Baader CMOS-Optimized 3.5/4nm Ultra-Narrowband Filter Set (H-a/O-III/S-II) - 1.25"
- This item is out of stock.
- Sign up for back-in-stock alerts to be notified when this item becomes available (account login required).
Stock count is accurate & shown in real time.
- This item is out of stock.
- Sign up for back-in-stock alerts to be notified when this item becomes available (account login required).
- This item is out of stock.
- Sign up for back-in-stock alerts to be notified when this item becomes available (account login required).
Contiguous US / Lower 48:
Free shipping applies to orders over $50 using our chosen carrier/method. Faster paid options are available at checkout.
Alaska, Hawaii & US Territories:
Free shipping applies to many—but not all—products. Enter your ZIP code in cart or upon checkout to confirm options and costs.
International:
International orders do not qualify for free shipping. Shipping, duties, brokerage, tariffs, and taxes are the customer’s responsibility. Some items may be restricted due to export, size, or manufacturer limitations.
Important Note About Torn Baader Filter Seals:
Recently, Baader started applying a new filter label on many filters that goes over the edge of the case and also acts as a seal. Unfortunately, these labels rip far too easily during transport, giving the false appearance that the filter case has been previously opened. Many filters we now get from Baader arrive like the ones shown in the photos below, and many others will rip en route from us to you. Rest assured that ALL filters we ship to you are brand new and unopened as received from Baader, whether the seal is intact or partially/completely ripped.
 |
 |
Baader has agreed to revert to their old design of 2-piece labels, but until they use up their current labels, we will continue to have this problem for a while and you might also get a mix of different filter label types. Thank you for your understanding.
- 1¼" x 2 mm Baader H-alpha / O-III / S-II Ultra-Narrowband Filter Set – Premium Grade – with 1¼" (28,5 mm) filter thread
- 3.5 / 4 nm FWHM (to harmonize the exposure time from H-alpha with O-III / S-II), recommended for optical systems from f/10 to f/3.5
- For highest contrast even at strongest light pollution, minimizes star size, emphasizes finest nebula detail – indispensable under Bortle 9/8/7/(6) skies
- Reflex-Blocker™ hard coated and planeoptically polished – with sealed coating edges (Life-Coat™)
- Blackened edges all around, with filter-lead-side-indicator in the form of a black frontside outer rim
- Optimized for modern CMOS cameras, but excellent for CCD camera technologies
- Mounted in Baader Low Profile Filter Cell (LPFC) – 6 mm height
We explicitly warn against observing the sun with a DeepSky 3.5 nm (equivalent to 35 Ångstroem) H-alpha narrowband filter, specialized solar chromosphere and prominence filters from SolarSpectrum start at 0.8 Ångstroem. Photographic experiments with a camera are theoretically possible, but by no means observe the sun with naked eyes – you endanger your eyesight!
The new generation of Baader CMOS-optimized filters features:
- CMOS-Optimized Baader Filter
- Increased contrast
- Ever more narrow passbands
- Reflex-Blocker™ coatings, for largest ever freedom from halos, even under most adverse conditions concerning aux-optics
- FWHM on each filter category carefully designed to allow for 1:1:1 exposures, matched for typical CMOS quantum efficiency and s/n ratio
- Identical filter thickness to existing standards, with utmost care for parfocality
- Blackened edges all around, with filter-lead-side-indicator in the form of a black frontside outer rim, to additionally eliminate any reflection due to light falling onto the edge of a filter
- Each filter coated individually, with sealed coating edge (NOT cut out of a larger plate with coatings left exposed read more)
- Life-Coat™: evermore hard coatings to enable a non-aging coating for life – even in a most adverse environment
Useful Resources
Filter Cell Specifications
D = Filter Cell Diameter = 30.9 mm / 1.21 in
T = Total Filter Height = 7.6 mm / 0.29 in
C = Filter Cell Height (Excluding Male Thread) = 5.9 mm / 0.23 in
M = Male Thread Length = 1.7 mm / 0.06 in
F = USABLE Female Filter Thread Length = 2.5 mm / 0.09 in
S = Glass Substrate Thickness = 2.0 mm / 0.07 in
CA = Clear Aperture = 26.5 mm / 1.04 in
Other Information
- Country of Manufacture: Germany
- 1¼" x 2 mm Baader H-alpha / O-III / S-II Ultra-Narrowband Filter Set – Premium Grade – with 1¼" (28,5 mm) filter thread
- 3.5 / 4 nm FWHM (to harmonize the exposure time from H-alpha with O-III / S-II), recommended for optical systems from f/10 to f/3.5
- For highest contrast even at strongest light pollution, minimizes star size, emphasizes finest nebula detail – indispensable under Bortle 9/8/7/(6) skies
- Reflex-Blocker™ hard coated and planeoptically polished – with sealed coating edges (Life-Coat™)
- Blackened edges all around, with filter-lead-side-indicator in the form of a black frontside outer rim
- Optimized for modern CMOS cameras, but excellent for CCD camera technologies
- Mounted in Baader Low Profile Filter Cell (LPFC) – 6 mm height
We explicitly warn against observing the sun with a DeepSky 3.5 nm (equivalent to 35 Ångstroem) H-alpha narrowband filter, specialized solar chromosphere and prominence filters from SolarSpectrum start at 0.8 Ångstroem. Photographic experiments with a camera are theoretically possible, but by no means observe the sun with naked eyes – you endanger your eyesight!
The new generation of Baader CMOS-optimized filters features:
- CMOS-Optimized Baader Filter
- Increased contrast
- Ever more narrow passbands
- Reflex-Blocker™ coatings, for largest ever freedom from halos, even under most adverse conditions concerning aux-optics
- FWHM on each filter category carefully designed to allow for 1:1:1 exposures, matched for typical CMOS quantum efficiency and s/n ratio
- Identical filter thickness to existing standards, with utmost care for parfocality
- Blackened edges all around, with filter-lead-side-indicator in the form of a black frontside outer rim, to additionally eliminate any reflection due to light falling onto the edge of a filter
- Each filter coated individually, with sealed coating edge (NOT cut out of a larger plate with coatings left exposed read more)
- Life-Coat™: evermore hard coatings to enable a non-aging coating for life – even in a most adverse environment
Important Note About Torn Baader Filter Seals:
Recently, Baader started applying a new filter label on many filters that goes over the edge of the case and also acts as a seal. Unfortunately, these labels rip far too easily during transport, giving the false appearance that the filter case has been previously opened. Many filters we now get from Baader arrive like the ones shown in the photos below, and many others will rip en route from us to you. Rest assured that ALL filters we ship to you are brand new and unopened as received from Baader, whether the seal is intact or partially/completely ripped.
|
|
Baader has agreed to revert to their old design of 2-piece labels, but until they use up their current labels, we will continue to have this problem for a while and you might also get a mix of different filter label types. Thank you for your understanding.
- 1¼" x 2 mm Baader H-alpha / O-III / S-II Ultra-Narrowband Filter Set – Premium Grade – with 1¼" (28,5 mm) filter thread
- 3.5 / 4 nm FWHM (to harmonize the exposure time from H-alpha with O-III / S-II), recommended for optical systems from f/10 to f/3.5
- For highest contrast even at strongest light pollution, minimizes star size, emphasizes finest nebula detail – indispensable under Bortle 9/8/7/(6) skies
- Reflex-Blocker™ hard coated and planeoptically polished – with sealed coating edges (Life-Coat™)
- Blackened edges all around, with filter-lead-side-indicator in the form of a black frontside outer rim
- Optimized for modern CMOS cameras, but excellent for CCD camera technologies
- Mounted in Baader Low Profile Filter Cell (LPFC) – 6 mm height
We explicitly warn against observing the sun with a DeepSky 3.5 nm (equivalent to 35 Ångstroem) H-alpha narrowband filter, specialized solar chromosphere and prominence filters from SolarSpectrum start at 0.8 Ångstroem. Photographic experiments with a camera are theoretically possible, but by no means observe the sun with naked eyes – you endanger your eyesight!
The new generation of Baader CMOS-optimized filters features:
- CMOS-Optimized Baader Filter
- Increased contrast
- Ever more narrow passbands
- Reflex-Blocker™ coatings, for largest ever freedom from halos, even under most adverse conditions concerning aux-optics
- FWHM on each filter category carefully designed to allow for 1:1:1 exposures, matched for typical CMOS quantum efficiency and s/n ratio
- Identical filter thickness to existing standards, with utmost care for parfocality
- Blackened edges all around, with filter-lead-side-indicator in the form of a black frontside outer rim, to additionally eliminate any reflection due to light falling onto the edge of a filter
- Each filter coated individually, with sealed coating edge (NOT cut out of a larger plate with coatings left exposed read more)
- Life-Coat™: evermore hard coatings to enable a non-aging coating for life – even in a most adverse environment
Useful Resources
Filter Cell Specifications
D = Filter Cell Diameter = 30.9 mm / 1.21 in
T = Total Filter Height = 7.6 mm / 0.29 in
C = Filter Cell Height (Excluding Male Thread) = 5.9 mm / 0.23 in
M = Male Thread Length = 1.7 mm / 0.06 in
F = USABLE Female Filter Thread Length = 2.5 mm / 0.09 in
S = Glass Substrate Thickness = 2.0 mm / 0.07 in
CA = Clear Aperture = 26.5 mm / 1.04 in
Other Information
- Country of Manufacture: Germany