sporadic/moving sensor dust?

[random one]

i haven't had any problems with anything on my sensor up until now (maybe).

last night i was taking pictures of an oncoming rainstorm. with the shots on my computer i noticed a fuzzy gray/black dot in the same spot on all the shots, along with some more smudged/less noticable dots in other areas. i attributed these to possible rain drops on the lens that i didn't notice. it wasn't raining where i was, but you never know.

today i was taking some shots with a lot of blue/gray sky in them and noticed quite obvious dots here and there on some of the shots. the fuzzy dots were in completely different spots on all the shots from today. i've seen examples of shots taken with dirty sensors and they look like what i'm seeing. although, there were quite a few mosquitos and other tiny insects flying around when i was taking todays shots. i was zoomed in to 75mm (aps-c sensor) using f5.6, so would it still be possible that the bugs were showing up in the shots. there were a few faded, big dots (about 1/2 inch when viewed at 100%) and a bunch (30-40) of really small dots with some of them looking more like tiny streaks or lines.

whats the best way to see if you actually have dust on your sensor?
should i take a shot of a certain coloured blank surface?

i would rather have a clean sensor than have to deal with the "dust delete data" option.

if anyone has any advice or info i would love to hear it. thanks.

[WesternGuy]

It would help if you could post some examples. The fact that the fuzzy dots were showing up in different places suggest that they may not be dust. In my experience, when I get dust on my sensor, it is in the same place in all my images until I get rid of it, which I can usually do with a blower. Take a photo of a plain, white surface and see what you get. HTH.

Cheers,

WesternGuy

[another view]

I think it's just dust on your sensor and it needs to be cleaned, that's all. Most of the time I've had dust on the sensor, it doesn't move - but sometimes it will. The mirror moving up and down inside the mirror box is apparently a powerful enough "fan" to do blow it around. Cleaning the sensor takes care of 95% of the problem but if there's dust inside the mirror box (stuck to the black surfaces around the sides) then it'll just move around and wind up on the sensor too.

One friend uses a miniature vacuum cleaner attachment for cleaning electronic stuff on the insides of his camera once in awhile, but I'm not quite that... particular... I think Oreck (the hotel vac people) make it.

[random one]

i took a picture of a plain whte sheet of paper and didn't really see anything when i loaded the pics onto my computer. there were a few spots with very, very subtle shaded circles, so i don't know if that's dust of my sensor or not. even if it is, it's not enough to notice in an actual picture.

and after looking at a few shots from today (with lots of sky in the frame) i didn't see any spots.
although now i see 2 specs in the upper-left of my viewfinder that don't show up on the pictures. i cleaned the lens, viewfinder eye-piece thing, and blew out the inside around the sensor and mirror with a rocket blower and it's still there. it's not a big deal, but where would it be coming from?
is it something that is really stuck on the mirror? and if it is, what's the best way to clean it if a blower doesn't work?

thanks again for any help.

[SmartWombat]

You need to shut the lens right down to see the spots.
They are less apparent when wide open, and become more prominent at higher f/ numbers.
You will see them much more often in shots with a lot of sky, or bright sand.

[another view]

You need to shut the lens right down to see the spots.

In case you're not sure what this means, set the lens at the lowest aperture (highest "f" number, like f22). Shoot a piece of white paper or a clear, wide open blue sky. Wider lenses usually help here too, due to the depth of field. Compare the shot to just looking through the camera and hitting the depth of field preview button on the camera.

With a blower, you could have just simply moved a piece of dust from one spot inside the mirror box to another; like the mirror to the focusing screen. Eventually it'll find its way to the sensor. That's the problem with blowers versus a vacuum. Try holding the camera upside down (open mirror box pointing towards the floor). This way dust can fall out aided by gravity, rather than fighting it.

Dust can get inside cameras almost regardless of how careful you are with your gear. Be careful to do your best to keep it out of the camera, but at some point you'll need to remove it.

[random one]

i did assume 'shutting the lens down' meant the same as 'stopping it down'. but when i first noticed these spots on my pictures (which i don't see from more recent shots, which leads me to believe that all those spots and specs might have actually all been bugs in the air) i was shooting at f5.6.

i'll try the test shots again at f22. i think i used f5.6 when i tryed it earlier.

[freygr]

The reason that dust spots show up better at high F stops is the light from the lens. The dust is not on the sensor it's on the IR filter in font of the sensor.