Baader ASF - ready to use AstroSolar filters
Baader ASBF/ASSF/ASTF is an AstroSolar filter in a fitting provided by Baader. For people who do not want to make an AstroSolar fitting themselves, this may be an option worth choosing. In this article I will present this series using ASBF 50 as an example.
Baader offers ASF filters for tubes from 55 to 340 mm in diameter. The smallest ASBF 50 is an expense of around 35 EUR while the largest ASTF 280 is an expense of around 100 EUR although prices seems to vary depending in which region you look. These filters are widely available in multiple stores. ASBF is for binoculars and very small telescopes, finderscopes. ASSF is for small telescopes while ASTF is for bigger telescopes.
Each ASF version is designed for tubes within a specific diameter range. To attach the filter to the front of the tube, three pins and strips with self-adhesive material are used. By changing the distance of the pins from the filter, we can adjust the spacing to a given tube.
The fitting is made of metal and should bear a lot. The filter can be stored in the cardboard packaging with which we bought it. Baader used AstroSolar ND5 film - for visual observations and for photography (as opposed to ND 3.8 intended only for photography - mainly with specialized filters limiting the
brightness of the obtained image).
The pins are not too long, which means that mounting may be a little uncertain. Baader added strips of material with a self-adhesive tip as a extra-safety option or for slightly mismatched tubes. Some other fittings use clamping screws on the sides, which gives a much more secure attachment of the filter, but usually limits the compatibility of individual models to a specific group of tubes.
When it comes to competition among AstroSolar filters, Astrozap or Euro EMC can be mentioned, which depending on the store and circumstances may be cheaper than Baader. Some stores also offer fittings only, in which we can insert the AstroSolar filter ourselves. The cheapest will be making your own simple fitting - if we have such possibilities and desire.