Photography / Tips and Solutions

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
Pentax Q 9.2mm Bayonet M39 (26tpi) 28.8mm Screw
Nikon 1 17.0mm Bayonet Contax G 29.0mm Bayonet
Fujifilm X 17.7mm Bayonet Nikon S 34.85mm Bayonet
Canon EF-M 18.0mm Bayonet Four Thirds 38.67mm Bayonet
Sony E 18.0mm Bayonet Canon FD 42.0mm Bayonet or breech-lock
Leica L 19.0mm Bayonet Minolta SR 43.5mm Bayonet
Micro Four Thirds 19.25mm Bayonet Exakta 44.7mm Bayonet
Samsung NX 25.5mm 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 47.0mm Bayonet
Pentax K 45.46mm Bayonet Contax 645 64.0mm Bayonet
Nikon F 46.5mm Bayonet Bronica ETRS 69.0mm Bayonet
Leica S 50mm 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.

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What about older Canon FD lens (e.g., mount to AE-1 Program) to Sony E mount (a6000)?

There are several options you could look at to mount older FD lenses onto an E-mount camera.  For a regular adapter, I would suggest looking at the Novoflex option.  Otherwise, there is a Speed Booster option from Metabones that you might look at: it would increase the angle of view and give you an extra stop of light.

Same question as Jonathon's, but for a Canon EOS 350D

The best option to mount an M42 lens onto a Canon DSLR, would be the Novoflex EOS/CO Lens Mount Adapter - Universal Screw Mount (Pentax M42) Lens to Canon EOS Body.  Novoflex makes some of the best adapters on the market.  Otherwise, if you are looking for a less expensive option, you could look at the FotodioX Pro Adapter for M42 Lens to Canon EOS Camera with Focus Confirmation Chip, V.2 with Flange. 

Thanks Christina - very helpful. John H.

Is there an adapter to use old Pentax screw thread lens to mount on current Nikon DSLR's?  I do understand that there won't be any auto functionality with this setup.

You might look at the FotodioX Pro Lens Mount Adapter for M42 Lens to Nikon F Mount Camera.  It would enable you to mount your Pentax screwmount (M42) lenses onto a Nikon DSLR.  Keep in mind that this adapter will require you to adjust everything manually with the lens.  Also, in order for the lens to retain focus at infinity on a Nikon body, the adapter has an optic which will act as a 1.4X teleconverter.   

How about an adaptor for connecting a Canon DSLR to a standard microscope?

We would need to know the Brand and model of the microscope in order to check to see what, if any, adaptor options are available. You could send an email to our Photo Department with this inquiry and the model microscope you have.  We would then be able to check on adapter options.

So, if I'm shooting Nikon and am considering picking up the Sony ARIIs for video, what's the best adapter style to maintain the quality and function of the latest AF-S ED IF G lenses? Specific suggestions? 

Thanks in adavance. 

The only one I have found is this.

Thanks, Vern. Well, I suppose the AF isn't neccessary really, so wondering if the Metabones et. al. suffice. Not a chance in Hades I'd send $400 for a product shipping directly out of Hong Kong on eBay! I really just want command-dial apeture control (since these lenses don't have manual adjustment and shooting in apeture priority would be silly). Curious to hear a detailed discussion of what's out there currently and what the pluses/minuses/sacrifices specifically for Nikon->Sony adapters.

Unfortunately, I’m not familiar with any auto adapters on the market for Nikon lenses to Sony E-mount bodies.  So, you won’t be able to control the lens through the camera body.  The lens will need to be manually focused, and the aperture will need to be controlled manually on the lens.  For G series lenses, this means looking at an adapter that has a mechanism for adjusting the lens’s aperture.  The best option would likely be the Novoflex Adapter for Nikon F Lens to Sony E-Mount Camera.  Novoflex’s quality control is excellent, and they make some of the best machined adapters on the market.  Otherwise, if you are looking for a less expensive option, you could look at the Metabones Nikon G Lens to Sony NEX Camera Lens Mount Adapter (Matte Black).   

I used to have a Mamiya/sekor 1000 DTL.  I had purchased multiple lenses of the highest quality I could get and did so for years as some of them were spendy to say the least. You get what you pay for.  I now have a double question.  I need to get a lens adapter to fit the screw style (Nikon) mounts on each lens.  That is probably the easy one.  Now, I need someone to advise me on a camera body that will work with my new adapter.  I have not used digital cameras before.  I know, that seems impossible.  My wife just died and I need something to do.  With photography always being my second love, I would like to do it right.  That means a camera body I can learn on without great cost and then I would hope to move way up in quality at a later date with the knowledge I have gained.  My guess is that is better for training and expense (to see if I still enjoy photography as I used to) for me to try to buy 'good' but user friendly and in a more moderate price range.  ANY help is sincerely appreciated.

I have Olympus 35mm OM Series Zuiko prime lenses ranging from 18mm to 300mm dating from the 1970s. I purchased an adapter to use them on my Canon EOS digital bodies. I paid a lot of $s for these lenses and felt they were the best image quality I could buy at the time. The results on my a first digital Canon 300D 1.6 crop factor body were good, but not great! It turns out most lenses manufactured in the 1960–1980 time-frame have much higher chromatic aberration, astigmatism, and other aberrations compared to the lenses manufactured today. If used on a full-frame digital body the results will be a lot closer to what you experienced with 35mm film. In addition most adapters do not provide electronics to enable focus-confirmation when manually focuing the lens and todays digital viewfinders are not designed to enable critcal focusing. You can achieve proper focus using live view mode and 10X display on the camera's LCD.

You'll need an M42 mount adapter, which will work with Canon EOS EF lens mount and some other DSLR bodies. Nikon's back focus distance is too short and you'll lose ability to focus at infinity. See more here:

B&H does carry several adapters that would enable you to mount M42 lenses onto a Nikon F camera.  You could look at the FotodioX Pro Lens Mount Adapter for M42 Lens to Nikon F Mount Camera.  It has a 1.4x Multi-Coated Focus Correction Lens, which would enable the M42 lenses to retain focus at infinity.  Though, this optic/correction lens can have a negative impact on the overall quality you are used to getting from your lenses.  If you are still interested in going the Nikon route with your lenses, I would suggest looking at the Nikon D7100 DSLR Camera.  It’s a step up from Nikon’s introductory line of DSLRs, but should still be user friendly.  It has fantastic image quality and low light performance, and is relatively inexpensive right now.  Otherwise, If you went with the Canon EOS system, the adapter options would not require an optic for infinity focus.  The best adapter on the market for the M42 to Canon EOS would be the Novoflex EOS/CO Lens Mount Adapter.  Novoflex adapters are machined extremely well.  For a less expensive option, you could look at the FotodioX Pro Adapter for M42 Lens to Canon EOS Camera with Focus Confirmation Chip.  As for a Canon DSLR, you might checkout the Canon 70D.  It would sit in Canon’s line about where the D7100 sits in Nikon’s line, and would be a good option for starting out with a DSLR when you already have experience with a 35mm SLR. 

I have a number of Voïgtlander lenses from the 1950s (not the current Voïgtlander). They are bayonet type but very intrusive.  I have been looking for adapters for Nikon mount but I haven't found any.  Does anybody know where I could find these adapters?  If not available for Nikon,  is there for any other digital camera? ( the lenses are too good).  Thank you for your help, Luis Oliveros 

Hi Luis,

Do you have any more information on the mount type of your Voigtlander lenses? Do you know which camera they were originally used with? Rangefinder or SLR style?

It's unlikely you'll be able to cleanly adapt them to a Nikon (since Nikon has one of the longest FFD measurements), but it could be possible via an adapter with a corrective element.

The best cameras to use in conjunction with adapted lenses are mirrorless cameras. If you check out the chart above, any of the mounts at the top end of the chart, on the left side, would be ideal- such as Micro Four Thirds, Sony E, Fujifilm X, etc. These mounts have shorter FFD measurements, and can accept adapted lenses from systems with longer FFD measurements very easily.

Any chance that there is an E-mount to A-mount adaptor? I have the inversion to adapt older minolta lens to my E-mount camera, but my girlfriend would like to use some of my native E-mount lens on her A-mount camera. I'm sure the A-mount lens would work much better for her, but the fact that I already have these E-mount lens makes the price right. 

Any ideas?

Unfortunately we do not carry any kind of adapter that will allow an E-Mount lens to be used on an A-Mount body. To the best of my know have not heard of such an adapter avilable elsewhere. 

Does anyone make an adapter that would allow me use an SMC Pentax F 4.5 500mm telephoto lense on a Canon EOS Rebel, or any modern digital camera including the latest Pentax K?

Thanks for any information.



We carry the FotodioX Adapter for Pentax K-Mount Lens to Canon EF-S Cameras (B&H # FOPENKEOSC) which will allow for this lens to be mounted to a Canon Rebel Series (EF-S Mount) camera. This is currently the only option available.

Thank you so much for the response nd the reference to the item on the Web Site.  I will order a soon as possible.



I have an older Vivitar 100 - 500 series 1 lense I would love to find and adapter for Nikon DSLR 800 & 600, any suggestions would be appreciated

Hi Paul,

Which mount type is your Vivitar 100-500? If it is the Nikon F-mount version, then no adapter would be required. If it's one of the other mounts, you'll need to look for an adapter from that mount type to Nikon F cameras; and these adapters will have a corrective lens so you can achieve infinity focus.

Its a Minolta bayonet mount

This Fotodiox adapter would be the sole choice we have right now to adapt Minolta SR (also called MD)-mount lenses to a Nikon DSLR. As you'll see, the adapter includes a corrective element to ensure you'll maintain infinity focus with the lens since it was originally intended for a system with a shorter flange focal distance.

Thanks Bjorn !!

Didn't see anything for Konica lenses. Have a nice zoom from the early 80's that I would like to use on my Canon T5i. What are the chances?

Hi Denny,

Konica lenses are unique in that they have one of the shorter flange focal distances for an SLR system of 40.5mm. The Canon EF mount has a 44mm FFD. The only feasable way to use your Konica lenses on a Canon DSLR will be with a lens adapter featuring a corrective element, such as this one.

In describing the screw mount, you state that it operates like putting a bolt onto a screw. I do not believe this is possible. Could you have possibly meant a nut onto a bolt?

I have two Fotodiox adapters, one for mounting my older Hasselblad lenses to my Sony A77ii, and the other for adapting my older Nikon AF lenses.  The Hasselblad adapter (which doesn't have a glass element), seems like it may be a bit long, as I can't get effective infinity focus (impossible to get a sharp full moon shot with either my 140-280 or 500 lenses).  Perhaps because of the extreme crop factor for a lens designed for 6x6 film to be used on an APS-C sensor, the resolution just isn't there?  Not much success with the Nikon adapter either--maybe the glass element degrades the image quality too much.  I get much clearer full moon shots with my little Lumix FZ-150.  Seems like I'll need a good lens with an actual Sony A mount to get good infinity shots.

I am interested in buying the Sony A7Rmk2. Most of my photos are of landscapes. Considering the Sony FE lenses, what two would you recommend. Weight is a consideration. Crisp focus is very important. Medium tele is o.k.Thanks for your consideration.

You might look at the Sony FE 16-35mm f/4.  It would be a very popular focal range for landscape photos, and isn’t overly heavy (18.27 oz).  Otherwise, for medium to long telephoto options, you might look at the Sony FE 70-200mm f/4.  While it is a zoom lens, it’s not too heavy (29.63 oz).  While a bit longer, it weighs roughly the same amount as some of Sony’s prime medium telephoto options.  Both are lovely lenses, with excellent optical quality. 

Does anybody offer  an adapter for using a Rodenstock Imagon Lens with a Nikon DSLR?

Hi Jeff,

It is possible to use an Imagon (or other large format lens) with a DSLR, but there are no dedicated adapters available due to how the lenses were initially designed to be used (with a lens board). A couple of options are available, however: view camera bodies from Horseman or Cambo will allow you to use large format lenses in conjunction with a DSLR, although infinity focus is not always guaranteed with each lens.

Thanks for the article.

I have several Minolta 101 telephoto lenses (like Tamaron 300) and would like to know if there is an adapter to mount it on my Nikon 3300?  Then, the real question is what will images look like?

TIA ~ Eric

Hi Eric,

Nikon cameras are notoriously difficult to adapt lenses to since their system uses one of the longer flange focal distances of 46.5mm; the Minolta SR (sometimes called MD) system has a 43.5mm FFD. These Minolta lenses will not be compatible with your Nikon cameras unless you use an adapter with a corrective lens, such as this one.

Paragraph 3 says  "thread a bolt onto a screw"    Should it not say "thread a nut on to a bolt"   or something similar ???    I have never know a way to thread a bolt on to a screw :-)

Otheswise, nice article

Government routinely does the equivalent...

I would purchase a Nikon to Sony E Mount with all the auto features right now.

Will Sigma be coming out with a Nikon to Sony E mount retaining auto focus and apature control like the recently introduced Canon to Sony adaptor ? 

Unfortunately, there are no auto adapters on the market at this time for Nikon lenses to Sony E-mount cameras.  With the popularity of the auto Canon adapters, I would think that Sigma and other manufacturers would be interested in making a Nikon auto adapter.  Though, it’s been several years since the first Canon auto adapters hit the market, and we have yet to see one for Nikon.  All I can think is that there is some difficulty with the Nikon lenses that manufacturers have yet to find a way to surmount. 

I believe Nikon has chosen to not license it's electronics for use with adapters at this time.

If I remember correctly, most Nikon F-mount lenses have a manual aperture lever, like Pentax K-mount lenses, so there's no way to automate that in an adapter.  The exceptions would be their most recent "E" lenses, of which there aren't many.

I am having trouble figuring out how my Nikon lenses work on my Nikon cameras. I would also like to see a Nikon mirrorless camera with a grown-up sensor.

Unfortunately, until Nikon announced a camera, we wouldn’t know what they might be working on.  So, there is no way to know if/when they might release a full frame mirrorless camera.  As for how your Nikon lenses work on your Nikon cameras, are you having issues with compatibility?  Or did you have specific questions about a function? 

You missed Konica mounts. Is there a converter to fit the Konican Hexanon of the Auto Reflex era to fit the Sony A mount?

Hi Larry,

The Konica AR-mount has a 40.5mm flange focal distance, making it one of the shorter FFDs for an SLR system. AR-mount lenses will not be compatible with Sony A mount unless you use an adapter with a corrective lens, such as this one.

Excellent article.  Regarding the adapters with the condensing lenses:  we recently bought a Metabones "speed" adapter to connect Canon EF lenses to a micro 4/3 camera.   When using any specific lens, say a 50mm, at a given aperature, say 2.8, the micro 4/3 should have roughly twice the depth of field than that lens on a "full-frame" camera.  That part I get.

My question is, how do I think about the aperture on that 50 through the condenser lens?  Does the condenser return the relative depth of field of that lens on the full frame, or is 2.8 on the 4/3 always 2.8? 

Asked another way, without the condenser if I put on a 50mm lens at 2.8 I should get the relative depth of field of that 50mm at 5.6 on a full frame camera.  What is the relative depth of field of that same 50mm lens at 2.8 through the condenser lens?

Hi Rob,

It's tough to say with absolute certainty, but using a 50mm lens at f/2.8 in conjunction with an adapter with a condenser element should give you approximately the same depth of field as if you had mounted the lens on a full-frame camera. It's approximate, though, since the condensers usually affect the field of view in more abstract figures, such as 0.71x and 0.64x. It's likely a more accurate figure could be along the lines of f/2.8 seeming like f/3.5 in terms of depth of field.

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