Durst M370 filter tray & MF condenser questions
I've just bought a Durst M370 BW on eBay, ready to make my first foray into printing. It came with a set of Ilford multigrade filters which I can cut down to fit in the filter tray, but I wonder if anyone knows whether the tray should have a glass insert in it? The plastic frame has some tiny lugs at one end, but there doesn't seem to be anything at the other end to stop a filter from dropping out.
The enlarger also came with the conversion kit for 6x7 medium format. I want to get into MF, but it will either be 645 or 6x6, most likely 645 because I can't see that I'll want square prints too often. According to the manual I'll need a Lidicon 80 condensor (the kit has a Lidicon 100), a Sixma 66 lower metal mask insert (I've got a Sixma 67 in the kit) and a Sivopar 45 glassless insert.
I know I can just try it for myself when the time comes, but what is likely to happen if I try to print from a 6x4.5 negative with the 6x7 condensor? The enlarger came with 50mm and 80mm EL-Nikkor lenses, and I know that MF needs longer lenses. What does a lower metal mask insert even do? It's all very confusing, so if anyone can throw any light on this I'd be most grateful.