This post shows about what to expect from short-exposure imaging of typical amateur subjects. M101 is used for this example. Click on individual images to see them full size. The final image after processing can be viewed here:
Single raw 180 second image, unprocessed, unstretched.
Raw image, screen stretched only. Note bad column, sensor structural elements on diagonal.
The camera used for this image is the Princeton Instruments Pixis 2k x 2k, with an e2v chip and cooling to -70C. This yields extremely low dark current and read noise, so that even a very ‘thin’ image like this one has excellent signal to noise ratio. The image of the histogram below shows just how thin the data is, but with low noise, it’s a useable image.
Stacked image histogram. Low-noise CCD sensor yields good signal to noise ratio even at very low data levels.
The image has been calibrated and been corrected for cosmetic defects, cleaning up artifacts from hot/cold pixels, dark current, and the bad partial column.
A stack of three 180s calibrated images, minimal stretch.
The integrated image was then deconvolved in PixInsight. This is the core at 100% showing the level of detail, which it fairly typical of an average night at the observatory. Seeing ranges from 0.8" to 2.0", with a median value of about 1.3".