Flange Focal Distance – also known as Flange Distance or Flange Depth – is the distance from the camera’s mounting flange to the film or sensor plane. Another way to look at this is Flange Focal Distance refers to the distance the lens needs to be mounted from the film plane.
This distance varies between cameras and lens mounts which explains the depth (or thickness) of lens mount adapters. If you scan to the chart below you will see that Canon EF-mount has a Flange Focal Distance of 44mm and Sony E-mount has a Focal Distance of of 18mm.
44mm – 18mm = 26mm
This means that Canon EF to Sony E lens adapters need to be 26mm thick in order to make up that difference so that the lens will mount the proper distance from the film or sensor plane which allows the full range of focus from infinity to the minimum focus distance.
Most lens mount adapters are constructed to be very slightly thinner than this distance which allows lenses to focus past infinity. While this may be frustrating to Leica lens users who are used to a hard-stop at infinity – it beats the alternative that if a lens mount adapter is even slightly too long – the lens will not focus to infinity.
While lens mount adapters might look like extension tubes – they are not. There is no light light loss – they simply place the lens at the proper distance from the film plane or sensor.
The Flange Focal Distance of the lens must be greater than that of the camera body it is to be adapted to in order to allow room for the adapter.
Simple math explains why it’s possible to make Canon EF lens to Sony E-mount body adapters but it’s NOT possible to make a Sony E-mount lens to Canon EF body adapter, because in order to mount a Sony E-Mount lens on an Canon EF body, the adapter would need to be a NEGATIVE 26mm thick!
It should go without saying (yet I get this question every month) but E-mount to E-Mount Speedbooster adapters are also impossible because they would need to be ZERO MM thick…
Focal Flange Depth Chart
| Lens Mount | Flange Focal Distance | Camera Type | Camera Format |
|---|---|---|---|
| Pentax Q-mount | 9.20 mm | Mirrorless | 1/2.3″ – 1/1.7″ |
| D-mount | 12.29 mm | Cine | 8mm |
| CS-mount | 12.50 mm | TV | 1/4″, 1/3″, 1/2″ |
| Nikon 1-mount | 17.00 mm | Mirrorless | CX |
| C-mount | 17.526 mm | Cine/TV | 8mm, 16mm, 1/3″, 1/2″, 2/3″, 1″, 4/3″ |
| Fujifilm X-mount | 17.70 mm | Mirrorless | APS-C |
| Canon EF-M-mount | 18.00 mm | Mirrorless | APS-C |
| Sony E-mount | 18.00 mm | Mirrorless | 24×36mm / APS-C |
| Sony FZ-mount | 18.00 mm | Cine | Super 35mm |
| Leica SL-mount | 19.00 mm | Mirrorless | 24×36mm / APS-C |
| Micro Four Thirds | 19.25 mm | Mirrorless | 17.3 x 13mm |
| Samsung NX-mount | 25.50 mm | Mirrorless | APS-C |
| Pentax Auto 110 | 27.00 mm | SLR | 13×17mm |
| RED ONE | 27.30 mm | Cine | Cine |
| Leica M-mount | 27.80 mm | Mirrorless | 24×36mm |
| M39 mount | 28.80 mm | Mirrorless | 24×36mm |
| Olympus PEN F | 28.95 mm | SLR | 18x24mm |
| Contax G-mount | 29.00 mm | Mirrorless | 24×36mm |
| Contax RF-mount | 34.85 mm | Mirrorless | 24×36mm |
| Nikon S-mount | 34.85 mm | Mirrorless | 24×36mm |
| 1/2″ TV bayonet mount | 35.74 mm | TV | 1/2″ 3-CCD |
| Minolta V-mount | 36.00 mm | SLR | APS-H |
| Sony 1/2″ TV bayonet mount | 38.00 mm | TV | 1/2″ 3-CCD |
| Olympus Four Thirds System | 38.67 mm | SLR | 17.3 x 13mm |
| Konica AR-mount | 40.50 mm | SLR | 24×36 mm |
| Konica F-mount | 40.50 mm | SLR | 24×36mm |
| Canon FD-mount | 42.00 mm | SLR | 24×36 mm |
| Canon FL-mount | 42.00 mm | SLR | 24×36 mm |
| Fujica X-mount | 43.50 mm | SLR | 24×36mm |
| Minolta MC/MD mount | 43.50 mm | SLR | 24×36mm |
| Canon EF-mount | 44.00 mm | SLR | 24×36 mm / APS-C |
| Pentaflex | 44.00 mm | Cine | 16 mm |
| Praktica B-mount | 44.00 mm | SLR | 24×36 mm |
| Sigma SA-mount | 44.00 mm | SLR | 24×36 mm / APS-C |
| Minolta / Sony A-mount | 44.50 mm | SLR | 24×36 mm / APS-C |
| Rollei / Voigtländer QBM | 44.50 mm | SLR | 24×36mm |
| Exakta | 44.70 mm | SLR | 24×36mm |
| M39 | 45.46 mm | SLR | 24×36mm |
| M42 | 45.46 mm | SLR | 24×36mm |
| Pentax K-mount | 45.46 mm | SLR/Mirrorless | 24×36mm |
| Contax C/Y-mount | 45.50 mm | SLR | 24×36mm |
| Kodak Retina DKL-mount | 45.70 mm | SLR | 24×36mm / 28×28mm |
| Voigtländer Bessamatic DKL-mount | 45.70 mm | SLR | 24×36mm |
| Voigtländer Vitessa T DKL-mount | 45.70 mm | Mirrorless | 24×36mm |
| Yashica MA-mount | 45.80 mm | SLR | 24×36mm |
| Olympus OM-mount | 46.00 mm | SLR | 24×36mm |
| Nikon F-mount | 46.50 mm | SLR | 24×36mm / APS-C |
| Leica R-mount | 47.00 mm | SLR | 24×36mm |
| KMZ Zenit DKL-mount | 47.58 mm | SLR | 24×36mm |
| B4 2/3″ TV bayonet mount | 48.00 mm | TV | 2/3″ 3-CCD |
| Contax N-mount | 48.00 mm | SLR | 24×36mm |
| Arri B | 52.00 mm | Cine | Cine |
| Arri PL | 52.00 mm | Cine | Cine |
| Arri STD | 52.00 mm | Cine | Cine |
| T-mount | 55.00 mm | SLR | 24×36mm |
| YS mount | 55.00 mm | SLR | 24×36mm |
| Panavision PV-mount | 57.15 mm | Cine | Cine |
| Mamiya 645 | 63.30 mm | SLR | 6×4.5 cm |
| Contax 645 | 64.00 mm | SLR | 6×4.5 cm |
| Pentax 645 | 70.87 mm | SLR | 6×4.5 cm |
| Rollei SLX | 74.00 mm | SLR | 6×6 cm |
| Pentacon Six | 74.10 mm | SLR | 6×6 cm |
| Hasselblad 500 / 2000 | 74.90 mm | SLR | 6×6 cm |
| Hasselblad 1000F / 1600F | 82.10 mm | SLR | 6×6 cm |
| Pentax 6×7 | 85.00 mm | SLR | 6×7 cm |
| Rollei SL66 | 102.80 mm | SLR | 6×6 cm |
| Mamiya RZ67 | 105.00 mm | SLR | 6×7 cm |
| Mamiya RB67 | 111.00 mm | SLR | 6×7 cm |
Chart Source: Wikipedia and Manufacturer Specs
Read More About Sony Lens Adapters:
Pulitzer Prize-winning photographer Brian Smith creates iconic portraits of the famous and infamous for magazines, books and advertising. He has appeared on The X Factor, Fine Living Network and Israel Channel One and exhibited at the Library of Congress and the Aperture Gallery.
Comments
What is the flange-to-focal distance of the Canon XL1?
29mm
Pingback: Sony a99 II -vs- a7R II 42.4MP Showdown September 27, 2016
[…] Because of its thin 18mm Focal Flange Distance, Sony a7RII allows you to adapt virtually any fullframe lens. The same cannot be said for a99 II since A-mount has a 44.5mm Focal Flange Distance that makes it far less viable for using adapted lenses. (Read More: Guide to Understanding Flange Focal Distance) […]
Would it be possible to use Fuji and Sony E mount lenses interchangeably since the difference is only 0.3mm?
Nope. Even if they were purely mechanical lenses (and they’re not) 1/3 of a millimeter is way too thin.
how much depth of focus would you get if you used a 46.5mm flange depth lens with a 46mm flange depth camera with a 5mm adapter?
That would only allow very close focus -?nowhere close to infinity.
thanks, but what about all the lens adapters that claim that they allow for infinity focus?
Because they did the math correctly. You did yours wrong.
But these filters are obviously more than 0.5mm, I was just wondering how big of a window there is between lens flange depth and camera flange depth where the lens is still usable?
Are you asking about filters or adapters? The adapter in the example you gave WOULD need to be 0.5mm or thinner to maintain infinity focus.
46.50mm – 46.00mm = 0.5mm adapter depth
But a Canon EF to Sony E mount adapter should be 26mm thick.
44.00mm – 18.00mm = 26mm adapter depth
It’s simple math.
Have a look at the illustration.
Hi,I want to make my own mft-m42 adapter and print it 3d.I made the difference : 45.46 mm-19.25mm=26.21mm.It`s that the dimenssion of the total adaptor or just the middle section,without the m42 mount and mft mount?If you could respond,I would appreciate,thanks
Assuming you mean M42 lens > MFT camera, your math is correct. HOWEVER you should trim at least .01 from the length. This will cause the adapter to focus past infinity. If you are even .001 too long you will not be able to focus to infinity. When it comes to adapters, it’s much better to be too short than too long.
It`s the 26.21mm only the middle section, without the mounts?
Flange plane to Flange plane.
will all m42 adapted lens work on a pentax k5 properly
Nope.
Yes they will.as long as a proper adapter is used (one that sits inside the K mount)
Pentax designed the K mount to be backwardly compatible. Both M42 & the K mount have a flange distance of 45.46mm. With a proper adapter the flange of the M42 lens sits directly on the flange of the camera.
sir, i am having a c mount on a beam splitter for my operating microscope.
i want to attach a DSLR camera over the c mount for live surgical video recording. what options do i have in sony DSLR without vignetting and loss of quality for high definition recording??
You don’t. C-mount lenses are 16mm cine
thanks for reply sir,
then how to connect beam splitter to a DSLR??
any mount or adapter available??
thanks regards
Hi! I’m planning on building my own camera (I know, I know, bold project) and find that the flange focal distance is the biggest problem. I have a 50mm f.1,8 lens, as well as a M42-> EOS adapter. The adapter will work as the mount for the lens to my camera (making it an interchangeable-lens-camera). First of all – the problem is to measure the correct distance from my lens to the point where I will install my film roll and shutter. From the table, I understand the distance would be 45,46mm (am I right?). Second, it will be hard to INSTALL the film and shutter at the right distance. Well, I’ll cross that bridge when I get to it.
My question is; if I install the film slightly off TOWARDS the lens, would I be unable to focus at all, or would I just eliminate the opportunity to focus at infinity and/or at a very close distance? And how far off would I have to be to not be able to get any focus at all?
I’m hoping for a response, and just ask me to clear things up a bit more if my explanations were bad!
Thanks in advance!
If you are slightly too shallow the lens focuses past infinity which is not really a problem.
If you are slightly too deep the lens won’t focus to infinity. Much bigger problem.
I want to connect my Micro 4/3 lens to C-mount camera. The lens producer told me it’s impossible. But according to your article the lens flange focal distance should be greater than camera flange focal distance and it is indeed. So what’s the problem?
It’s theoretically possible BUT you’d need someone to make an electronic adapter that was a mere 1.75mm thick (which is basically impossible) if you wanted to control the aperture. Given that C-mount is pretty much a “dead” lens mount…don’t hold your breath…
Okay, that’s good news. I don’t want to control the aperture because the lens I want to use is a mirror lens (Tokina Reflex 300 mm f/6,3) with fixed aperture. Why you have said that adapter should be 1,75 mm thick? The MTF lens flange focal distance is 38,7 mm and C-mount flange focal distance is 17,526 mm. The difference bettween them shouldn’t be equal to adapter length? The problem is I haven’t seen such adapters yet…
Nope. Flange Depth of Micro Four Thirds is 19.25mm so roughly 1.75mm.
But once again, I don’t see anyone making C-mount lens adapters since there is not a sufficient market for them.
Right. So the lens manufacturer gave me the wrong numbers. Thank you very much for the right ones. My colleagues have just designed (scetched) such adapter and we must manufacture one. Do you see some other disadvantages of connecting such lens to C-mount camera?
It’s pretty much limited to the lens you mentioned but if you can make one cheaply, you might give it a try…
Are you by any chance in possesion a knowledge about the possible spot size of this particular lens? I just heard that this kind of lenses (mirror ones) are “soft” so I assume that spot size is quite big…
Pingback: Sony Fullframe Flagship Showdown a9 -vs- a99 II May 22, 2017
[…] Because of its thin 18mm Focal Flange Distance, Sony a9 allows you to adapt virtually any fullframe lens. The same cannot be said for a99 II since A-mount has a 44.5mm Focal Flange Distance that makes it far less viable for using adapted lenses. (Read More: Guide to Understanding Flange Focal Distance) […]
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[…] understand flange focal distance (FFD). For details, you can visit the link from Brian Smith. For basic understanding, flange focal distance is the distance between the camera sensor and the […]
Hi Brian!
Thanks for this information. It really helped clarify things for me. I am looking to make some janky lomo adapters where I will be able to use Pentax Q lenses on a Micro Four Thirds camera. My plan is to epoxy a body cap and a rear lens cap together, then see what sort of visuals that results in. Based on your math, the focus quality is going to be terrible. But would it be in any way workable? Like in an artsy abstract sense? Either way, I’ll be shaving those caps down to as thin as possible now that I’ve read your info. I’m sure it will all turn out horrible in the end, but it’s a fun experiment for an uneducated pleeb like me.
Cheers!
Pam
I would NOT advise that.
You’d need to mount the lens 10.05mm INSIDE the camera. Forget about shaving the lens cap down – you need to cut a hole in the cap and mount the lens almost 1/2 inch inside the body.
You’d risk damaging your sensor and even if all went well, the lens would not cover the M43 image sensor.
Pingback: Sony a7R III -vs- a99 II 42.4MP Camera Showdown March 5, 2018
[…] Because of its thin 18mm Focal Flange Distance, Sony a7RII allows you to adapt virtually any fullframe lens. The same cannot be said for a99 II since A-mount has a 44.5mm Focal Flange Distance that makes it far less viable for using adapted lenses. (Read More: Guide to Understanding Flange Focal Distance) […]
Hi I have a canon eos rebel t5i and i bought a 50mm cctv lens. I purchased a c mount adapter separately and found out that because of difference on focusing distances between Canon and 16mm sensors, it can focus on very close objects only (about 20-30 cm). Is there any c mount adapter or optimizer or any othee solution to make a 16mm cine operate normally on my canon camera? Although i like the macro focus, i would love to be able to use the camera cctv lens as originally intended. Thank you in advance for your answer.
If you wish “to be able to use the camera cctv lens as originally intended”, you must select a body thinner than the camera it was designed for. Canon EF mount is too thick.