Finally got the adjustable slits from the US but find they are not easy to integrate into the Mk1 Littrow design, however... managed to set the slit mounting blocks I have at correct gap and position. Now find I can better focus the webcam but the eyepiece for visual is just ( well not really!) being held by the locking screw.
I had the chance to set the spectro up with the ETX90 with a diffuser over the aperture ( a hankie!!) to get visual spectra of the sun. WOW it's unbelievable there must be literally hundreds and hundreds of lines visable!!!
I could even see lines between the D1/D2 sodium etc etc. Very exciting.
I'll set up the webcam to get some images, I need to accurately determine the field coverage and the resolution.
With my "new" OAG also trialing the set up to be able to get the slit into focus and guided to allow stellar exposures, ....coming soon.
In parallel building a Mk2 version using a 40mm f5 lens as collimator, 1200 lpm grating and a 50mm/ 135mm Olympus camera for both visual/ Starlight CCD. The mock up looks very promising and WILL allow the use of the new variable slit and ANY webcam/CCD.