Visual colour filters can be a really beneficial accessory for planetary observing, allowing you to see more detail by improving the contrast of surface features.This kit of 1.25" filters from Revelation contains four different colours; Red #25A, Blue #80A, Green #58, and Yellow #15 all which stored in a handy, transparent, twist-top case.
They are attractively finished in black anodised metal with knurled tops and we had no issues screwing them fully into the barrel ends of different makes of eyepiece.
We tested the filters on a low altitude Jupiter and Saturn one steady night in July.
Without filters, the low altitude caused significant dispersion with yellow fringing at the top and blue at the bottom of each disc, as the atmosphere acted like a giant prism spreading the light into a mini rainbow and smearing details vertically.
Colour filters helped here by narrowing the spectral bandwidth and we found significant benefits in levels of detail.
In particular, using the yellow filter, which was the brightest of all, and allowed us to spot a shadow transit of Europa not seen without the filter. Green helped a bit too but not until the surfaces were cleaned with an optical tissue to remove a haze inducing film from both sides.
Blue improved the contrast noticeably but surprisingly Jupiter still had traces of a yellow fringe on the top side which must indicate a particularly wide bandwidth to this filter.
With an atmospheric dispersion corrector (ADC) in the optical train this yellow fringing disappeared and then Blue took top spot for pulling out detail on Jupiter followed by Yellow then Green and Red being of less benefit.
On Saturn, Blue and Green showed good differentiation between disc and ring and showed obvious equatorial banding whilst Yellow and Red were less useful although they may be more beneficial with Mars.
This is a great value set of quality visual colour filters that would make a useful addition to any planetary observer's armoury.
Vital stats
- Price £34
- Size 1.25" screw in
- Weight 65g for set in box
- Supplier Telescope House
- Tel:01342 837098
- www.telescopehouse.com
