Minolta's SRT - A Symphony in Springs & Strings

Symphony in Black #1: Minolta SRT-101 with its original 55/1.7 MC Rokkor kit lens

    Updated Oct. 19, 2021

    The mid-1960s were heady days in SLRland. From 1964-66 all of the Big 4 Japanese manufacturers brought out new top-of-the-line enthusiast models: the Pentax Spotmatic (1964); the Nikkormat FT (1965); Canon's Pellix (1965) and FTQL (1966); and the object of our attention in this article...Minolta's SRT (1966). The feature all of these cameras had in common was: built-in through-the-lens (TTL) metering. We take it for granted now, but five decades ago this was revolutionary. Of the five models, the Pentax and Canons used stop-down metering (meaning that the photographer had to manually close (stop-down) the aperture on the lens to get an accurate reading and then focus at maximum aperture). The Nikkormat offered full-aperture metering (the lens remained at maximum aperture for the brightest view and ease of focusing while the meter reading was taken), but required the user to manually index the aperture ring every time that they changed lenses. Then came the SRT-101. Full-aperture metering and the aperture automatically indexed whenever you mounted a lens. No muss, no fuss. And all it took was:

a little spring...
a little string...
and a little tab on the aperture ring ;-)

  From SR to SRT

    Before we take a closer look at the SRT, let's get a bit of context. Minolta introduced its state-of-the-art SR (likely for Single-Lens Reflex) lens mount in 1958. This mount was the fastest-acting 35mm lens mount system available at the time. It only required the user to match up index marks on the lens and camera, insert the lens, and give it a 54-degree twist to lock it in place. Beginning with the SR-2 in 1958 and embarking on a constant improvement program with the follow-on SR-3 and SR-7 models through 1965, Minolta laid the foundation for the SRT-101 that debuted in April 1966. Here is a brief summary of that evolutionary process:

• SR-2 (1958-60) - the first Minolta SLR. It featured the SR-mount, an instant-return mirror, and semi-automatic aperture operation (it closed the aperture down automatically right before the shutter fired, but required the film to be advanced to re-open the aperture for the next exposure) 
• SR-3 (1960-62) - successor to the SR-2 as the top-of-the-line Minolta. Improvements over the SR-2 included: an accessory meter that coupled to the shutter speed dial of the camera to provide semi-automatic exposure control, a split-image rangefinder focusing aid, and from August 1961 onward, fully automatic aperture operation (the aperture now re-opened automatically at the end of an exposure)
• SR-7 (1962-66) - the ultimate expression of the original SR-series and the first SLR with a built-in (but non-TTL) CdS (cadmium sulphide) meter. Over its lifespan, constant improvements were being made, contained within three separate versions. The first iteration featured a sleeker look by eliminating the meter coupling appendages of the SR-3 as there was no longer a need for an external add-on meter. The SR-7 also was the first Minolta SLR to feature a mirror lock up (MLU) function to allow mounting of the new 21mm super wide angle Rokkor that protruded into the mirror box of the body and required the use of an auxiliary viewfinder that attached to the pentaprism of the SR-7. The final major innovation of the SR-7 was an "oversized" mirror that prevented image cut-off in the viewfinder of the camera when longer telephotos were mounted. A year after the original SR-7 debuted, Minolta corrected a few issues by introducing the second iteration SR-7: providing a proper ON/OFF switch for the meter, improving the ergonomics of the film advance lever, and improving the MLU mechanism so that it no longer wasted a frame of film when activated. Finally, in 1965, the ultimate SR-7 appeared, and a spate of ergonomic and cosmetic changes came with it. The resemblance between it and the forthcoming SRT-101 was not slight. It had a more squared-off look than earlier SR-7s, a larger shutter speed dial, and many other small improvements. A seemingly minor change, the addition of a bevel to the lens-mount flange, made lens changes even more convenient by centering the bayonet lugs on the lens with the mount automatically.

    With the SRT-101, Minolta chose to bypass the intermediate step of stop-down TTL metering. It was not that they didn't consider such a move (they had developed a prototype SR 777 that used such a system), but they astutely chose to push ahead of Pentax instead of just being content to catch up to them. Nikon faced a similar choice with their Nikkormat line and put an extra five months of development into the FT rather than stick with their original stop-down design. Although the fruitage of such decisions was some time in coming (Pentax absolutely dominated SLR sales through the late-'60s with their Spotmatics), full-aperture TTL-metering was here to stay. By late-1970, Canon had seen the writing on the wall and introduced its FD-mount (basically the FL-mount modified for full-aperture metering and automatic exposure). Pentax hung onto stop-down metering until 1973 and this decision (along with failing to replace the M42 screwmount prior to 1975) dropped them from the top of the sales charts for good; a strategic misstep from which they never quite recovered. But it was not just the metering method that made the SRT a success.​

A brace of SRT-101s in black and chrome with the 58/1.4 and 58./1.2 MC Rokkors circa late-1969

 
​ A Closer Look 

    Obviously, the SRT was not the first SLR to offer full-aperture TTL metering. That honor went to the Topcon RE Super (Super D in the USA, which even pre-dated the Pentax Spotmatic, being developed in 1962 and introduced in 1963). But being first does not necessarily mean being the best or most successful. The otherwise-superb Topcon's problem was its antiquated Exakta-style lens mount and Nikon F-topping price. Outside of the US Navy, customers were few and far between. So while not necessarily superior in capability, the SRT was far more affordable, had a modern lens mount with plenty of room to grow, and the simplest full-aperture metering mechanism available. It basically consisted of a spring-loaded collar that rotated behind the lens-mount flange coupled to the exposure meter by (wait for it...) a spring...a string...and a couple of pulleys. A post on the collar engaged a tab on the aperture ring of the simultaneously-introduced MC (Meter-Coupled) Rokkor lenses and voila!...full-aperture TTL and no messing around with goofy rabbit ears and making sure that the aperture ring was set to f/5.6...yadda, yadda, yadda. Speaking of Nikon :-), over ten years later they would copy this system when they introduced their AI (Automatic Aperture-Indexing) lenses in 1977. That's as much of a ringing endorsement of someone else's innovation as you would ever get out of the Nikon boys and their usual NIH (not-invented-here) mindset. I'm pretty sure they and Minolta worked a little something out behind closed doors...you know what I'm saying...badda-bing...badda-boom? Annnywaaays...this was a classic example of Minolta engineering at its best - simple & effective.

Cutaway of CLC meter

    It wasn't just on the meter-coupling front that the SRT broke new ground, it was also with the metering pattern itself. The averaging meters then common were easily fooled by a bright sky with a darker foreground, or vice-versa. Minolta's solution was CLC (Contrast Light Compensator) metering. It used two CdS cells mounted to the pentaprism, one of which read the overall scene in the viewfinder, while the second was biased toward the top of the viewfinder (where the sky would generally be in a horizontal composition). The cells were wired in series, so a combined reading was obtained and the meter would adjust for strong backlighting. While admittedly not infallible, CLC was just as good as and often better than other in-camera meters then on the market and could be considered the second rudimentary multizone meter (behind Topcon's more-sophisticated RE Super). Minolta used CLC metering in its top cameras, both SLRs and rangefinders, until the late-'70s, and they stayed near the forefront of meter development for the next 30 years or more.

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    ​Nor was it just in technical capability that the SRT moved the needle, it was also in the way it felt and functioned. Eight years of improvements in manufacturing expertise and design by Minolta's engineers were immediately evident. The controls moved with precision and purpose. Build quality and reliability were improved over its ancestors and would continue to advance during the first decade of its existence. One handy thing that did carry over to the SRT from the SR 777 prototype was a lockable depth-of-field (DOF) preview lever, which allowed stop-down metering with the older (non-MC) Auto Rokkors, thus maintaining backward compatibility with the entire Minolta lens lineup. The SRT-101 was also among the first SLRs to display the set shutter speed (thanks to another string and pulley system :-)) in the viewfinder. Such features made it state-of-the-art at the time. Minolta would iterate the SRT up and down its model lineup over its 15-year lifespan, with remarkably few changes to the basic chassis and layout. Here is an overview:

• 1966 - The SRT-101 became the top Minolta SLR, replacing the SR-7. The SR-1(s) continued to be the more affordable Minolta SLR, with a smaller feature-set and a bit less refinement than the -101.
• 1969 - Minolta made some internal upgrades to improve film-handling and reliability on the -101. Cosmetically, the finely-knurled black shutter speed dial (late SR-7 style) was replaced by a coarser, checker-patterned version that was color-matched to the body (chrome or black). Another visible indicator was the change to cross-point JIS screws (they look like Phillips but they aren't :-)) that secured the top & bottom plates and the lens mount. Using these points of identification as a guide, go for the 1969-and-newer copies for their improvements over their predecessors.
• 1970 - The SR-M, a meterless, motorized SRT was introduced. With its integrated motor drive and handle, the SR-M was a distinctive (and is now a very rare) piece of Minolta kit. An attempt by Minolta to push effectively into the pro photojournalist market, (in which they always managed to fail ;-)), the SR-M did away with the meter because CdS cells could not adjust fast enough to ensure correct exposure at full speed (3 frames/second). Although capable of being equipped with a 250-frame film back and other pro-oriented accessories, the specialized nature of the SR-M and its somewhat clumsy integration was no match for the more versatile and configurable Nikon F in the pro market. But it still looks stinkin' cool and I would take one in a New York-minute :-).
• 1971 - The SRT-100 replaced the SR-1s as the budget Minolta SLR. Top shutter speed was 1/500 instead of 1/1000, and the self-timer, MLU, and the shutter speed display were all deleted. There were individual PC sockets for FP and X sync versus the single PC socket with a switch for the two settings on the -101. The SRT-100 also initially came with a 50/1.9 kit lens later followed by a 50/2 version that was not available separately nor with the SRT-101.
• 1973 - Minolta went to a three-tiered mechanical-shutter lineup with the debut of the new top-of-the-line SRT-102 (aka SRT-303 in Europe, aka SRT Super in Japan/Asia). Upgrades from the SRT-101 included: the set aperture value on the lens was now projected into the viewfinder, a split-image rangefinder focusing aid was now integrated with a microprism ring surrounding it, the cold-shoe (no electronic flash contact) of the SRT-101 was replaced by a hot-shoe allowing for direct flash synchronization with a mounted flash unit, and finally, a proper multiple-exposure function was installed. This pushed the SRT-101 mid-market with the SRT-100 rounding out the bottom of the lineup. As noted above, Minolta also started their practice of regional demarcation at this time by means of using different model numbers. The SRT-102 was the high-water mark of mechanical Minolta SLRs. From this point on, almost every change would involve the loss of a feature or some other method to reduce production costs as electronic SLRs began to supersede mechanical models as the focus of the manufacturers. Minolta also introduced two department-store SRTs in 1973 that were kind of hybrid -100/-101s. The SRT SC was sold through Sears exclusively and was a chrome-only SRT-100 with a top speed of 1/1000 sec. The SRT MC was sold at K-mart and JC Penney and added the shutter speed display along with the 1/1000 speed of the -101 to the standard -100 configuration and was only available in black.
• 1974 - At some point during 1974, the MLU function was deleted from both the SRT-102 and -101. At least the -102 gained the film Safe-Load-Signal (SLS) feature in its place, but there was no such provison for the -101. The heyday of the all-manual mechanical SLR was rapidly coming to a close. When shopping for either of these models, if MLU is important to you, make sure that the MLU dial is present on the side of the lens mount below the model number.
• 1975 - The entire lineup was re-badged. You now had the SRT-202, -201, & -200 in North America, SRT-303b, -101b, & -100b in Europe, and SR-505 & SR-101 in Japan (there was no budget model in Japan). On the top and mid-level models, a film memo holder was added to the film door back, and all SRTs changed to a plastic metering collar from the older metal version. The -201 inherited the hot-shoe that had previously only been available on the top-dog -102. The SRT-200 received the 1/1000 sec. speed that the -100 had lacked with no other changes.
• 1977 - This was the year when de-contenting really began to hit the SRTs. The -202 was not affected too much, as only the selector switch for FP/X-sync flash was eliminated (not a big loss as flash bulbs had been displaced by electronic flash by this point), and the DOF preview lever was no longer lockable. When it came to the mid- and budget-level offerings, however, the knife began to carve a little closer to the bone. Along with the deletions described above, the -201, -200, SC II, and MC II lost CLC metering, with a single oval-shaped CdS cell in its place. This is readily apparent with the pentaprism-located CLC badge missing from such cameras. How much of a difference this made in actual operation is a good question, but the fact that Minolta retained CLC on the -202 suggests that it remained a more capable system in their minds and they were willing to keep the extra components and entailing production costs in the top model. This was definitely the biggest change that the SRT lineup as a whole underwent during its existence. There was some consolation in that all of the mid and budget models inherited the snappier focusing screen from the -202. The SC II added the shutter speed readout and the MC II dropped it. In Europe, the -100b became the -100x and in Japan the SR-101 became the SR-101s.
• 1980-81 - The end of the SRTs. The -202, SC II, and MC II all left in 1980, with the -201 and -200 hanging on until 1981 as the last of the mechanical Minoltas. They just couldn't make 'em like that, anymore.

​  Life With an SRT

     So, why consider an SRT? It often comes down to the letter "M". If you need/want a Minolta with...

• Mechanical shutter
• Manual exposure 
• Mirror Lock Up
• Leica M3-style integrated shutter release and film-wind lever. Minolta could copy with the best of them, too ;-)

...then the SRTs are the pick of the crop. 

    SRTs are solid, reliable, easily serviced, and plentiful (over 3.5 million bodies were sold in 15 years). There were literally millions of SR-mount lenses produced too, and most of them are available at bargain prices, nowadays. SRTs did use the now-obsolete 1.35V 625 mercury cell to power the meter, but conversion for a modern 357 silver-oxide battery (with an o-ring to center it in the battery chamber) takes about 20 minutes with modest soldering skills, or you can use a 675 hearing-aid battery (super-cheap to purchase in bulk) with an o-ring, which will last for a few months at a time. Or you can always opt for a handheld meter or Sunny 16.​

​    One functional faux pas is the ON/OFF/Battery Check switch. A hold-over from the SR-7, it is located on the bottom plate of the camera and it is very easy to leave in the ON position accidentally. You have to train yourself to check it EVERY time you are putting the camera away. A common occurrence is that the plastic tip on the film advance lever will be missing or partially broken off due to someone's overzealous winding technique. This is a minor issue, but there are enough SRTs out there that you can easily find one with an intact tip. Like most of its contemporaries, the SRT has a longish film stroke of 170 degrees (20 degree standout + 150 degrees actual winding). Fortunately, it uses a ratcheting mechanism, so you can use multiple short strokes if you prefer. The advantage of the long winding throw is a fair amount of mechanical advantage, so winding is smooth and light.  

    For the absolute full-meal-deal, look for an early -102, -303, or Super. They have the full viewfinder display, hot shoe, MLU and multiple exposure capability. If you don't need MLU, the -202, -303b, or SR-505 (the SR-505 is quite rare) are the next best thing and they get you the film-safe-load window. If you choose an SRT-101, I highly recommend getting a post-1969 body (easily identified by the coarse checker-style knurling on the shutter speed dial and the cross-point (+) body and mount screws). That makes turning the shutter speed dial a one-finger affair along with getting you all of the internal improvements made during the preceding four years of production. On the other hand, if you are looking for the minimalist SRT experience, an SRT-200 will fill the bill nicely. Think of it as a Pentax K1000-equivalent, minus the silver oxide 357 battery. It is a perfect candidate for the 675 hearing-aid battery treatment. And they can be had for dirt-cheap with a 50/2 lens. In other words, there is an SRT for just about anyone. They also make great cold-weather cameras and long-exposures are a breeze, too. I have used my -102 @ -20 Celsius with no problems whatsoever. SRTs also pair beautifully with any Minolta MF lens, although there is something special when you plunk an all-metal MC Rokkor on one loaded with B&W :-). Totally symphonic, brah. Later days.

Symphony in Black #2: SRT-102 w/ MLU and the classic 58/1.4 MC Rokkor

  References:

    The Rokkor Files @ http://www.rokkorfiles.com/
    Minolta, Pentax, Nikon, Canon, & Topcon Manuals @ www.butkus.org
    Part 5: Nikomat FT/FS @ http://imaging.nikon.com/history/chronicle/
    Part 6: Nikomat FTN @ http://imaging.nikon.com/history/chronicle/
​    Canon Pellix QL & FT QL @ https://global.canon/en/c-museum/
    Asahi Pentax Spotmatic @ http://www.pentax-slr.com/71760549
    Topcon RE Super @ https://www.shutterbug.com/content/