Richard Shagam

I've been having similar problems with the following equipment:

AstroTech AT72ED II
AstroTech Field flattener
Optolon L-eXtreme filter
ASI294MC Pro camera
 8" Amazon Fire Tablet

My flats look suspiciously similar to those posted by xEOIx.  I'm making my flats with an 8" Fire Tablet using the 'White Screen' Android app and a sheet of white printer paper to further diffuse/attenuate the light.  The dew shield is extended, and I place the tablet on top.  Using the APT flat tool, my exposures for 20,000 ADU come out to 9 seconds.   I don't think I'm getting ambient light leaks.  I get the same results whether or not the room is darkened.  I've also had similar results with a larger USB artist's tracing tablet  panel I purchased on Amazon.  Frankly, I'm getting way better results without using flats in my processing.  That is to say, using the flats gives me garbage!

Is there any more insight to this problem?  Is it in the 294?

What are the dimensions of your shed?  Did you build from plans, or was it built just from basic framing knowledge?

Thanks