You can find T-2 extension tubes (with variable and fixed length) at http://www.baader-planetarium.com/en/accessories/adapters-imaging-accessories/astro-t2-system.html?filter_adapters_type=237&limit=36
But you need the ClickLock 1,25" clamp to use it with your 1,25" eyepieces, please see this graphic
I need to source a Barlow that is short so I can achieve in-focus with a DSLR. thanks.
It has a female T-2 thread inside that would thread directly onto your T-2 thread on your eyepiece clamp.
The question is if you have the 25 mm of additional backfocus which would be required. If yes, then the ClickLock will hold the camera with absolute rigidity.
The real question remains though. Please excuse but we question if the drawtube (the moving tube) of your focuser can be adjusted to be stiff enough to "wiggle" inside the holding tube.
The Q-Barlow is a classic doublet-lens design. Optically it works absolutely on par with other doublet barlow-lens designs - but it offers that extra tack of magnification (2.25x instead of 2x - just like the Zoom Barlow) so that eyepiece focal lengths are not just cut in half to repeat itself.
With a 2x barlow you produce a 5 mm effective focal length out of a 10 mm eyepiece - or receive a 6 mm eyepiece from a 12mm eyepiece. But it is very likely that exactly those focal lengths the eyepiece manufacturer is offering already. So - in the case of the Q-barolw, the purpose of the 2.25x is to convert a 10 mm eyepiece into a 4.5 mm or a 20 mm eyepiece into an 8.9
given with the spectiv. As the result you no more reach the focus. Anyway eye pieces with less than 6mm focal length are not
suitable under real condition. The image gets too dark and the exit pupil too small.
Manufacturer Baader Planetarium SKU (#) 2956180 Weight (kg) 0.12 Inner Connection (lens sided) Thread, M28,5 Outer Connection (lens sided) Barrel, 1¼" Inner Connection (eyepiece/-camera-sided) Thread, M28,5 Outer Connection (eyepiece/-camera-sided) Thread, M28,5, T-2 (M42 x 0,75) Magnification (x) 2,25 AR-Coating Phantom Coating® Group Usage Aus dem normalen Brennweitenbereich von 8 - 24 mm des ClickStop Zooms ergibt sich durch Adaption der Barlowlinse ein Brennweitenbereich von 3,5 bis 10,5 mm Barrel Size (in) 1¼" Optical Design Barlow
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