The Antlia OIII 3.5 nm filter 1.25-inch size.
This filter is suitable for imaging of OIII nebulas from sites with light pollution and from dark sites as well, while only allowing 3.5 nm bandwidth of high transmission at a center wavelength of 500.7 nm. This extremely narrow bandwidth filter can effectively improve the contrast of the band while it blocks the interference of light from other wave bands, especially artificial mercury and sodium lamps.
Contrast:
Antlia narrowband filters are designed to enhance the contrast. Contrast brings out faint features by reducing the background – the narrower the filter, the better.
Suitable for most emission nebulas, planetary nebulas, and supernova remnant, this filter can well highlight the details of OIII contained in these imaging objects.
Bandwidth:
Extremely narrow bandwidth results in a small amount of light, Antlia Filters recommends you use a large-aperture telescope and long exposure times. This will let you collect enough signal to obtain the details of those faint objects with the OIII ultra-narrow filter.
Blocks other bands:
The unwanted light from other wavelengths is cut off, leaving only a width of 3.5 nm at 500.7 nm, so that you get the highest contrast and the background is greatly increased. The result is an extremely dark background and minimized halos around bright stars.
Antlia 3.5 nm filters
In the production process, Antlia Filters uses very strict quality control standards. Each filter is individually tested and scanned to ensure that the product meets the parameters needed. In particular, starting from the selection of the substrate, they must control the tolerance of each substrate to a very high standard of +/-0.05 mm. As we all know, when light passes through optical materials, it will be refracted and the thickness of the glass will affect the length of light refraction. They allow Antlia filters to achieve parfocal by minimizing tolerance of +/-0.05 mm.
All Antlia narrowband filters edges are blackened. This is critical to minimize stray light for a filter that blocks most light except for the narrow bandpass. As edge blackening must be hand-made, it becomes a very costly detail.
Their cut-off rate has reached a very high technical data point. Many users will be very concerned about how high the filter transmission rate is and ignore the cut-off rate. Antlia Filters keeps the signal 88%T at the 500.7 nm line stable. As the filter becomes spectrally narrower to ensure the best signal-to-noise ratio, a cut-off rate of OD3 (0.1%) is required to reduce interference from other wavelengths. It is a very important quality index, and the accomplishment is very difficult. This process requires very high-end equipment, constantly thickens the layers of coating, adds to longer production times, and adds more costs to the completed product.
Wavelength Graph
To see the graph, click on the Gallery thumbnail image to expand. Then use [CTRL]-scroll-up for an even closer look.
Images like Hubble
Many images of planetary nebula and supernova remnants are taken only with H-a and OIII filters; With an HSO-set of filters (H-alpha, SII, and OIII) you are able to process your images like the ones from the Hubble Space Telescope.
See the Gallery Tab for an example.
Not Recommended:
- Solar Observing and imaging.
- Visual observation.
- DO NOT LOOK AT THE SUN WITH ANTLIA FILTERS.
- Serious eye damage will result if you fail to observe the warning.
Technical Data:
- Schott optical substrate.
- 1.25-inch (2 mm+/-0.05 mm).
- Surface Quality: 60/40 (Refer to MIL-O-13830).
- 2 sides fine-optically polished to ensure accurate 1/4 wavefront.
- 30 arcsec parallelism.
- Center-Wavelength of Antlia OIII 3.5 nm filter: 500.7 nm.
- OIII 500.7 nm T＞88%, (88% transmission at OIII line 500.7 nm).
- ＞OD3（0.1%）at 300 to 1100 nm.
- 2 sides Multi-layers anti-reflection coating,
- Single / Non-glued substrate,
- Filter Ring: 1.25-inch (M26*0.6).
- Ultra-thin filter cell to minimize vignetting by maximizing possible clear aperture,
- Black Anodized Finish.
- Laser Engraving No Fading.
- Size Mounted： 1.25-inch.
