Wratten #21: Orange Colour Filter

• Large 26mm in clear aperture
• Manufactured from the purest crown optical glass
• Dyed-in-the-mass (not "colour coated")
• Each filter is mounted in a machined aluminum cell with the Wratten No. of the filter marked on the side of the cell.
• Filters may be piggybacked; or stacked; to achieve selective filtration of the visual colour spectrum.

For visual applications Astronomica Colour filters thread into the barrels of virtually all other 1.25 " eyepieces. Each filter is packed in a foam-fitted plastic case for secure long-term storage.

Our colour filters solve; or greatly reduce the effects of:

(a) Irradiation is the fuzzing of a boundary between lighter and darker areas of the Moon or a planetary surface and can be caused either by the effects of highly contrasting light impacting the human eye or by the motion of the Earth`s atmosphere; through which the observation is being made.

(b) Contrast is the separation of adjacent surface regions according to their colour; for example; a light green area on Mars can become mixed in the eye with an adjacent light yellow area; to the effect that the combined area appears yellow-green; unseparated into its component regions.

The filter is brand new; we are UK based and all this item will be shipped directly to you from our stock. There are no additional duty or taxes to pay.

What makes us different?
We are experienced practical astronomers; with many years experience who are happy to offer advice and guidance. We personally have tested each line we sell for quality and suitability. Images taken by us with our equipment are available on request; where appropriate. Please feel free to contact us by telephone; post or email.