I haven't used any "new" Adox/Agfa MCP 312 but did use the original Agfa stuff with a 100W tungsten halogen bulb in a Durst 605 and never got exposures this low for 8x10 and 6x6 negs. I can come close with Kentmere VC Select but at 5x7 and f8 and Kentmere is about one speed faster than Ilford whereas Agfa as it was and I presume Adox MCP as it is now and Ilford are about the same speed.

It tends to suggests there is something different about the OP's set-up. Not much margin for dodging. Most 80mm lenses go to F22 so only about 12 secs max and don't most 50mm lenses only go to f16?

5x7 prints' exposure would be very short indeed with no room for dodging at all.

Stopping down might solve the issue but I'd be inclined to look further for a solution.

pentaxuser