Telescope thumb screws for diagonals, adapters and focusers screw size
M3 · 7 to 8 mm long
Telescope thumb screws for diagonals, adapters and focusers takes M3 metric screws in lengths from 7 to 8 mm.
Where it is used: 'TS Optics M3 thumb screw 7mm ... Suitable for many diagonal mirrors, adaptors and focusers'.
Head and drive, as the source states them: thumb screw (knurled) head.
This entry is marked confirmed and comes from omegon.eu.
M3 means a 3 mm nominal diameter with a 0.5 mm thread pitch. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3.
Telescope thumb screws for diagonals, adapters and focusers screw specifications
One row per fitment record. Head, drive are shown only where the source states them; pitch is the ISO coarse pitch for the thread.
| Thread | Length | Pitch | Head | Drive | Where it goes | Status |
|---|---|---|---|---|---|---|
| M3 | 7–8 mm | 0.5 mm | Thumb screw (knurled) | not stated | 'TS Optics M3 thumb screw 7mm ... Suitable for many diagonal mirrors, adaptors and focusers' | Confirmed |
Fitment records and sources
'TS Optics M3 thumb screw 7mm ... Suitable for many diagonal mirrors, adaptors and focusers'
pitch 0.5 mm · tap 2.5 mm · clearance 3.4 mm · PH1 / Torx T10
How to check the screw before you buy
- Do not confuse metric mounting screws with the 1/4-20 or 3/8-16 tripod threads that cameras and clamps also carry.
- Diameter: across the threads an M3 screw measures about 3 mm with calipers (usually a hair under). If yours measures noticeably more or less, it is a different thread.
- Pitch: 0.5 mm from one thread crest to the next (20 crests per centimetre). A thread pitch gauge or the pitch-gauge tool settles it in seconds.
- Length: for thumb screw (knurled) screws, measure from under the head to the tip (countersunk heads are the exception: they are measured overall).
- The records span 7–8 mm, which means different positions take different lengths — match each hole to its own screw.
- Driver: the source does not name the drive. Standard M3 heads take PH1 for Phillips and T10 for Torx, and a 2.5 mm hex key for socket heads; a bit that fits loosely will cam out and strip the head.
- Tightening: no device-specific torque is published in these records. The site's general figure for M3 is about 80-130 N·cm into metal threads and 35-60 N·cm into plastic bosses; snug it up and stop.
Common mix-ups with M3
- Telescope thumbscrews are sold in a wide non-metric legacy range too (1/4-20, 8-32, 10-32 on many Meade/Celestron mounts), so metric M3/M4 fitment applies mainly to newer/international accessory ecosystems (SkyWatcher, generic 1.25" accessories) and should not be assumed universal.
- GoPro's own official Dive Housing user guide does not itself state a metric screw size for the housing body; only third-party accessory manufacturer (INON) manuals explicitly cite M6 screws for their add-on arms/adapters attaching to the housing.
Buy these screws at TechSpare Warehouse
In stock and shipped from South Carolina. Our black screws are Phillips wafer head (low profile); match the head style and length to the original before you order.
-
M3 x 8mm Screws for Leather Spike Attachments Guitar Straps 10-Pack
$4.99 -
M3 x 8mm Phillips Wafer Head Screw for SLA Resin 3D Printer VAT Film - Single Replacement Black
$0.10 each · min. 50
-
M3 x 8mm Phillips Flat Head Countersunk Machine Screws Zinc Silver 100-Pack for RC & 3D Printers
$9.99 -
M3 x 8mm Phillips Flat Head Countersunk Machine Screws Zinc Silver 10-Pack for RC & 3D Printers
$4.99
More in Cameras & Optics
1.25" eyepiece/diagonal/SCT visual back thumb screwAimpoint Comp M4 / M4s LRP & TNP mountAimpoint Micro T-1/T-2/H-1/H-2 standard mountAimpoint Micro T-1/T-2/H-1/H-2 standard mount screwAimpoint SM-2001/2007 Micro T1/T2 mountAirsoft red dot sight mounting screw set (Laylax/Quintes Sence)Airsoft/firearm red-dot sight optic mounting screws (Vortex Viper, Swampfox patterns)Alpine and touring ski bindings (Binding Freedom inserts)Arca-style quick-release plateARRI plate for Sony VENICE 1/2Artesky 340mm Vixen Dovetail BarAstromania finder scope dovetail base
Browse all 278 in Cameras & Optics →The same screw also fits
Devices whose records share a thread with Telescope thumb screws for diagonals, adapters and focusers, closest length match first.
- Wimberley AP-640 replacement lens foot also M3 × 7–8 mm
- Olympus BH-2 microscope frame also M3 × 7–8 mm
- Microscope objective turret and stage also M3 × 7–8 mm
- OpenFlexure Microscope AMS translation stage also M3 × 8 mm
- Airsoft/firearm red-dot sight optic mounting screws (Vortex Viper, Swampfox patterns) also M3 × 8 mm
- Vivotek IT9389-H / IT9389-HT dome camera also M3 × 8 mm
- Glock MOS cover plate screw also M3 × 8 mm
- Refrigerator light cover and shelf clips also M3 × 7–8 mm
Questions about Telescope thumb screws for diagonals, adapters and focusers screws
- What size screw does Telescope thumb screws for diagonals, adapters and focusers use?
- M3 × 7–8 mm for 'TS Optics M3 thumb screw 7mm ... Suitable for many diagonal mirrors, adaptors and focusers'.
- How long are the screws in Telescope thumb screws for diagonals, adapters and focusers?
- The records range from 7 to 8 mm depending on the position, so match each screw to its own hole.
- What is the thread pitch of an M3 screw?
- 0.5 mm (coarse), which is the standard pitch for M3 machine screws; a 0.35 mm fine pitch exists but is uncommon. The tap drill is 2.5 mm and the normal clearance hole is 3.4 mm.
- What screwdriver do I need for Telescope thumb screws for diagonals, adapters and focusers?
- The sources do not name the drive. For M3, Phillips heads normally take PH1 and Torx heads T10; socket heads take a 2.5 mm hex key.
- Can I use an imperial screw instead of M3?
- No. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3. Use a true M3 screw so it does not cross-thread or strip the hole.
- Where can I buy replacement screws for Telescope thumb screws for diagonals, adapters and focusers?
- TechSpareWarehouse (our own store) lists M3 x 8mm, which matches the length in the records above.