I've posted previously to ATM on my LSC - here updated.
Today I made [out of a pizza box!] an 'aperture mask' for my piggybacked Meade 11cm f/4 quasi-Newtonian [with a spherical mirror] and converted it into a LSC. I reused the ali strut from an earlier incarnation @ http://home.freeuk.c...gavin/lscmg.htm and await the next clear night to test. I use the new SX Lodestar-Cx2 OSC camera in brief exposure in near-live display to laptop.
The pics below show the set-up plus schematic of the LSC. The fixing of the aperture mask to the strut is slotted and can be rotated around this axis to provide precise alignment of the 'hole' to the optical axis.
I have in the past tested various 'aperture masks' from 70mm to 90mm diameter - in theory the smaller the aperture the sharper the images in minimising spherical aberration eg the primary optical defect. But this makes a 'slow' system when the central obstruction is taken into account - hence my preferred 90mm aperture and nominal f/ratio of f/5.