Herschel Altair 1.25-inch solar prism (image-ready)

Please note that this product is designed for use with REFRACTORS ONLY, and is not intended for use with reflecting telescopes.

Altair 1.25" Solar Prism Features

• 1.25" Push-fit adapter.
• Ceramic diffuser on the back that aids alignment and controls heat, allowing use with refractors up to 5" all day without overheating.
• The T-thread on the top of the adapter allows a magnetic or Hypercam filter holder to be screwed directly onto the sun wedge to hold Altair contrast filters such as G-Band or Altair 540nm, Altair NUV, CaK.
• Unlike other brands, the Altair Solar Wedge allows both visual and imaging applications without having to change internal filters to adjust brightness. The top section can be rotated to adjust the brightness level to suit your accessories or camera.
• The light path is 100mm and weighs only 185g.

The Altair Solar Prism is "image ready" because it can precisely adjust image brightness without disassembling the camera for the best exposure, gain and contrast settings. This is ideal for "lucky image" CMOS cameras such as the Altair Hypercam or GPCAM series. Using filters such as Altair G-Band, Altair 540nm Continuum and Altair NUV is easier thanks to the brightness control.

Sun wedges are well known for providing a sharper, higher contrast image than traditional front-mounted metallized solar film. This is achieved by eliminating reflections between the filter and the telescope lens. The result is a sharper, higher contrast view of sunspots, including solar photosphere features such as granulation. Sunspot centers appear much darker black compared to those seen with solar film filters, and many customers report never having seen the finer structures before. The difference is quite noticeable and immediately visible in the eyepiece. The Altair Solar Prism has special anti-reflection coatings on the internal polarizing filter and prism. A high specification prism provides the ultimate in sharpness and resolution for imaging and observation.

Safe and easy to use: Cheaper solar prisms direct excess energy to the ground, or worse, heat a metal block on the back that you can burn yourself on. The Altair Imaging-Ready solar wedge directs energy into a special extra-thick polycrystalline ceramic diffuser disk on the back of the wedge. Ventilation holes allow air circulation by convection. The polycrystalline disk has the added advantage of being translucent to some extent, thus acting as a sort of narrow-field "solar seeker". It does not completely replace the Altair solar finder, but works in tandem with it, allowing final adjustments even with a high-power eyepiece installed. The sun appears projected on the back of the diffuser as a "ball of light". Simply move your telescope until the ball of light is in the center of the diffuser disk, and it will be aligned with the sun, even with a high-power eyepiece!

one prism does it all! For both solar photography and visual observation: Solar prisms often do not give enough light for high-speed exposures needed to "freeze" air movement and get a sharp image. The Altair solar prism has an internal polarizing filter with AR coating, which allows you to control the brightness of the image. Brightness can be increased or decreased by turning the upper turret assembly and locking it in the desired position with a thumbscrew. Variable brightness is very important for both visual and imaging use, to fine-tune the ideal exposure time, or ideal contrast levels at the eyepiece - especially when adding a color filter such as the Altair 540nm continuous filter, or the G-Band filter for extra contrast. Unlike other brands, the Altair solar prism allows for both visual and imaging applications without having to change internal filters. With the solar prism in "bright" mode, exposure times as low as 2 milliseconds are routinely possible with high-speed CMOS cameras such as the Altair Hypercam or GPCAM. This "freezes" the seeing (air movement), resulting in an incredibly sharp image.

Q: What telescopes can I use with the Herschel solar prism? A: Only refracting telescopes up to 6" (152mm) aperture can be used with the Altair Herschel Solar Prism. Refracting telescopes have a front lens and no mirrors. It is dangerous to use ANY telescope with mirrors with a Herschel Solar Prism. This includes Maksutov Cassegrains, Schmidt Cassegrains, Newtonians and Ritchey Chretiens, among others. If in doubt, please contact Altair Astro or your authorized dealer.

Q: Can I use color filters with the Altair Solar Prism? A: Yes, but only if they are placed AFTER the wedge. NEVER add ANY filter in front of a Solar Prism, because it will crack or melt due to the concentrated heat of the sun, and can deposit metal vapor on the back of the objective lens. Never place a filter, Barlow lens or flattener/reducer in front of the prism.

Q: How can I "adjust" the image brightness for high quality images? A: Being designed for visual or imaging use, the internal polarizer module (controlled by rotating the top of the turret) has a wider brightness range than normal Hershel prisms, allowing fast frame rates and short exposure durations suitable for "lucky imaging". When imaging the Sun using "lucky imaging" techniques with a high frame rate camera such as the Altair Hypercam, it is best to keep the camera exposure duration as short as possible, ideally below 15 milliseconds for apertures up to 100 mm and faster for large apertures. This "freezes" air movement to show graininess and other small details. When set for fast frame rates, the image can appear very bright visually through an eyepiece, as if looking at a light bulb. This is uncomfortable, but not dangerous due to the protective ND filter attached to the unit. CMOS cameras can be used at full brightness. If you are using the prism for imaging only, simply insert the camera and rotate the turret until you are satisfied with the exposure duration and gain settings. If you are using the Altair G-band, NUV or CaK filters, it is recommended that you shoot at maximum brightness.

Q: How long can I keep the 1.25" Mini Sun Wedge pointed at the sun? The Altair 1.25" Solar Prism has been fully tested with the Sun remaining in the center of the field of view for 4 hours of continuous use centered on the Sun with a 152mm aperture refractor telescope in midsummer from 11:00 to 14:00, and a cloudless sky. At no time did the outer prism housing get too hot to the touch, a common problem with cheaper sun wedges. While we cannot recommend its use with telescopes larger than 152 mm aperture for longer or shorter periods, if your telescope is larger than 6", we suggest that you try the wedge for a shorter period, to assess heat buildup, and then make your own informed decision.

Q: What if I drop or disassemble the product? Do not use the product unless it is in perfect condition. Always contact Altair Technical Support first.

Q: What filters can be used behind the sun wedge? The Altair G-Band, Altair 540nm, Altair CaK and Altair NUV filters can be used behind the prism to increase contrast and highlight various solar features.