It may appear, at first glance, that the Baader Planetarium Universal Filter Changer (UFC) is for use with larger 2″/50mm sized filters. Not so! You can use popular, and more often used smaller 1.25″, 31mm unmounted or 36mm unmounted filters too. So how can the filter slider drawer made for use with larger sized filters be used with smaller filters? Simple – with a step-down adaptor. Baader call these step-down adaptors AUX Filter Holders.
Apart from the UFC base, and the associated telescope- and camera-side adaptors for your telescope/camera combination, you will need Baader’s D50.4mm unmounted filter slider (#2459113). It is to this particular filter slider that any of the AUX step-down adaptors attach to.
Baader UFC D 50.4 Filter Slider
Baader offer three AUX step-down filter holder adaptors for use with the D50.4mm slider:
- For 1.25″ mounted filters (#2459153): This adaptor is (female) threaded to accept the standard 28.5mm filter cell threads.
1.25″ UFC Aux Filter Holder (left) and inserted into the D50.4 Slider.
- For 31mm round unmounted filters (#2459151): This adaptor comes with three Allen-key socket screws and washers to securely clamp a 31mm unmounted filter in the AUX filter adaptor holder.
- For 36mm round unmounted filters (#2459152): As with the above AUX filter holder, this adaptor comes with three Allen-key socket screws and washers to securely clamp a 36mm unmounted filter in the AUX filter adaptor holder.
31mm/36mm Unmounted UFC Aux Filter Holder and inserted into the D50.4mm Slider
The 31mm and 36mm unmounted AUX holder have a small narrow “shoulder” on the inside of the unit to support of the filter once the filter is in place (otherwise the filter would drop or fall straight through the holder!).
The AUX filter holder is simply inserted into the UFC filter slider’s circular opening and then it is secured in place using the three Allen key hex-screws that come with the filter slider. As with the 31/36mm AUX filter holder, the D50.4mm slider also features a small “shoulder” in the “base” of the filter opening to support the AUX holder in place (as well as to support 50.4mm unmounted filters when the AUX holder is not used).
The 1.25″/31mm/36mm filters can be inserted, removed or exchanged with the AUX holder either in place or with it removed from the UFC filter slider – its personal preference.
So now that you know that Baader’s UFC system can easily be adapted to use smaller sized filters – these AUX filter holders, and the rest of the UFC system, are available and can be purchased from your local/favourite astronomy retailer, a list of which can be found here.
