omd:focalreducer
focal reducer adapters and the Olympus OM-D cameras
introduction
focal reducer adapters are designed to use lens with larger image circles than the camera sensor needs (eg. full frame camera lenses used on cropped sensor cameras such as Micro Four Thirds), and in the process, effectively reduce the degree of cropping thereby giving a wider field of view than without the adapter
0.72x adapters
effectively change the lens focal length by a factor of 0.72
if the adapter has excellent optical design, there are two other main ramifications of this:
ZY Optics Mitakon Lens Turbo focal reducer
made in China, and quite affordable at $US149
4 elements in 4 groups (including 1 ED lens)
30mm long
the first version of the NEX adapters were terrible for image quality and have been replaced by a far better version II adapter
the version I Micro Four Thirds adapter apparently is the version II optical quality and it is priced the same as those version II adapters
in late 2015, they released a version II for MFT which has:
improved optics with improved flare and contrast
aperture control ring for Nikon G lenses
currently these are available in Canon EOS or Nikon F mounts
neither have electronic communications with the lens thus:
you will not be able to change the f-stop of the lens unless it has a manual aperture control
your camera will not know which focal length so you need to enter in the actual focal length x 0.72 for the
image stabiliser to function accurately
your images will not record the aperture or focal length in the EXIF
the optical IS (if exists on the lens) will not function
autofocus will not be possible
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Kipon Baveyes 0.7x focal reducer adapters
announced in Dec 2013 and introduced in 2015 and cost around $US300
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minimal reviews as yet
have a range of 35mm full frame adapters for various mirrorless camera systems
for medium format lenses:
much more expensive (~$US600) as it has electronic communications with the lens
be aware the initial versions will NOT mount on OM-D cameras as they hit the EVF protrusion - you need the “S” version for use on OM-D cameras
enables change of aperture
AF may be possible but will be slow
EXIF will record focal length and aperture (but probably not the “adjusted” focal length or aperture)
camera sensor IS hopefully will be given the correct adjusted focal length to function accurately
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reviews:
Viltrox AF EF-M2 0.71x adapter
announced may 2017
Canon EF to MFT
generic cheap Chinese Speed Booster
examples of potential usage on the Olympus OM-D E-M1 camera
manual focus is made much easier thanks to:
the beautiful large electronic viewfinder
the sensor based IS assists with focus
option of magnified view focus assist or focus peaking
lens is automatically image stabilised (just need to manually set the adjusted focal length)
when using a lens with manual aperture ring such as the Rokinon lenses, aperture can be changed with either style adapter
Canon EF 50mm f/1.8 lens
Sigma 50mm f/1.4 ART lens
Rokinon 85mm f/1.4 lens
Canon EF 135mm f/2.0L lens
0.64x adapters
effectively change the lens focal length by a factor of 0.64 giving a 1.28x crop factor instead of 2x crop factor for a Micro Four Thirds sensor
these then allow a Micro Four Thirds sensor to in effect behave like a 1.5x crop Super 35 sized sensor when used on GH-4 in 4K Cinema movie mode or otherwise as a 1.3x crop APS-H sensor when used with full frame lenses
if the adapter has excellent optical design, there are two other main ramifications of this:
much more expensive (~$US650) as it has electronic communications with the lens
be aware they are NOT recommended for some cameras including the OM-D cameras as they may touch the shutter cover and risk damage
enables change of aperture
AF may be possible but will be slow
EXIF will record focal length and aperture (but probably not the “adjusted” focal length or aperture)
camera sensor IS hopefully will be given the correct adjusted focal length to function accurately
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examples of usage
24mm f/1.4 lens becomes 15mm f/0.9 ⇒ 30mm f/1.8 in full frame fov and dof terms
85mm f/1.4 lens becomes 54mm f/0.9 ⇒ 108mm f/1.8 in full frame fov and dof terms
135mm f/2.0L lens becomes 86mm f/1.3 ⇒ 172mm f/2.6 in full frame fov and dof terms
omd/focalreducer.txt · Last modified: 2017/05/10 10:11 by gary1