Sun | September 2021

Sun imaged with a 4 inch f/5.65 refractor, a Baader ND 5.0 solar filter, UV-IR cut filter, and an ASI 533 camera.

Active regions AR2871 (lower center), AR2872 (center left), and AR 2873 (upper right) are visible in this image.

For a complete list of astrophoto images, click here.

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

Baader ND 5.0 Solar Filter

I have been using a Baader Neutral Density 5.0 Solar Safety Film filter for several years now in solar photography and visual observation. According to the specifications, it reduces solar intensity by a factor of 100,000.

The filter looks like a thin reflective plastic sheet, about A4 size (20 cm by 29 cm). When used with binoculars or telescope, it must be cut to the right size to cover the whole aperture of the optical instrument and installed securely on a rigid frame. Alternatively, the filter may be used without a telescope. Based on my experience, while the solar film may look very delicate and fragile, it is very durable and does not easily get damaged. Special attention, however, must be given to ensure that the film does not get stretched or folded to retain its properties.

Sunspot AR12192 | Sky-Watcher 4 in f/9 refractor

The Baader ND 5.0 solar filter produces sharp images with good contrast without changing the white balance. The filter I purchased in 2011 which has been used extensively in almost every solar event visible in my locality is still in excellent condition.

To view posts on DIY projects and astronomical equipment, click here.

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines