Centered on the 470nm wavelength, the Alpine Astronomical Baader Blue Colored Bandpass Eyepiece Filter can be used by itself or stacked with other filters to enhance your observations when viewing or imaging comets or planets such as Venus, Mars, Jupiter, and Saturn. The optical glass filter is planeoptically polished and treated with seven-layer Phantom Group anti-reflection multi-coatings to improve contrast and clarity while eliminating reflections, scattering, or image dimming. Holding the filter is an black anodized aluminum frame made to fit standard 2" eyepieces and other accessories such as diagonals and Barlows.

Planetary Viewing/Imaging Filter    470nm Wavelength Bandpass    2" Eyepiece Threads    7-Layer Anti-Reflection Multi-Coated    No Reflections, Scatter or Image Dimming    Planeoptically Polished Optical Glass    70% Throughput Transmission    Blackened Aluminum Frame    Stackable with Other Filters

• For visual and photographic planetary use
• Observe high clouds on Mars, enhances contrast of hazes on terminator of Mars
• Appears to make reddish structures darker—ideal for observing the Great Red Spot on Jupiter
• Shows Saturn rings better
• Monitor the structures in the atmosphere of Venus
• Highlights the fine details in gas tails produced by comets
• 70% average transmission bandpass throughput

Related Questions and Answers

Q: 1. what does focal length of 21mm eyepiece become when the snout is removed?

A: The Alpine Astronomical Baader Hyperion 68° 21mm Astronomical Eyepiece (1.25"/2") would become 32.2mm with the snout removed.

Q: 2. how to adapt this to a camera lens with a 62mm thread (yes, this will result in some vignetting which I will have to tolerate)?

A: Currently B&H does not stock an adapter allowing the Alpine Astronomical H-Alpha 20nm Bandpass Filter (2") to a camera lens with a 62mm thread.

Q: 3. How can we adapt the 2" UV bandpass filter to a Sony E-mount 49mm lens?

A: I know of no adapter to mount a 2" (50.8mm) filter on to a 49mm opening. I do know some that use gaffing tape.

Q: 4. How do you fit this eyepiece to the diagonal that comes standard with Celestron Nexstar 8SE?

A: It fits the Celestron 8se directly as long as you are not using the 2" Schmidt-Cassegrain Adapter.

Q: 5. how can I adapt the Baader U-Filter 2" to a Nikkor AF-S 50mm 1:1.8G Lens?

A: 2" is the outside diameter of the filter, not the thread. It's an M48 thread as stated on the manufacturer website, baader-planetarium. Use a normal step-up ring.

Q: 6. Can I use the Baader 76 degree Morpheus 4.5 mm eyepiece in the Celestron Regal M2 100ED spotting scope I have ordered from B&H?

A: It probably wont work properly because its too magnified. The Spotting scope is too short a focal length, I would recommend a 12 mm & higher.

Q: 7. Does this filter block IR and UV?

A: The Alpine Astronomical Baader Green Colored Bandpass Eyepiece Filter (2") BH #ALFCFG2 • MFR #FCFG-2 does not block UV or IR rays.

Q: 8. What is the outer housing diameter of this piece?? I need it to fit inside the 1.25" Orion Variable Universal Camera Adapter. So this eyepiece needs to have an outside diameter of less than 38.3mm.

A: The outer housing diameter of this eyepiece is listed at 101.5 mm so it would not fit.

Q: 9. Is this a #8 Yellow?

A: No it is not. A Yellow #8 is typically used for an increase in contrast with black and white films. The Alpine Astronomical Baader Yellow Colored Bandpass Eyepiece Filter is centered on the 495nm wavelength suppresses the secondary blue spectrum when using achromatic and half-apochromatic refractor telescopes, increasing image sharpness.

Q: 10. what is the filter factor, i.e., by how many stops does white light get diminished?

A: Depending on the subject, the Alpine Astronomical H-Alpha 20nm Bandpass Filter could reduce light by a factor of fifty or more.