Baader Astro T-2 System™ Component Chart
For over 30 years we have focused on the Astro T-2 thread system (M 42 x 0.75 mm); virtually every telescope manufacturer must offer this thread far ahead of the focal point of his instrument, such a universal T-ring (for DSLR cameras) can be connected.
The only exceptions are (still) Russian equipment, there the thread diameter is the same, but the pitch is still 1mm per revolution - rather than 0.75mm! Therefore, we offer among other things a "Russians adapter". At only 7mm additional optical length it can allow so many Russian lenses or telescopes to be compatible with an international Astro T-2 (M 42 x 0.75mm) connector!
For the sake of better recognition mostly are marked. See marking small 'a' or small 'i' in the respective indication! "a"; identifies an external thread (male); or, if Ø sign which a diameter, "i"; - a female is always (female) or - Ø character - an inner diameter.
The Optical Length
A small selection from the variety of products from the Baader Astro T-2 System™
The optical length describes the extension of the optical path caused by an adapter or accessory when inserted into the beam path of the telescope. The values listed in the system table rounded to 1/2 mm. For pure threaded adapters or tubes such as the T-2 ring (#25), the optical length arises directly from its geometric shape. Because the optical design lengths apply to the assembled, external threads are not included in the bill. This explains the extremely short optical length external thread adapters compared to female threaded adaptors.
Parts that contain optical elements (such as Zenit prisms and binocular) the optical length can vary strongly from the geometrical form of the housing. Hence the values for the optical length by such accessories was determined directly on the telescope. When used with the unique Alan Gee tele-compressor the optical length depends in addition to the distance from the primary focus.
In general: If you add an accessory an item from the Astro T-2 System ™ into the beam path of the telescope, the extension length of the focuser to the value of the specified optical length must be shortened so that the eyepiece tubes moves closer to the lens. For negative values, the focuser must be extended because the distance between the focal plane of the lens increases.
The Baader Astro T-2 System™ Overview
| T-2 Component # |
LABEL (i)=internal THREAD, (a)=external THREAD | Opt. length (mm) | Connection: objective | connection: eyepiece | auxiliary thread or diameter |
|---|---|---|---|---|---|
| # 1A | Baader T-2 Maxbright Mirror Diagonal (T-2 part #01A) (#2456100, € 190,09) | 43 | T-2(i) | T-2(a) | M34(i) out #3 |
| # 1B | 38.5 | T-2(i) | T-2(a) | M34(i) out #3 | |
| # 1C | Baader Prism Diagonal T-2/90° 32mm (#2456005, € 92,60) | 35 | T-2(i) | T-2(a) | M34(i) out #3 |
| # 2 | 47.5 | T-2(i) | T-2(a) | M34(i) out #3 | |
| # 3 | 0.5 | M36.4 x 1(a) | T-2(a) | M34(i) | |
| # 4A | Glasspathcorrector 1:1,25 for Baader-Binoviewer with T-2 thread (MaxBright® II and MaxBright®) (#2456314, € 89,68) (incl. Teflon-centering) | ≤ -30 | ----- | M34(a)/T-2 clamp Ø 38mm | ----- |
| # 4B | Glasspathcorrector 1:1,70 for Baader-Binoviewer with T-2 thread (MaxBright II® and MaxBright®) (#2456316, € 93,58) (incl. Teflon-centering) | -65 | ----- | M34(a)/T-2 clamp Ø 38mm | ----- |
| # 4c | Glasspathcorrector 1:2,60 for Baader-Binoviewer with Zeiss ring dovetail (MaxBright® II and Mark V) (#2456317, € 96,50) (incl. Teflon-centering) | -120 | ----- | M34(a)/T-2 Kclamp Ø 38mm | ----- |
| # 5 | Baader 1¼" - 31.8mm nosepiece extension with 1¼" filter thread on both sides (T-2 part #05) (#1905130, € 14,13) | 18.5 | M28(i) | M28(a) | Ø 26mm(i) |
| # 6 | 11 | T-2(i) | Ring-clamp | ----- | |
| # 6A | Baader Heavy Duty T-2 QuickChanger (T-2 part #06A) (#2456313A, € 63,36) | 11 | T-2(i) | Ring-clamp | ----- |
| # 7 | Baader (TCR) Hardened Steel T-2 ChangeRing (T-2 part #07) (#2456320, € 38,01) | 4 | Ring-clamp | T-2(a) | Ø 38mm |
| # 6+7 | Baader Complete T-2 Changer System (T-2 parts #06 & #07) (#2456321, € 62,38) | 15 | T-2(i) | T-2(a) | Ring-clamp |
| # 6A+7 | Baader TQC/TCR Heavy duty T-2 Quick Changing System (T-2 part #06A & #07) (#2456322, € 93,58) | 15 | T-2(i) | T-2(a) | Ring-clamp |
| # 8 | 32-38 | T-2(i) | Ø 1¼"(i) | T-2(a) | |
| # 8A | Baader Focusing Eyepiece Holder 1¼" / T-2 (T-2 part #08A) (#2458125, € 37,04) | 29-34 | T-2(i) | Ø 1¼"(i) | ----- |
| # 9 | 14 | T-2(i) | M44 x 1(i) | Ø 40mm | |
| # 10 | Baader Reducer 1¼" / 24,5mmwith filter holder (T-2 part #10) (#2408191, € 26,32) | 6.5 | Ø 1¼"(a) | Ø 24,5mm(i) | M28,5(i) |
| # 11 | Baader Eyepiece 1¼"/36.4mm (T-2 part #11) (#2408195, € 40,94) | 27 | M36.4 x 1(a) | Ø 1¼"(i) | ----- |
| # 12 | Baader M43a x 0.75 / T-2a Adapter (e.g. for Takahashi) (#2458199, € 24,37) | 0,8 (!) | M43(a) | T-2(a) | M34(i) for #4a,b,c |
| # 13 | Baader ZEISS Camera adapter M44/T-2 (#1508005, € 35,09) | 5 | M44 x 1(i) | T-2(a) | Ø 38mm |
| # 14 | Baader Nose piece 1¼" / T-2 (T-2 part #14) (#2458105, € 23,40) | 0,5 | Ø 1¼"(a) | T-2(a) | M34(i) / M28,5(i) |
| # 15 | Baader Reducer 2"/ 1 ¼" (T-2 part #15) (#2408190, € 37,04) | 9 | Ø 2"(a) | Ø 1¼"(i) | M48(i) / T-2(a/i) / M34(i) |
| # 15A | Baader Pushfix Reducer 2" to 1¼" (T-2 part #15a) (#2408151, € 38,01) | 1 | Ø 2"(a) | Ø 1¼"(i) | M48(i) / T-2(i) |
| # 15B | Baader 2" to 1¼" ClickLock Reducer (T-2 part #15B) (#2956214, € 67,26) | 9,5 | Ø 2"(a) | Ø 1¼"(i) | M48(i) / T-2(i) |
| # 16 | Baader 2" nosepiece to T-2 / M48 (T-2 part #16) (#2408150, € 35,09) | 2 | Ø 2"(a) | T-2(a) | M48(i/a) / T-2(i) |
| # 17 | 2" SC Deluxe eyepiece (#2408140, € 49,-) | 53 | UNC 2"(i) | Ø 2"(i) / S65 | M58(i) |
| # 17A+B | 2" SC Deluxe eyepiece with 2" filter holder (for SC & HD) (#2958144, € 65,-) | 53 | UNC 2"(i) | Ø 2"(i) / S65 | 2" Filter Thread / M58 |
| # 18 | Baader 3.3" Celestron Nut (T-2 part #18) (#2408145, € 56,54) | 0 | UNC 3.3"(i) | ----- | ----- |
| # 19 | Baader 2" Nosepiece with 2" filter thread (#2408155, € 34,12) | 0 | Ø 2"(a) | UNC 2"(a) | M48(i) |
| # 20 | Alan Gee Telecompressor Mark II (T-2 part #20) (#2454400, € 238,82) | ≈≤ 50 | T-2 clamp | T-2 clamp | ----- |
| # 21 | Baader T Adapter (BTA) for SC and MAK Telescopes (T-2 part #21) (#2408160, € 54,59) | 16 | UNC 2"(i) | T-2(a) | T-2(i) |
| # 21 B | Baader SC / HD Ultra Short T-Adaptor, 7mm optical length (#2958500B, € 43,87) | 7 | UNC 2"(i) | T-2(a) | T-2(i) |
| # 22 | Baader M43a x 1 / T-2a Adapter (e.g. for Vixen) (#1508037, € 28,27) | 2,5 | M43 x 1(a) | T-2(a) | Ø 38mm |
| # 23 | Baader M42x1 (female) / T-2 (M42x0.75 male) SLR Camera Adapter (#1508015, € 27,29) | 7 | M42 x 1(i) | T-2(a) | Ø 38mm |
| # 24 | Baader Variable Locking / Sliding T-2 Focuser (T-2 part #24) (#2458010, € 34,12) | 27.5+11,0 | T-2(i) | T-2(a) | Ø 1¼"(i) |
| # 25A | Baader T-2 / 15 mm Extension Tube (T-2 part #25A) (#1508154, € 17,55) | 15 | T-2(i) | T-2(a) | Ø 38mm |
| # 25B | Baader T-2 / 40 mm Extension Tube (T-2 part #25B) (#1508153, € 19,50) | 40 | T-2(i) | T-2(a) | Ø 38mm |
| # 25C | Baader T-2 / 7.5 mm Extension Tube (T-2 part #25C) (#1508155, € 16,58) | 7.5 | T-2(i) | T-2(a) | Ø 38mm |
| # 25V | Baader VariLock 46, lockable T-2 ExtensionTube 29-46mm with spanner tool (T-2 part #25V) (#2956946, € 63,36) | min. 29 / max. 46 | T-2(i) | T-2(a) | T-Adapter |
| # 25Y | Baader VariLock 29, lockable T-2 ExtensionTube 20-29mm with spanner tool (T-2 part #25Y) (#2956929, € 57,51) | min. 20/ max. 29 | T-2(i) | T-2(a) | T-Adapter |
| # 26 | Baader T-2/T-2 Inverter Ring (#1508025, € 27,29) | 0 | T-2(a) | T-2(a) | Ø 38mm |
| # 27 | Baader Adapter 2" (male) / T-2 (male) (#1508035, € 34,12) | 0.5 | UNC 2"(a) | T-2(a) | M48(i) |
| # 28 | Baader Expansion Ring 2"a/T-2i with 1mm optical path length (T-2 part #28) (#2958242, € 22,42) | 1 | T-2(i) | Ø 2"(a) | ----- |
| # 29 | Baader Expanding Ring T-2f / M48m (T-2 part #29) (#2458110, € 19,50) | 2.5 | T-2(i) | M48(a) | ----- |
| # 30 | Stop Ring 1¼" (T-2 part #30) (#1905131, € 24,37) | ≤ 10 | Ø 1¼"(i) | Ø 1¼"(i) | ----- |
| # 31 | Baader Double T-Filterholder 1¼" (#1508030, € 28,27) | 0 | T-2(a) | T-2(a) | M28.5(i) |
| # 32 | Baader Ultrashort 2" eyepiece clamp (#2458196, € 67,26) | 17 | M68 x 1 | Ø 2"(i) | M68 x 1 |
| # 33 | Baader Variable locking T-2 extension (12-16mm) incl. lock ring (T-2 part #33) (#2958130, € 38,01) | 12 (10) | T-2(a/i) | T-2(a/i) | ----- |
| # 34 | Baader T-2 Conversion Ring (#2958110, € 18,53) | 10 | T-2(i) | T-2(i) | ----- |
| # 35 | Baader T-2 Lock ring 2mm optical path length (T-2 part #35) (#2958120, € 13,64) | 2 | T-2(i) | T-2(i) | ----- |
