BACHES Echelle Spectrograph

You should need the 2" ClickLock M54i x 0,75 (Bresser / Omegon / Explore Scientific) #2956253
https://www.baader-planetarium.com/en/accessories/adapters-imaging-accessories/eyepiece-clamps/baader-2%22-clicklock-eyepiece-clamps.html#574=1224

We don't have a transmission diagram for this filter ourselves currently. The base of the filter is a Schott-equivalent absoption glass RG 630 (you can look up its properties in the Schott catalogue). For this reason it is assured that blocking is effective down to 300 nm.

You can find example assemblies in this PDF: https://www.baader-planetarium.com/en/downloads/dl/file/id/1612/product/4550/universal_alan_gee_ii_uag_ii.pdf

The 7.5m T-2 extension #2 mentioned on the left side of the PDF is included in the scope of delivery of the UAG, so you can screw the UAG between any binoviewer with T-2-thread like the MaxBright II or the old MaxBright and any of our T-2 star diagonals.

If you have a standard 1.25" star diagonal without T-thread, this will not work to your satisfaction, as these star diagonals do have a longer optical length and no thread for attaching the binoviewer. We recommend a T-2 prism diagonal (they have the shortest optical length) plus the BTA-adapter for Schmidt-Cassegrains # 2408160, which can be screwed onto the back of your telescope, or a 2"/T-2 nose piece #2408150, if you have a 2" eyepiece holder on the back of your telescope.

EOS-M cameras are not common in Astrophotography. We would need to produce thousands of adaptors at once in mass production to make it happen, but unfortunately there is no demand for such an adaptor, your inquiry was the first ever.

Please note - the standard base has a sine-curve shaped bottom and does fit diameters from 4" to infinity. Means - it will sit snuggly on a flat surface.

Several makers have copied the design - but did not understand the reason for the bottom shape - hence their copies wiggle, when fastened onto a flat surface.