One day I will succeed in properly imaging the ISS, but not on this occasion, unfortunately.  I took a gamble in using my deep sky mono CMOS imaging camera on my Alt/Az mounted large Dobsonian.  It was a trade off gaining a wider field of view with the larger sensor but losing out on the lower frame rate (~14 vs 130fps for my planetary camera - ASI224MC with it's much smaller sensor, that I had used previously).  I still only ended up with around 50 of the 1500 captured frames showing the ISS, the rest were just black.  A bigger error was to still not use the correct exposure time.  Working at f/12 (focal length 6000mm) and using a camera gain of 240 the exposure time of 0.4ms was not long enough with this filter.  I was only able to salvage any images captured using SharpCap by converting the avi video file into separate tiff files using PIPP and applying 2x2 binning in post processing. The ISS then became visible but presumably at the expense of lost detail.  I also found it almost impossible to stack images, even those captured sequentially to give an improved averaged image. Either the ISS had subtly altered it's orientation in a fraction of a second, atmospheric turbulence had intervened or the captured image had been slightly blurred by movement of the ISS or the telescope.  I was actually quite lucky to capture anything as after 2 minutes of manual tracking and recording I heard my laptop "beep" and was dismayed that in following the target I managed to disconnect the USB cable connection to the camera.  Fortunately the programme saved what it had already collected otherwise it would have been a Hamlet cigar moment! I'm determined to improve my images but this is one of the most challenging and stressful targets with more failures than successes.  The images show the ISS at distances from my observation site of between approximately 460 and 570km.