Neo, thank you for your explanation, however, I am still puzzled where to put the LED. Let me clarify: I am constructing according to the Stellafane Instructions. I guess that is a slitless tester. Anyway, the LED shuld positioned on the side of the face where I will place my eye, I guess at the bottom of (behind) the framed razor blade and facing through the opening, past the blade towards the mirror stand. My question is - should the LED be physically connected with the plastic frame, being connected with the razor in a way that half of the LED front surface is facing past the razor blade and the other half right behind the razor, or should the LED be positioned just a bit behind the frame holding the razor, not connected with the frame, so that the frame can be moved along the rails from right to left while the LED is sitting in a fixed position behind? I have failed to find any thorough instruction about where exactly to place the LED. So, again I ask for your help, thx in advance.
22" f/3.61 David Lukehurst Ultra-Portable Dobsonian, mirror set by John Nichol
Nagler 26 mm, Ethos 13 mm, Ethos 8 mm, Nagler 3.5 mm
TV Paracorr
Lumicon 2" UHC, Lumicon 1.25" H-Beta, Orion 2" ND 13% transm.
Unihedron - SQM-L
Canon EOS 350d