Introduction to Lens Mounts and Lens Adapters


You may be thinking, "What a boring subject for an article," and you would be right. However, as boring as the interface between your camera and lens might be, the significance of your camera's specific mount, along with which lenses can be used on your camera, which lenses can be adapted to your camera, and why some lenses work and others do not, can prove to be a more interesting subject that may even inform which camera or lens system you eventually buy.

What Does a Lens Mount Do?

A lens mount is a standard or proprietary interface used by camera and lens manufacturers to ensure a secure and accurate means for attaching a lens to a camera body. Each camera system nowadays uses its own unique mount that limits compatibility between lenses and other manufacturers’ cameras, and also enables electronic communication between the lens and camera to achieve accurate focus and exposure.

Left to right: Canon EF, Nikon F, and Sony E bayonet-style lens mounts

Most lens mounts in current use are bayonet style, in which a lens is attached to the camera body by registering the lens in proper orientation with the camera body, then giving a slight twist of about 45-90° to lock the lens in place. Prior to the bayonet mount, a couple of other mounting styles were commonly used, namely thread and breech-lock mounts. Thread mounts, or screw mounts, are self-referential and describe the action of threading your lens onto the camera body, much in the same way you thread a nut onto a bolt. Breech-lock mounts are more closely related to bayonet mounts; however, they use a self-contained rotating ring on the lens itself to tighten the lens onto the camera body with friction.

Bayonet mounts are the most favored of these three mounting types, due to the ease and speed of installing and removing lenses from camera bodies, the ability to incorporate electronic contacts using this attachment method, and the repeatable precision afforded by a simpler design.

Left to right: Breech-lock mount on a Mamiya RB lens and an M39 screw mount on a Leica lens

What’s in a Lens Mount?

Besides connecting a lens to a camera and sporting a certain design style, lens mounts also have a number of distinctions from manufacturer to manufacturer. Size is the main differentiator between the various mounts, and is a slightly more complex measurement than you may imagine. The number of tabs in a specific bayonet can vary from one manufacturer to another (although most use three tabs), the direction in which you rotate the lens to connect with the camera body varies among brands, and the incorporation of electronic contacts will also be unique to the camera and lens manufacturer. Furthermore, each mount corresponds, arguably, to the most important element of this article, a specific flange focal distance (FFD). This measurement, which describes the length from the mounting flange (the edge of the lens mount on the camera body) to the image sensor or film plane, varies from manufacturer to manufacturer, and is one of the true limiters of the interchangeability of lenses with specific cameras.

Left to right: Canon FD breech-lock mount and a Mamiya 7 bayonet mount

The flange focal distance of each camera system is factored into subsequent lens designs, and is a constant length used by each manufacturer to ensure accurate focus from a specific lens’s minimum focusing distance to infinity. Using a lens with a specific FFD on a camera system with a shorter flange distance, you will not be able to achieve infinity focus. This distinction is the key element in which lenses can be used on camera systems other than the original one the lens was designed for, via a lens adapter.

Current Lens Mounts Popular Historic Lens Mounts
Lens Mount Flange Focal
Mount Type Lens Mount Flange Focal
Mount Type
Nikon Z 16.0mm Bayonet Pentax Q 9.2mm Bayonet
Nikon 1 17.0mm Bayonet Samsung NX 25.5mm Bayonet
FUJIFILM X 17.7mm Bayonet M39 (26tpi) 28.8mm Screw
Canon EF-M 18.0mm Bayonet Contax G 29.0mm Bayonet
Sony E 18.0mm Bayonet Nikon S 34.85mm Bayonet
Hasselblad X 18.14mm Bayonet Four Thirds 38.67mm Bayonet
Micro Four Thirds 19.25mm Bayonet Canon FD 42.0mm Bayonet or breech-lock
Leica L 20.0mm Bayonet Minolta SR 43.5mm Bayonet
Canon RF 20.0mm Bayonet Exakta 44.7mm Bayonet
FUJIFILM G 26.7mm Bayonet M42 (x1) 45.46mm Screw
Leica M 27.8mm Bayonet Contax C/Y 45.5mm Bayonet
Canon EF 44.0mm Bayonet DKL 45.7mm Bayonet
Sigma SA 44.0mm Bayonet Olympus OM 46.0mm Bayonet
Minolta/Sony A 44.5mm Bayonet Leica R 64.0mm Bayonet
Pentax K 45.46mm Bayonet Contax 645 64.0mm Bayonet
Nikon F 46.5mm Bayonet Bronica ETRS 69.0mm Bayonet
Leica S 50.0mm Bayonet Pentacon Six/Exakta 66 74.1mm Breech-lock
ARRI PL 52.0mm Breech-lock (cine) Hasselblad V 74.9mm Bayonet
T Mount 55.0mm Screw (M42 x 0.75) Pentax 6 x 7 84.95mm Bayonet
Hasselblad H 61.63mm Bayonet Bronica SQ 85.0mm Bayonet
Mamiya 645 63.3mm Bayonet Mamiya RZ67 108.0mm Bayonet
Pentax 645 70.87mm Bayonet Mamiya RB67 111.0mm Bayonet or breech-lock

Lens Adapters

Spurred by the somewhat recent advent of mirrorless camera systems, a renewed interest in the ability to use a wide array of third-party lenses has also occurred. Due to the self-referential design of these cameras, the lack of having a mirror in a camera body design affords, besides a more compact overall design, a shorter FFD. By having this shorter registration distance, you can theoretically mount any lens with a longer FFD on a camera with shorter FFD through the use of a lens adapter

The lens adapter effectively serves to make up the difference in focal flange distance between the camera and lens—for example, a Nikon F lens to Sony E adapter makes up the difference of 28.5mm to provide the proper total 46.5mm of focal flange distance for a Nikon F-mount lens to achieve infinity focus. While this is the ideal situation, to mount lenses with a longer FFD on cameras with a shorter FFD, adapters do exist that allow you to physically attach lenses with shorter FFD measurements to camera bodies with a longer FFD. The caveat with these adapters is that you will not be able to achieve infinity focus without the inclusion of a corrective element in the adapter itself, and it is unlikely the quality of this corrective element will match the quality of the lens being mounted. However, without the corrective lens in place, this combination will afford the ability to work at focusing distances less than infinity, since the lens adapter is now functioning as an extension tube.

Top left to bottom right: Metabones Speed Booster for Canon EF to Sony E, Metabones Nikon F to Sony E adapter, Fotodiox Nikon F to Canon EF adapter with Dandelion Focus Chip, and Fotodiox M39 to Leica M adapter

With this basic concept in mind, lens adapters can also be substantially more sophisticated and maintain electronic communication between the adapted lens and body through the use of dandelion chips, with some adapters even capable of retaining a lens’s autofocus and image-stabilization capabilities. On the other hand, completely manual adapters will not convey any information between the camera and adapted lens, forcing you to manually focus and adjust the aperture settings on a lens, and work in manual or aperture-priority mode on the camera.

One additional type of adapter that has gained tremendous attention over the past few years is a style designed exclusively for APS-C and smaller format mirrorless cameras, most commonly Sony E, Fujifilm X, and Micro Four Thirds systems, that has been popularized by Metabones and Mitakon Zhongyi. With the exception of Sony E-mount now being featured on full-frame cameras, these mounts typically correspond to crop-sensor sizes and, as such, are associated with terms like “crop factor” and “equivalent focal length.” This batch of lens adapters strives to make these terms somewhat moot by incorporating a condensing lens into their design to minimize, or in some cases eliminate, the crop factor and increase the amount of light reaching the sensor. This is accomplished by projecting all of the light gathered by the lens onto the image sensor, rather than just simply losing the light that would typically be cropped out by the smaller sensor dimensions.


I have a auto vivitar telephoto  400mm #3707222. Is there an adaptor to hook it up to a blackmagic pocket 4k?

Assuming that your Vivitar lens has a T-mount, the Vello T-Mount Lens to Micro Four Thirds-Mount Camera Lens Adapter, BH #VELAMFTT would allow it to mount to the Blackmagic Pocket Cinema Camera 4K.

I have a sony a7ii.  I have a old lens I used on my minolta maxxum camera. The zoom lens is a Vivitar 52mm 100-300mm.Is there a adapter I could buy?

Yes, you can certainly adapt your Minolta Maxxum mount lens to the Sony A7 II. That lens mount is the same as the Sony A mount DSLR lenses. A suitable adapter is the Sony LA-EA5 A-Mount to E-Mount Adapter, BH # SOLAEA5.

Hello, I have a Vivitar 28mm f 2.8 wide angle lens and want to use it on my Canon 6D, which adapter should I get? It looks like it has a breech-lock mount but I'm not entirely sure. Thanks!

Hello Gomi,

If possible, please send us an e-mail to [email protected] along with your inquiry and a photo of the mount so we can try matching it up with the appropriate adapter. Thank you!

Hi, I was recently given a Vivitar 75-205mm macro focusing zoom lens and I have a Panasonic GH5. What adapter would I want to buy to use this lens with the Pana micro 4/3? I have a Vitrox for my Canon lenses, but I assume that won't work. Thanks.

Hi Steven,

Since that lens came in a few different mounts, we would need to see a photo of the mount in order to make a recommendation on the adapter. Please e-mail us a photo with your inquiry to [email protected] so we can investigate this further. 

ik heb een Chinon 135mm 2.8 lens multicoated (geen schroefdraad versie) komt van een Chinon camera CM-4 en zou die willen gebruiken op mijn Fuji X-T30 Welke adapter zou ik daarvoor moeten hebben ??? DAnk alvast !!!

Hello.  From what we can see, the Chinon 135mm f/2.8 lens used the M42 lens mount. You may use an adapter such as the Vello M42 Lens to FUJIFILM X-Mount Camera Lens Adapter, BH # VELAFXM42 for your Fujifilm X-T30.

I have an old Vivatar 300mm telephoto lens f5.5 with I think a screw mount.  I am looking for an adaptor to mount it on my Canon 6D with an EF mount,   Any ideas if such an adaptor exists and any idea on the limitations in doing this…assuming an adaptor exists.

Thanks so much.

It's possible that you have yourself an M42 lens. The Vello M42 Lens to Canon EF/EF-S-Mount Camera Lens Adapter, BH # VELACEFM42 would be an adapter to consider to get that lens mounted on your Canon 6D.


I am mistaken regarding the above lens.  It is not a screw mount but has a black ring that turns to tighten the lens on to the old Canon FTB camera I had.  Do think the mount you suggest above would still work?  Or is there another type of mount to consider.  The original set up years ago was the Vivatar lens above on a Canon FTB from the 1970’s.  Now I want to mount the lens to my Canon 6D fulll frame dslr.   Thank you so much for your input.  Rob

Hi, I have a Fujifilm X-T30 with several lenses including the Fujinon XF 16-55mm F2.8 which I absolutely love shooting with. My partner has an Olympus Pen E-PL9 camera, are you aware of any adapters that would allow her to use my Fujifilm lenses?

Thank you!

Hello Roy,

Unfortunately, there no existing adapters allowing a Fujifilm X series lens to mount onto a Micro 4/3 series camera at this time. 

I have a Fuji xt4 and want to mount some variable focal length Nikon glass to it. In the Fuji XT4 what focal length do I set the camera to to accommodate, in example, a 24-70mm lens? 24MM or 70mm or ??

As with using a zoom lens on the Nikon DSLR camera, the focal length you choose to use when using the Nikon lens on a Fujfilm X-mount camera will depend on how you wish to compose the image, and will depend on compositional and creative decisions.  Setting the lens at 24mm would allow you to frame more items in the image as it is a wide-angle focal length, whereas 70mm will be a short telephoto focal length used for candid and portrait-type images.  If you are looking for an adapter recommendation, the Vello Nikon F-Mount G Lens to Fujifilm X-Mount Camera Lens Adapter with Aperture Control, B&H # VELAFXNG, would be a good option for your usage needs.  The adapter has a built-in aperture ring, so it may be used on newer lenses that do not have a built-in aperture ring as well as older Nikon lenses that have their own aperture ring.  Do note that you will have to focus the lens manually as there is no electronic communication between the Nikon lens and the Fujifilm X-mount body when using the above lens adapter between the camera and lens.

Hi, wanting to know if I need a Viltrox NF-M1 adapter to mount a Nikon DX  & N lens to a Panasonic Lumix GH4 camera? I have two Nikkor lenses being, AF/S 18-200mm 1: 3.5-5.6GII ED & also AF-S 105mm 1: 2.8G ED. 

Please let me know.

Yes, the Viltrox NF-M1 would allow for the use of Nikon DX lenses in the AF-S type to function on a Panasonic Lumix GH4. 

What would I need to adapt a Fuji X-Mount Lens/APS-C Format lens to Sony e?  Would it be different for a6000 series vs full frame like A7r3?  Thanks!

Unfortunately, there are no adapters that are currently offered to fit a Fujifilm X series lens on a Sony E mount body.  However, an adapter for Sony E mount bodies would be the same whether you have a full frame model like the A7R III or an APS-C model like the A6000. 

Hi I got passed down a Canon FD lenses and I was wondering which adapters would I need for a DSLR Nikon D3400



Hi, I bought a used fujifilm X-M1 with a couple of lenses in the pack. 

(1) Petri 28mm 2.8 MC Manual

(2) AUTO EXAKTAR EEK 1:2.8 135mm PK

Unfortunately adapter was missing. Do you know which adapter(s) should I buy to make them fit my Fujifilm X-m1?

Kind regards,


It looks like you will need two adapters. Your Petri 28mm 2.8 MC lens should be an M42 mount, so it will take the Vello M42 Lens to Fujifilm X-Mount Camera Lens Adapter, BH # VELAFXM42. For the AUTO EXAKTAR EEK 1:2.8 135mm that would take the Vello Pentax K Lens to Fujifilm X-Mount Camera Lens Adapter, BH # VELAFXPK


I have many Nikon prime lenses.  I have adapters to put them on my Canon 6D.

I just got an older 16mm Arri SR with a bayonet type mount: can I mount my Nikon lenses to the Arri (via Bayonet to Nikon or EOS?)?  

I have access to many EOS lenses, so ideally it would be an EOS lens to bayonet (and I use my Nikon to EOS adapter)... does this exist?

Informative article. I have a Samsung NX2000 and am looking to attach a Samyang 85mm f/1.4 lens for Nikon Z. Could you direct me to the appropriate lens adapter for me? (If it is not possible, can you point me in the right direction for lens and adapter? I'm needing an 85mm f/1.4 lens to attach to my NX2000). Thanks!

Hi Jim,

Unfortunately, there are no adapters that will allow a Samyang 85mm f/1.4 with the Nikon Z mount to fit a Samsung NX2000 nor are there any lenses in the 85mm focal length with an NX mount any longer. We're very sorry.

Thank you for a great explanation.  Since the Canon EF-M  and the Sony E have the same FFD will I be able to use the Canon on my A6000 without an adaptor?  Also, I bought the LAE-5 Sony E adaptor from you but other than the Minolta and Sony full frame I don't know which other lenses I could use it with.  It seems pretty expensive for just those only. Any articles that you can point me to?  You all are awesome!

Hi Wendy,

Thank you for the kind words! Unfortunately, there currently no adapters allowing Canon EF-M mount lenses to work with a Sony Alpha Series mirrorless camera like the A6000. As for using the LAEA5 with your A6000, any Sony A mount lenses or Minolta Maxxum lenses can work. Aside from Sony's own A mount lenses, there are other brands such as Sigma and Tamron which offer some options. I've linked some below.

My apologies Kirk, is my sales request allowed, and if so your, advice and help will be appreciated. Regards David

I have the following for sale:

Nikon FG Camera, Bayonet lens fitting

Nikon - H Auto  1:2 F - 50mm

Hoya HMC Wide- Auto F28mm

Vivitar 100-200mm,2 X Matched Multiplier

Vivitar 75-205mm 1.38Close Focus Auto Zoom

Vivitar 70-300mm 1:42-5.8MC Makro Focus Zoom

1 Hard Shoulder Strap Camera Case, all the above are packed securely into the case.


Hi David,

No need to apologize.  The best option to sell your gear to us would be to contact our Used Department at 1-800-606-6969 option 2, extension 2700 or e-mail them directly to [email protected].

I have a Sony A7s which works fine with the Sony 16-35mm f4 zoom. To expand its range I have been trying to use some vintage all-manual lenses with three different manufacturers' lens mount adapters - a Tamron Adaptall-2 25mm f2.5 prime, a Tamron Adaptall-2 28-80 f3.8 zoom and a Pentax Takumar 55mm f2 prime. In each case I cannot get infinity focus (or in practice anything beyond a few feet) unless the lens is stopped down to around f11 (or narrower) and then the images are sharp. Optically I suspect this is because all of the adapters are slightly too long. Has anyone else encountered this problem?

Hi Tim,

We're sorry to hear about the trouble you're having. While most lens adapters would allow for infinity focus, there are many that do not. We invite you to reach out to us via Live Chat today or call 1-800-606-6969 so we can go over your options in greater detail.

I am working up a presentation on lens adapters for my photo club.  I am well versed on Nikon compatablity with old Nikon lenses and I have other old lens brands adapted to Nikon that shoot in full manual mode.  I need some help with Canon lenses and their many mounts related to modern Canon DSLRs.

Hi John,

In the past, Canon utilized the FD mount which worked on their manual SLR bodies and there were also a series of lenses for their rangefinder cameras. The most common lens mount that Canon uses now is their EF mount, which has been around since the early days of their autofocus SLR line up.  Added to the line up is the EF-S mount which is strictly for their APS-C type DSLRs, the EF-M mount which is their APS-C type mirrorless line up and the new RF series which are for their full frame mirrorless bodies. Below are links to the adapters that utilize some of these mounts.


Hi Kirk, I see how helpful you are with people, and hope you can help with my own odd situation. I recently bought a Vivitar 800mm f/8 telephoto from the 1970s. I had read that this lens comes stock with a male T2 thread, which was pretty standard for these third-party makers at the time. However, this lens does not have that thread. Instead, it has a threadless 48mm (outer diameter) smooth ring, that is slightly flanged, to allow a secure mating with screws embedded in the ring. On top of this was something that looks like a T2 ring adapter for a Minolta mount. But, it's NOT a T2 ring adapter! It's some oddball with a smooth 48mm inner diameter ring. There are tiny hex screws on the outside that keeps it secure on the lens. I have looked all over the place, but I cannot find any info on this, or how to get an adapter for another mount. The lens looks completely stock and unmodified in any way. Any ideas? Do you guys have something that would mate the lens to something besides Minolta?

Hi Scott. We would like to make sure we offer the right type of adapter for you.  If possible, please e-mail us some photos of the lens mount along with a brief description to [email protected]. Thanks for your patience. 

Hi there, I’m rather new to the photography world. I currently have the Canon EOS M50 mirrorless camera. I just purchased the Sigma 56mm f1.4 lens, but I can’t seem to attach it to the camera the way I can attach my Canon lenses. Excuse me if this is a silly question, but do I need an adapter to be able to use the Sigma lens on the Canon? If so, do you know which adapter?

Hi Mackenzie,

If you have the Sigma 56mm f/1.4 DC DN Contemporary Lens for Canon EF-M, it would fit directly to the EOS M50 without the need of an adapter. In the event that you're still having an issue with the fitment, we invite you to reach out directly via our Live Chat feature on the B&H Website so we can troubleshoot the issue further. 


I have a vintage soligor auto-focus 75-260 that looks to need a mountspecific to a camera brand,  to be at all usable. it's got a vivitar 'ring' for my Minolta MD camera, I want to adapt it to our canon ae1..non I would like to be able to use one ring ,the way it is now, but if need adapter to go on the existing minolta bayonet to then fit to the canon, second choice, that would b ok too. I"ve googled until I"m bleary eyed. Hope you can help,thanks !

Unfortunately, there are no adapters allowing a Minolta MD mount lens to fit a Canon FD body at this time. I'm very sorry.

Hi thanks for the article I have more of a specific question for you. What are the options for lens adapters for putting a sigma 18-38 1.8 on my black magic pocket cinema camera 4K? I’ve hear of the meta ones micro four thirds one. Are their any cheaper options?

I current purchased the Sony sigma 135mm f1.8 art for my Sony a7ii . Will I need an adapter ?? 

That lens will have a direct Sony E mount, so there is no need for an adapter when using it with the A7 II. 

Greetings; I have just picked up a Camera case that had a Vivitar 70-150 1:38 Auto Zoom lens that appears to be in wonderful shape. It has a mount bracket with "N/A1". I wish to use it on my old Pentax Spotmatic SPII which has a screw mount (M42 ?). Can the N/A1 mount be removed and replaced with the proper mount for my camera. Is the replacement available. Thank you for your time

Dave Perin

It sounds like the lens could have a Nikon mount, but to make sure, we ask that you e-mail us directly with this question along with a photo of the lens mount to [email protected]

I have just replaced my old Pentax ME super wind-on with a Sony alpha 65 SLT A65V.  Can you supply an adapter.  I understand I will lose lots of functionality but the Sony should cope with my longer FFD lenses. 

Pentax K mount lenses that originally worked on your Pentax ME can be adapted to your Sony A65 using the Fotodiox Pro Lens Mount Adapter for Pentax K Lens to Sony A Mount Camera, BH # FOPSAAPK.


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