Digital SLR bodies have reached that magic point where the quality of the image is limited by the lenses and where the price, although high, is not out of reach for a non-professional. This re-opens the option of using filters and lenses in a much more controlled manner – something that even with kits like the CHDK is very difficult. It is always better to optimise and control the signal rather than to try to reconstruct from flawed data.
The next few photos show some preliminary experiments and comparisons using the in-camera HDR on a Nikon D5100 with polariser and various coloured filters.
Polariser vs. Polariser with HDR on Landscapes
The polariser on its own brings out the clouds, but compared with polariser/HDR the level of detail and drama is weak.
Polarizer and HDR
Using both the polariser and HDR give the best results for landscapes.
Polariser vs. Polariser with HDR when there is less contrast
This photo of a Buddleia flower shows (in the original) good detail and contrast.
Buddleia with Polariser and HDR
HDR tends to wash out the image when it doesn’t have a lot of contrast to start with.
Getting Good Black and White Images.
Back in the day one trick to get high quality black and white images was to use a coloured filter with the film and emphasise the red/yellow colours with respect to the blues.
Something similar can be done. The D5100 will convert from colour to “monochrome” and thus produce reasonable images.
The red filter produces a bizarre image.
Converting to black and white brings out the clouds but loses the details.
Red Converted to B&W
The details are still lost, even when correcting for the highlights with the Gimp. (the correction is simply to adjust the histogram of density values so that it fills the whole range, the black and white generated by the camera from this image does not produce white for the brightest pixels)
Original contrast corrected
Yellow preserves more colour information.
Yellow Converted to B&W
However converting from yellow to black and white leaves a lot to be desired as well. (This looks a bit like old-fashioned Infrared film)
Using HDR with a yellow filter recovers features in the sky.
Yellow with HDR
These features are preserved in the black and white image.
Yellow with HDR converted to B&W
The yellow/b&w is not quite as contrasty as the red/b&w so this is a matter of taste.
Red with HDR
HDR with the red filter is interesting.
Red with HDR converted to B&W
The HDR/Red gives good results. Especially after correcting the highlights with the Gimp
Contrast corrected Red/HDR