Highlights

Lockable T-2 extension tube, adjustable 20-29 mm with clamping
Telescope-side connection dimension: T-2 (M42 x 0.75), Eyepiece connection dimension: Optional T-2 (M42 x 0.75) or T-2 Ring Schwalbe 52 x 6.5mm optical length: 20-29 mm continuously adjustable over millimeter scale
Outer diameter: 50.8mm / 2 "inside diameter: with eyepiece side T-2 thread insert = 38mm with 52mm dovetail eyepiece sided = 42mm

Both Baader VariLock T-2 (M42x0.75mm) extensions are stepplessly adjustable extension rings, with the added ability to firmly readjust the camera rotation position. By loosening or tightening a locking ring, the inner extension sleeve can be adjusted to the desired length by means of a millimeter scale. A clamping key (hook wrench) for the locking ring is included. Both VariLocks 29 and 46 are the result of an otherwise fruitless search for adjustable extension rings that are absolutely torsion-resistant, because almost all so-called "helical fokusers" are not torsionally stiff.

As further application, the ring with the rotatable T-2 outer thread can be removed by loosening 6 headless set-screws (hexagonal wrench included) and replaced by a separately enclosed adapter with ringed-dovetail (ring-groove), whose 52 mm diameter dovetail can be inserted directly into all Baader T-rings for EOS, Protective for Canon, as well as NEX bayonet cameras – likewise into all other manufacturers standard T-rings with the appropriate 52 mm inner diameter to accommodate a rotating ring. This increases the VariLock clear inner diameter because the common bottleneck at the height of the T-2 thread is getting eliminated. By necessity, the maximum inner diameter of all T-2 adapters is 38mm as standard. On the other hand, the clear inner diameter at this point increases up to 42 mm if one uses the enclosed direct S52 adapter instead.

VariLocks are ideal tools for permanently setting exact focal distances, e.g. for H-alpha solar filters or field correctors/reducers with critical focal position.

Functionality of the VariLock

Both VariLocks consist of several parts:/p>

an engraved outer housing with six headless set screws and an M48 female thread.
a knurled M48 locking ring with an oblong hole for engaging the clamping key(6)
one rotating and removable ring with T-2 outer thread (pre-assembled in 1)
one separately enclosed T-ring-adapter with S52 ring groove, suitable for all Baader (and many others) bayonet T-rings and Baader Wide-rings
one clamping key (hook wrench) to lock down the knurled ring (3)
A hook wrench to loosen or secure the locking ring
one hexagonal wrench (size 1.3 mm) for interchanging the adapters (4/5)

Both VariLocks are delivered with a pre-installed T-2 adapter(4), so that in the basic configuration a T-2 male/female thread is available on both sides. At the narrowest point (which is the T-2 adapter), the VariLock then has a clear inner diameter of 38 mm. In order to equip the VariLock housing (1/2) with a larger clear inner diameter of 42 mm, use the S52 T-ring adapter(5) instead.To change the adapters, loosen the six hexhead screws with the enclosed hex wrench(7) and replace the T-2 male adapter(4) with the adapter(5) featuring a S52 ring groove.

To adjust the housing length, hold the outer housing (1) and loosen the M48 tube(2) by unthreading the knurled locking ring(3) from part 1 by using the hook wrench(6). The oblong hole in the knurled locking ring serves as an attachment point for the hook of the clamping key, so that the locking ring can be loosened and tightened again. When the locking ring (3) is loosened, the part (2) is turned within part (1) until the desired length is reached. The millimeter scale on part 2 serves as a guide to the set length. The effectively set total length of part 1 and 2 can be read off on the visible side of the locking ring. For precise control, it is recommended to measure the set length with a caliper gauge and to readjust it by loosening the locking ring again, if necessary.

The set length of the VariLock can be read off from the visible side of the locking ring. As soon as the desired length has been reached, tighten the locking ring again until it is completely tight.

To set the Varilock to e.g. 26.5mm, turn the knurled locking ring(3) until the millimeter scale on part 2 shows the value 26.5mm and hold it with one finger. Now turn the M48 tube(2) together with the locking ring into part 1 until the locking ring is completely in contact with part 1. Only then is the locking ring tightened to final strength with the aid of the hook wrench(6).

The following figure B shows the VariLock 29 with T-2 male thread, set to 26.5 mm overall length.

Specifications

Manufacturer	Baader Planetarium
SKU (#)	2956929
EAN Code	4047825022417
Net weight (kg)	0.07
Optical length (mm)	20 – 29
T-2 Part #	25V
Usage	to set precise focus distance
Screw Type	6x M1,3 Allen wrench screws
Inner Diameter / Clear Aperture (mm)	mit okularseitigem T-2 Gewindeeinsatz = 38mm mit okularseitiger 52mm Ringschwalbe = 41mm
Outer Diameter	50,8 (2")
Outer Connection (eyepiece/-camera-sided)	M42 x 0.75 (T-2)
Inner Connection (lens sided)	M42 x 0.75 (T-2)
Compatible Brands	Astro T-2, Baader Planetarium
Type of Adapter	Extension, Variable Focusing