I have am having an intermitant problem with pictures taken using the built-in flash. The problem is that the top 1/8 to 1/2 of the image will be darker than the bottom portion on some photos, some but not all.
Nikon says: 1.Use a fully charged battery. - I always do. 2.Use a Nikon recommended SD card - It is not, but is a good quality Kingston card with fast transfer speed. 3.If all else fails reset the camera and if the problem persists it may be something with the lens.
Last night I took 40-50 flash pics just to see if there was any pattern to the problem. I had the dark image problem with the first few and everything was fine after that.
FYI, I am using the 18-55mm lens, automatic everything.
A hood shadow would be the opposite of this shadow. This looks to me like the flash is only iluminating the lower 2/3 of the image. The color shift at top says it's not getting flash illumination - this area is getting its color from the ambient lighting.
My guess? Were you wearing a hat? Either the flash isn't popping up to the full height and it's pointing downward slightly or the brim of your hat pushed it down a little bit. Check the pop-up action on your built-in flash.
It seems to me as if the pop up flash is not in the fully upright position. But you said that it was...
The longer zoom has a narrower angle of view so it may be that the flash is still vignetting but it doesn't matter as you are recording a smaller area of the scene vs. a wider angle lens.
I think the flash is somehow faulty. Perhaps a reflector is out of alignment.
The only fix I can think of now would be to use an accessory speedlight (SB-600 or SB-800) and then have the camera (and possibly the lens) sent to Nikon for warranty repair as it is obviously not performing as it should.
What bothers me most about image is how sharp the demarkation between flash and no flash is.
If the flash was in the wrong position it would be a lot softer and more graduated. I know, I have had flashes in the wrong position for close up shots of wedding rings.
The other thing that bothers me is how close the two exposures are to each other so it is not a flash synch problem. When that happens with film cameras, the demarkation is black and the other part properly exposed.
I do not know what this is but it is not simple. Those problems I have seen only too often and there are other experts on this board who would have been able to say it is XXXX and that would be the end of the thread.