I'm actually quite embarrassed to post this at this time...I've been in communication with Harry Siebert concerning a custom barlow & fitting.
For the purpose of this thread it is for a low-powered barlow capable of delivering that amplification at a specific back-spacing from the rear of the unit's T-adapter...
It's actually 3 weeks since I first asked him about this possibility & much of that time has been taken up with explaining exactly what the requirements are. (I'm pernickety as well as pedantic & it's often the case that folks can get confused when their primary form of communication is via email - both of us have had to draw up sketches/plans to clarify what we are asking/saying. )
On my part this desire to clarify everything to the nth degree as well as a couple of other aspects has probably been a (if not the) major time-factor in the past 3 weeks...Harry for his part has explained that there is a lot going on at his end, but with the utmost respect I'd just like to hear if anyone knows anything here - of course I could just ask Harry - I'm an old fella & in some ways I can understand it'd be best to ask him directly, but there is also an element of reserve on my part to ask him directly.
Harry, if you read this I trust you will understand & forgive me but I'd like to be informed if anyone knows anything additional: Siebert optics was recommended to me quite a long time ago for their quality products.