take a look at the attached photo (it's photoshoped but it's exactly what I see in my phone), what could cause this ? it's not just that the colors levels also seem to change automatically while moving the camera and sometimes it gets so dark at the edges.

I have Fcam installed, and I am pretty sure that the lens is clean.

EDIT :
the upper picture is what the camera sees (the problem)
the bottom picture is what the camera should see

I ssem to recall one of the FCam developers mentioning that they were working out a way to correct for that kind of vignetting -- looks like they were successful

so removing Fcam will solve this ?

it is called vignetting. the version with brighter edges is the modified one, the version with darker edges is what the sensor really "sees"....

yeah
the upper picture is what the camera sees (the problem)
the bottom picture is what the camera should see

No I don't think that's what you want to do at all. As ossipena says, the vignetting is a component of the image being projected onto the sensor by the N900's lens.

Basically what you're seeing is light fall-off at the edges of the image circle created by the lens -- had Nokia used a better quality optic, they might have been able to prevent this, but that would have raised the price of the device considerably. As we know, few consumers would notice the absence of vignetting, but many would notice the higher price

What the developers of FCam have done is work out a way to correct for the vignetting in software, which is why I definitely wouldn't recommend uninstalling FCamera. Quite the opposite, in fact!

so it's a hardware malfunction ....does it affect the camera accuracy ?
because my brother's n900 takes very sharp photos unlike mine

then you have 2 options:

1. pop out the lens and get better one in place

2. switch to a camera with better lens.


or then option 3: use software correction for vignetting

ok, it may sounds random but .. Fcam was actually the problem, I've just uninstalled it and the camera is now working as it should, looks like Fcam falsely detected that my phone camera has this "vignetting effect" and tried to correct it.

thank you guys!

it is not malfunction, it is a compromise in design&manufacturing.

built in camera app corrects the vignetting by default but fcam probably interferes with the correction.