Hi @leighk!
The reason this is failing is that micrographs are downsampled to a 3 Å pixel size before denoising, then denoised in 512 x 512 pixel patches. In your case, downsampling the micrograph to 3 Å results in a micrograph that’s only 455 x 640 pixels, which is too small for a single patch.
So, for this issue, I believe the smallest pixel size that will work is (512 px * 3 Å/px) / (smallest detector dimension). In your case, this is 512 * 3 / 4092 = 0.376 Å/px (i.e., ~0.19 Å/px superres). However, this is still a much higher magnification than we tested with, so I cannot guarantee that this would currently work either.