Spectrum Telescope filters slip over the sky end of the optical tube of the telescope or Binoculars. To get the proper fit, measure the outer diameter by using a caliper, ruler, or tape measure. Measure the widest distance of the telescope end starting from the exterior of the casing, across the center and to the exterior part of the casing of the other side.
After you have your measurements, you should order a size larger than what you measured. This is because your measurement is being compared with the solar filter ID (inside diameter).
For instance: If you measure 4″ across the optical tube end needs a 4.25” size solar filter. This will make it just a little bigger than the measurement you took.
Are the glass and thin film solar filters safe?Yes, all of our filters are safe, blocking up to 99.99% of the sun’s rays, perfect for unlimited visual use as well as photography. These filters are rated with a neutral density of 5. With proper care and handling, our filters will last for many years. All Spectrum Telescope filters meet ISO Certified 12312-2 while meeting or exceeding International Standards for safety.
What can I expect to see using these filters?
You can expect to see a solar eclipse when present, sunspots, and surface granulation.