Spectrum Telescope Thin Polymer Film Solar Filter: 4.25" Cell Inside Diameter
Stock count is accurate & shown in real time.
- This item is out of stock.
- Sign up for back-in-stock alerts to be notified when this item becomes available (account login required).
- This item is out of stock.
- Sign up for back-in-stock alerts to be notified when this item becomes available (account login required).
Contiguous US / Lower 48:
Free shipping applies to orders over $50 using our chosen carrier/method. Faster paid options are available at checkout.
Alaska, Hawaii & US Territories:
Free shipping applies to many—but not all—products. Enter your ZIP code in cart or upon checkout to confirm options and costs.
International:
International orders do not qualify for free shipping. Shipping, duties, brokerage, tariffs, and taxes are the customer’s responsibility. Some items may be restricted due to export, size, or manufacturer limitations.
ALL SALES FINAL. NO RETURNS OR EXCHANGES. PLEASE MEASURE YOUR TELESCOPE/LENS OUTSIDE DIAMETER VERY CAREFULLY AS EXPLAINED BELOW BEFORE ORDERING.
Spectrum Telescopes thin film polymer solar filter mounted in a 4.25" inside diameter cell # ST425BP1.
1. Selecting the Correct Solar Filter for your Telescope
This solar filter is designed to be fitted on the front (sky-end) of your telescope, spotting scope, or camera lens. The filter slides over the front of the tube and is locked down in place with the included thumbscrew.
This filter cell has an inside diameter of approx. 4.25" and has a clear filter aperture of 3.5" (90mm). It is meant to fit on tubes with an outside diameter between 3-7/8" (98mm) to 4-1/8" (105mm).
This filter is known to fit the following items:
- Meade ETX 90
- Celestron: NexStar 60/80/80GT, FirstScope 90EQ
- Orion StarMax 90, Apex 90
- StellarVue NightHawk APLANAT, NightHawk Next Generation (with dew shield), SV809D (with dew shield)
- Questar 3.5
- Williams Optics ZS80 II ED, Megrez 80
- Vixen A80MF Refractor
- Others? Let us know!
However, we very strongly recommend that you buy this filter only after measuring your tube size carefully (as explained below), even if your telescope is mentioned in the list above.
To get the proper fit, measure the outside diameter very carefully by using a caliper, ruler, or tape measure. See the 3rd product photo above. Measure the widest distance of the telescope tube starting from the exterior of the casing, across the center and to the exterior part of the casing on the other side. After you have your measurements, you should order a size slightly 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 outside of the tube end, you should order a 4.25" inside diameter size solar filter. This will make it just a little bigger than the measurement you took.
Also, for example, If you have a 4" telescope, do not buy a 4" solar filter! Telescope aperture is not the same as telescope tube size. The telescope tube diameter will always be slightly larger than the telescope aperture. Measure it carefully before ordering to avoid disappointment and expensive returns.
2. Filter Film and Cell Details
This full aperture thin film solar filter allows only a safe amount of light to pass through your telescope, spotting scope, etc. for solar viewing or imaging. It is an ND 5 filter and therefore blocks 99.999% of the Sun's visible light. The .002" thick black plastic polymer used for the filter substrate is an extremely durable, high quality material that will last you for many years with proper care and handling. It is a single-layer design with absorptive filtering material spread throughout the substrate. Note that slight warps, bends or wrinkles present in the film will not affect the solar image. The Sun appears in a natural looking yellowish-orange color.
The filter film is mounted in an aluminum cell than can be securely attached to the telescope tube with the included nylon thumb screw. This filter comes packaged in a foam-lined shipping/storage box.
3. Warning
Never look at the sun without special eye protection. When viewing the Sun, use this filter in front of your optical instrument at all times when any part of the Sun is visible.
Other Information
- Country of Manufacture: United States
Spectrum Telescopes thin film polymer solar filter mounted in a 4.25" inside diameter cell # ST425BP1.
1. Selecting the Correct Solar Filter for your Telescope
This solar filter is designed to be fitted on the front (sky-end) of your telescope, spotting scope, or camera lens. The filter slides over the front of the tube and is locked down in place with the included thumbscrew.
This filter cell has an inside diameter of approx. 4.25" and has a clear filter aperture of 3.5" (90mm). It is meant to fit on tubes with an outside diameter between 3-7/8" (98mm) to 4-1/8" (105mm).
This filter is known to fit the following items:
- Meade ETX 90
- Celestron: NexStar 60/80/80GT, FirstScope 90EQ
- Orion StarMax 90, Apex 90
- StellarVue NightHawk APLANAT, NightHawk Next Generation (with dew shield), SV809D (with dew shield)
- Questar 3.5
- Williams Optics ZS80 II ED, Megrez 80
- Vixen A80MF Refractor
- Others? Let us know!
However, we very strongly recommend that you buy this filter only after measuring your tube size carefully (as explained below), even if your telescope is mentioned in the list above.
To get the proper fit, measure the outside diameter very carefully by using a caliper, ruler, or tape measure. See the 3rd product photo above. Measure the widest distance of the telescope tube starting from the exterior of the casing, across the center and to the exterior part of the casing on the other side. After you have your measurements, you should order a size slightly 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 outside of the tube end, you should order a 4.25" inside diameter size solar filter. This will make it just a little bigger than the measurement you took.
Also, for example, If you have a 4" telescope, do not buy a 4" solar filter! Telescope aperture is not the same as telescope tube size. The telescope tube diameter will always be slightly larger than the telescope aperture. Measure it carefully before ordering to avoid disappointment and expensive returns.
2. Filter Film and Cell Details
This full aperture thin film solar filter allows only a safe amount of light to pass through your telescope, spotting scope, etc. for solar viewing or imaging. It is an ND 5 filter and therefore blocks 99.999% of the Sun's visible light. The .002" thick black plastic polymer used for the filter substrate is an extremely durable, high quality material that will last you for many years with proper care and handling. It is a single-layer design with absorptive filtering material spread throughout the substrate. Note that slight warps, bends or wrinkles present in the film will not affect the solar image. The Sun appears in a natural looking yellowish-orange color.
The filter film is mounted in an aluminum cell than can be securely attached to the telescope tube with the included nylon thumb screw. This filter comes packaged in a foam-lined shipping/storage box.
3. Warning
Never look at the sun without special eye protection. When viewing the Sun, use this filter in front of your optical instrument at all times when any part of the Sun is visible.
ALL SALES FINAL. NO RETURNS OR EXCHANGES. PLEASE MEASURE YOUR TELESCOPE/LENS OUTSIDE DIAMETER VERY CAREFULLY AS EXPLAINED BELOW BEFORE ORDERING.
Spectrum Telescopes thin film polymer solar filter mounted in a 4.25" inside diameter cell # ST425BP1.
1. Selecting the Correct Solar Filter for your Telescope
This solar filter is designed to be fitted on the front (sky-end) of your telescope, spotting scope, or camera lens. The filter slides over the front of the tube and is locked down in place with the included thumbscrew.
This filter cell has an inside diameter of approx. 4.25" and has a clear filter aperture of 3.5" (90mm). It is meant to fit on tubes with an outside diameter between 3-7/8" (98mm) to 4-1/8" (105mm).
This filter is known to fit the following items:
- Meade ETX 90
- Celestron: NexStar 60/80/80GT, FirstScope 90EQ
- Orion StarMax 90, Apex 90
- StellarVue NightHawk APLANAT, NightHawk Next Generation (with dew shield), SV809D (with dew shield)
- Questar 3.5
- Williams Optics ZS80 II ED, Megrez 80
- Vixen A80MF Refractor
- Others? Let us know!
However, we very strongly recommend that you buy this filter only after measuring your tube size carefully (as explained below), even if your telescope is mentioned in the list above.
To get the proper fit, measure the outside diameter very carefully by using a caliper, ruler, or tape measure. See the 3rd product photo above. Measure the widest distance of the telescope tube starting from the exterior of the casing, across the center and to the exterior part of the casing on the other side. After you have your measurements, you should order a size slightly 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 outside of the tube end, you should order a 4.25" inside diameter size solar filter. This will make it just a little bigger than the measurement you took.
Also, for example, If you have a 4" telescope, do not buy a 4" solar filter! Telescope aperture is not the same as telescope tube size. The telescope tube diameter will always be slightly larger than the telescope aperture. Measure it carefully before ordering to avoid disappointment and expensive returns.
2. Filter Film and Cell Details
This full aperture thin film solar filter allows only a safe amount of light to pass through your telescope, spotting scope, etc. for solar viewing or imaging. It is an ND 5 filter and therefore blocks 99.999% of the Sun's visible light. The .002" thick black plastic polymer used for the filter substrate is an extremely durable, high quality material that will last you for many years with proper care and handling. It is a single-layer design with absorptive filtering material spread throughout the substrate. Note that slight warps, bends or wrinkles present in the film will not affect the solar image. The Sun appears in a natural looking yellowish-orange color.
The filter film is mounted in an aluminum cell than can be securely attached to the telescope tube with the included nylon thumb screw. This filter comes packaged in a foam-lined shipping/storage box.
3. Warning
Never look at the sun without special eye protection. When viewing the Sun, use this filter in front of your optical instrument at all times when any part of the Sun is visible.
Other Information
- Country of Manufacture: United States
Spectrum Telescope Thin Polymer Film Solar Filter: 4.25" Cell Inside Diameter