I give up!

It's possible, with vigorous blowing or canned "air", you may have forced dust between the sensor and its filter stack. More likely you have a stubborn spot of mineral or organic residue sticking to the cover glass. Suspects include salt spray and blowing with your mouth. For that you will need to use a liquid cleaning process, with Eclipse Fluid (highly purified methanol) and PEC Pads. The same solution is available on pre-moistened swabs. These can only be used once, or at most, one pass in each direction on the sensor.

A very sensitive test for dust is to stop down as much as possible, and point the camera to a clear section of sky. Shutter speed doesn't matter, because the position of any spots is fixed. Be warned that everything is revealed, even those of no consequence in normal use. Some describe it as like "Trying on swim suits under fluorescent lights."

Fujifilm X-E1?

If you've worked it over, it may just be time to send it in for cleaning at the source. I found that to be necessary with my Canon 5D (mark 1), which is another camera that can be tricky to clean.

There is a spot the sensor of my XE1 I just can't get rid of.

Had the same thing - took it to a good camera shop where they cleaned it quickly & handed it back repaired. $35 - a little ridiculous for the time & effort involved, but I couldn't do it. You do remember, when cleaning, the effect of the lens - the spot on the sensor will be in a different place than you expect!

We had some fine camera stores in the area at one time...all gone.

Don't know if you ever get up to San Francisco, but I've bought used cameras and brought cameras into Camera Heaven in the Tenderloin (748 Larkin @ Geary) for sensor cleaning and repairs and always been happy with their service. Cool little place. Very nice, easygoing, knowledgeable guy who owns it. Call ahead. Variable hours.

if you shine a bright light with the mirror up, can you see whats causing the problem as you change the angle the light hits the sensor?

most times diy cleanings will leave dusf behind, especially if you are just doing a dry clean.

what youprobably need is a good wet clean. if youve never done this sort of thing befor, leave it ro the pros to do it right. most walk in shops will do it on the spot n only charge a few bucks.

Amen on San Francisco driving. I burned out the clutch on my manual-transmission car and bought an automatic transmission next time. I think San Franciscans must replace their clutches as often as they change oil.

Regarding sensor dust, my Nikon D80 was afflicted with a large number of mysterious spots on the sensor. My rocket blower had no effect. Next I tried wet cleaning with PEC pads and Eclipse fluid. Multiple cleanings, increasingly aggressive, no effect. Desperate, I tried distilled water, then finally resorted to lighter fluid, which easily dissolves glue. No effect! The camera was 12 years old, so I didn't weep over it. Instead I bought a lightly used D7200. The D80 is still usable at f/8 or larger.

I use a blower, Visible Dust brush set, and Sensor Swabs in that order, if needed. All of my Sony alphas have developed what appeared to be oil spots in the first few weeks of operation. You can't blow that off, nor brush it. Sensor Swabs did the trick, and the same problem never recurred. Every so often, something will get on and stick (e.g., ocean spray, which can travel miles inland). However the blower suffices on a routine basis, namely every time before I go out, and should something occur during the day (and I happen to notice). I carry a few Sensor Swabs in my camera bag, just in case.

I would not use a carbon fiber brush on a sensor. Carbon fibers are literally as hard as diamond, and can scratch the relatively soft optical surfaces. Nor would I use a Lens Pen, which can leave traces of its sticky plasticizer. It won't matter on a lens or filter, because it's out of focus. On a sensor is a different matter. Visible Dust and others make microfiber brushes which won't scratch, and suck up dust like a vacuum when properly "charged" by spinning or with canned "air." Wet cleaning always leaves some dust or fibers at the edges of the sensor. They usually won't blow off, but the brushes remove them completely.

Any idea about what could make spots on a sensor that even lighter fluid can't remove? As you can see in the photo, the sensor has lots of little spots clustered around the center of the frame. Maybe they're between the cover glass and the sensor. One thing I've established is that even a solvent as powerful as lighter fluid doesn't seem to cause harm. The camera still works fine and takes good pictures at f/8 and wider apertures. I wouldn't recommend lighter fluid to anyone else, though. I resorted to it in sheer desperation, and I didn't have much to lose with a 12-year-old Nikon D80.

How large are those spots? Could they be dead pixels?

The fact they're clustered in the center argues against dust under the filter stack, which would be concentrated near the edges. It suggests corrosion or physical damage to the filter stack, particularly the tin oxide anti-reflective coating used about that time. You might take a look with a low power (20x or so) inspection microscope. I have one from Edmund Scientific, hand-held, 25x with a 3" working distance, but no longer available. You can't get close enough (1/2") to a DSLR sensor with a high power hand magnifier.

Any idea about what could make spots on a sensor that even lighter fluid can't remove? As you can see in the photo, the sensor has lots of little spots clustered around the center of the frame. Maybe they're between the cover glass and the sensor. One thing I've established is that even a solvent as powerful as lighter fluid doesn't seem to cause harm. The camera still works fine and takes good pictures at f/8 and wider apertures. I wouldn't recommend lighter fluid to anyone else, though. I resorted to it in sheer desperation, and I didn't have much to lose with a 12-year-old Nikon D80.

just for gigles... ask the manufacturer? nikon may have a recall on that sensor or some information with similar complaints?

i wonder if nikon makes their own sensors? have any idea who the oem might be?

The mysterious spots on my Nikon D80 sensor aren't dead pixels. But neither do they resemble typical dust spots. You can see two typical dust spots near the lower left and lower right corners of the photo I previously posted. They are dark spots. If not for the mysterious atypical spots clustered near the center, they would be the only significant dust spots on this sensor -- thanks to my repeated wet cleanings.

I agree with Ed Ingold that the center spots probably aren't dust spots. They're some kind of corrosion or deterioration. I'm always careful when changing lenses, but these spots appeared spontaneously. Although I have a couple of loupes for examining slides and negatives, they can't get close enough to the sensor to examine these spots. Neither can my magnifying glasses.

Sanford makes a good point, too. I can afford a high-end camera but am reluctant to purchase one, now that I know a sensor can spontaneously show spots that even powerful solvents can't remove. What if this happened to a full-frame Nikon DSLR or a $7,000 Leica M10? Egad. To replace my 12-year-old Nikon D80, a friend sold me a Nikon D7200 that had shot only about 200 pictures. He decided to get a full-frame body instead. The like-new D7200 is plenty good enough for me.

Even the afflicted D80 still takes good pictures at f/8 or wider if the ISO is 800 or less. I'm thinking about having it converted to infrared, which would remove the hot filter overlaying the sensor. Removing the filter glass might get rid of the spots, too.

The like-new D7200 is plenty good enough for me.

An excellent camera - mine, also used, is nearly as good as my FX Nikons, and I post its output here often. You'll enjoy that camera, I suspect!

Some Leica M9 sensors have been subject to corrosion, and will be replaced by Leica. I haven't seen any examples, and mine seems to be okay.

The only things lighter fluid (naphtha) will remove are non-polar substances like grease. It won't dissolve Inorganic substances like salt and water-born contaminants. Saliva is probably somewhere in between. It is likely that plastic components in the camera will be damaged, along with any lubricants. Naphtha is a mixture of hydrocarbons in a certain boiling point range, and will leave a residue consisting of waxes and higher molecular weight compounds. Furthermore, it evaporates so slowly that it may have time to migrate behind or between the filter stack components.

Ed, thanks for being subtle and not calling me an idiot for using lighter fluid on my Nikon D80 sensor. Your polite and informative comments are appreciated.

In my defense, the lighter fluid was a last resort to salvage an old camera. I knew the spots weren't ordinary dust, because repeated cleanings with Eclipse alcohol did nothing. I hoped the lighter fluid might work the same miracle on the spots that it has worked on glue residue stuck to other things. I did fear that any fluid seepage or even the strong fumes might dissolve glues holding internal plastic parts together. It did leave streaks on the sensor that I had to clean with Eclipse. But several months have passed and the camera still works, so apparently my desperate attempt at sensor cleaning didn't cause structural damage.

An important clue is that despite repeated and increasingly aggressive cleanings using Pec Pads soaked with various fluids (Eclipse, distilled water, lighter fluid), the center spots have not changed. Even stubborn dust spots usually move around if the cleaning doesn't remove them. My before and after pictures of these spots always look the same. So they must be under the glass or some kind of corrosion spots on the glass surface. That's why I'm considering an infrared conversion. Or I could keep the D80 as a backup for my D7200 and apply a label reminding me not to shoot smaller than f/8.