Photosphere 7.5nm 1.25″ Filter E-series

Product Overview

The Player One Astronomy Photosphere 7.5nm 1.25″ E-series filter isolates a narrow 7.5 nm slice of green light centred on 540 nm to lift the contrast of the Sun's visible surface. Working in this continuum band makes sunspots, faculae, and granulation stand out more crisply than a broadband white-light view, giving your solar images cleaner photospheric structure. It transmits about 97% in-band while blocking out-of-band light to OD4.

Who It's For

This filter is for white-light solar imagers who already view the Sun safely and want more contrast on the photosphere. If you photograph sunspot groups and granulation and want to sharpen that detail, the Photosphere 540 nm continuum filter is made for the job.

Key Features & Design

• 540 nm continuum band: centres on green light where photospheric contrast is high, making sunspots and granulation pop.
• Narrow 7.5 nm bandwidth: restricts the passband to a slim window for cleaner, higher-contrast detail.
• ≈97% in-band transmission: keeps the solar surface bright for short, sharp exposures.
• OD4 out-of-band blocking: suppresses light outside the passband to preserve contrast.
• PV 1/4λ wavefront: figured to a quarter-wave to protect resolution through the imaging train.
• 1.25″ thread (M28.5×0.6): fits standard 1.25-inch cells, drawers, and wheels.

Optical/Mechanical Design

The Photosphere filter passes a 7.5 nm-wide (FWHM) band centred on 540 nm at about 97% transmittance, while rejecting out-of-band light to optical density 4 (OD4). Restricting the view to this green continuum window raises the visible contrast of photospheric features because sunspot umbrae, penumbrae, and granulation modulate strongly there; narrowing the band trims the surrounding light that would otherwise wash the detail out. The 1.85 mm-thick optical-glass substrate carries a multi-layer composite coating and is figured to a PV 1/4 wavelength wavefront. Mechanically it uses the 1.25-inch M28.5×0.6 thread with a 5 mm body plus 2.5 mm thread section (7.5 mm total).

Recommended Uses

• High-contrast white-light imaging of sunspots and granulation.
• Continuum-band solar photography where a broadband view looks flat.
• 1.25-inch solar imaging trains that already include safe aperture-side solar filtration.

Compatibility & Accessory Notes

• Fit: 1.25″ M28.5×0.6 filter thread — works in 1.25-inch cells, drawers, and filter wheels.
• Solar setup: used within a properly filtered white-light train (for example behind a safe aperture solar film or a Herschel wedge), not on its own.
• Backfocus: the 7.5 mm cell and 1.85 mm glass add to your optical path; include them in your spacing calculation.

Good to Know Before You Order

• This is a contrast-enhancing continuum filter, not a solar safety filter; the Sun must already be made safe to view by an approved aperture or wedge filter ahead of it.
• Player One does not publish a bandwidth tolerance or a net weight for this filter; the shipping weight shown at checkout is an estimate. Contact us if you need exact figures.
• Inserting the filter shifts focus slightly, so refocus after fitting it.

FAQ

Is it difficult to set up? No. It threads into a standard 1.25-inch cell, drawer, or wheel within your existing safe white-light train and needs no power; refocus once after fitting.

What does a 540 nm photosphere filter do? It confines the view to a narrow green continuum band where photospheric contrast is highest, so sunspots and granulation appear sharper than in a broadband white-light image.

Is this a solar safety filter? No. It enhances contrast only; a safe aperture or Herschel-wedge solar filter must already be in place to make the Sun safe to view and image.

Why the narrow 7.5 nm band? A slim passband trims surrounding light that would otherwise reduce contrast, letting fine surface structure show more clearly.

Bottom Line

The Photosphere 7.5nm 1.25″ E-series filter sharpens white-light solar detail by isolating a 7.5 nm continuum band at 540 nm with ~97% transmission and OD4 blocking, bringing out sunspots and granulation in your images.