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Ribcage ModKit For The GoPro Hero 4

$ 199.99

Do it yourself and save some coin! Install Back-Bone’s custom, all aluminum Ribcage mod kit on any GoPro Hero4 Silver or Black (not included). Your camera will then be able to take micro M12, CS-Mount or C-Mount lenses. Attach almost any other type of lens with optional C-Mount adapters!



**Please note that this product is not necessarily for everybody. It requires you to take apart and re-assemble your camera which will void the manufacturer’s warranty. Back-bone has no control over the end user’s skill level and cannot be held responsible for accidental damage. We recommend that you view the installation video on our support page before you buy to make sure this is right for you. If you don’t feel comfortable performing the installation yourself we also offer Hero4 Silver and Black cameras that have already been modified and tested.


**InFocusHD performs installation services if you already own a compatible camera.  Fee is $100.00, and all associated shipping charges, please email us at for total cost and timing RFQ.



Transform the awesome GoPro Hero4 into a killer 4K interchangeable lens camera that will take all popular lens types! Designed with emphasis on widely available M12, CS-Mount and C-Mount our new Hero4 design refines that of our popular Hero3 mod to give you even more great features. All of the lens mounting rings are easily removable for filter replacement and sensor cleaning. Combine up to two custom filters in camera at the same time.  You won’t need filters for all your lenses, just  for the camera! Now you can use ND and NDVI and other custom bandpass filters with your M12 lenses, or lenses that have no filter threads on the front. Choose from our line of tried and tested high resolution lenses, or use your own. Browse through our library of C-Mount lens adapters to find what you need!


Features include:

  • Compatible with Hero4 Silver and Black editions
  • Out of the box compatibility with M12(S-Mount), CS-Mount , C-Mount lenses and accessories
  • Fully compatible with the Ribcage ‘EXO’ cage coming soon!
  • Easily removable mounting rings allow access to the image sensor for cleaning
  • Adjustable flange distance
  • Combine up to two different filters of two different sizes in camera at the same time
  • Use ND filters with most M12 lenses
  • Custom filters such as ND 0.3, 0.6 & 0.9, IR bandpass, NDVI and more coming soon!



Finally, a light weight, small form factor 4K camera with interchangeable lenses! It’s the GoPro Hero4 Black that you know and love, but supercharged with Back-bone’s custom all aluminum Ribcage kit. Now you have the ability to pick the perfect lens for any situation so you can shoot in amazing 4K 30fps or 1080p at speeds up to 120fps. Out of the box the Ribcage is compatible with micro M12, CS-Mount and C-Mount lenses. You can attach virtually any other type of manual lens via readily available C-Mount adapters found online and in stores.  Take advantage of what professional lenses have to offer: manual focus control, a more cinematic depth of field, macro shooting, optical zoom and iris control. You’ll receive a removable tripod mount so you can connect your camera to professional mounts and supports. Want night vision? Just take out the IR cut filter so you can see in the dark with any IR light source! Have a difficult lens? Use the adjustable flange distance feature to get the perfect results. The Ribcage modified camera is configured with a removable IR-cut filter for maximum versatility and easy cleaning of the filter and sensor if required. Note that the filter must be added when using the camera for the first time.


*Note: Some M12 lenses require more distance from the sensor than the built-in M12 socket allows. We recommend also purchasing our optional M12 to CS adapter to guarantee compatibility with all your favourite lenses.

Package includes:

  • Premium CNC machined aluminum parts
  • 2x IR-cut filter
  • 1x Filter Spacer/holder
  • 1x Protective cap
  • 2x Micro Allen key for adjusting the flange distance.
  • 1x packet of necessary screws, connectors and hardware.
  • 1x M12 Locking ring


While you can connect any M12, CS or C-Mount lens, 1/2” and 2/3” lenses are best. Ribcage has a crop factor of 5.7 for 35mm SLR lenses, so wide angle lenses are generally more useful.

  • 1/2.3”, 1/2”, 1/1.8” and 2/3” M12, CS-Mount and C-Mount lenses are ideal.
  • 1/2.5” lenses are ‘technically’ slightly too small for the sensor but in most cases give complete coverage and excellent results.
  • 1/3” or 1/4” lenses are not recommended because they are too small for the sensor, although they can still be used with the camera’s ‘medium’ and ‘narrow’ shooting modes.
  • Auto iris lenses are not recommended as they require an external power supply in most cases.
  • Focal lengths ranging from 4mm up to 25mm will prove to be most useful. Focal lengths under 4mm will have a similar or more pronounced fish-eye effect than the stock GoPro lens.
  • We’ve found it best to use lenses labelled ‘HR’ or ‘Megapixel’ for HD shooting. 3MP, 5MP and 10MP lenses should produce outstanding results.
  • If you want to use the optional night vision feature of the Ribcage, IR corrected or D&N (day & night) lenses are recommended.
  • Only lenses with manual features are supported. The GoPro is not capable of controlling fully automatic lenses.
  • The built in M12 socket of the Ribcage will support M12 lenses with a maximum of 4.65mm back focus distance. At maximum distance the set screw may not engage. For M12 lenses requiring a longer back focal distance we offer an optional M12 to CS-Mount adapter which provides all the necessary distance required.
  • Brands we have tested and find to be generally quite good are Computar, Kowa, Tokina, Fujinon, and Tamron. A selection of recommended lenses can be found in our shop.

Visit for a magnification calculator. Choose the “Digital Compact with 1/2.3” Sensor” option. You can then punch in different focal lengths to see their 35mm equivalent. This is a great tool for deciding what focal length will best suit your needs.

Below is a diagram showing the image circles projected by the most common lens types in relation to the Hero3 Black image sensor. You may find it helpful to visualize the crop factor. 



Cleaning and maintaining Filters: