<p>The Kodak 9x12 (different from 3-1/4 x 4-1/4) sheet film holders will fit the Maximar. As for Zeiss-Ikon, beware. They made several different sheet film holders for their plate cameras. You want those marked 665/7. Metal holders marked 726/7 are clip on rather than slide in and were made for the Ideal and Universal Juwel cameras. They will not fit the maximar. There are also wooden holders (teak) for their tropical cameras (tropen adoro and tropica) that will not fit the maximar.<br>
In addition to the holders you will also need 9x12 film sheaths for the Zeiss holders. I have some Kodak holders that were made for film rather than glass plates but right now they are buried somewhere and so I cannot give you specifics. Finally, there are reducers (marked 725/4) that will fit into the Zeiss 9x12 plate holders and allow use of 3-1/4 x 4-1/4 plates. You can combine these with Kodak 3-1/4 x 4-1/4 film sheaths to allow use of that film in the 9x12 plates. As if that were not enough, several companies made slide in ground glass spring backs that allow use of modern (eg Lisco) double sided 3-1/4 x 4-1/4 sheet film holders.<br>
You might want to consider looking for a RADA or SUYDAM 120 roll film back made for the 9x12 plate cameras (careful here too because they also made these for 6x9 and probably other sizes as well). This will allow use of any of the current 120 roll-films, your 135mm lens becoming a modest telephoto lens.<br>
Welcome to the wonderful (and confusing!) world of the old plate cameras! Once you get the hang of them they are still capable of first rate photography.<br>
Ron Gratz</p>