Why does the film in my ASTF filter look wrinkled?
This is intentional and a sign of correct mounting. For the AstroSolar® film to deliver diffraction-limited images, it must be completely free from tension. The slight waves indicate the film is "floating" in its temperature-compensated cell, ready to perform like a high-precision optical window. A taut, perfectly flat film would produce a poor image.
What is the difference between an ASTF filter and a simple glass solar filter?
Baader ASTF filters use diffraction-limited AstroSolar® film, which acts as a precision optical window, providing much higher contrast and resolution than most affordable glass filters. The film also produces a neutral white image, whereas many glass filters add a strong orange or yellow color cast.
How do I attach an ASTF filter securely to my telescope?
Slide the adjustable centering bolts into the filter frame and position them so they grip the rim of your telescope tube or dew shield for a snug, centered fit. For maximum safety, you must also use the included safety straps, which create a secure connection between the filter cell and the telescope tube, preventing accidental removal by wind or a bump.
Can I use the Baader ASTF filters for solar photography?
Absolutely. The Optical Density 5.1 film is designed for both visual observing and high-resolution solar photography. Its high-contrast, neutral color image is ideal for capturing fine details like sunspot umbra and penumbra, faculae, surface granulation, and planetary transits with a DSLR or dedicated astronomy camera.
Which ASTF size should I choose for my telescope?
The ASTF range covers telescope classes from 80mm (ASTF 80) to 280mm (ASTF 280), e.g. small refractors, 8-inch Schmidt-Cassegrains and Dobsonians, and 11-inch SCTs. Because the filter clamps around the front of your instrument, always measure the outer diameter of your telescope tube front or dew shield before ordering to ensure a proper fit.
Is an ASTF filter safe for viewing a total solar eclipse?
ASTF filters are essential and perfectly safe for viewing all the partial phases of an eclipse. However, you MUST remove the filter from the telescope the moment totality begins to see the faint solar corona. As soon as the sun begins to reappear from behind the moon, the filter must be securely replaced immediately.
