 mercury battery	one 625 mercury battery
DOF/Stop-down button	Yes, locking type	Yes, locking type	Yes, locking type
Film Back	Non-interchangeable	Non-interchangeable	Non-interchangeable
Multiple exposures	No	No	No
Film advance	Lever type	Lever type	Lever type
Self-timer	Mechanical, overrideable, non-cancellable, adjustable from 4 to 10 seconds	Mechanical, overrideable, non-cancellable, adjustable from 4 to 10 seconds	Mechanical, overrideable, non-cancellable, adjustable from 4 to 10 seconds
Film reminder	ASA speed selector Rotating ASA/DIN converter	ASA speed selector Rotating ASA/DIN converter	ASA speed selector
Other	Cable release connection, tripod socket	Cable release connection, tripod socket	Cable release connection, tripod socket
Body size	1 7/8 x 3 3/4 x 5 3/4 inches	1 7/8 x 3 3/4 x 5 3/4 inches	1 7/8 x 3 3/4 x 5 3/4 inches
Body weight	One pound nine ounces	One pound nine ounces	One pound nine ounces

RETURN TO THE MANUAL MINOLTA HOME PAGE

We didin't want to do this, but since other websites have been stealing our stuff, we have no alternative but to state:
COPYRIGHT@1995-2023 by Joe McGloin.

All Rights Reserved. The material on this website is protected by US Federal copyright laws. It cannot be copied or used in any manner without specific approval from the owner.

The material on this website is protected by US Federal copyright laws. It cannot be copied or used in any manner without specific approval from the owner.