Solar Filter Cap for 70 mm Refractors (50 mm, ND 5.0)
Solar filter in Pakistan for small refractors: an ND 5.0 film cap that fits the 46.5 mm opening in a 70 mm telescope dust cap, for safe sunspot viewing.
Rs 3,999
In stock- Solar filter cap
Before you buy
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Fits only a 46.5 mm opening, such as the removable centre cap in the dust cover of many 70 mm refractors. Measure yours first.
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ND 5.0 solar film: shows sunspots and eclipses safely. It does not show flares or prominences.
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Uses part of the telescope's aperture; that is enough light for the Sun.
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Cover or remove the finder scope before pointing at the Sun.
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Check the film against a bright lamp before every use; discard it if there is any pinhole or scratch.
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Adult supervision for children, always.
Frequently asked questions
Will it fit my telescope?
Only if the front dust cap of your telescope has a removable centre cap that leaves a 46.5 mm opening, as many 70 mm refractors do. Measure the opening before ordering. For any other size, ask us about a full-aperture filter.
Is it safe to look at the Sun with it?
Yes, when it is fitted firmly over the front of the telescope, the film is undamaged and the finder scope is covered. ND 5.0 is the density used for safe solar viewing. If the film has any pinhole, scratch or crease, do not use it.
What will I see?
The Sun as a sharp disc with sunspots, which change from day to day, and the Moon or a planet crossing it during an eclipse or transit. Flares and prominences need a special hydrogen-alpha telescope.
Can I photograph the Sun with my phone through it?
Yes. With the filter on the front of the telescope, a phone adapter on the eyepiece gives good sunspot photos. Never photograph the Sun through a telescope or phone without the filter.
Full description
This is a solar filter cap for small refractor telescopes. It is a 50 mm plastic ring holding a sheet of ND 5.0 solar film, PET coated with aluminium, which lets through about one part in a hundred thousand of the Sun's light. It fits into the 46.5 mm opening found in the front dust cap of many 70 mm beginner refractors, the small cap you can pull out of the middle of the large one, so the telescope looks at the Sun through the film and through nothing else.
With it fitted you can see sunspots, which change from day to day, the darker edge of the Sun's disc, and the Moon or a planet crossing in front of the Sun during an eclipse or transit. The Sun appears as a sharp-edged disc with a coloured tint. You will not see flares or prominences; those need a dedicated hydrogen-alpha solar telescope.
Because it covers a 46.5 mm opening rather than the whole lens, it uses only part of the telescope's aperture. That is normal for a filter of this type and is plenty of light for the Sun; the image is simply a little less sharp than the full lens would give.
Check the fit before you buy. Measure the opening in your telescope's dust cap: it must be 46.5 mm, and the filter must sit in it firmly with no gap. If your telescope has no such cap, or a different size, this filter is not the right one, and you should ask us for a full-aperture filter instead.
Safety, every single time. Fit the filter before the telescope is pointed anywhere near the Sun, and make sure it cannot be knocked off. Cap or remove the finder scope, because an unfiltered finder concentrates sunlight just as a telescope does. Hold the film up to a bright lamp before each use and throw the filter away if you see any pinhole, scratch or crease. Never use a filter that screws into the eyepiece, and never let children observe the Sun unsupervised. A telescope without a working filter can blind an eye in a fraction of a second.
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