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I’m looking to buy a DSLR and I’m stuck between buying a Canon with an EF mount or a camera with Micro 4/3s. I have a good set of old Canon FD lenses (From a 28mm to a telephoto) that I’d like to use, and ideally not buy many new lenses.

So - which system is best for use with FD lenses?

I see the FD to MFT adaptor doubles the focal length, so does that mean it’s not worth it? None of my lenses would be particularly wide any more.

On the other hand, I’m having difficulty finding resources for using FD lenses with an EF mount - surely if there’s a full frame sensor then the lenses will be closer to their original focal length?

Or are there too many downsides to using the old lenses completely? I’m not too fussed about autofocus etc.

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So - which system is best for use with FD lenses?

Neither EF nor MFT are ideal for adapting FD lenses.

  • To adapt FD to EF requires corrective optics with a 1.4x multiplier.
  • MFT has a 2x crop factor. With a 0.72x focal reducer, this can be converted to 1.44x.

If you intend to use adapted lenses extensively, consider an APS-C or full-frame mirrorless camera. Mirrorless cameras have shorter flange focal distances, which makes it easier to adapt foreign lenses.

  • Full-frame is expensive, but the sensor matches the film format for which the lens was designed. Options: Sony, Nikon, Canon, Leica?

  • With APS-C, focal reducers provide near-full-frame coverage (1.1x) with some trade offs (edge/corner sharpness, risk of "blue dot" flaring, other aberrations). Pairing a focal reducer with a plain adapter allows lenses to serve double duty (1.5x and 1.1x). Options: Sony, FujiFilm, Canon, Nikon?

Or are there too many downsides to using the old lenses completely?

Pros of using adapted lenses:

  • Inexpensive – There is no need to limit yourself to only FD lenses.
  • Image quality – Lenses have different "characters".
  • Fashion – Old lenses look cool.
  • Manual focus and aperture – Slow down and spend more time composing. Feel like a "real" photographer.

  • Nostalgia – Use the glass you cut your teeth on.

  • History – Relive the (photographic) dark ages with slow, uncoated optics.

  • Two for one – Lenses can serve double duty when used with focal reducers and plain adapters. 50mm doubles as 36mm. 135mm doubles as 97mm.

Cons:

  • Lens buying addiction and GAS

  • Manual focus – Too slow for sports and birds?

  • Manual aperture – Just pretend you're using aperture priority mode.

  • Extra rings to attach to camera and lens. With enough adapters, you never have to remove them from the lenses.

  • Lenses don't behave exactly as they did on film because of crop factors and sensor technologies. Like any other change, it just takes time to adjust.

  • Some lenses may not be able to resolve to the level of the sensor. Canon FD lenses, especially the newer bayonet style, should work well enough for 24mp APS-C or 54mp full-frame sensors.


I’m looking to buy a DSLR and I’m stuck between buying a Canon with an EF mount or a camera with Micro 4/3s.

There is no DSLR with MFT mount because there is no room for a mirror box.

I have a good set of old Canon FD lenses (From a 28mm to a telephoto) that I’d like to use, and ideally not buy many new lenses.

The best experience with any camera system is with native lenses. Consider obtaining at least a kit lens, which you can complement with adapted primes.

... if there’s a full frame sensor then the lenses will be closer to their original focal length?

Not necessarily. Suppose you were to adapt an FD lens for use with an EF mount. The flange focal distance of EF is greater than that of FD. Corrective optics that multiply the focal length by 1.4x would be needed. So a 50mm lens would behave like a 70mm lens. However, the same lens used with a focal reducer (0.72x) on an APS-C mirrorless camera (1.5x) will behave like a 54mm lens (in the original 135 format).

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I see the FD to MFT adaptor doubles the focal length, so does that mean it’s not worth it? None of my lenses would be particularly wide any more.

So, uh... buy a wide angle lens or two to complement your existing lenses?

On the other hand, I’m having difficulty finding resources for using FD lenses with an EF mount - surely if there’s a full frame sensor then the lenses will be closer to their original focal length?

The FD mount has a flange focal distance of 42mm, the EF mount uses 44mm. Simple mechanical adapters can only allow using lenses on a mount with a flange focal distance shorter than their native one, not the other way round (because an adapter can only add space, not remove it). To use FD lenses on an FE mount, you'd need an adapter that contains corrective optics, which would be bulky, expensive, and almost certainly add aberrations.

According to Wikipedia, Canon did produce a high quality FD-to-EF-Adapter, but it only worked with certain telephoto lenses, is discontinued and very rare and expensive to buy used. Other adapters are more easily available but result in severely diminished quality.

The Micro Four Thirds system has a flange focal distance of only 19.25mm, so using FD lenses on it is relatively easy.

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FD lenses will be optimized for 35mm cameras, which makes them ideal for adapted use on a full frame (FX) camera.

Arguably, there is another "sweet spot" when using them on an APS-C (DX) camera, because you will then only get the very best of the juicy center of the image circle. Do be aware that a 24MP APS-C sensor is extremely demanding of lens resolution - even if we take Nyquist into account, a lens should optimally deliver good at 60lpmm to make full use of it. Also be aware that it is said that some lens designs (I do not know if any genuine Canons do) optimize for the center AND corners at the cost of the area in between (which will be your corners on APS-C) in order to get the best test results in magazines that test center and corner.

MFT is likely to be "too far away" from what the lens was built for - you will get the good stuff from the center, but you will also have a lens that is MUCH heavier and larger than it needs be, and if we are talking high resolution MFT, the resolution demands can be even higher.... Also, huge amounts of stray light from the wasted parts of the image circle, and lens designs used far far off the angle they are optimal for (eg for a 50mm lens for MFT, you would probably go for a telephoto or Sonnar-ish design, not for a Planar/Ultron type as most FX 50mm are...)

As others explained in detail, a mirrorless camera is almost always a better choice than a DSLR for adapted lenses, and generally for manual focus lenses.

You will find that original Canon FD/FL prime lenses, if they are intact, are still of great quality and can deliver results on modern digital cameras. Zooms, especially if they were meant as an inexpensive consumer option, will need experimentation. Off-brand FD compatible lenses will be a mixed bag - some will be great, but especially when you try some of the lower-tier off brands (as in, not Sigma/Tokina/Tamron/Vivitar-Series-1), you will occasionally find some genuinely bad/disappointing ones...

The one area where almost all 1980s lenses will be inferior to modern primes is absolute, global contrast; this has to do with advances in coating technology mostly...

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