Pentax ES

It’s hard to state how incredibly successful the Spotmatic line was for Pentax. Selling for over a decade, there were seven main models in the Spotmatic series, with a handful of variants made in between. By the early 1970s, Asahi had not strayed too far from the concept of the original ‘Pentax’ from the late 50s. Over the course of the next twenty years, only a few improvements were made. The addition of a meter, a hot shoe, and small mechanical, optical, and metering upgrades. Nothing was truly new or different. By 1970, the m42 screw mount was starting to show its age, along with the Spotmatic.

Pentax would be part of only a handful of makers to stick with the m42 mount through the 70s, but not in the way one would expect. Wanting to upgrade the Spotmatic, while keeping backwards compatibility would be no easy task. A first attempt by Pentax for a successor was flawed in a multitude of ways, and very much a market test run. The short lived 1970 Electro Spotmatic would be relegated only to Japan, with little of the negative press released about it to the outside public. During the following year, these reliability problems were heavily worked on and ironed out, completely redesigning the electronics and simplifying them considerably. Gone was the incredibly cramped circuit board with hosts of wires, replaced by a newly fabricated group of custom microcontrollers. The update to the Electro Spotmatic was finally ready for a worldwide release that holiday season. This would be the start of something special. Quite the technical marvel for the time and a way to breathe new life into m42 lenses. A new camera from Pentax and a wonderful piece of ingenuity, this is the 1971 Pentax ES.

The Electro Spotmatic’s Second Attempt

Comparing a Pentax ES to any of the previous models, at a glance, there is almost no difference. Featuring many of the same components inside and out as the SP II, the ES really is 90% the same camera. The Pentax ES follows closely in design to the other Spotmatics before it, differing from the earlier cameras by having less sloping features and much harder lines. The bottom plate was slightly extended, to accommodate the new electronics added to the camera, and would be the most striking difference. More subtly done was the removal of the self timer, with a battery compartment in its stead, along with an across camera move of the ASA dial to underneath the rewind lever. Available in chrome or black paint, the ES still retains the beauty of the Spotmatic line, while moving it into a more industrial design and timeless appearance.

The Pentax ES does not require batteries to function, but you would be limited in operation. On the front of the camera’s left hand side is a small cylinder located next to the lens. Unscrew this cap and you will find the battery chamber, requiring a 6v #544 battery, but a 4LR44 works, as well as four individual LR44 batteries with some challenges. Once a battery is inserted, look through the viewfinder and press the small button between the prism and the rewind crank on the left top side of the camera. This is the battery check. Looking to the right hand of the viewfinder, you will see a shutter speed scale going from 1 second up to 1/1000th of a second. Built into this scale is a small cutout, intended as the battery check area. When testing the battery, the meter needle will need to fall within this area. Besides the shutter speed scale, the only other thing in the viewfinder is the center microprism focusing aid.

Looking back to the top of the camera, on the left hand side, the ASA dial has now been moved to underneath the rewind crank. The meter of the ES goes from ASA 20 up to 1600, with a quick setting for an exposure compensation of x1/2, x2, and x4. There is also a film type reminder on top of the ASA dial. The rewind crank behaves as expected, lifting up to open the back of the camera. Moving to the right is the battery check button once again, and a hot shoe (X sync) on the top of the prism. The right side of the top plate contains the usual winding lever, wound indicator, threaded shutter release, and a newly updated shutter speed dial. Manual speeds of 1/1000th down to 1/60th (marked as X sync) and bulb can be used without battery power, but not the automatic setting. This new automatic selection puts the Pentax ES into an aperture priority mode, having a slightly increased shutter speed range from 8 seconds up to 1/1000th of a second in a stepless design. For those unfamiliar with a stepless shutter, the camera has the ability to pick any speed, like 1/163rd of a second for example, making the exposure system on the Pentax ES extremely accurate.

Once again looking to the front of the camera, on the right side next to the lens are two PC ports, labeled as X and FP sync, with a switch above them. This switch turns on the stop down metering for non SMC (Super-Multi-Coated) lenses, similar to how other Spotmatic meters work. If you are using a SMC lens, you have the benefit of open aperture metering and do not need to mess with this switch at all. However, the meter behaves a bit differently depending on a few things. With an SMC lens attached, the camera will only take a reading when the shutter button is half pressed, unlike the Spotmatic F. The stop down switch does not affect the meter, working in either position and acting as a regular aperture preview if engaged.

If you are using regular m42 lenses, this camera behaves considerably different. Similar to the SMC lenses, if you're using a manual shutter speed, the camera’s meter is disabled and the stop down switch works as an aperture preview once again. In automatic, things take a slight turn. If you attempt to take a picture without stopping down the lens, when half pressing the shutter button, the needle in the viewfinder will drop dramatically past 1 second. A full press will lock the shutter open and essentially put the camera in a time mode, staying that way indefinitely. The only way to fix this is to turn the shutter speed dial to a manual speed setting. This will release the shutter and unfortunately leave a ruined frame. With the meter switch engaged, the camera can now take a picture normally. This will make the viewfinder darker the smaller the aperture you choose. Lastly, moving to the bottom of the camera, you have a standard tripod socket and rewind release button.

THE SPECS AND FEATURES

Shutter Speeds - Automatic (aperture priority) or Manual (unmetered)

• Automatic - 1/1000th down to 8 seconds, stepless

• Manual - 1/1000, 1/500, 1/250, 1/125, 1/60th (X sync), bulb

Aperture - dependent on lens

Meter Type - CdS TTL meter, averaging center weighted, EV 1-18

• open aperture metering with SMC (Super-Multi-Coated) lenses, all else stop down metering

• full shutter speed scale and needle in viewfinder

Focus - fresnel and microprism

Shutter - horizontal, cloth focal plane, automatic with manual override

ASA - 20 to 1600 ASA

• exposure compensation -1/2, +2, and +4

Lens - m42 mount

Flash Option - X sync hot shoe, PC ports (X and FP sync)

Batteries - 6 volt silver #544 originally, 4LR44 works as well

Film Type - 35mm

Other Features - film type indicator, battery check, shutter wound indicator

The Experience

I will preface this by saying, I was mostly indifferent in my feelings for Pentax cameras before this. Never really diving into the company, the Spotmatic and its various iterations were beautiful in design but not necessarily exciting to me. The ME Super I had was back and forth in the repair queue, so I did not have much to go on or the best impression. I really liked the PC 35AF, but that’s a much later Pentax point and shoot; I guess their SLR cameras never really spoke to me. That was until one day I ran across an online lot of cameras, previously gone through with a few attempts at repairs. Sold ‘as is’ for parts. At the price they were asking, if nothing ended up working, I would have been satisfied with having spare parts and learning how these cameras worked. Among this lot of ten or so cameras, was a handful of Pentax SLRs, one of which was a worn looking ES. I’m a big fan of black painted cameras, especially if there is a bit of wear that shows the brass underneath. I resolved to look into what was wrong with the ES, only after repairing a few others that were in the queue before it.

A few weeks later after finishing a flex repair on an MX and a meter repair on a Spotmatic F, I decided to finally look at the ES. Both of those cameras are quite closely related to the ES, having an extremely similar electronic layout as the 1976 MX and the additional functionality of the SMC lenses and mechanics of the 1973 F. It ended up being a quick look as the mirror was stuck up, there was corrosion in the battery compartment, and the shutter curtain was jammed half way open or closed.

Without a hint of functionality, I did a bit of research on the ES before poking into the notably temperamental circuitry. I knew of the rumblings of reliability issues with the ES line, but in a deeper look into these failures, there was a distinct lack of explaining what exactly goes wrong with the Electro Spotmatic, ES, and ES II. They just seem to suffer from reliability. I decided to disassemble the ES anyway and see if I could figure out any of the problems. It was already not working, so if anything were to break, I wouldn’t be too upset. This would prove to be the hardest camera I have ever worked on to date, and quite the lengthy repair process.

With the recent experience of repairing the Spotmatic F, disassembly was almost identical. To start, I scraped the corrosion off the battery terminals and cleaned the carbon pads under the ASA dial. Testing continuity between a few points, everything seemed to be connected, so I roughly put the camera back together and put in a battery. It was registering something, but the needle in the viewfinder was erratic. Most likely a connection problem from hidden damage to the wires leading to the battery compartment. On closer inspection, corrosion was slightly creeping out of the back side of the terminals, but not enough to visually raise a red flag. I decided to replace the wires anyway, and have that checked off the list of possibilities. Following the positive wire to its starting point was not too difficult, but the path it traversed would be hard to copy. The wire fed through a very small hole toward the base of the camera, winding and weaving between a host of other wires and mechanics. It took a bit of doing, but once the battery terminals were rewired, the erratic needle was no more… sometimes. This took a considerable amount of time, as I trusted that the battery check button was my indicator of a good connection. Only after a few hours of struggling to find any sort of consistency, did I take a quick look at the battery check contacts themselves. There was a tiny spot of corrosion on the button that was aiding in the inconsistency. It’s those small things that have you scratching your head for hours upon hours.

With the meter slightly working now and remembering how dirty the ISO dial was, I decided the best course of action would be to clean the carbon pad and wiper on the aperture detection mechanism. The arm was delayed a bit as well, sticking when small amounts of tension were applied to it. Four screws held down a few Teflon like washers that kept the various rings and their contacts within a precise track. Cleaned and freely moving now, the concentric rings did not go back together without a fight.

I must have assembled and reassembled the camera a million times trying to figure out what could possibly be going wrong. I tried shortening the spring, seating the rings differently, greasing the mount, gluing the screws so they would not move, anything and everything. A few times I got the mechanism to work properly, except on the extreme points. The meter was starting to not respond, and I was at my wit’s end. Finally, after far too long, I looked at my Spotmatic F and found the indexing tab to be a fraction farther to the right. In my next attempt, while seating all of the rings, I made sure it was in the same position. I paid close attention while I screwed it back together, and saw it slip a millimeter. This was my problem, I needed to not only hold them in place, but have a specific amount of tension on the aperture arm itself. Unscrewing, cleaning everything once again, and carefully reassembling it, I made sure nothing even slightly moved. The mount was finally in the correct position and registering at all points. I was thankfully done with this incredible test of patience.

Things were seemingly working as they should, however the meter was off by about six stops. At this point I consulted the internet once again and stumbled upon an invaluable resource. The Camera Craftsman magazine was a publication that went deep into detail on how the mechanics and electronics on a specific camera worked. Every part, mechanism, drawback, triumph, and ingenuity is addressed in a friendly and conversational way. It was published for 30 or so years, and I’m now an immense fan. It’s incredible and something I could find myself reading just for the heck of it, but enough praise. Without this guide, I don’t think I would have been able to repair the ES.

After the borderline spaghetti electronics that were in the Electro Spotmatic, the ES redesign cleaned up the internals considerably. For some context on how exposure works on the Pentax ES, mechanically there is almost no difference between the ES and the Spotmatic SP II. The genius here is the electronics, more precisely in the second curtain. A fixed speed for the first curtain can be mechanical, and only the second needs to have electronic timing. The second curtain uses a memory and timing capacitor, working in tandem to take a properly exposed picture. Simple in theory, there are a lot more things in play here like aperture values, film speed, even distance and voltage. The new chips included with the ES do all this and more, but in this case, something was wrong.

I tried my hand at adjusting the meter via the variable resistors on the board, and got it within four stops. Still not quite sure what the problem was, I looked at each component on the board for any failures. No broken traces, cold solder joints, or obvious damage. Everything seemed to check out. Knowing that the ES uses a few capacitors for timing, I thought I would replace one or two and see if it changed anything. On this particular board variation, there were three capacitors you could see, C1, C3, and CT. The shutter timing capacitor was denoted as CT, and I replaced it with a similar value. No difference, so I put the old capacitor back and kept looking for the problem.

Reading the Camera Craftsman article again, I checked a few points to make sure voltage values were correct, hoping to find the culprit. I decided to look at the resistance of the CdS cells in complete darkness and found my answer. They were way off, even from each other. In testing, if a CdS cell is properly working, depending on the light level it receives, it increases or decreases resistance. The more light a cell receives, the less resistance it has. In complete darkness, the cell would be reading a considerably high resistance, but that depends on the range it was made to measure. The cells in my ES were barely working, and that would explain why the meter was off by so much. I would have to replace them, but finding replacements would be tricky.

If you don’t know the original value of the CdS cells, it’s hard to find a replacement besides in a guess and check scenario. These CdS cells were in a particular package size (canned) and had two leads. Digging through some parts cameras, they all had meters with varying cell shapes and mostly had three leads. From what I could surmise, the three lead versions were measuring high and low light levels with a common ground. Those were the only ones I could find in the right size, so I gave them a shot. I was able to get the meter within two stops now, but that wasn’t good enough.

Mentioning the trials and tribulations of the ES to a colleague who also works on film cameras, I regaled them with a few points of failure that were dead ends so far. After taking a million readings with a multimeter, and learning how to read the values of the light meter, I figured that it was most likely the CdS cells that were the problem. I tried a few others and got close, but nothing quite worked. He just so happened to have a junker original Spotmatic laying around and I was welcome to try those CdS cells, as the rest of the camera was pretty much toast. Thanking him, I figured it was worth a try, as a Pentax original CdS cell may get me closer than the previous two. The following day after work I brought home a pair of CdS cells still attached to a prism, eager to give them a try.

I replaced the cells once again and the prism on the ES, due to a desilvering line I was seeing only faintly. The values were off as expected but in the other direction. Adjusting the variable resistors on the board, I was able to get the meter spot on! The original cells were still good and had the right values. The Spotmatic ES meter was now working perfectly, but a new problem arose, the shutter was still jammed.

The mechanical issues with the ES were a bit obtuse to start but ended up being not too difficult of a repair. Like a lot of other SLR cameras from this era, its all about grease. A latch that handles the holding and firing of the mirror was laggy and getting stuck, not allowing the curtains to finish their travel. Scrubbing and lightly lubricating the mechanism, the mirror and shutter curtains now moved freely. Everything worked as it should, except on 1/60th. The shutter would jam pretty consistently and was another head scratcher. It turns out that the arm was ever so slightly bent, rubbing on one side. A slight bend later, and the ES was finally fully working. Firing on all speeds, shutter accurate, and meter working perfectly.

After a lengthy repair, and carrying some pride for getting a troublesome camera to work, I went right out and ran a roll of black and white through it taking random pictures of everything. Unsurprisingly, nothing too special came of that roll. The ES was subject to a handful of challenging lighting conditions on that roll and once developed proved to me that the meter in the ES was spot on. I ran the camera here and there without film for a week or so, double checking that the meter was still working and that the automatic aperture coupler on the lens mount would engage correctly. Satisfied with the performance of the ES, I took a chance and decided to bring the camera with me on an upcoming trip. With ten rolls on standby and four cameras in tow, my parents and I traveled across America for a week during Christmas to visit one of my sisters and our newest family member in California.

Escaping the cold and dismal weather of the Midwest in December, I was excited to put the ES through a real test. Not only mechanically and electrically, but in feel and use. I only brought one lens with the camera, a zebra striped Zeiss Jena Tessar 50 f/2.8 that I also recently repaired. This combination was perfectly compact and felt natural. Even without the advantage of open aperture metering, I really ended up bonding with the camera. I had a backup with me in case the ES failed in some way, but it never did. The ES was the one I carried with me at all times, and helped capture some magical moments with family. From the chilly mornings to the warm afternoons, shooting inside, outside, and in fast action or slow moments, the Pentax ES really impressed me. Stop down metering can be unnatural, and with some cameras a right pain. For whatever reason, it came easily and clicked with me using this camera.

Focus, compose, pull up the stop down meter switch, look at the scale to the right while adjusting the aperture, stop on the shutter speed you want, and take the picture. It may seem like a lot, and I’ll be honest, at first it was. However, after a few rolls, I found myself falling into a comfortable rhythm. At times I would take an initial meter reading and preset the lens to take the picture quicker. In this scenario, unlike other m42 cameras, you still need to manually stop down the lens with the switch, or the ES will lock up. Stop down metering was becoming second nature, with only one or two missed frames per roll when I was rushing.

After a bit of chaos coming home, I came away from that trip with a lot of film shot, 4 rolls of color just with the ES. The following couple of days I went on a developing marathon of the countless rolls. Mixing a new liter of ECN-2 developer, I developed the three rolls of Fuji 200 and one roll of Mitsubishi MX-100 taken with the ES. Waiting for the film to dry, they looked perfectly exposed, and for the most part they were. It was only after I scanned them, that I found an issue. Seemingly random shutter capping was happening, and opposite the side I was use to. About 90% of the pictures were perfectly usable, with a small black part toward the edge of the frame that was easily cropped. All in all I was still really impressed by the performance of the ES, and decided my repair journey was not yet finished.

Looking closely at the negatives, like the examples above, I was at a loss of what it could be. The exposure deviation was not always consistent to one side, or in size and length. Very confusing, but I had to start somewhere. I’ve repaired shutter capping issues a few times before, so I knew vaguely where to look into. The first step was finding out if the shutter was capping on the first or second curtain. One thing I learned over the years repairing cameras is never do speed adjustments in a scenario like this, it is almost certainly a mechanical or lubrication issue. I do not have a dedicated shutter tester, but I feel I can get pretty close by eye with a few techniques I’ve learned at this point. It’s not the most scientific way of going about this but using a bright light, I fired the shutter at all speeds and watched the curtains run. The worst of the capping was at lower speeds, which would mean the first curtain slowing down and letting the second curtain catch up to it before it reaches the end of its travel. That was only half right. After really taking my time watching it work, and recording a slow motion video of it running with my phone, I found the issue. Shutter bounce, and a lot of it.

A new to me problem, and one I had no clue how to repair. Another few days of research and a few hours of reading led me to the answer; with Spotmatics at least. There is a mechanism that engages right when you start to wind the lever of the ES or any Spotmatic camera. You will feel and sometimes hear a click or slight thump in the winding mechanism at the very beginning of travel. This is the brake lever moving into position to stop and dampen the first curtain. Within the organized chaos that is the winding portion under the top plate of the ES, I positioned this lever in front of the brake control screw instead of behind it. Once disassembled and the part moved to the correct position, I checked the speeds again and reassembled the camera. The ES was finally ready for another roll.

With the Pentax ES truly and fully repaired, that weekend I went to visit my parents, ES on the passenger seat. I took a few pictures of flowers and such around the house, hoping everything would be working smoothly. Blazing through the door once I was home, I eagerly developed the roll. Looking good out of the tank, I scanned them a few hours later to find they were… perfect! Elated, I set the camera aside until the following weekend to throw a couple more rolls through it.

One underexposed roll of night photography later, mainly due to a mistake on my part, I decided the last roll used for this article should be something special. I broke out some bulk Kodak Panatomic-X 32 I’ve had for a number of years, setting the meter to an ASA of 25 and traversing down the riverwalk. As a lot of people know, this film is legendary and stunning, and it sure lived up to that name. My results were great, and I came away with a picture of a dog I caught through a gate that I quite enjoyed.

Recommending the camera is easy in my eyes, it’s genuinely one of my favorite cameras I’ve ever shot with. However, this recommendation comes with an asterisk. Yes, it’s an incredible camera, if you're lucky enough to find a working example. They tend to show up in far greater numbers as repairs than other Pentax SLRs. A swap of the CdS cells and slight tuning of the board may be all it takes. Or you may have to fight it to the death like I had to. Even through the many hair pulling hours of wondering what the hell was wrong, I honestly would do it all again. I really ended up liking this camera and I did not expect to. Other stop down cameras I’ve used seem to pale in comparison. Hopefully, my experience here will help others in repairing their own ES or at the very least inspire some appreciation for the ingenuity Pentax put into this camera. It truly is an impressive and clever bit of engineering. The Pentax ES is something special and I absolutely adore mine.