As ever when I experience a knotty and intractable problem, I turn (after trying a range of solutions) to this wonder brain's trust for advice and help.
I am a big fan of my 645Z in many ways. It has transformed my photography, even by comparison to the 645D + D800E I was using previously. However, I am finding a couple of problems that are very frustrating given how I tend to shoot.
Firstly, when shooting high contrast scenes (which is often the case around sunrise/sunset, where parts of the scene tend to be very dark and light), it has for many years been my practice to bracket +/-2 stops then layer the files and brush selectively using layer masks. It has worked well with every digital camera I have used, from 1Dsii and 5Dii to 645D. However, with the Z, I find that this has become problematic. The dark areas tend to be very noisy, which is counter to my general experience that there is low noise and high DR on this camera. Layering in a lighter exposure and brushing those areas in seems only to accentuate the noise, until I brush the areas in so much that they are so light that the noise doesn't show up (which of course is not my intention, as I want those areas to look relatively dark in the scene). I can make it work by allowing those areas to become very light, then darkening them again using curves, but that seems counter to the very benefits of this camera and I can't believe it should be necessary.
Look at the bottom right hand area of this picture for the effect I mean. This happens a lot. In this case, I layered in a lighter exposure for that area - which in the past has mean a nice noise-free image for the dark places:
[IMG]_IMG0725Step4sRGBSMALL by Ed Hurst, on Flickr[/IMG]
Furthermore, I have noticed that skies tend to be prone to banding. Here is an example:
[IMG]_IMG2089Step5sRGBSMALL by Ed Hurst, on Flickr[/IMG]
That banding in the sky is not a result of JPG compression or Flickr crushing the file - it's there on the 16 bit TIFF.
Now I will admit that I tend to edit fairly vigorously, but no more so that I have always done without this occurring. So I am flummoxed. Is it a problem with the sensor (I have tried two different 645Zs, with the same results)? Can I change my technique somewhat to get around this? I have tried using Prophoto colour space in case it's about that somehow (it didn't help). I do all my processing in 16 bit mode.
All advice gratefully received!