Antlia Sulfur II (SII) 3nm Pro Highspeed 2" Filter (ANT-SII-3NM-PRO-2-HS)
ANT-SII-3NM-PRO-2-HS
Antlia Sulfur II (SII) 3nm Pro Highspeed 2" Filter (ANT-SII-3NM-PRO-2-HS)
ANT-SII-3NM-PRO-2-HS
Products in the Same Family
Why Purchase from All-Star Telescope?
Free Expert Support
Whether you are a first timer needing help with setting up or an enthusiast that can't quite make that one thing work, our expert staff are ready to support your needs. With decades of knowledge and first hand experience we've been there and we can help you through it!
Stress Free, Secure Transactions
You can trust purchasing and delivery with All-Star Telescope. All of our transactions are 100% secure and Level 1 PCI DSS compliant thanks to Shopify's ShopPay platform. For additional protection, we insure 100% of the value of every shipment we make. If it get's lost during shipment, we replace it. If it gets damaged during shipment, we replace it. We make sure your product arrives exactly as you would expect it to; we promise.
We also ensure privacy protection. We never keep any of your credit card information on file and any of your personal data is stored according to our policies.
30 Day Return Policy
Buy with confidence knowing that we accept returns up to 30 days after purchase. We want you to have something you will actually use and we are confident that we keep good quality products in our store with No Junk.
Price Match Promise
Shipping around for the best price is tough, we make it easier by offering the best pricing in the market. But if you find a better price on an in-store item somewhere else we will match it!
Product Description
Antlia's SHO 3nm Pro Highspeed Filters are further optimized for high-speed imaging systems by pre-shifting the center wavelength. This specially-optimized version will provide significantly SNR (Signal to Noise Ratio) for the fast telescopes with focal ratio between f/2.6 and f/3.6 than the standard 3nm Pro version.
The optical light path of a telescope is cone-shaped, which creates an angle, and the center wavelength of the interference filter will shift toward shorter (blue) wavelengths as the angle of incidence (AOI) increases; the greater the angle, the greater the shift. The amount of beam deviation depends on the refractive index and the thickness of the substrate. The blue shift data by the simulation indicates that at a focal ratio of f/2.6, the angle of incidence of the light cone is 10°and its bandwidth shift 2.2nm to shorter wavelengths. Therefore, the Highspeed 3nm Pro narrowband filters are designed to be pre-shifted by 1.2nm towards the longer (red) end in order to compensate for the Blueshift and ensure high signal acquisition by telescopes with fast focal ratios.
Using these highspeed SHO 3nm Pro narrowband filters for the telescopes with focal ratio between f/2.6 and f/3.6 shows much stronger and more contrasted in astronomy imaging compared to the standard Pro version.
For optics f-ratios slower than f/3.6, the standard 3nm Pro filters are highly recommended. Meanwhile, if you use optics faster than f/2.6, the 4.5nm EDGE filters are the good choice.
Main Features
- High transmittance Ha/SII/OIII＞90% and 3nm bandwidth to maximize contrast
- Antlia narrowband Pro Highspeed filters can be used with focal ratio f/2.6-f3.6 systems with minimal loss of signal
- Improved sharp cut-off astrophotography 3nm Pro series filters are designed to minimize halos around bright stars
- The out of band blocking specification is rated OD5 (0.001%) which delivers an excellent SNR(signal to noise ratio) and effective cut-off rate to minimize interference from other wavelengths
- A single substrate to eliminate internal reflections
- Narrowband Objects: Emission Nebulae, Planetary, Wolf Rayet Nebulae and Supernova Remnants
- Use in light polluted areas and dark sites
- Extends imaging time when the moon is up
- All Antlia unmounted narrowband Highspeed filters are edge blackened to eliminate internal reflections from stray light
- Superior optical reliability reduces post image processing
- Basic Substrate: Optical, Single / Non-glued substrate
- Surface Quality: S/D (scratch/dig)= 60/40 (Refer to MIL-O-13830)
- Transmitted Wavefront: Lambda/4 or better.
- Parallelism: less than 30 arcsec
- Warranty: 3-years against delamination
Specifications
| Model | Sulfur II | Hydrogen-Alpha | Oxygen III |
| FWHM | 3.0nm | 3.0nm | 3.0nm |
| CWL (Central Wavelength) | 673.6nm | 657.5nm | 501.9nm |
| Peak Transmission | >90% | >90% | >90% |
| Blocking | ≥OD5 @ 300-1000nm | ≥OD5 @ 300-1000nm | ≥OD5 @ 300-1000nm |
| Filter Thickness | 2mm+/-0.05mm (1.25"/2"/31mm/36mm) 3mm+/-0.05mm (50mm/50x50mm) |
2mm+/-0.05mm (1.25"/2"/31mm/36mm) 3mm+/-0.05mm (50mm/50x50mm) |
2mm+/-0.05mm (1.25"/2"/31mm/36mm) 3mm+/-0.05mm (50mm/50x50mm) |
Additional Articles, Videos, and Links
Astrophotography for Beginners Step 4: Shooting Deep-Sky Images
Taking deep sky pictures can be daunting, luckily there is an easy process to follow to allow you to get great shots! Here is the typical process for actually taking deep-sky images in the field.
Astrophotography for Beginners Step 3: Choosing Gear for Deep-Sky Imaging
Using a star tracker gains you experience with the fundamentals of deep-sky imaging. Shooting the Moon gains you experience focusing and framing through your telescope. Through your sessions you’ll...
Astrophotography for Beginners - Start Here: Getting into Astrophotography Step by Step
Shooting the night sky has never been more popular, nor easier. The choice of equipment has also never been better, or more affordable. However, as per the advice given by Dickinson and Dyer in the...
Astrophotography for Beginners Step 1: Using the Star Adventurer Tracker
By far the most economical and easiest way to capture beautiful images of the Milky Way and large deep-sky objects like the Andromeda Galaxy (shown here) is to use a star tracker. Here are steps an...
Astrophotography for Beginners Step 2: How to Shoot the Moon
Close-ups of the Moon are rewarding, and an easy way to learn to shoot through your telescope. While good results are possible with a phone camera clamped to an eyepiece (as shown below), this tuto...