For owners of Canon EOS wide-angle or zoom lenses as well as Sony E-Mount lenses the NOVOFLEX RETRO-Adapters open up the world of extreme close-up photography with outstanding quality.

"The new NEX-RETRO reversing adapter from NOVOFLEX is a powerful addition to any Sony user's toolkit. It allows any Sony E mount lens to be attached to the camera in a reverse orientation changing the focal length to macro functionality with full electronic transmission as though the lens were mounted directly to the camera in its usual manner. We're delighted to bring this functionality to Sony users just as the EOS-RETRO provides to Canon users."

The NOVOFLEX RETRO-Adapters lets you mount the lens in reverse position on the camera. The ring transfers all control functions.

Example: With a Canon EOS 28-105 mm zoom lens in reverse position, you get an image ratio of 1:7 with a focal length of 105 mm from 1:7 to 2.8:1 at 28 mm.

This is a wider setting range than is possible with a macro lens.

The NOVOFLEX RETRO-Adapters are supplied standard with a 58 mm filter diameter. Stepping rings are available for other filter sizes.

• Bring to life the finest details: NEX-RETRO allows reverse mounting of Sony E-mount lenses for close focus macro applications.
• No compromise in flexibility: NEX-RETRO retains complete electronic functionality between Sony E-mount lenses and bodies.
• Precision engineering: NEX-RETRO is the perfect tool to make the perfect picture even better.

Technical specifications:

• Size: 75 mm (2.95”)
• Weight: 160 g (0.35 lbs)
• Maximum extension: 550 mm (21.65”)

https://www.novoflex.com/en/products/macro-accessories/reverse-adapter-eos-retro/