see also:

• the Olympus OM-D system and how to make the most of it

• 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

• 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:
  • the f/ratio is also multiplied by 0.72x to give 1 stop MORE light coming in and effectively more shallow depth of field (DOF)
  • the sharpness of the image can actually INCREASE

• 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• the first version of the NEX adapters were terrible for image quality and have been replaced by a far better version II adapter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
• my lens tests with the Micro Four Thirds version I Zhongyi focal reducer on an E-M1
• my blog review of the Zhongyi adapter

• announced in Dec 2013 and introduced in 2015 and cost around $US300
• http://kipon.com/en/articledetail.asp?id=62
• minimal reviews as yet
• have a range of 35mm full frame adapters for various mirrorless camera systems
• for medium format lenses:
  • Baveyes HB-S/E 0.7x (Baveyes Hasselbld-SONY E 0.7x)

• announced Aug 2015
• Model Code: MB_SPEF-m43-BT4 (Canon EF mount) , MB_SPNFG-m43-BM3 (Nikon F/G mount)
• as for the previous version below but:
  • improved optics
  • slowish CDAF capability when used on Panasonic cameras with certain Canon EF lenses - “faster” than AF when using Four Thirds lenses on these cameras but no continuous AF
  • Sept 2015 firmware update adds CDAF for Olympus OM-D cameras and fast PDAF for the E-M1
  • $US649
• reviews:
  • https://jimchungblog.wordpress.com/2016/12/29/first-blog-post/

• 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
• http://www.metabones.com/products/details/MB_SPEF-m43-BM2
• reviews:
  • https://jimchungblog.wordpress.com/2017/01/14/evaluating-focus-speed-with-metabones-speed-booster-s/

• announced may 2017
• Canon EF to MFT

• see Ebay sold by c.kee for $US90
• example images:
  • http://beomagi.blogspot.com.au/2014/03/evaluating-cheap-focal-reducer-with.html
  • http://beomagi.blogspot.com.au/2014/04/evaluating-cheap-focal-reducer-with.html

• 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

• effectively becomes a 35mm f/1.4 lens = 70mm f/2.8 field of view and DOF on a full frame camera

• effectively becomes a 35mm f/1.0 lens = 70mm f/2.0 field of view and DOF on a full frame camera

• effectively becomes a 62mm f/1.0 lens = 120mm f/2.0 field of view and DOF on a full frame camera

• effectively becomes a 100mm f/1.4 lens = 200mm f/2.8 field of view and DOF on a full frame camera

• 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:
  • the f/ratio is also multiplied by 0.64x to give 1.33 stops MORE light coming in and effectively more shallow depth of field (DOF)
  • the sharpness of the image can actually INCREASE

• 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
• http://www.metabones.com/products/details/MB_SPEF-m43-BM3

• 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