As I was building a cornerfix profile for the lens, I noticed something odd - not the magenta corners, they were expected, and CornerFix takes care of them pretty well, but on top edge there is a yellow blob (and possibly a cyan blob at the bottom, pretty hard to see). Cornerfix does not fix it and it does show up, even in corrected images.
Yellow is harder to see but its still obviously there.
Is that something expected with combination of this lens and NEX7? My other CV lenses (35mm f2.4, 75mm f1.8) don't have this issue, nor does the 18-55mm kit lens. Could the lens be defective - or possibly an issue with the sensor?
I haven't tried Lightroom, but it actually has nothing to do with the profile, since I see it in the original, uncorrected images (the 1st photo). 2nd photo was just contrast boost. In 3rd photo I actually applied profile correct, and it makes the yellow discoloration harder to spot.
The 1st photo was made by just moving the camera with shutter open in circles around a gray sheet of paper ...so the stationary yellow spot would not come from an external source.
LightShow wrote:
Have you tried Lightroom's version of corner fix?
Have you tried more profiles for the CV15? Could it be a color cast from when you made the profile?
But it could have come from light source? Try turning the camera upside down and do the same and see if the yellow is coming from the physical up side? If not, then I can only think of perhaps light leak from the adapter, maybe?
Yes I think this probably comes from inconstant illumination in the picture. This causes trouble making the profile. The best way I found was to make my monitor white, and essentially hold the lens up to the monitor itself (careful not to push on it, as that will discolor it). Otherwise, perhaps a gray card in really super-uniform lighting (eg daylight) would be the best way to go.
There are WB aids you can get that will work, but as sebboh suggested in a different thread, a KEM wipe stretched over the lens and pointed at the sky works just as well.
Taylor Sherman wrote:
Yes I think this probably comes from inconstant illumination in the picture. This causes trouble making the profile. The best way I found was to make my monitor white, and essentially hold the lens up to the monitor itself (careful not to push on it, as that will discolor it). Otherwise, perhaps a gray card in really super-uniform lighting (eg daylight) would be the best way to go.
I've tried using a monitor but found the vignetting was much stronger than normal. Might have to do with how light is emitted from each pixel and those pixels not actually being white. Perhaps smooth white diffusion material between the lens and monitor could work?
freaklikeme wrote:
There are WB aids you can get that will work, but as sebboh suggested in a different thread, a KEM wipe stretched over the lens and pointed at the sky works just as well.
Except super-ultra-wides stopped down, even focused at infinity, can pick up the material's texture. Maybe Kimwipes are smooth enough for this, but I've seen texture when using other tissue-like materials.
rscheffler wrote:
I've tried using a monitor but found the vignetting was much stronger than normal. Might have to do with how light is emitted from each pixel and those pixels not actually being white. Perhaps smooth white diffusion material between the lens and monitor could work?
I"ll have to try this method.
Except super-ultra-wides stopped down, even focused at infinity, can pick up the material's texture. Maybe Kimwipes are smooth enough for this, but I've seen texture when using other tissue-like materials.
I had this issue with my CV15, DOF is so great that differences in texture or density will be slightly dimmer or brighter. I'm still not happy with the lack of synergy between the 7 and the CV15, I have hope for a future camera.
The way I have built my profiles is to take a giant piece of neutral gray backdrop paper, lay it on the floor in even light condition, open shutter and just move the camera around in circular / random motion. This eliminates all texture and evens out light. The technique worked fantastic for CV35 ... and it does work for CV15, except for that weird yellow blob thing ...
rscheffler wrote:
Except super-ultra-wides stopped down, even focused at infinity, can pick up the material's texture. Maybe Kimwipes are smooth enough for this, but I've seen texture when using other tissue-like materials.
I've tried the tissue trick too with the CV15 and it picked up too much of the texture to be useful. I ended up using my monitor which worked ok but wasn't ideal.
