Artesky ERF rejection filter
The purpose of using an Energy Rejection Filter (ERF) is to prevent as much solar energy as possible from entering the telescope, thus avoiding excessive heating of the H-alpha filter etalon.
This effect can be achieved effectively by adding an ERF filter to the front of the telescope.
At the same time, the air inside the tube is prevented from heating up - the telescope remains close to room temperature and there is no air turbulence inside the tube due to the temperature difference. If we look at the solar spectrum, we see that this filter mainly blocks visible light. Ideally, it reflects solar energy rather than absorbing it, and does not heat up in the process - which is why these filters are called Energy Rejection Filters (ERF).
Artesky ERF filters are unique in the world, their dielectric coating provides a beam of pure light, with a FWHM of 60 nm!
The glass substrate in this case is not of any soft and colored absorbent type with streaks, but transparent of very high homogeneity, finely polished to the quality grade of the lens surfaces and with all reflective performance coatings on one side.
This reflects the entire desired spectrum from 300nm down to 1100nm, leaving only that 60nm wide spectral window around H-alpha (656.26nm) open.
If these coating systems on both sides of the plate are not done correctly, to cancel the stresses induced by the coating layers, the surfaces parallel to the plane can be easily distorted, which means that the 1/10 wave flat plate it deforms into an irregularly curved substrate that acts as a (bad) target.
The filter layers of the ERF Artesky are designed with the utmost care, applied with the most advanced optical coating machines in the world,
This level of attention preserves the resolving power of the entire aperture of the telescope lens, dramatically reducing the thermal energy that passes through the telescope and reaches the solar spectrum filter.
Not only is this the main reason for the significant reduction in thermal stress inside the telescope, but it also greatly diminishes heat-induced visual effects.
Artesky ERF rejection filter 100mm (ERF-100)
- Diameter (mm): 100
- Edge chipping: <0.2mm
- Thickness (mm): 12mm
- Surface shape: λ/4
- Finish: 60-40
- Center wavelength (nm): 656.28
- Bandwidth (nm): 60
- Peak transmittance (%): 95%
- Cutoff range (nm): 200nm-1100nm
- Cutoff Depth (OD): OD4
Artesky ERF rejection filter 130mm (ERF-130)
- Diameter (mm): 130
- Edge chipping: <0.2mm
- Thickness (mm): 12mm
- Surface shape: λ/4
- Finish: 60-40
- Center wavelength (nm): 656.28
- Bandwidth (nm): 60
- Peak transmittance (%): 95%
- Cutoff range (nm): 200nm-1100nm
- Cutoff Depth (OD): OD4
Artesky ERF rejection filter 150mm (ERF-150)
- Diameter (mm): 150
- Edge chipping: <0.2mm
- Thickness (mm): 12mm
-
Surface shape: λ/4
- Finish: 60-40
- Center wavelength (nm): 656.28
- Bandwidth (nm): 60
- Peak transmittance (%): 95%
- Cutoff range (nm): 200nm-1100nm
- Cutoff Depth (OD): OD4
Artesky ERF rejection filter 200mm (ERF-200)
- Diameter (mm): 200
- Edge chipping: <0.2mm
- Thickness (mm): 12mm
-
Surface shape: λ/4
- Finish: 60-40
- Center wavelength (nm): 656.28
- Bandwidth (nm): 60
- Peak transmittance (%): 95%
- Cutoff range (nm): 200nm-1100nm
- Cutoff Depth (OD): OD4
Artesky ERF rejection filter 240mm (ERF-240)
- Diameter (mm): 240
- Edge chipping: <0.2mm
- Thickness (mm): 15mm
-
Surface shape: λ/4
- Finish: 60-40
- Center wavelength (nm): 656.28
- Bandwidth (nm): 60
- Peak transmittance (%): 95%
- Cutoff range (nm): 200nm-1100nm
- Cutoff Depth (OD): OD4
In the Box
- Artesky ERF rejection filter 100mm
OR
- Artesky ERF rejection filter 130mm
OR
- Artesky ERF rejection filter 150mm
OR
- Artesky ERF rejection filter 200mm
OR
- Artesky ERF rejection filter 240mm
Warranty & Manual
Artesky Warranty
Important Note: Artesky ERF Energy Rejection filters are intended for use only as a pre-filter for solar spectrum H-Alpha filters.
The ERF filter must always be present and mounted in front of the telescope objective.
The filter should be oriented with the main liner surface facing the sun (an arrow on the edge of the filter points to this side).
The ERF filter must be used together with the H-Alpha Daystar filter or similar.
If the ERF is used alone for visual observation, irreparable eye damage will occur.
Important note: This filter is sold without cell, if you need the version with the cell already included look for it in the solar filters section or contact us
