Capture high-quality images using a full-frame camera with a Canon RF mount with this NiSi ATHENA PRIME 25mm T1.9 Full-Frame Lens. The lens features 10 aperture blades, micro-contrast control, and low chromatic aberration to highlight image details without distortion. It has an aperture range of T1.9 to T22 and an 80mm front diameter with minimal focus breathing.

The focus ring is capable of rotating 300° for intuitive control. Markings on the lens are fluorescent and in both feet and meters. The lens has a wide 71.7° horizontal angle of view and a 46mm image circle to capture as many details as possible. An included drop-in filter mount places your lens filters of choice in between your camera sensor and lens body.

Full-Frame | T1.9 to T22    80mm Front Diameter    10 Aperture Blades    0.8 MOD Focus and Aperture Gears    300° Focus Rotation    Lens Markings in Feet and Meters

• Maximum T1.9 aperture for deep depth of view and increased area of focus
• 10 aperture blades for smooth, circular bokeh
• 300° focus ring rotation
• Fluorescent markings in feet and meters
• 80mm front diameter, 77mm filter thread
• Drop-in filter mount
• 11.8" minimum focusing distance
• Industry-standard 0.8 MOD focus and aperture rings for use with follow focus systems

Related Questions and Answers

Q: 1. So if I put this on the Sigma 24mm f1.4 Prime Lens, what would it make the aperture on it? Also does it work with that lens?

A: This is compatible with the Sigma 24mm f/1.4 DG HSM Art Lens for Canon, and it'll be roughly equivalent to a f/0.9.

Q: 2. Will this adapter work for conversion to a super 35mm sensor? Particularly to pair with a RED Komodo 6K.

A: Yes, it'll work. When you attach a 50mm lens to the adapter, it'll be equivalent to a 35mm. Once you attach the lens + adapter to a Super 35 format camera, it'll be roughly a 49mm equivalent lens. Focal Length * 0.71 * Sensor Crop Factor = Equivalent Focal Length

Q: 3. I am using Canon 5D Mark IV. This mount is using for rf lenses. Camera mount EF Lens mount RF This mount is supporting?

A: No, this is meant to put EF lenses on an RF camera.

Q: 4. Metabones says EF50mm F1.2L (II?) USM works fine without hard vignetting. It has a 55mm image circle much like EF40mm F2.8 STM also with 55mm image circle; so, it should work fine without vignetting, too. Will it work with TSE 24mm F3.5L II with 67.2mm image circle? At what image circle diameter does the SpeedBooster cut off between 55mm and 67.2mm cause a hard vignetting; since 0.71x proportionately works already for EF Lenses with 55mm image circle: 55mm 0.71x = 39.05mm (S35 minimum is ~31.6mm; APSC minimum is ~28.85mm). Inverse of FF 43.27mm is 60.94mm; does SpeedBooster not fully cover at least 60.94mm out of 67.2mm image circle available on Canon FF TSE Lenses, or just 55mm image circle of Canon EF Lenses? Metabones offers nothing "specific" (exact details missing) in its official "specifications" online. Please help with exactness.

A: As long as you are using an EF lens that is designed to cover a full frame sensor there will not be any vignetting with this lens adapter.

Q: 5. Would it vignette on the Canon EOS R5/6?

A: No, you shouldn't get any vignetting.

Q: 6. will the assignable wheel be recognized by komodo? Can you assign it to adjust iris?

A: According to the manufacturer, the RED Komodo camera (firmware V1.5.3) is not compatible with the Control Wheel function of the Metabones T Speed Booster Ultra 0.71x Adapter for Canon Full-Frame EF-Mount Lens to Canon RF-Mount Camera.

Q: 7. I noticed on 10 Sep. 2020 Sean had asked if FD lenses could work with this booster and received a negative answer. If an FD lens has a FD to RF mount adapter on the back of the FD lens would the optical path produce sharp images at infinity focus? Of course the legacy FD lens functions would be fully manual meaning no auto focus or auto aperture.

A: The FD to EF adapters have a 1.4x teleconverter which would almost negate the 0.71x factor of the booster. For example 50mm x 1.4 (with the FD to EF adapter) equals 70mm. The booster reduces is by 0.71x thus making it 49.7mm. Metabones makes this adapter for mounting FD lenses to the RF cameras (just an adapter, not a booster): https://bhpho.to/2XeOOHG.

Q: 8. For use with an R5, any advantage of this vs. Canon's $100 Mount Adapter EF-EOS R?

A: You must read the overview. the Metabones adapter is an optical system that modifies your lens. The Speed Booster Ultra 0.71x Adapter from Metabones allows a full-frame Canon EF-mount lens to be used on a Canon RF-mount camera. While providing a one-stop increase over the lens's aperture range, up to a maximum output aperture of f/0.9, the adapter's optics help to maximize the connected lens's apparent angle of view during UHD 4K video capture. It will also change your lenses angle of view. You are comparing totaly different product designed for totaly diferent outcomes.

Q: 9. the Sigma 18-35 seems to give me fairly bad auto focus, eye auto focus doesn't seem to work well either. Canon EF lenses are working fine, anyone else have this issue with the speedbooster?

A: the sigma 18-135 lens is an EF-S lens and is not supposed to be used with the MEBSEFEFRBT1

Q: 10. is this lens compatible with the lumix g7?

A: Yes, the Yongnuo YN25mm f/1.7 Prime Lens for Micro Four Thirds is compatible with the Panasonic Lumix G7.