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Care & Use Instructions

SOLAR FILTERS White Light  (580-630nm)

Printable SolarLite Filter Instructions


SolarLite Film:  Metallic coating outside surface & absorptive material within substrate.

Silver-Black Polymer Film:  Metallic coating outside surface absorptive material within substrate.

Glass 2+:  High quality hand selected glass with metallic coating on inside surface facing optics.

All filters block 99.999% of the energy from entering the instrument. For visual and photographic use.


  • Check the solar filter for damage before each use.
  • The filter must be FIRST in-line between sun and instrument. Do not use filter behind any lens.
  • Truss design telescopes must NOT be used without covering the open section of tube. Sunlight entering from the side will reflect off mirror and damage the solar filter.
  • Secure filter properly. (See mounting instructions)
  • Do not leave instrument unattended where a child or inexperienced adult could point it at the sun without the filter properly attached.
  • Keep the finder-scope covered if not equipped with a proper solar filter.
  • Point the instrument away from sun when attaching and removing solar filter.
  • Do not place the filter up against a smaller instrument. The end of the tube will damage the filter.
  • When looking through the focusing tube without an eyepiece, there may appear to be small defects in
  • the coating that are not seen when observing through the eyepiece. This is normal and is not a coating defect or safety concern.
  • “Ghosting” can occur due to internal reflections (glass filters only). If this is a problem, simply tilt the filter slightly.
  • Filter may absorb solar energy and get hot during use. Use extra care when removing.

Pinholes and minor surface scratches are common in glass solar filters; however, our multi-coating technique keeps them to a minimum. A “bright” pinhole in the coating may cause “ghosting” due to scattered light. If this is seen during observation, the pinhole(s) should be blocked out. Block out any pinholes on inside surface facing telescope. Hold the filter 1-2 feet in front of a 50-100 soft white light bulb. Blocking can be done using a fine point felt marker. There is no danger if a few pinholes or minor scratches are present. The touch-up(s) will not lessen the optical performance. Small pinholes need not be blocked if not causing an image problem.


If your filter is too loose, it can be custom fitted using the extra felt included. If the paper backing is difficult to remove, dampen with water or alcohol using a wet sponge or fine spray mist. Peal backing off slowly. Let dry if necessary before installing on inside of cell. Extra felt can be added over any existing felt. Test fit before removing the backing and permanently installing the felt. We cannot exchange for another size if the felt is installed.


  • Allow instrument and filter to equalize to the outside temperature for at least 15 minutes.
  • If possible, do not view over pavement or buildings. Viewing over grass or water will help avoid heat currents that will degrade the image.
  • Cover dark colored instruments with a light colored cloth.


Glass: Loose dust can be blown off with up to 15 PSI. Clean with Isopropyl (rubbing) alcohol and a soft tissue. Do not use a cloth. It’s best to mist the filter with a spray versus soaking the tissue. Use a 3 inch or larger circular wad of tissue and lightly rub across surface using long strokes. Lightly wipe dry with a fresh dry tissue.

SolarLite & Silver-Black Polymer Film:  Same as glass, however, polymer is more susceptible to small surface scratches, so extra care should be taken. Surface scratches will not compromise the safety.


Glass 2+ and SolarLite 15 years, Black Polymer 10 years. All filters are covered by a limited liability warranty from defects in material and workmanship. This warranty does not apply if, in the judgment of Thousand Oaks Optical, the product fails to be safe due to shipping damage, damage from improper handling or storage, abuse or misuse, or has been used or maintained in a manner not conforming to product’s instructions or has been modified in any way.


Download Printable H-alpha Instructions


Both the ERF (Energy Rejection Filter) and HAU (H-Alpha Unit) MUST be properly attached to telescope before pointing telescope at the sun. You cannot safely look at the sun with the ERF or HAU separately. Looking at the sun without proper filters can damage your eye in a fraction of a second. The ERF also protects the HAU and telescope optics from excessive solar radiation.


Looking at the sun without a proper solar filter can damage your eye in a fraction of a second. If you do not have a solar filter for the finder, keep it covered.


The aluminum cell with the ERF simply fits over and around the front of the telescope tube. The off-axis version should be mounted with the filter at or near the 12 O’clock position.

The HAU slides into telescope back or star diagonal. Any 1 ¼” eyepiece can be used, however, we recommend starting each observing session with low magnification, then  increasing magnification as desired and as “seeing” conditions allow.


For optimum performance, the system should be used at f/10 and above. The ERF is sized and mounted in a mask designed for each brand and aperture of telescope to increase the effective focal ratio. A Barlow lens can be used if necessary to increase the focal ratio further. A Barlow lens may be necessary to reach focus on telescopes with limited focuser travel since the HAU extends focus approximately three inches.

With eyepiece removed, watch the H-Alpha filter while turning the thumbscrew in both directions. If the thumbscrew is completely unscrewed from the body, simply screw back in using care not to “cross thread.” Start observation with filter straight (center of travel). Tilting the filter holder “tunes” the filter to the correct bandpass.

Start with low power and center sun in eyepiece. If no prominence is seen after focusing, slowly turn thumbscrew in either direction. With higher magnification this procedure should be done on portions of the limb. Activity varies greatly from day to day and even hour to hour. With careful observation, changes can be seen within minutes. An observing cloth is very helpful for blocking ambient light at the eyepiece.

Our system is designed for maximum transmission to allow observation of faint prominence detail not seen with other brands. This also helps with image brightness when using higher magnifications. If the image seems too bright when using low magnification, color or ND filters can be used at the eyepiece if desired.


Clean and care for as you would any telescope optic.


  • Check filters for possible damage before each use.
  • Allow telescope and filters to equalize to outside temperature. (At least 15 minutes)
  • Direct sunlight may warm the tube assembly enough to cause internal heat currents that can degrade image quality. Cover tube assembly with a light colored cloth.
  • Point telescope away from sun before attaching and removing filters.
  • Do not leave telescope unattended where children or inexperienced adults could point it at the sun without the filters properly attached.
  • If possible, do not view over pavement or buildings. Viewing over vegetated areas or water will help avoid surface heat currents. In most cases, “seeing” will be better during morning hours.


The complete H-Alpha system is warranted for two years against defects in material and workmanship. The warranty does not cover accidental damage, abuse or damage to the H-Alpha filter if telescope is pointed at the sun without the ERF attached. Do not remove the H-Alpha filter from the HAU assembly. The filter is specially sealed to keep out air and moisture. Removing the filter from the holder will break the seal and void warranty.