Lens Mount | What You Should Know Before Buying A New Lens

Lens Mount | What You Should Know Before Buying A New Lens

It’s not you this time. Seriously, this isn’t your fault…it is a jungle out there. Since time immemorial, I have faced this myself and have heard countless other souls screaming in desperation asking just one question, “Will ‘x’ lens fit my ‘y’ camera?”

Camera manufacturers never leave any stone unturned to hide from you all traces of what is happening. Amateur photographers starting to take images or video are always inundated with an ocean of camera jargon and settings. Even this isn’t enough! Now that you want to get yourself a new lens and try out some new shots, there is a new monster in the room….would that lens even fit?

Let’s face it then…once and for all.

Lens Mount

Yes, ‘Lens Mount’ is the term you should be looking for whenever you are surrounded by the question of lens and camera body compatibility. But what the hell is it?

Let me explain.

Lens mount is an interface which helps connect a camera body with a compatible lens. The mount is what connects the lens both mechanically and electronically to the camera body.

If you are reading this and want to know if a specific lens would fit your camera body, I assume you have an interchangeable lens camera. In other words, you can change the lens attached to the front of the camera. The lens mount is nothing but the contraption that allows you to change the lens. It looks like a circular metal ring surrounding the opening in front of your camera sensor.

Nikon Z7 with a new Z mount front side image

On the lens, it looks something like this.

EF-lens-mount on a Canon Lens


The primary function of a lens mount is to hold the lens firmly and in position, in front of the camera, enabling the photographer to take images. In the last decade, however, there has been a very important secondary function that the lens mount is responsible for, establishing an electronic connection between the body and the lens.

The electronic connection between the two most important components of the camera is what enables modern high precision controls like AutoFocus, aperture control and in some cases lens stabilization. Basically, the lens has a few motors to move optical elements (for AutoFocus), to stabilize, etc. and needs a way to draw power from the camera body. The lens mount is the node in between that makes it happen.


There are many types of lens mounts which are used for various forms of photographic and non-photographic purposes. Some of them (by design) are as follows:

  • Screw-thread type
  • Bayonet type
  • Breech lock (friction lock)

Among all the lens mounts above, the bayonet type is the one used in nearly all of the DSLRs and mirrorless cameras manufactured in the last half a century. You can easily recognize it by the iconic three tabs on the circumference of the lens ring which fits perfectly into the female counterpart of the camera body every time.

The reason why the bayonet type mount is so popular is because it is wicked quick (half a turn and you are done) and it is impossible to mess it up. The tabs are all unique sizes which means you have to put in the lens in a specific orientation every time. Then you can only rotate the lens in a specific direction to lock it in. Once attached using the bayonet mount, the lens is very precisely aligned with the camera body which makes it very easy to create a reliable and strong electrical connection between them.

Detaching a lens is even easier. All you have to do is just press the spring-loaded pin and give the lens a twist in the opposite direction.

Now that you know the basics of lens mounts, let’s talk a little about some of the most popular mounts that you are most likely to have on your own camera.

Canon EF Mount

This is a type of bayonet mount which is exclusively used by Canon on all its full-frame and professional-level cameras. EF, by the way, stands for Electro Focus. The name reflects the fact that the mount allows power to flow from the body to the lens to help use the AutoFocus motor built inside.

Unlike Nikon,  nearly all Canon cameras have their AutoFocus motor built in the lens itself and NOT the body. This makes the flow of power through the mount an absolute necessity for AutoFocusing.

Owing to Canon’s amazing innovations like the Dual Pixel AutoFocus technology and its seriously good color science, it has been the favorite among both small and large filmmakers and photographers. Although Nikon rivals the photography market in close succession, in the video and film-making market Canon trumps Nikon by a long margin. It is no wonder hence that the EF mount is everywhere…literally!

Third-party lens manufacturer like Zeiss, Schneider, Tamron, Tokina, Sigma, and Rokinon also wanted a share of this humongous market for Canon EF lenses. Hence they started manufacturing lenses for Canon cameras too. Like all beautiful things, now we have a plethora of choices for a lens of a particular focal length or aperture size.

Sigma Art series lenses, for example, very often beats Canon in its own game. It has some seriously beautiful lenses. Try them out before you buy anything else. In most cases, they are cheaper and provide more bang for the buck.

Canon EF-S Mount

Introduced in 2003, Canon’s EF-S mount is an extension of the original EF mount system. It is mainly used in Canon’s APS-C sensor cameras.

Some popular camera bodies which use the EF-S mount are:

Nikon F Mount

Introduced far back in 1959, Nikon’s F mount is by far one of the oldest mounts that is still in use today. Originally designed for 35mm format single lens reflex (SLR) cameras, which had 44 mm throat and a 46.5 mm flange distance.

If you have a Nikon camera that was built in the last sixty years it is an F-mount.

Nikon D7000 with the iconic F mount and Electrical Contacts

Nikon has somehow managed to not only keep the F-mount alive even in the electronic age but also make it more efficient and powerful enough to deliver the most amazing images ever. It goes without saying that because of this long-standing relationship with this mount, Nikon has given rise to the most adaptable and backward-compatible lens lineup ever! You don’t even need to buy a lens manufactured in this decade. Go hunt for some jewels in some garage sales and if it’s a Nikkor lens chances are it is an F-mount lens as well, which means it would fit your camera perfectly.

Anytime Nikon makes a new lens or comes up with a new camera body, you can easily and seamlessly upgrade to the next lens or the body without even having to think about compatibility issues. All lens fits all bodies (because they all use the same mount to attach the lens to the camera). Beat that!

Apart from Nikon’s own lineup of fabulous lenses (Nikkor), there are a plethora of third-party lenses available for Nikon bodies. Sigma, Zeiss, Schneider, Samyang, Tokina all manufacture extremely good quality F-mount lenses.

Micro Four-Thirds (MFT)

Keeping in sync with the Nikon F-mount tone, the micro four-thirds lens mounting system is probably the one which resonates with Nikon’s philosophy the most. It has been co-created by two giants of the optical imaging world, Panasonic and Olympus. The objective was simple and straightforward, creating a universal mount.

This needs a little explanation.

Nearly all the mounts used by camera manufacturers are unique. Unique shapes, unique sizes, unique designs. This means that you cannot use a Canon 50mm lens on a Nikon camera or vice-versa. The mounts are designed this way so as to force the buyer to buy the lenses from the same manufacturer they bought their cameras from. Essentially locking in the buyer into their lens ecosystem once they purchase the camera body.

So if you have a Canon body with an EF-S mount, you will have to buy the lens from Canon as well. The third-party lenses are a relatively new phenomenon. And even then Canon earns a heck lot by issuing licenses to all the non-Canon EF-S lens manufacturers. All included, Canon is the one which benefits from it all. This is exactly the same for Nikon, Sony, Pentax, etc.

What Panasonic and Olympus tried to do while trying to come up with the Micro Four-Thirds (MFT) mount system was to create an interface that would NOT be tied to and controlled by just one manufacturer. Any manufacturer invested in this concept can build lenses or camera bodies using the MFT mount. Theoretically, all the lenses should perform equally well on a MFT camera irrespective of the manufacturer.

Give And Take

The micro four-thirds system like any other system has its fair share of problems too. Thanks to the small flange distance, the camera bodies and the lenses are extremely small, light, and cheap to manufacture. The small distance also eliminates the possibility of a mirror and pentaprism system, thereby making this a mirrorless system after all.

All MFT cameras use Electronic ViewFinders (EVF), and, usually, have to rely on just Contrast Detect AutoFocus (CDAF). DSLR, on the other hand, has access to Phase Detect AutoFocus which is much faster and accurate as compared to CDAF.

As compared to a standard 35mm sensor, the MFT system can only house a sensor just 18mm X 13.5mm, which is 75% smaller. That is also significantly smaller than an APS-C sensor.  This smaller sensor, in turn, creates a 2X crop factor. A 50mm lens on an MFT body would have the equivalent field of view of a 100mm lens on a full frame camera. Wide-angle lenses are going to be a major problem.

Sony A and E Mount

Caution! Confusion ahead. Sony deliberately or to transfer its own misjudgments onto us has made a mess of its own mounting systems. To be perfectly honest even I sometimes wonder which lens would fit which camera.

The two main mounts that Sony has historically used are the ‘A’ and the ‘E’ mounts.  The A-mounts developed by Minolta, are found on relatively older Sony bodies and were designed to be used in conjunction with a mirror, pentaprism system. It allowed the use of full-time PDAF and a standard 35mm image sensor.

Sony Alpha ILCE-7 (A7) full-frame camera (mirrorless interchangeable lens camera) with the E mount

As compared to the A-mount, Sony’s E-mount is a little smaller both in diameter and flange distance. It was mainly designed to be used as a mount for mirrorless cameras. All modern Sony mirrorless cameras which have come out in the last few years have all had the E-mount system installed.

Since the diameter of the A-mount is larger than that of the E-mount, you can use an A-mount lens on an E-mount Sony body using an adapter. The reverse, however, is not possible.

Typically names of lenses with an A-mount start with ‘SAL’ while that of E-mount lenses start with ‘SEL’.

New Kids In The Block

Nikon, just a few days ago, launched its latest and greatest mounting system called the Z-mount. Since 1959, this has been Nikon’s first upgrade in the mount department. Designed to be used for Nikon’s full-frame mirrorless cameras, the mount has a large 55mm wide diameter and can easily house a 35mm sensor.

Canon also has a new mount to offer, which it is calling the RF-mount. It was first introduced on Canon’s version of the full-frame mirrorless camera, the EOS R launched on 12th September 2018. It also sports a wide diameter with a short flange distance.

Nikon's native mount FTZ adapter

Both Nikon and Canon have come out to say that the new mounts they have designed for their mirrorless lines of cameras have opened up a “world of possibilities” which did not exist earlier. To help photographers who already have a substantial collection of lenses, both the companies have announced native lens adapter which should allow older EF and F-mount lenses to be used on the newer mounts effortlessly and without any lack of performance.


So to answer the age-old question, “will that lens fit my this camera?” I have a simple and easy solution. All you have to do is look for the mount your camera has. If the lens also has the same mount, you are in luck as it would fit perfectly. You can always use an adapter to attach a lens with a different mount onto your camera but that would, in most cases, result in lower image quality and Autofocus performance.

Some adapter manufacturer solely dedicated to making mount adapter is making good progress in this department. But overall most of the adapters available today are expensive. The inexpensive ones, on the other hand, are almost always useless. If you are one such photographer who was loyal to a particular brand for a long time and has amassed a truckload of lenses in the period and is thinking of jumping ship, adapters are the only economical way to make things happen.

Metabones is a good company which makes good quality adapters for many camera bodies. Check here for prices on Amazon.

Let me know how your new lens shopping went and if the lens finally fitted your camera. I hope there would never be any doubts in your mind about lenses and camera compatibility anymore. Shoot me questions below if you still got some.

Keep shooting amazing.

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