What step down adapter is suggested from a 52 mm to "-- mm"?
For adapting any cell mounted Baader 2 inch Filter onto a camera lens with 52mm front filter thread you will need:
#2408166 Baader DSLR 2" Filter-Holder M48/SP54: http://www.baader-planetarium.com/en/baader-dslr-2%22-filter-holder-m48sp54.html
#2958052 Baader Lens-Adapter-Ring SP 54/ M52: http://www.baader-planetarium.com/en/baader-hyperion-dt-ring-sp54m52-for-dtadapter-iiandiii-and-hyperion-eyepieces.html
Both thread sizes come with our proprietary pitch - which is not the same for the female and male threads.
This is our own proprietary "emergency solution" for uniting a world were manufacturers all over the world copy from each other - to the point that there are almost a dozen different pitches in use for male and female threads. Traditionally US-companies used to do a UNF-based pitch and the rest of the world went for metric threads - but these do vary from 0.5 to 0.75.
For this reason it does not make sense to publish our non standard pitch because our pitch is made to cope with all existing metric and US-pitch standards - and as said - our solution has evolved from sheer necessity. It is a mixture of a queer pitch and under-/over-dimensioning . We will not want to declare this as a standard and get bashed up for it. It works for us and is a result of 20 years adaptation to fit our filters onto all crazy threads we have seen. And inspite of this - every now and then there comes another "dragonboat-eyepiece" were even our filters may not fit...
The inner clear diameter of the LPFC filter cell is 47.4 mm. A filter bottoms out against a clear opening of 46 mm diameter.
The cell has an M48 internal thread of 5.5 mm in height and a retainer ring with an M48 make thread, the mechanical height of that retainer ring is 1,6 mm.
In essence this creates room in the chamber for our 2 mm thick, round filter discs of 47.4 mm diameter and it leaves room enough to thread the next filter cell into the first one - so that filters can be combined.
Manufacturer Baader Planetarium SKU (#) 2459252 Weight (kg) 0.003 Filter size 2 inch Filter mounted Mounted (classic 8mm)