Here is following an information from an article i copied from the internet. No name of the author. It is condensed but still precise.
Its about constructing a filter-holder to replace filters. I would rather make one holder for every filter. Info will be uploaded to panoramic camera yahoo-tech-group-files. incl. new images later. all informations about horizon filters/closeup filter are now out no need to send you copies.
Making your own Filters for Horizon Panoramic Camera
resume of an article camprice.com. by someone from HK having daughter Kelly.
I was using my Horizon 202 the other day and wanted deep red filter. But there were only ND, light green and UV.
Modifying would mean taking a knife and take the filter apart. (Old horizont had other filter-technology. Glass was attached by a spring. So easy replacing was possible.)
The new filters have four parts. I name them the Bottom(1), the Top(4), the Metal part(2) and the Filter insert(3).(He mentions images showing these-but i dont have these, only have two showing the finished product. will show them someday.)
The Bottom has four stems which penetrate the Metal Part and trap the filter Insert before ending in the Top where they are peended/melted over to secure the entire assembly.
Before starting, it is wise to gather all the supplies and tools and accessory to make the modification. Here are some suggestions:
1. a sharp bladed knife(Exacto or other, I used my Swiss Army Knife)
2. File (fingernal file will do)
3. a 2mm drill bit or other method of making a clean hole in the new filter material. I used a combination of a heated pin held in a pin vice, and a 2mm tap.
4. four x 5mm screws, depending the thickness of the filter material
5. Cokin filter
6. A Plastics cutting knife. This has a deep "V" shaped blade and is the only method short of actual sawing that I have found works on the hard acrylic of the Cokin filters.
7. Needle of Pin which you can heat and hold for making holes.
Here are the steps I followed to arrive at my finished filter. I cut the Green filter apart by slipping the knife blade gently between the Bottom and Metal part and severing the stems. The filter fell apart. I then pushed the resulting plugs(5) out of the Top and threw them away. I also threw the filter away because I couldnt think of a use for it.
I measured the width and lenght of the Top and Bottom (17mm) and used the Plastic cutting knife to core the Cokin filter. Be sure to bend the filter away from the cut you have made. It will snap smoothly. I didnt the first time and I ended up with a very ragged edge. After the first cut I had a piece of Deep Red filter material 17mm wide and more than 50mm long. I had to make another score to end up with a square of 17mm on a side. I ran the edges of the cut piece a couple of times over the flat side of the file, just to get rid of the sharp ridges. Using the holes in the corners of the Metal Part as a template, I made small pricks with a very hot needle in the center of each hole. I used the 2mm tap to enlarge these pricks but 1.5/2mm drill would do just as well. Avoid pressing too hard on the drill, or you may shatter the filter material and have to cut another piece to begin again.
I trimmed the excess "stem" material from the Bottom which my knife and used the Metal part and heated needle again as a pattern to make starter holes for the screws at each coner. A word of caution here. The black plastic of the Top and Bottom are very soft. Too much heat on the pin and you will send it right through and possibly make a hole that is too big, thereby messing up any chance of the screw holding. Its better to make your first attempt too small than to end up with a hole too big. This is the extent of the hard work. The assembly was very fast and the resulting filter looked so good that I wner right out and bought and Orange Cokin Filter to cut up to replace the ND filer which I never use.
Because the only screws I could find were chrome, I darkened the heads with a Black Magic Marker, just for cosmetic purposes.
I thought about darkening the threads too, but I dont think there is any chance of flare coming in that direction.
My friend Tony Lo reported this morning that he found a 0.5+ diopter which he thinks can be adapted to allow closer focussing than the Horizon 202 is setup for.
(Click on the picture to see an enlarged view of my daughter Kelly on the deck of the USS Independence during the ships visit to HK)
(I dont have this picture-the Coauthor)
Febr 4, 2013-Michael Przewrocki-MPA