Updated Apr. 27, 2022
Greetings, and welcome to our fifth vintage SLR system overview, this time featuring Pentax (or Asahi Optical Co. as they were originally known). In this installment we will examine their first SLR system, which (aside from the Asahiflex models) utilized the M42 screwmount introduced by Zeiss in 1949. Over time, such was their success, M42 became commonly referred to as the Pentax screwmount. The M42 mount was used by Pentax for 20 years (1957-76) and today represents one of the most affordable and accessible SLR systems available to the vintage-focused photographer. In the second part of our Pentax overview, we will dig into the bayonet-style K-mount system introduced in 1975, and which is still used (in a modernized electronic form) by Pentax. As usual, we will break things down by: 1) Lenses, 2) Bodies, 3) Flash, 4) Accessories, 5) Reliability & Servicing.
In 1952, the Asahi Optical Company introduced its first SLR, the Asahiflex, in contrast to the other Japanese manufacturers who had made rangefinders their mainstay. The German Praktiflex of 1939 served as the basis for this model. It used the M37 (its metric thread designation) screwmount and had a waist-level viewfinder. The Asahiflex was basically a straight copy of the Praktiflex, but with the introduction of the IIb model, Asahi introduced the first quick return mirror on a Japanese SLR. They had now set out on a continual program of improvement and automation that would kickstart the Japanese SLR industry that came to dominate the world market. For our purposes, we will pick up the trail in 1957, when Asahi introduced its first pentaprism-equipped (for right-side-up, un-reversed viewing) M42 mount SLR -- the PENTAX (derived from PENTAprism and AsahifleX).
Takumar. This was the designation chosen by Kumao Kajiwara, founder of Asahi, for the lenses that would grace his company's SLR cameras. He derived the name from his brother's given name, Takuma Kajiwara. Asahi was heavily influenced by Zeiss' approach to optics and that was who they measured themselves against. The Takumar family of lenses went on to build a fine reputation for both optical quality and some of the best, if not the best, mechanical quality of the Big 5 Japanese manufacturers. (Into the early 1970's there were four major Japanese SLR companies. Besides Asahi Pentax, there was Canon, Minolta, and Nikon. Olympus elbowed their way in with their innovative OM series of SLRs in the mid-'70s and brought the number to five.) They are a joy to use. Focusing and aperture rings were oriented in the general Zeiss fashion, with the focus ring turning clockwise toward infinity, and aperture numbers increasing from right to left (aside from one exception :-)).
Takumar Nomenclature. There were five main variations of Takumar lenses. They can be easily differentiated by the name engraved on the front trim ring of the lens:
Features. Focal lengths eventually covered from 17mm to 1000mm in Pentax M42. Early on, there was coverage from 35mm to 1000mm. Focusing helicoids were aluminum-on-brass, providing the best feel and wear characteristics. It took Minolta until 1966 to come close to the feel of the Takumars and Nikon never did. Pentax also led the way when it came to coatings among the Japanese manufacturers, particularly when they introduced S(uper) M(ulti) C(oating) in 1971. Among the Big 4, Pentax had the most compact lenses and often the lightest, despite their solid construction. As noted above, there were a few lenses that used radioactive rare-earth elements to increase the refractive index of the glass used in them. The decay of such elements does impair the optical performance of such lenses. Fortunately, with UV treatment, that performance can be restored. Pre-SMC Takumars have a bit less contrast and color saturation than their descendants, which is preferable to some people. The standard filter size was 49mm, with 58mm and 67mm rounding out the regular lineup. A few of the early Takumars used the 46mm size, and there was the odd 55mm and 62mm thrown in for good measure.
Noteworthy Lenses. Pentax was the first Japanese manufacturer to produce a wide angle (35mm f/4) lens for an SLR. Within three years, they had improved it into the 35/3.5, which stayed in production (with improvements in coatings and glass, but the same optical formula) into the K-mount era. Its small size and simple construction, together with its very credible performance make it an excellent lens that no M42 Pentaxian should be without. The fact that it is also one of the least expensive Takumars is just icing on the cake. For about five times the cost, on average, the 35/2.3 Auto Takumar is a very unique lens, its character changing with every stop of the aperture.
When it comes to normal lenses, the 55/1.8 (and its 55/2 sister lens on the lower-end bodies) in its many guises was one of the finest kit lenses from any Japanese manufacturer. Good samples give up little to the more acclaimed 50/1.4s. Speaking of the fast 50s, you will probably not find a more-hyped Super Takumar than the quasi-"divine" eight-element first version from 1964-65. Claims that its continued production would have bankrupted Asahi have only added to the mystique of this lens. However, the seven-element version had lower production costs, with good samples offering equivalent-or-better performance to their illustrious predecessor.
The short telephoto Takumars were well-regarded and even today fetch strong (cough-cough ;-)) prices. Although varying in construction and character, the 83/1.9 Takumar, 85/1.8 Auto and Super-Multi-Coated Takumars, and the 85/1.9 Super and Super-Multi-Coated Takumars all offer excellent performance. The 85/1.9 is generally viewed as the weakest of the three and sells for $225 - $300 USD. For an 85/1.8, tack on another $100 USD on average. The 83/1.9 is much rarer and a collectible and lives in the $1000 + USD range. Less-recognized is the 105/2.8, which came in two different optical constructions and five generations. While not as highly-regarded as the 85s, the 105s are much more affordable ($100 USD or so) and very good lenses in their own right.
Pentax was one of the first companies to use fluorite and quartz in lenses. There was the 85/3.5 Quartz Takumar (introduced in 1963) for use with bellows and the Ultra-Achromatic-Takumar 85/4.5 & 300/5.6 (1968) lenses for UV, infrared and standard photography. These are specialized, truly rare pieces, and very pricey as a result.
Radioactive Lenses. This can be a hot topic ;-). It is very much a personal decision as to whether you will use one of these lenses. Research it thoroughly before making a decision. What we will discuss here are the lenses that have thorium elements and how to maximize their performance if you choose to use them. The most visible problem with thorium lenses is their tendency to develop a yellow to brownish color cast as the thorium decays. *NOTE* Not all yellowing is due to radioactive decay, in some (rare) situations it is the deterioration of the Canada balsam used to cement elements together. Here is a list of Super & SMC Takumars confirmed to be radioactive:
The yellow to brownish color cast that results from the decay of thorium can be reduced or eliminated, depending on the severity, by exposure to UV light. There are a number of methods described online. One that has worked for me is a small IKEA desk lamp that emits enough UV light with its standard LED bulb to cure the color cast after a few weeks. If you are using a dedicated UV lamp that gets hot, be careful not to heat the lens up excessively, as this can cause separation of cemented elements and migration of lubricants to places you don't want lubricants to migrate ;-). The UV treatment is not just for cosmetics, it restores the optical performance of the lens.
Recommendations. In Takumarland, the moderate-aperture lenses (28/3.5, 35/3.5, 55/1.8 & 2, 105/2.8, 135/3.5, 150/4) offer a wonderful balance of performance in a tiny package for very reasonable prices. They are definitely worth a hard look for someone just getting into the system. Many Pentaxians prefer the look that the 50/1.4s give, and they are a good value for the money, too. If you are looking at adapting M42 Takumars to other brands of cameras, be aware that the Super-Multi-Coated and SMC versions can have interference problems with some adapters due to the location of the open-aperture metering lug on the lens-mounting flange.
There were three basic eras (with some overlap) of Asahi Pentax M42 SLRs:
Asahi not only produced SLRs under its own brand but also was an OEM supplier for Sears in the USA during the late 1950's under the "Tower" brand. When the 1960s came along, in the US market, Pentax bodies were initially badged as "Honeywell Heiland Pentax" and later "Honeywell Pentax" denoting the local distributor. In the rest of the world, "Asahi Pentax" was the common designation. An exception was in South Africa (and possibly some other small markets), where the "Pentax" designation was still owned by Zeiss/Pentacon, so the SLRs were called "Asahiflex", "Penta Asahiflex", or "Asahi Pentar".
First-Generation Mechanical Bodies
Recommendations. The original Pentaxes have a wonderful, integrated feel to their operation. Film winding is delicious, the shutter release is positive, and it's like they said in the old advertisements, "just hold a Pentax". The S2-and-newer models are the most convenient to use, and their control layout is instantly familiar to anyone that has laid hands on a Spotmatic or K-series Pentax body. The three earliest models, with the slow speed dial, are desired by collectors, with the rare "S" or second-gen "Tower 26" (less than 5,000 produced) fetching the highest prices. The rare SB & SB2 Japanese military models are also valued by collectors. As far as a user body goes, our top recommendation is the SV/H3v. It had the benefit of all of the improvements made over during the first six years of Pentax production and possibly the coolest self-timer of all time :-). Over 480,000 were made, so they are fairly easy to come by, and prices are very reasonable. But any model from the S2 and up makes a great camera to build around. A couple of caveats: 1) the 1/1000 speed on the first-gen Pentaxes (and early Spotmatics, for that matter) seems to be more problematic than average. They can get a bit draggy and cause exposure issues. It's almost like Pentax had a good 1/500 shutter but they were pushing the design too hard at 1/1000. Because these bodies are at least 50 years old, a CLA (clean, lube, adjust) is often in order (especially when it comes to getting properly regulated shutter speeds), but just be aware that a CLA will not always cure a slow 1/1000 speed, and 2) the pre-Spotmatic Asahi Pentaxes do not seem to like cold weather, in general, and will often jam once their temperature threshold has been met. This is due to their fine tolerances combined with the lubricants' viscosity increasing. Other than that, the wonderfully sparse finder and mechanical excellence of these SLRs is a joy to experience. Just remember, you'll need a handheld or clip-on meter (make sure that your body has the machined cut-out in the shutter speed dial to allow the clip-on meter to couple), or you can just use Sunny 16, to get good exposures :-).
Second Generation Mechanical Bodies
Recommendations. Mechanical Spotmatics have much to offer as learning tools or just enjoying the vintage SLR experience. They are simple, inexpensive, reliable, and are a gateway to an absolute avalanche of M42 lenses of all kinds and brands. The Spotmatic F sits at the top as far as features are concerned, and if full-aperture metering is a must for you, it's the only game in M42-town. A modern 357/SR44/S76 silver-oxide battery can be used with a 10mm (3/8") o-ring to power the meter. For all other mechanical Spotmatics, a silver-oxide 387S battery is the best option to power the meter (if you cannot get a 387, you can use a 394/380 cell with an 8mm (5/16") o-ring to achieve the same result). Spotmatics have a bridge circuit that automatically compensates for the voltage difference between the original mercury cell (1.35v) and the current silver-oxide battery (1.55), so the meter will work just fine as long as its calibration is on. Next comes the Spotmatic II with its integrated hot-shoe and internal improvements over the original Spottie. Another nice thing with most Spotties (except the Spotmatic F) is that there is an actual switch to shut off the meter. On the Spotmatic F (along with the K-mount bodies - KM and K1000), you have to put the lens cap on to shut off the meter, which can sometimes be an inconvenience. Another advantage over the K1000 is the built-in DOF Auto/Manual lever on all Super Takumar and newer M42 Pentax lenses. So an SP1000, which other than the lens mount and meter switch is identical to the K1000, offers the DOF preview that the K1000 does not. There is nothing wrong with an SP500, but why lose out on 1/1000 sec. when a Spotmatic or SP1000 can be had so easily :-)? As noted above, carefully watch for draggy 1/1000 settings on mechanical Spotties of all ilks (same deal with KMs & K1000s, again in Part 2).
Recommendations. As alluded to above, the Electro Spotmatic is more noteworthy for its place in 35mm SLR history than as a great working camera for today. The ES was made more reliable (in two stages) and the ESII the best of the lot. The lack of metering in manual mode is a turn-off for many potential users. Functionally, these are beautiful cameras to use, with all of the classic Spottie ergonomics. Prices are generally very reasonable, but as with any vintage electronic body, ensure that the meter and shutter are fully functional before buying. The self-timer and viewfinder blind of the ESII add to its versatility. However, if those features are not a priority, a 65xxxxx-numbered ES can fit the bill, nicely.
Pentax had the earliest connections with electronic flash due to its relationship with Honeywell (and by extension, Heiland, who had worked with Harold Edgerton of MIT in his groundbreaking experiments in electronic stroboscopic photography in the 1930s & '40s). They featured Pentax SLRs in their advertising from the time that they became the US distributor for Asahi in the late '50s. Heiland was the market leader in flash technology from the 1940s through to the late 1960s. The Heiland Futuramic (1958) was the first self-contained electronic flash on the market. In 1965, now using the Honeywell name, they brought out the first auto-sensor electronic flash. There was a full line of flashes, from the off-camera "potato masher"-style units to compacts, and slaves for studio use. There were literally dozens of models offered throughout the era of M42-screwmount Pentaxes, although there were only 5 or 6 basic configurations. There was also a plethora of accessories to go along with the basic flash units themselves. Because Pentax used horizontal shutters in all of its production SLRs during the M42 period, maximum flash sync speed with electronic flash (X-sync) was 1/50 - 1/60 sec.
From the original Asahi Pentax (1957) until the arrival of the Spotmatic II (1971), Pentax SLRs did not have an integrated shoe for flash. There was an ISO "cold" shoe (no electrical connections, a PC cord had to be connected to the appropriate terminal on the camera) accessory that mounted to the viewfinder of the camera. If you want to mount a flash directly to any Pentax SLR from that era, you will need to get one of these detachable shoes. Back in the day, serious photographers often opted for off-camera flash via a mount bracket. This enabled them to use more powerful units while minimizing red-eye. It also made for a much sturdier setup.
You are by no means restricted to using Honeywell flash units, as there were a wide variety of aftermarket flash manufacturers and there was no worry about compatibility in those days. Flash was a manual job, with only a single X-sync contact or PC cord required. "Dedicated" (where the camera displays a flash-ready signal in the viewfinder) and TTL (through-the-lens metered) flash did not come to the Pentax system until the K-bayonet mount came along. So any manual or auto-sensor flash with a PC cord can be used with any pre-1971 M42 Pentax body. The Spotmatic II, F, Electo Spotmatic, ES, and ESII all have integrated hot shoes, for direct electrical flash sync without the use of a PC cord.
Recommendations. As groundbreaking as the Honeywell flash system was in its day, there are some things to consider for the prospective user:
There are definitely many options for flash with the Pentax screwmount system if you have the time and desire for manual flash. If you want more advanced features (like TTL) you will need to look elsewhere.
When the Asahi Pentax debuted in 1957, there was a small selection of accessories that mostly centered on close-up and copy photography. A copy stand, extension tubes, a bellows unit, and a microscope adapter ("adaptor" in the manual), along with a few filters and lens hoods were the extent of the lineup. By the time the S1 & S3 came along, a 90-degree viewfinder and a clip-on accessory shoe for external flash units had been added. Leather lens and camera cases also appeared about this time.
By the time the Spotmatic came around, a reverse adapter and a clip-on viewfinder magnifier had joined the party. For all of those budding, Pentax-packing private eyes, along with the Spotmatic II came a mirror adapter for the 200 & 300mm lenses that allowed the photographer to surreptitiously snap suspicious subjects while pointing the camera away from them. Seriously, we're not making this up. Somebody at Pentax must have been a '60s spy show addict ;-). On a less intriguing note, there was also a new helicoid extension tube that basically combined the function of the standard #2 and #3 tubes in an infinitely variable range of 16.8 to 30.6mm.
Motor Drives. Pentax introduced a motor drive option for the Spotmatic in 1969. Such models were special order and very rare. Considerable modification to the film transport and mirror assemblies was required. The top speed was 2.5 - 3.3 fps (frames per second) depending on shutter speed. Such cameras had "MOTOR DRIVE" engraved on the front or back edge of the bottom plate. The detachable drive unit had a centrally-mounted vertical battery grip underneath the motor housing. The original MD I (which was also used on the Spotmatic II) had three electrical contacts, while its successor, the MD II had four. The MD II (with matching Battery Grip II) was designed for use with the ES & ESII, and Spotmatic F bodies. A person must be very careful to match the proper drive unit to the particular camera body being used. A very helpful article can be found here at Asahi Optical Historical Club. The original Ni-cad batteries are nearly impossible to find nowadays (and therefore, are very expensive), but there was an adapter that allowed the use of 8 - alkaline AA cells (unfortunately, it is also very rare). Motor Drive units are basically a collectible due to their rarity and the scarcity of components available today. The Motor Drive-capable bodies retained a manual advance mechanism and can be used like any standard Spottie.
Focusing Screens. Until the ES came along, there was no provision for using different focusing screens on a Pentax. The original screen was a matte field with a central microprism focusing aid. With the ES came the option of two other choices: a plain ground glass with central cross (for macrophotography), or a matte field with a central split-image rangefinder. These were not user-interchangeable; the camera had to be taken to a Pentax Service Center for the exchange to be made.
Reliability & Servicing
A major advantage of the M42 Pentaxes is their overall simplicity and they are easily serviced by any competent repairman. By the time the SV came on the scene, the basic design had been fettled to a high degree of refinement. Nevertheless, the Spotmatic was virtually all-new in its design. The rated shutter life rose very significantly to 100,000 exposures with the Spotmatic from the 20,000 of the SV and-earlier models. Brighter viewfinders, larger pressure-plates and film rails that improved film handling and flatness also were part and parcel with the Spotmatic. Constant, if minor improvements occurred well into the 1970s. The Spotmatic II brought more refinement to film handling. Parts bodies are generally plentiful and CLAs are among the least expensive of any vintage SLR. Sluggish high-speeds (1/125 - 1/1000 sec.) are the most common issue I have come across with the mechanical M42 Pentaxes. Most of the time this can be addressed with a CLA. One other thing to watch for is de-silvering of the pentaprism. This appears as grey or black smudges or lines in the viewfinder, and is generally the result of a body being stored on a hot, moist environment for long periods. The resulting fungal growth eats away the coating of the prism. It has no effect on photographs, it is merely an annoyance when composing and focusing. This can happen to any SLR; it is by no means exclusive to Pentax.
When it comes to lenses, it is very tough to beat a Takumar when it comes to build quality and reliability. Many of these 40 - 60 year old lenses handle as if they came off the production line yesterday. The SMC coatings are very durable and the lenses themselves are easily serviced if necessary. They are truly one of the biggest draws of the M42 Pentax system. The other accessories were well built and will last for decades if properly cared for.
The M42 Pentax system has much to recommend it as a viable vintage choice. Lenses and bodies can be had for very reasonable prices and build quality is excellent. Probably the biggest drawback is the screwmount itself. It takes 2 3/4 turns to secure a lens to a body, not the fastest procedure, and not even close to the convenience of a bayonet mount. But if you are not a compulsive lens changer, this may be something you can easily live with. If you just have to have a bayonet, don't despair...next up we will look at the Pentax K-mount in Part 2.
Obviously, this article is merely an overview of the Pentax screwmount system. If you want to go further down this rabbit hole, I highly recommend Gerjan van Oosten's excellent book - The Definitive Asahi Pentax Collector's Guide 1952-1977 (2021). It is an updated version of his previous volume, The Ultimate Asahi Pentax Screw Mount Guide 1952-1977 (which, being long out of print - 1999, commands STUPID used prices). You get the benefits of two more decades of research and updates and for a fraction of the present cost of the older edition. You can purchase a copy directly from Mr. van Oosten at a very fair price via eBay (his Seller ID is garry-easton). It is a high-quality, 288-page, hardcover book. Be prepared for longer shipping times from the Netherlands, but the wait is well worth it :-).
Pentax Forums @ https://www.pentaxforums.com/camerareviews/
The History of Penta Prism SLR @ http://www.pentax-slr.com/
Japanese SLR Production Numbers @ http://knippsen.blogspot.ca/
Various Pentax User Manuals @ http://www.butkus.org/chinon/pentax.htm
Radioactive Pentax Takumar Lenses
The Definitive Asahi Pentax Collector's Guide 1952-1977 by Gerjan van Oosten
Suffers from a two-decade and counting film and manual focus SLR addiction. Has recently expanded into 1980's AF point and shoots, and (gack!) '90s SLRs. He even mixes in some digital. Definitely a sick man.