http://www.baader-planetarium.com/en/accessories/adapters-imaging-accessories/astro-t2-system/baader-2%22--t-2-nose-piece-and-camera-adapter-%28same-as-used-by-sbig%29-%28t-2-part-16%29.html wich has a 48mm filter thread
Your website about your Baader T-ring tells, quote: “Represents the standard exact distance of 55.0mm from the front support surface of the T-ring to the image plane of the camera body forth”
Now, this 55,0mm is longer than the 45,46mm registerdistance from Pentax.
Does the ring still work and let focus?
If you use a PENTAX T-2- T-ring-adapter (for instance our item # 2408302), you gain the exact additional distance to produce the required distance of 55mm with your PENTAX camera body.
55 mm is a well established industry standard for DSLR-T-2 rings (dating back to the days of SLR-emulsion films). Accordingly the T-2-rings matching different DSLR-cameras have got different heights. This is to provide a standard lens distance for any DSLR camera body, so that also third party lenses (Tamron, Soligor a.o.) can be used on any DSLR camera.
This is the reason why the MPCC had been designed for the 55 mm focus distance.
Today the standard has "softened" somehow with the advent of mirrorless 4/3 cameras and many other imaging tools that continue to replace DSLR-cameras these days. It is the reason why we have been designing a multitude of other variable length adapters like the "Vari-Lock-system". Also many modern telescopes do require larger light cone throughput than the T-2 standard can supply. For this reason the latest design of the MPCC even can unthread the T-2 male thread and be attached with the outer M48 thread supplied at the camera-end of the MPCC. However, finding the right parts for producing the correct sensor-distance is somewhat trickier than using the well established T-2 standard.
Manufacturer Baader Planetarium SKU (#) 2408302 EAN Code 4047825012586 Weight (kg) 0.038 Optical length (mm) 9,5 Usage to connect (D)SLR cameras to the Astro T-2 thread system Camera Adaptable Pentax K Inner Diameter / Clear Aperture (mm) 41 Outer Diameter 59 Inner Connection (lens sided) Thread, T-2 (M42 x 0,75) Outer Connection (eyepiece/-camera-sided) Bayonet Compatible Brands Astro T-2, Baader Planetarium, Pentax Type of Adapter Camera Adapter