“Once More Unto The “Breech” Dear Friends…..” - Ray Fletcher

“Once More Unto The “Breech” Dear Friends…..” - Ray Fletcher

In today's guest post, Ray Fletcher offers an in depth analysis into Canon breech lock lenses. 

I admit to being a relative newcomer to the analogue scene (although I did use the old 127 film in my very first “Brownie” camera!). When digital came along, I thought this was the best thing since sliced bread and embraced the technology. However, I became disenchanted with it over time as I felt myself becoming a “slave to sliders” and spending more time in front of my computer than actually out “doing real photography”; I suppose I’m a technological dinosaur as I now really enjoy what I call “thoughtful photography” – no longer banging off dozens of shots and then staring at them with glazed eyes trying to select the best of an often bad bunch - but taking the time and trouble to stand back and consider what I’m trying to do; all of which leads me into what I really want to write about.

The heading says it all, and with apologies to Shakespeare, with whom this has nothing to do, I would like to talk about not just a 40+ year old camera (a lovely Canon AT-1), but equally importantly, a suite of lenses I have managed to acquire, the last one being via West Yorkshire Cameras.

Canon, in their earlier days, experimented with a class of FD lenses they called “breech-lock”. One of their sales pitches for these lenses was that this system was not merely safer in terms of the lens not falling off the camera body, but also that the lens itself did not interact with the mount, which reduced both friction and wear. Reading some of the reports from users particularly in America, I first gained the impression that, as one reviewer put it, “… a waste of time because I can’t change the lenses in the dark…”. Looking back over decades of using cameras, I can’t really recall ever changing a lens in the dark – his argument didn’t wash for me. Ok, it could be argued that the system is fiddly, but in my opinion the positives outweigh the negatives and if it reduces wear and tear, I’m all in favour.

FD mounts may be regarded as a bayonet mount, but still breech-lock in nature.


The concept of the non-rotating, mating surfaces of the FD mount is quite unique as none of the competing manufacturers offer a similar concept and design. To mount a FD lens, you first align the red dot on the lens with the red dot on the body (an older FD has a tiny dot at the chrome ring). The positioning pin on the lens nests in the alignment slot on the camera mount. You then rotate the entire lens barrel clockwise until the pin pops out and the lens is locked to the body. The pins and levers on the FD lenses remain stationary, mating with their counterpart when you first align the lens with the camera. 

Canon's Breech-Lock Mount

The above diagrams were sourced from an excellent website - Mir. 

They give a good idea of the quite complex mechanism that Canon developed; I have coupled these with some shots (using my Canon EOS M3 digital camera with a 28mm f/3.5 macro lens) of my lenses, some of which specifically show the locking mechanism. One simple method of identifying the Canon FD “breech-lock” lenses is to look for the green “A” on the barrel; non-breech-lock lenses usually had a white “O” on them.

So, three lenses, all breech-locking: an FD 28mm f/2.8 SC; an FD 50mm f/1.8 SC; and an FD 135mm f/3.5 SC. I am delighted to say these lenses are sharp and give great definition. The spread of focal lengths is quite sufficient for me as my main areas of interest are landscapes and seascapes. I am very lucky to live in South Devon in an Area of Outstanding Natural Beauty (and about 10 meters from the River Dart) which allows wonderful landscapes and seascapes as well as some stunning sunrises in the winter months.  Currently, I am using Kodak Pro Image 100, a 100 ASA colour negative film and find the combination of the quality glass plus the colour latitude of the film gives pretty damn good results. In due course, I want to run some rolls of “Fomapan 200” through the Canon; I have used this monochrome film in my Zenza Bronica ETRSi and been more than happy with the end results, so am expecting something similar from the Canon.

This shot shows my Canon AT-1 with the 50mm f/1.8 lens attached:

The 28mm f/2.8 lens front & rear:

The 135mm f/3.5 lens front & rear:

Overall, I am delighted with the quality of the lenses and the first results have shown each of them to be of a high quality with no “nasties” lurking inside them. I have no desire to change anything I have bought; these three lenses will be more than adequate for my needs. However, I note that Howard has a 100mm f/4 macro FD lens in stock; now, how can I justify buying it….hmmm.

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