How to add filters to fisheye lenses

Mounting filters on a fisheye lens can be tricky because of its curved design, but there are several methods depending on your lens type and needs.

Rear-Mounted Filters

Image Source：Canon

Many fisheye lenses include a slot near the lens mount for small gel or sheet filters. For example, the Canon EF 8-15mm f/4L Fisheye USM, Nikon AF DX Fisheye-Nikkor 10.5mm f/2.8G ED, and Sigma 8mm f/3.5 EX DG Circular Fisheye all support rear-mounted filters. These filters are typically thin and may need to be trimmed to fit the slot. Carefully insert the filter, ensuring it’s clean and positioned properly to avoid light leaks or vignetting.

Built-In Filters

Image Source：wikipedia.org

Some fisheye lenses come with integrated filters that are easy to use and eliminate the need for external accessories. Lenses like the Nikon 6mm f/2.8 Fisheye or vintage Canon 7.5mm f/5.6 Fisheye feature built-in options such as neutral density (ND), UV, or color correction filters. These can be accessed by rotating a dial or toggling a switch, making adjustments straightforward and quick.

Front-Mounted Filters

Image Source：Tokina

Though less common due to the bulbous front element of fisheye lenses, certain models can accommodate filters on the front. Lenses like the Tokina AT-X 10-17mm f/3.5-4.5 Fisheye DX may work with large diameter screw-on or clip-on filters. Magnetic or slip-on adapters are another option for lenses without traditional filter threads. These solutions allow for protective or creative filters while maintaining the lens's unique effect.

Square filter systems

Square filter systems can indeed be a solution for mounting filters on fisheye lenses, though their suitability depends on the lens design and the specific filter system being used. These systems typically involve a filter holder mounted in front of the lens, with rectangular or square filters slid into the holder. For fisheye lenses, specialized holders are often required to avoid issues such as vignetting or blocking the field of view. Oversized filter systems, such as 150mm or 165mm formats, are commonly used to ensure the filter fully covers the wide field of view inherent to fisheye lenses.

One of the primary advantages of square filter systems is their flexibility. They allow for the use of various filter types, such as graduated neutral density (GND) or polarizing filters, which are not easily available for rear-mounting or built-in options. Additionally, these systems are designed for quick filter changes, making them particularly useful in dynamic shooting conditions. The lack of reliance on traditional screw threads also makes square systems compatible with fisheye lenses that have bulbous front elements or no threading.

However, there are challenges associated with using square filters on fisheye lenses. The extreme field of view of these lenses often makes it difficult to avoid capturing parts of the filter holder or the edges of the filter in the frame, leading to unwanted vignetting or obstruction. Moreover, the large size of these filters and holders can add significant bulk, making them less portable and harder to manage in outdoor or handheld setups. Compatibility is another potential issue, as not all fisheye lenses work seamlessly with standard square filter systems, sometimes necessitating costly custom solutions.

Square filter systems are particularly useful for scenarios where built-in or rear-mounted filters are impractical, such as when precise graduated effects are needed for landscape photography. To make the most of these systems, photographers should ensure the filter holder and filter size are appropriate for the lens to avoid vignetting. Investing in high-quality filters and holders can also minimize artifacts such as reflections or flare, preserving the image quality. When square filters are impractical or cumbersome, alternatives like magnetic adapters or software-based effects may be more suitable.

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