Optolong L-Ultimate 2 Filter
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The Optolong L-Ultimate 2 is a dual-narrowband light pollution filter designed for deep-sky astrophotography, passing only H-alpha and OIII wavelengths to suppress broadband light pollution and enhance nebula contrast. It builds on the original L-Ultimate with improved multi-layer coatings and tighter bandpass tolerances for cleaner, higher-contrast images. Overall it delivers impressive results for one-shot color cameras and is a strong performer in its price range among dedicated narrowband imaging filters.
Key Features & Specs
| Filter Type | Dual narrowband (H-alpha 656nm and OIII 500nm), designed for use with one-shot color (OSC) cameras |
|---|---|
| Bandpass | Ultra-narrow 3nm FWHM passband on both H-alpha and OIII channels for maximum light pollution rejection |
| Compatibility | Works with DSLR, mirrorless, and dedicated astronomy cameras; available in 1.25-inch, 2-inch, and 2-inch clip-in formats |
| Coatings | Ion-assisted multi-layer anti-reflection coatings with greater than 95% peak transmission at target wavelengths |
| Construction | Optical glass substrate with scratch-resistant hard coatings and precision-machined aluminum cell |
| Light Pollution | Effectively blocks LP, moonlight, and broadband sky glow, suitable for use from Bortle 4 through heavily light-polluted Bortle 8-9 skies |
| Focusing | Minimal focus shift reported compared to some competing narrowband filters, easing workflow when swapping filters |
Best for: Astrophotographers shooting emission nebulae with a one-shot color camera from suburban or urban locations who want a premium narrowband filter capable of producing SHO-style results without switching to a monochrome setup.