Originally posted by bm75 Hi all.
I've already brought a M 20mm f/4 in perfect conditions. I've taken some photos during a mountan trip with my k-5 and results were strange.. .There's a light blue dominance in the pictures. I tought it could be really high UV radiation in mountain (altitude not higher than 1950mt) or WB ( I controlled it: was ok on auto and "natural"
no custom settings, no digital filters) and I had to shoot compensating -0,3 -0,5 ev .The same pictures taken with DA 17-70 are much better , but settings are the same.
Had anyone noticed the same behaviour of the lens? I'll be grateful for any suggestion.
Best Regards.
Matteo
Having to adjust towards underexposure is normal, because since the lens IS NOT an "A" lens, the camera is switching to centerweighted metering instead of matrix. Due to high altitude and wide angle of coverage, it is normal to get a lot of light in frame that can throw the meter towards overexposure.
About the blue tinting.. hmmm that is strange. Of course, high altitudes and clean skies are two strong reasons for excess UV radiation, but that should not affect nor shift the color balance on digital. It was normal on film. That is why "Skylight" filters were slightly pink.
Before doing any changes in camera or chasing the "blue ghosts" around lens and camera, I suggest checking first the color balancing of your computer monitor. Maybe photos are fine but your monitor is overadjusted to to high color temp.
Let us know your findings.
---------- Post added 10-24-2014 at 11:06 AM ----------
Originally posted by wtlwdwgn Although filters are not supposed to have an effect on digital sensors, I use Skylight filters which were designed to control the Kodachrome blue skies which were unnaturally dark blue. Worth a try.
Right, filters are not supposed to do any effect on digital sensors, except polarizers of course. Any color shifting that is needed can be done by white balance adjustment or digital custom filtering... but (big BUT HERE):
Filters DO have an effect on digital cameras. Not by shifting color. Instead, they create lots of ghosting and double images, especially at night when you have bright lights in frame. This is more noticeable with medium to long telephoto lenses. On wide angles, filters do produce a loss of contrast and lots of glaring inside lens. Low cost filters like old Tiffen, Hoya or such are very prone to this ghosting and flaring. The worst I've seen are Cokin's Optilights (plastic) and Kenkos. Even old B&W filters have this flaw. Just newer super multi coated (both faces) filters can reduce this ghosting and flaring a little better.
Check this examples of ghosting: