The X1 has an adaptor mounting concealed under a knurled ring around the lens assembly.
So far Leica have not issued anything that fits it. For KAP, unless I am forced to fly in poor light, I always use a polarising filter to reduce the all too common glare from ground object reflectance. Glare ( sometimes called flare) from all manner of things is a common problem for an airborne camera, particularly as I rely on auto exposure control. Adjusting the EV value (between -2/3rds and -1 has been recommended) to ‘cool’ the whites helps a bit but I have found the half and half exposures of land and sky problematic. A PL filter really seems to help as it darkens the sky without under-exposing the ground in most cases. Although it tends to slow shutter speeds down, results show it’s worth a few lost exposures. With the right fitting it should be possible to fit a polarising filter or even a wide-angle adaptor whilst the tube itself can function as a lens hood too. The Nikon UR E8 Lens adaptor for the Coolpix 5700 and 8700 has been found to fit.
I found and ordered a UR-E8 for £1.50 from ScopesnSkies excellent ‘Astroboot’ shipped by Royal Mail in its own sweet time from just down the road in Ely.
When fitted the URE8 ‘front’ thread looks like a 52mm male but isn’t; it’s something weird like 53.5mm! There is nothing that fits it so with help from Campkins Cameras a 49mm filter was found to be a near ‘interferrence’ fit to the insde of the tube and a glassless filter was glued into the tube end. Now I have a 49mm thread on the inside of the tube which accepts a 49mm CPL filter at last!
It’s a shame to have to resort to glue but as luck would have it the sun shone as soon as the glue was dry:
..and the filter works a treat
So thanks to Martin Mann for the steer and thanks to all at Campkins Camera Centre I can look forward to getting more polarised shots!
Billboyheritagesurvey's Blog 
hi bill,
can you list out what parts/accessories needed of this tube?
I am so confused.
Thanks for your help
The tube is Nikon part URE8 nothing else will do!
The next thing you will need is a glassless 49mm UV fliter which is glued into the open end.
That’s it!
Good Luck,
Bill
hi bill,
do you know this adapter ring can be fit to the URE8 lens hood?
http://www.camerafilters.com/detail.aspx?ID=1348
thanks.
cy
The URE8 has a thread which will only take a Nikon special mounting, it is no use for ‘standard’ filter fittings at all. We found a 49mm filter would fit snugly in the opening and this was then glued in place to accept the accessories I need. The filter was an ’empty’ one so it was in effect a 49mm to 49mm ring! Once this ring is in place the reversing ring you suggest would work.
Good luck.
Bill