* Prices may differ from that shown
There are hundreds and hundreds of accessories available to the Astronomer, that avail any observer with a more detailed and scrutinous view of the cosmos. But to the modern Astronomer, an entirely new branch of the hobby has developed and is growing at a prolific rate.
In the last 2 decades Astrophotography has really taken off, enabling Astronomers of various skill levels to capture what they see at the eyepiece, whether for scientific study or simply to share their passion with friends and family.
The exponential advancement of technology has allowed the production and distribution of the most invaluable tools, aiding the die hard Skywatcher in the capture of their quarry, from planets to planetary nebula, from immense galactic star factories to the cooling red light of distant dying stars.
Enter the UV/IR filter, Baader's secret weapon against the unwanted infiltration of infrared and ultraviolet light, the presence of which can render images ill defined and blurry as well as producing conspicuous halos around some of the brighter stars.
What the Baader does is to block the majority of the non visible spectrum, coming down sharply on 400nm and 700nm. Effectively, this allows all the good and useful light through to your cameras ccd while blocking the bad light, detrimental to image quality.
It has a 98% transmission which means you don't suffer an appreciable loss of brightness in the object you are imaging and the filter also goes a long way to combating atmospheric dispersion (whereby light is seperated out into it's constituent colours by the Earths own atmosphere). Planets that are low on the horizon (below around 20 degrees or two hand spans) will suffer from this phenomenon, producing unwanted red and blue spectres that surround the planetary body. This allows you a longer window in which to image as you are no longer constrained by the planets low altitude.
Practically the filter is easy to use, it's threaded and can simply be screwed to the nosepiece of any 1.25" camera. It's incredibly robust to, and scratch resistant. Mine has been through the wars and remains completely boo boo free.
Even when not in use the filter serves an important purpose, of blocking the hordes of dust that prey upon unsuspecting ccd sensors, just keep the filter permanently attached to the nose of your camera and you'll notice a big difference, a drop in the presence of dust bunnies and minute hairs on your imaging system.
To concisely summise, this UV/IR cut filter from Baader is a top quality accessory, it comes down almost precisely on the limits of human vision and effectively blocks harmful and extraneous light. Being one of the most effective of its type it may come as some suprise that Baaders offering remains one of the cheapest UV/IR filters on the market, a steal at £35.
***For visual reference, I used this very filter in the acquisition of the Saturn in my avatar picture***