With the advent of mirrorless cameras, there was a shift in registration distance for lenses. That opened possibilities to use existing lenses on these newer mounts.
This is all about flange focal distance. It’s the distance from the lens mount ring to the sensor or film plane. https://en.wikipedia.org/wiki/Flange_focal_distance
Older camera systems have a long distance. Newer camera systems have a short distance. So that means with something between an old lens and a new mount you can make the combination work.
The distance is measured in millimeters.
A few examples:
- Canon FD: 42mm
- Canon EF: 44mm
- Canon EF-M: 18mm
- Nikon F: 46.5mm
- Nikon Z: 16mm
- M42: 45.46mm
- L39: 28.8mm
A little test you can do is holding a lens like the EF 50mm in front of the M50 camera without a lens. Moving it back and forth shows where that registration distance is… the same as the thickness of the adapter.
The details of adapters are not so simple.
Let’s talk about some of the adapter types…
The cheapest and most common have no control through the camera or any levers.
- Cheapest more available type.
- The simplest option for old film era lenses because you don’t need anything more.
- If your lens doesn’t have a manual aperture then you will not be able to adjust it. This is the case for Canon EF lenses. You can see the two that I have would not work with a basic adapter.
There are adapters that have a mechanical way to control aperture. This depends on the lens being adapted. Only certain ones have mechanical properties to them that allow this type to work.
- Some older lenses had a physical lever for controlling aperture. In my case I have a Nikon F-mount lens with the lever and an M42 lens with something similar.
- The adapter I have for F-mount does physically adjust the adapter, but it is imprecise with no way to set a specific value.
Some control through the camera.
- There are adapters that allow for some level of control.
- For example, the official Nikon F to Z mount adapter can control aperture, but does not have a motor for autofocus with D-type lenses.
- These are better than basic adapters when you need some level of control through the camera.
- There are other adapters that have quirks or limitations like not being able to do a special focusing mode that a native lens would be able to do.
Adapters with full control through the camera.
- These adapters allow for the same amount of lens control compared to a native lens usually.
- The official Canon EF lens adapters for EF-M and the RF mount have full control.
Speedbooster adapters (focal reducer)
- These adapters take lenses meant for a larger format such as Full-Frame but focus the light into the area of a smaller format like APS-C.
- It reduces focal length and increases lens speed.
- You can see that my Viltrox 0.71x speedbooster is physically shorter than the standard adapter and it has optical glass inside.
- Most of these adapters are fully electronic and work with a specific lens and mount combination.
- These tend to be some of the most expensive types of adapters.
- Expect overall image quality to depend on the optics of the speedbooster.
Other more obscure adapters
- Check out Fotodiox lens adapters through my B&H Photo Video affiliate link.
- The company Fotodiox has a large number of speciality adapters from tilt/shift to internal iris and auto focusing.
- Canon’s official EF to RF adapter with a built-in variable ND filter or circular polarizer. Their adapters also allow for a custom control ring.
I hope that helped you understand what lens adapters for mirrorless lens adapters do. Having a change in flange focal distance allowed for a lot of inventive adapters to be created. It’s a reason to hold on to your older lenses and a reason to pick up a mirrorless camera if you haven’t yet.
Below are the subtitles for the attached video if you prefer to read it than watch…
Hey, this is Scott of Photography Banzai. Today we're talking about attaching non-native lenses to mirrorless cameras. There are a lot of adapters out there. I'm gonna go over why they work, and a few of the different types. So let's get started! All of this about the flange focal distance. It's the distance between the lens mount... that metal ring you see. It's a bayonet mount usually. And then the sensor plane or film plane. So at the most basic level, older lenses have a longer distance and newer lenses have a shorter distance. All this means is that having something between the older lens and the newer camera makes it work properly. That flange focal distance is measured in millimeters. I'm going to talk about a few different mounts and their measurements. Just helps you get an idea of how it all works together. Most of my current equipment is Canon, so I'm going to use them as the main example. They had the FD mount, which is 42 millimeters for that flange focal distance. And the EF mount.. DSLR.. SLRs, but that is 44 millimeters. So they actually made it a little bit longer than the older FD mount. And the EF-M mount, which is the M50 that I have. It is 18 millimeters. That difference between 44 and 18 allows the EF lenses to work on the EF-M cameras with the proper adapter. Another example is the Nikon F-mount. It's 46.5 mm... So that's even a little bit longer than the EF mount from Canon. And Nikon's new Z-mount is 16 millimeters. So that's even shorter than the canon EF-M mount. And I also have an M42 lens. It's an older film lens. Pentax... A lot of other little companies. Some Russian lenses are in that M42 screw mount. That's 45.46mm for that flange focal distance. I have a Canon EOS 30D. It has a standard EF mount. You can see that distance on there. It's a large area inside. Because they had a mirror. They had various optics that they needed to fit inside there which explains why they're so long compared to the new mirrorless cameras that don't need that technology inside. Because they have an electronic viewfinder. I can actually hold the EF 50mm lens up to the M50 camera, and if I get the distance right between the lens and the camera don't even need an adapter. You'll still see a sharp image in the back of screen. Because you can basically get that flange focal distance when you're moving it back and forth. Of course, there'll be a lot of extra light in there that you don't want. But it does work for the most part. The specific details on lens adapters are not so simple. There's a lot of them. There's a lot of different types, which I'll go over some of them in this video. Help you out. Try to get you an idea of what you might need. The cheapest and most available lens adapters have no information going between the lens and the camera itself. So think about old film era lenses that have an aperture ring on them. They don't need the aperture control through the camera. Those work just fine. You just need basically a separator to get the right distance. If you have some old M42 lenses like the one that I do have. Has an aperture ring on the lens itself. Just keep in mind there is usually a setting in the camera you need to toggle to make it possible to take photos without the camera sensing a lens attached. However, these basic adapters do not work with all lenses, of course. With these EF lenses they do not have an aperture ring... So you need a more advanced adapter to get aperture control through the camera. Otherwise, you just will have to use the largest aperture and that's it. Some adapters allow for mechanical control of the aperture. So we don't need actual data connections between the lens and the camera. You get that mechanical control. I do have a Nikon F-mount lens that has a mechanical aperture on it. And the adapter that I have has a little ring on there that physically moves that aperture lever back and forth. It's not ideal. It does not allow you to get exact aperture sizes, but it works well enough that you can adjust your aperture if you need it super wide or more narrow. Other adapters allow you some level of control through the camera. So, for example, the Nikon official adapters from F to Z mount allow you to control the aperture. They allow you to control autofocus, with most of their most recent lenses for the DSLRs, but not all of the older ones. For the D-type lenses that do not have a motor inside the lens itself... like the one that I have. You can't do autofocus. There are definitely little quirks here and there with some adapters you need to know about. But there are so many different types of combinations. It's really going to be up to what you have or what you want to use. Other adapters allow you full control from the camera to the lens and back. So with my EF to EOS M adapters, the EF-M mount... I get full control for those EF lenses. The aperture, the autofocus... everything works. There are speed booster adapters available. These are a special type. Usually third parties make these, and they're called focal reducers. What it does is that you take a larger format like full-frame. Put it into an APS-C sized area. Gives you a focal reduction. And you get more light for that smaller area. I have this Viltrox 0.71x speed booster that I use with the EF lenses to the EF-M camera, which is APS-C... You can see that this Viltrox adapter is actually shorter than the standard EF to EOS M adapter. And it also has some glass inside that allows it to do that speed boosting ability. That focal reduction. For Canon's newest mount, the RF Mount, which is mirrorless and it's also full-frame for the moment. You have a few unique official adapters. You've got one for filters. Where you can do a circular polarizer, or a variable ND filter. So those are pretty interesting. There are a lot of third-party stores and companies that sell very unique adapters. I'm gonna go over a few of them. Fotodiox has a huge amount of adapters on the website. For example, they have a tilt-shift adapter. So you put a standard DSLR or SLR lens, and then the mirrorless camera, with that tilting adapter. That allows you to do things like architecture with straight lines. Because you can physically shift the lens without buying a specialty lens. So that's pretty cool! They have internal iris adapters. Also, they have auto focusing adapters for very old lenses. Having that change in flange focal distance from the older cameras to the new mirrorless ones allows for a lot of possibilities with adapters. So I just scratched the surface here with a few of them, but know that they're out there. And a lot of them are pretty interesting. Might want to check them out! Hope you enjoyed this video on lens adapters for mirrorless cameras with older lenses. I'm Scott from Photography Banzai. If you enjoyed the video, please consider subscribing... That helps me out a lot. Likes and shares help out a lot as well. Thanks again!