Starfield 1.25" Solar Wedge

Product Overview

The Starfield 1.25" Solar Wedge is a white-light Herschel wedge for refractors, built for both visual solar observing and solar imaging. It replaces a standard 1.25" diagonal and gives a controlled, high-contrast view of the Sun's surface. The prism is anti-reflection coated, brightness is set with an integrated adjustable CPL filter, clear aperture is 26.5 mm, and M42 threads on the output side take a camera directly. Starfield recommends it for refractors up to 100 mm aperture; for larger refractors the 2" Herschel Solar Wedge covers up to 150 mm.

Who It's For

This is a good match if you observe or image the Sun with a small refractor — a 60 to 100 mm apochromat or achromat is the natural home for it. The M42 thread makes it a straightforward path to a planetary camera, which is how most people end up imaging sunspots and granulation, and the integrated CPL means brightness is adjusted at the wedge rather than by swapping filters. If your refractor is larger than about 102 mm, the 2" model is the one to use.

Key Features & Design

• 1.25" Herschel wedge format, mounting like a diagonal on compatible refractors.
• Anti-reflection coated prism for detailed, high-contrast solar views.
• Integrated adjustable CPL filter for brightness control.
• 26.5 mm clear aperture.
• M42 threads on the output side for direct camera attachment.
• Suits visual observing and solar photography equally.
• Recommended for refractors up to 100 mm aperture (about 4").

Optical Design

A Herschel wedge attenuates by rejection rather than by blocking. An angled prism directs a small fraction of the incoming light up to the eyepiece and lets the great majority of the Sun's energy pass straight out of the back of the housing, where it is dissipated as heat. Because the attenuation happens behind the objective instead of in front of it, no filter surface faces the telescope lens — which removes the reflections between filter and objective that soften the image on a front-mounted film filter. The prism's anti-reflection coating serves the same end on the surfaces that remain in the path.

Final brightness is set by the integrated CPL filter, which varies transmission continuously as you adjust it rather than stepping between fixed densities. That control sits on the output side of the prism, downstream of the heat, and it is the reason nothing needs to be mounted ahead of the wedge — where a filter would be exposed to the full solar load and would be at risk of cracking.

Recommended Uses

White-light observing of sunspots and surface detail with a refractor up to 100 mm. Solar imaging with a planetary camera on the M42 thread. Day-to-day monitoring of active regions as they cross the disc. Partial eclipse and transit observing. Travel and grab-and-go solar setups, where a small refractor and a 1.25" wedge pack into very little space.

Compatibility and Accessory Notes

• Telescope type: refractors only.
• Aperture: recommended up to 102 mm (about 4"). Above that, the 2" Herschel Solar Wedge is rated to 150 mm.
• Not for Petzval designs or similar telescopes with a rear lens element close to the focuser. The wedge is not suitable behind a lens sitting in that position.
• Not for telescopes with plastic components in the optical path or focuser.
• Connection: replaces a standard 1.25" diagonal in the focuser.
• Cameras: M42 threads on the output side. Most planetary cameras reach it with a standard T-thread nosepiece or adapter — tell us which camera you are using and we will confirm the adapter.
• Additional filters: only ever on the output side, after the prism.

Good to Know Before You Order

• Refractors only. A Herschel wedge is intended for refractors because of the heat and energy involved in pointing a telescope at the Sun. It is not for reflectors, Schmidt-Cassegrains or Maksutovs.
• Not suitable for Petzval-style telescopes with a rear lens element near the focuser, and not for telescopes built with plastic components.
• Never place a filter in front of the wedge. Filters must only be mounted after the light has passed through the prism, where they are out of the heat.
• Solar observing is hazardous and depends on the equipment being correct and used as intended. Follow the safety guidance supplied with the product, and remove or cover any finder not made for solar use before aiming at the Sun.
• The 1.25" model is sized for refractors up to 100 mm. If your telescope is larger, the 2" model is the correct one rather than a matter of preference.
• Specifications are Starfield Optics' published figures.

Frequently Asked Questions

Is it difficult to set up?

No. It goes into the focuser in place of a 1.25" diagonal, the eyepiece drops into the top, and brightness is set on the integrated CPL filter. For imaging, a camera threads onto the M42 output.

What is a solar wedge used for?

White-light solar observing and imaging with refractors. It shows the photosphere — sunspots and surface detail — at higher contrast than a front-mounted film filter.

What telescopes can I use it with?

Refractors up to about 100 mm. It is not suitable for Petzval-style designs with a rear lens near the focuser, nor for telescopes with plastic components.

Can I use filters with it?

Only after the prism, on the output side. Nothing goes in front of a Herschel wedge.

I have a refractor larger than 4". What should I use?

The 2" Herschel Solar Wedge, which Starfield recommends for refractors up to 150 mm.

Can I attach a camera?

Yes — the M42 threads on the output side are there for it, which makes a planetary camera a direct fit.

Bottom Line

In short: a 1.25" Herschel wedge for refractors up to 100 mm, with an anti-reflection coated prism, a 26.5 mm clear aperture, integrated adjustable CPL brightness control and M42 camera threads. It replaces your 1.25" diagonal for white-light solar observing and imaging.