Kase, best known for its high‑quality photographic filters, is reportedly preparing to enter the lens market with a highly unconventional product: an ultra‑compact 150mm f/5.6 reflex (mirror) lens with autofocus for Sony E‑mount.
A leaked image that surfaced in late 2025 suggests a design that dramatically rethinks what a full‑frame telephoto lens can look like, leveraging a catadioptric reflex optical path to achieve long‑reach performance in an exceptionally small barrel.
Unlike traditional mirror lenses, which are almost exclusively manual focus, reports indicate that Kase’s 150mm f/5.6 Reflex lens features built‑in autofocus, with manual focus override also supported. If confirmed, this would place it among the very few modern autofocus reflex lenses ever produced, marking a significant departure from legacy designs such as the Minolta 250mm f/5.6.
Compact Reflex Design with Full‑Frame Coverage
The reflex construction folds the optical path using mirrors, allowing the 150mm focal length to be housed in a body far shorter and lighter than conventional telephoto lenses. Early descriptions from leak sources call it “the most compact 150mm lens ever seen,” a claim that appears plausible given the visible proportions in the leaked image.
The lens is said to offer full‑frame coverage, making it compatible with Sony’s A7 and A1 series cameras without cropping. As expected from a reflex design, the aperture is fixed at f/5.6, producing the characteristic donut‑shaped bokeh that mirror lenses are known for. Modern multi‑coating is expected to help control flare and contrast loss, historically common weaknesses of older catadioptric optics.
Autofocus, Filters, and Practical Use
One of the most surprising reported features is the inclusion of autofocus, potentially driven by a quiet internal motor, though exact specifications remain unconfirmed. Combined with Sony’s in‑body image stabilization, the lens could offer a level of usability rarely associated with mirror optics, especially for travel, street telephoto work, and lightweight outdoor shooting.
Another notable detail is the reported 67mm front filter thread, allowing the use of standard ND or polarizing filters without special adapters—an uncommon but highly practical feature for a reflex lens.
Positioning and Market Impact
Kase’s move into lenses appears to be a natural extension of its filter business, aligning with a broader trend of third‑party manufacturers exploring niche optical designs. With an estimated price range of $400–600 USD, the 150mm f/5.6 Reflex lens could significantly undercut traditional telephoto zooms while offering a unique rendering style that cannot be replicated digitally.
While reflex lenses inherently involve optical compromises compared to conventional refractive designs, the combination of 150mm reach, full‑frame coverage, autofocus, and extreme portability positions this lens as a compelling option for photographers who want telephoto capability without the bulk of lenses like 70–200mm or 100–400mm zooms.
The lens is rumored to debut in Sony E‑mount, with unconfirmed reports suggesting possible future versions for Nikon Z and Fujifilm X mounts. An official announcement is expected in early 2026.
Key Specifications (Rumored)
| Feature | Details |
|---|---|
| Lens Mount | Sony E‑mount |
| Format | Full‑frame |
| Focal Length | 150mm |
| Maximum Aperture | f/5.6 (fixed) |
| Optical Design | Catadioptric reflex (mirror) |
| Focus System | Autofocus with manual focus support |
| Filter Thread | 67mm |
| Weight | Under 400g (estimated) |
| Bokeh Style | Donut‑shaped highlights |