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Dew control

Explore Scientific Dew cap for the Telrad finder (620225)

A dew cap for the Telrad projection finder, preventing the projection window fogging and covering it when the finder is not in use.

Explore Scientific dew cap fitted to a Telrad finder

Explore Scientific Dew cap for the Telrad finder (620225)

A dew cap for the Telrad projection finder, preventing the projection window fogging and covering it when the finder is not in use.

Tube fit
The Telrad projection finder, named by the maker
Outside diameter
Not published by the maker.
Shield length
Not published by the maker.
Construction
Dew cap for a projection finder · Impact-resistant plastic
Heater width
Not published by the maker.
Power draw
Not published by the maker.
Controller support
Not published by the maker.
Cable
Not published by the maker.
Connector
Not published by the maker.
Amazon reference
B07VG8B9CD (same reference on 5 Amazon marketplaces)
EAN
4007922063492
  • Addresses the single commonest failure of a projection finder on a damp night
  • Doubles as a cover, so it earns its place in the case twice
  • Made for one named finder only

Best for: A Telrad owner whose finder fogs before the telescope does

≈ €29
Check price on Amazon

Specifications

Tube fit
The Telrad projection finder, named by the maker
Outside diameter
Not published by the maker.
Shield length
Not published by the maker.
Construction
Dew cap for a projection finder · Impact-resistant plastic
Heater width
Not published by the maker.
Power draw
Not published by the maker.
Controller support
Not published by the maker.
Cable
Not published by the maker.
Connector
Not published by the maker.
Amazon reference
B07VG8B9CD (same reference on 5 Amazon marketplaces)
EAN
4007922063492

The first thing on a telescope to dew

A projection finder’s window is flat, thin, and pointed at the sky. It has almost no thermal mass, so it radiates heat away and reaches the dew point long before the main optic does. An evening that ends with a fogged finder ends with a telescope nobody can aim.

What this is

A moulded cap in impact-resistant plastic, made for the Telrad housing. It shields the window from the open sky while observing, which is what delays dew.

And what it is for the rest of the time

A cover. A projection window rattling loose in a case gets scratched, and a scratched window scatters the projected dot into a smear. Using the same part for both jobs is the sensible design.

Its limitation

One named finder. There is no adjustment and no range, and the other red dot finders on this shelf have different housings.

Availability

German, French and Italian Amazon stores ran from 29 € to 38 € on the day of the survey.

British and Spanish Amazon catalogues hold a record for it that nobody is selling.

American Amazon store gave no result whatever, so the buy button there opens a search rather than an empty page.

Figures as Keepa reported them on the day this page was last updated. Stock and pricing shift without warning.

Prices quoted in this text were read on 17 September 2026. The live price is at the top of the page.

What this fits

More dew control

  • Omegon flexible dew shield for 8 inch telescopes

    Omegon Flexible dew shield 8 in (225–245 mm)

    A flexible plastic dew shield with a velvet inner finish for tubes of 225 to 245 mm outside diameter, closed with hook-and-loop.

    Tube fit
    225 to 245 mm, from the title
    Outside diameter
    Not published by the maker.
    Shield length
    Neither is published
    Construction
    Flexible wrap-around dew shield · Flexible plastic with a black textile velvet finish inside · Hook-and-loop
    Heater width
    Not published by the maker.
    Power draw
    Not published by the maker.
    Controller support
    Not published by the maker.
    Cable
    Not published by the maker.
    Connector
    Not published by the maker.
    Amazon reference
    B00X5KH8SE (same reference on 6 Amazon marketplaces)
    EAN
    4049467457848
    • Covers the 8 in class, which is where dew is most expensive to fix
    • Velvet finish inside against both dew and reflections
    • Neither the height nor the length is published

    Best for: An 8 in Schmidt-Cassegrain or a 200 mm reflector on an autumn evening

    ≈ £88 / €96
    Check price on Amazon
  • Astromania flexible dew shield wrapped on a telescope tube

    Astromania Flexible dew shield 148–167 mm (FDS580)

    A flexible black ABS dew shield with a velvet lining and a foam contact strip, for tube outside diameters of 148 to 167 mm.

    Tube fit
    148 to 167 mm, as the maker publishes them
    Outside diameter
    Not published by the maker.
    Shield length
    200 mm, as the maker publishes it · 580 mm, as the maker publishes it
    Construction
    Flexible wrap-around dew shield · Black ABS, lined with a black velvet-like fabric · Non-slip foam rubber against the tube · Hook-and-loop, adjustable within the range
    Heater width
    Not published by the maker.
    Power draw
    Not published by the maker.
    Controller support
    Not published by the maker.
    Cable
    Not published by the maker.
    Connector
    Not published by the maker.
    Amazon reference
    B01LZPCQBV (same reference on 6 Amazon marketplaces)
    EAN
    6970019295695
    • Four published dimensions where most dew shields give one vague size
    • A velvet lining does two jobs: it absorbs moisture and it kills stray light
    • The diameter to measure is the tube outside, not the aperture — an easy mistake

    Best for: A 150 mm reflector or a Schmidt-Cassegrain whose front diameter has been measured

    ≈ $36 / £44
    Check price on Amazon
  • Bresser dew shield fitted to an MCX102 telescope

    Bresser Dew shield for MCX102 (4930700)

    A rigid dew shield sized for the Bresser MCX102, preventing the front lens fogging and cutting stray light.

    Tube fit
    Bresser MCX102 GoTo, named by the maker
    Outside diameter
    Not published by the maker.
    Shield length
    Not published by the maker.
    Construction
    Rigid dew shield · Not stated
    Heater width
    Not published by the maker.
    Power draw
    Not published by the maker.
    Controller support
    Not published by the maker.
    Cable
    Not published by the maker.
    Connector
    Not published by the maker.
    Amazon reference
    B07V43Y912 (same reference on 5 Amazon marketplaces)
    EAN
    4007922058627
    • Made for one named telescope, so no measuring is required
    • The maker names all three benefits, including the protective one
    • No dimensions, no material and no weight

    Best for: An MCX102 owner who wants the part made for it rather than a wrap

    ≈ £29 / €29
    Check price on Amazon

The rest of this rack

  • Sky-Watcher Star Adventurer ball head adapter in green

    Sky-Watcher Star Adventurer ball head adapter (S20550)

    A green ball head adapter for the Star Adventurer, listed with two different post lengths both labelled 3/8 inch.

    Profile
    Not published by the maker.
    Length
    Not published by the maker.
    Hole spacing
    Not published by the maker.
    Slots
    Not published by the maker.
    Material
    Neither is published
    Thickness
    The listing gives “0.95 cm (3/8 in)” in one bullet and “1.9 cm (3/8 in)” in another; both are reproduced
    Safety stops
    Not published by the maker.
    Accessory holes
    Attaches a ball head to the Star Adventurer
    Amazon reference
    B00YWPCNJU (same reference on 6 Amazon marketplaces)
    EAN
    0050234205504
    • The part that makes a photographic ball head usable on a tracker
    • Made by the manufacturer of the mount
    • Two different post lengths are given for the same fitting

    Best for: Putting a photographic ball head on a Star Adventurer

    ≈ $18 / £22
    Check price on Amazon
  • Wisyurt 48 mm dovetail plate for a finder base

    Wisyurt 48 mm dovetail plate

    A short 48 mm metal dovetail plate for extending a telescope finder base to carry a smartphone mount or another accessory.

    Profile
    Not named
    Length
    48 mm (1.89 in), from the product name · Two bullets
    Hole spacing
    Not specified
    Slots
    Not published by the maker.
    Material
    Metal, not further specified
    Thickness
    Not published by the maker.
    Safety stops
    Not published by the maker.
    Accessory holes
    Extends the finder base to carry another accessory
    Amazon reference
    B0G6LHJQP6 (same reference on 5 Amazon marketplaces)
    EAN
    4894962836304
    • Very small and light, so it adds little to the top of a tube
    • Extends an existing base rather than requiring a new one
    • Neither the profile nor the hole pattern is specified

    Best for: Adding a second small accessory where a finder shoe already exists

    ≈ €9
    Check price on Amazon
  • Absolute Eclipse Stranded design eclipse glasses, six-pack

    Absolute Eclipse Stranded 6-pack (AE-STRANDED-P6)

    A six-pack of eclipse glasses with a 50 mm frame, an individually verifiable scratch-off QR code, and a named notified body and test laboratory in the listing.

    Cited standard
    ISO 12312-2, with CE PPE category II, as the listing states
    Maker identification
    MTIC InterCert, number 0068, as the listing states · ICS Laboratories, cited for UV transmission below the detection limit · A scratch-off QR code with a unique serial on each pair; the maker states its system detects repeat scans · European manufacturer, recognised by the American Astronomical Society as an accredited maker, per the listing
    Film construction
    Not published by the maker.
    Frame type
    50 mm — the maker states this is 43 % more than a 35 mm standard frame
    Fit
    Not published by the maker.
    Supplied quantity
    Six pairs
    Inspection guidance
    Not published by the maker.
    Amazon reference
    B0FSLRD4NT (same reference on 6 Amazon marketplaces)
    EAN
    5060574198041
    • Names a notified body with its number, which is the most checkable claim on this shelf
    • Individual serial numbers allow a specific pair to be verified rather than a batch
    • The most expensive pack in this family

    Best for: A buyer who wants to check the chain of claims rather than take a marking on trust

    ≈ £20 / €20
    Check price on Amazon

All dew control