Beastgrip DOF Adapter MK3

Enhance your smartphone filmmaking with the new Beastgrip DOF Adapter MK3.

Our third and latest version is designed to transform your smartphone into a powerful tool for creating beautiful visuals using full-frame SLR/DSLR lenses. It will allow you to add more depth and dimension and achieve a true shallow depth of field to make your shots look like classic film footage. When filming with this adapter, you can perform a manual focus pull and draw the viewer's attention to the most critical elements in your shots.

The new Beastgrip DOF MK3 adapter features an all-new optical and mechanical design for optimal performance on modern smartphones with larger camera sensors and older smartphone models. Beastgrip DOF Adapter MK3 is based on a Canon EF mount, enabling its users to film with a wide range of full-frame Canon lenses and lenses from other brands*. With various adapter rings offering numerous possibilities for selecting the perfect lens, it allows you to explore a diverse range of focal lengths and gives even more creative freedom to experiment and capture those exceptional shots.

Compatible with the universal rig Beastgrip Pro and our dedicated Beastcage for iPhone, it caters to both Apple and Android smartphone users, providing complete freedom to choose which device to film with.

The DOF Adapter MK3 opens the door to the exciting world of smartphone filmmaking and empowers you to bring your creative ideas to life. It unlocks limitless possibilities and will be a valuable tool for any smartphone filmmaker or content creator looking to elevate their craft and capture breathtaking cinematic shots.

Attention: DOF adapter MK3 is not compatible with Beastgrip Pro Series lenses. The DOF adapter MK3 is only compatible with full-frame SLR and DSLR lenses.

• Beastgrip DOF Adapter MK3 x 1
• Front and Rear Caps x 1

• Compatible phones: iPhone and Android phones
• Compatible Rigs: Beastgrip Pro universal rig and Beastcage for iPhone

*Compatible SLR/DSLR Lenses

The primary objective of the DOF Adapter MK3 is to achieve a shallow depth of field and to allow you to use full-frame SLR/DSLR lenses with your smartphone. To ensure compatibility and the best results, it is crucial to verify that your lenses meet the following criteria:

Full-frame: The DOF Adapter MK3 is designed explicitly for full-frame lenses. Using a full-frame focusing screen delivers optimal performance and compatibility with a wide range of lenses. Using crop-sensor lenses with the DOF Adapter MK3 is not recommended, as it will result in severe vignetting.

Canon EF Mount: The DOF Adapter MK3 features a Canon EF Mount, enabling compatibility with Canon EF lenses and a wide range of other brands and mounts. These include Nikon F-mount, PL-mount, Pentax K-mount, M42, and Olympus OM-mount (with an additional adapter ring).

Manual focus control and open aperture: The crucial aspect of the DOF Adapter MK3 is the ability to control focus and achieve a shallow depth of field manually. As the DOF Adapter MK3 operates purely mechanically, your lens must have a manual mechanical focus control. Lenses such as the Canon STM series, which rely on electronic connections to the camera body for focusing, are NOT compatible with the DOF Adapter MK3. Lenses that offer manual aperture control must be set to their widest aperture to achieve the shallowest depth of field. Canon EF lenses, which lack a manual aperture control ring, are generally set to wide open by default and are also compatible with the DOF Adapter MK2.

Fast lenses: We recommend using fast SLR/DSLR lenses with aperture values ranging from f/1.2 to f/2.8 for optimal results. Generally, the faster the lens, the better the performance you can expect from the DOF Adapter MK3.

• Size: ⌀68mm H: 112mm
• Weight: 431g (15.2oz)
• Bayonet mount: Canon EF
• Thread mount: M37 x 0.75
• Enclosure material: Machined 6061-T6 aluminum with black anodized finish
• Optical design: 7 glass elements, focusing screen

What the DOF Adapter Does

The Beastgrip DOF Adapter allows smartphones to achieve real optical shallow depth of field using photographic or cinema lenses, without relying on computational blur.

The image from the lens is projected onto a focusing screen and then re-imaged by the smartphone camera. This enables manual focus control directly on the lens and creates natural depth separation.

Because a focusing screen is part of the optical process, the final image reflects a blend of the lens’s optical character and the adapter’s own rendering.

The DOF adapter is best understood as a creative optical tool, designed to introduce genuine depth of field and manual lens control into a smartphone workflow.

Optical Path Explained

The mounted lens first forms an image on a focusing screen inside the adapter. This image includes the lens’s natural depth of field and focus behavior.

A relay lens system then re-images what appears on the focusing screen and projects it onto the smartphone camera sensor.

In simple terms:

Lens → Focusing Screen → Relay Optics → Smartphone Camera

This allows the phone to capture a real, optically formed image using interchangeable lenses.

Focusing Screen Texture

In this type of DOF adapter design, the focusing screen is the surface where the image from the mounted lens is formed before being re-imaged by the smartphone camera. It allows the phone to capture real optical depth of field by recording a physical image plane rather than a simulated effect.

The focusing screen combines a diffusion surface with a fine Fresnel pattern. The diffusion layer makes the image recordable and contributes a subtle, film-like softness, while the Fresnel structure helps distribute light more evenly across the frame and reduce vignetting. Because the smartphone records this small image area at very high resolution and then magnifies it, the screen’s micro-texture can sometimes appear in the image as a fine grain or structure.The Fresnel pattern can also interact with certain scene details and capture settings, producing moiré-like or ring-pattern artifacts. When visible, this behavior is most noticeable particularly around bright highlights and at transitions between in-focus and out-of-focus areas.

Focusing screens are precision parts, but they are still physical components with natural manufacturing tolerances. Tiny fixed marks or specks can be present in the diffuser layer and may appear in the same position from screen to screen. When visible, these characteristics are a normal part of screen-based DOF adapters and are most noticeable in bright plain scenes.

Expected Tradeoffs & Limitations

The system introduces a focusing screen texture, light loss from the mounted camera lens (f-stop or T-stop) and the relay optics, and additional optical aberrations caused by the mounted lens and relay optics. Image detail is highest at the center of the frame, with gradual softness and detail falloff toward the edges.

Third-party camera apps are required to correctly orient the image and provide precise manual focus control. The DOF adapter is based on a Canon EF mount design, and compatible lenses must meet specific requirements; refer to the Compatibility section for details.

Best Practices for Optimal Results

Fast lenses in the f/1.2–f/2.8 range are recommended to minimize focusing screen texture and achieve the shallow depth of field this system is designed for. Using slower apertures increases focusing screen texture visibility, can introduce more noticeable vignetting, and is generally not recommended for optimal results.

Correct image orientation and accurate manual focus control are critical. Third-party camera apps such as Beastcam for iPhone or Blackmagic Camera (iOS and Android) are required to properly orient the image and provide precise manual focus control.

Precise manual focus allows fine adjustment of the smartphone camera’s focus plane relative to the focusing screen. Focusing exactly on the diffuser surface provides maximum image detail but can also make screen structure more visible. Slightly shifting focus away from the diffuser screen surface can reduce visible texture at the cost of a small amount of sharpness, often resulting in a cleaner overall image. The optimal balance depends on scene content and personal preference.

This system performs best in controlled shooting environments where focus pulls, composition, and lighting can be managed intentionally. It excels in cinematic, narrative, and creative workflows where real optical shallow depth of field and manual lens control are the priority.