Helios Glass Telescope Solar Filter 5 in ND5 - Safe Solar Viewing

In this review the Helios Glass Telescope Solar Filter 5 in is examined for amateur and semipro astrophotographers who want a safe, highcontrast way to observe the sun. The bottom line: this ND5 rated filter blocks 99.999% of sunlight and is built from reflective Helios Solar Glass mounted in an aluminum cell, so it delivers clear, stable views of sunspots and partial eclipse phases while protecting eyes and optics.

Key Features

• ND5 light attenuation: Blocks 99.999% of incoming sunlight so direct solar observation and photography are safe when the filter is used correctly.
• Helios Solar Glass: Reflective coating on both sides enhances contrast and delivers a crisp image of solar surface detail and sunspots.
• Aluminum outer cell: Durable but lightweight mounting keeps the glass secure without adding unnecessary weight to the telescope.
• Clampon design: Attaches to the objective lens quickly and centers on the tube for consistent framing during observing or imaging sessions.
• Protective mounting details: Nylon thumb screws and felt tabs prevent scratching and hold the filter firmly in place during use.
• Eclipse friendly: Easy to remove and reattach for quick transition to totality and back to filtered viewing.

Who It's For

The Helios Glass Telescope Solar Filter is well suited to hobbyists who own a refractor or small reflector with an objective outer diameter between 4 5/8 in and 4 7/8 in and who want reliable, highcontrast solar viewing or photography. It is especially useful for observers planning to image sunspots or follow partial and annular eclipse phases.

This is not aimed at users who need filters for very large aperture telescopes, for wide field solar projection systems, or for longterm permanent installations where a custom fit would be required. Those users should seek larger or custom diameter solutions.

Pros & Cons

Pros

• Very high attenuation (ND5) provides secure protection for direct solar observation.
• Reflective doublecoated Helios Solar Glass gives excellent contrast for surface features.
• Clamp design with felt tabs and nylon screws is easy to use and stays firmly in place.

Cons

• Fits a narrow objective diameter range (4 5/8 in to 4 7/8 in), so it will not fit larger or much smaller telescopes.
• Requires careful handling and correct attachment every use; not intended as a permanent or unattended solution.

Specifications

Our Verdict

The Helios Glass Telescope Solar Filter 5 in is a practical, valueoriented choice for observers with a compatible objective size who want safe, highcontrast solar views and straightforward setup. Its ND5 attenuation and doublecoated glass make it a reliable option for sunspot observation and eclipse photography, provided users confirm fit and attach the filter carefully.

Frequently Asked Questions

Does this filter fit my telescope?
It fits optical tube outer diameters from 4 5/8 in to 4 7/8 in; measure your tube OD before ordering.

Is it safe for solar photography?
Yes, the ND5 rating blocks 99.999% of sunlight and is suitable for safe viewing and imaging when properly mounted.

Can I remove it during totality?
Yes, the clampon design is intended to be removed quickly for totality and reattached afterward.