DeltaOptical yellow filter #12 2″
If you are fascinated by observing solar system objects and want to get the most out of every observation session, the DeltaOptical yellow filter #12 is exactly what you are looking for. This planetary filter in the standard 2″ format is designed to suppress unwanted blue components of light and significantly increase the contrast of surface details you observe. Thanks to the standard ø 2″ thread, you can easily screw it into any widely available eyepiece - no adapters, no complications.
How it works
The yellow filter operates on the principle of selective transmission - it passes the red and green components of the spectrum while effectively blocking blue light. This has a major practical impact when observing Mars: the contrast between dark albedo regions (such as Maria and Syrtis Major) and bright desert regions is significantly increased, allowing you to distinguish finer surface details even under average atmospheric conditions. When observing Venus, the filter helps to reduce the planet's dazzling brightness and can assist in detecting atmospheric structures. It is therefore a versatile filter, not a narrow single-purpose specialist.
Observing the Moon
When it comes to lunar observation, one important rule applies: filter #12 delivers a visible improvement in contrast with telescopes whose primary mirror diameter exceeds 10″ (254 mm). With smaller instruments the effect will be less pronounced, since the light flux through the eyepiece is lower and the filter could unnecessarily darken the image. Owners of large Newtonians, Dobsonians or Schmidt-Cassegrains above 10″, however, will appreciate how the filter helps distinguish fine rilles, crater walls and bright rays from the surrounding background.
Build quality and mounting
The filter is made from optical glass with a precisely applied color coating and is set in a solid metal body with a standard thread. Mounting into eyepieces with a 2″ threaded cell takes only a second. We recommend storing the filter in the included case to protect the optical surface from scratches.
Who is it for?
The yellow filter #12 will be appreciated primarily by planetary observers who already have experience with visual observation and want to take the quality of their sessions further. It is well suited as the first color filter in a collection - its use is intuitive, the effect is immediately noticeable, and it works well across multiple objects. More experienced observers will use it in combination with other filters - for example, orange #21 or red #25 - for even finer contrast tuning when observing Mars at various stages of its approach to Earth.
Specifications
| Parameter |
Value |
| Filter type |
Color planetary filter - yellow |
| Filter number |
#12 |
| Thread size |
2″ (standard) |
| Optical element |
Optical glass with color coating |
| Body material |
Metal |
| Recommended aperture (Moon) |
Over 10″ (254 mm) |
| Primary use |
Mars, Venus, Moon |
| Includes |
Protective case |
Summary
DeltaOptical yellow filter #12 is a precise, reliable and affordable choice for anyone who takes planetary observation seriously. Get it before the next Mars opposition season - you will not regret it.
