Short duration flats and shutter issued

[Thidor05]

Hello,

I own an ATIK 383L mono model. I keep getting some sort of a shadow effect on one side of my flats. One side of all my flats is fine, the other half of all my flats get progressively darker. I do sky flats...very short duration like 1/10 sec or 2/10 sec.  Is it possible that the shutter could not keep up with that speed?


Doris Thibeault