DUST Visible from F2.8 - F5.6 in picture


Dec 1, 2009
125
2
18
#1
Hi guys, just want to ask if you encountered a dust problems in your pictures but only visible when using a big aperture like F2.8 - F5.6. By F6.3 and up until F18, the dust can no longer be seen. I just find it really strange as the dust is not with the lens since I tried using 2 of my other lenses. Looks like the dust is inside the camera..not sure if it's in the mirrors/sensor. Could anyone share similar experiences? Please click on the sample pics below. Thanks!

Here are sample pics:
F2.8


F4.0


F5.6


F6.3


F7.1
 

Last edited:
Dec 1, 2009
125
2
18
#2
Hi guys, just want to ask if you encountered a dust problems in your pictures but only visible when using a big aperture like F2.8 - F5.6. By F6.3 and up until F18, the dust can no longer be seen. I just find it really strange as the dust is not with the lens since I tried using 2 of my other lenses. Looks like the dust is inside the camera..not sure if it's in the mirrors/sensor. Could anyone share similar experiences? Please click on the sample pics below. Thanks!

Here are sample pics:
F2.8


F4.0


F5.6


F6.3


F7.1
 

2evans

New Member
Nov 8, 2007
1,862
0
0
#3
If it's the sensor, you can try using a blower and if that fails, take it to the service centre for cleaning.
 

karnage

New Member
Feb 26, 2005
1,325
0
0
35
Ang Mo Kio
#4
Got anything where you circled meh? Perhaps you should try to traditional way of checking for dust, which is to shoot at a blank area at small apertures... like the blue sky in the mornings... Can't really tell if your sample picture is of the same subject at the same position, coz it could very well be the subject itself, or lighting artifacts, or dead pixel, or whatever... If you see the same spot on different photos, then the possibility of it being dust is higher.
 

daredevil123

Moderator
Staff member
Oct 25, 2005
21,662
68
48
lil red dot
#5
I am sorry. The pics are too small. It would be nice if you can show 100% crops of the dust speck in question.
 

Fotophilic

Senior Member
Jun 18, 2006
2,388
0
36
big tree town
#6
the part where u circled in the picture does not look like dust to me.
it looks more like "dead pixel" from what i see in ur small picture. i could be wrong, i am just guessing here. if it is dead pixel then when u shoot at such small apertures (F18) and bump up the ISO, u can't distinguish it from the noise.
do u have other larger pictures which u can post here?
 

Dec 1, 2009
125
2
18
#7
Already tried the traditional way of shooting at small apertures and when I checked my pictures (even at 100%), there was no dust visible. Please click on the small image and it will take you to a site which you can view the image at 100% crop. In that way you can see the small speck inside the circle.

I'll post again some pics later after work with a different subject and including smaller apertures :(
 

Dec 1, 2009
125
2
18
#8
If I take a F2.8 exposure and check the lcd screen of my camera zoomed in at 40-100%, the dust is visible. I checked my raw files in lightroom using my laptop and the speck of dust (can only see 1) is still there. I did one final check and viewed the raw files in my 27inch imac and dust is there. I hope its just dead pixel but its not. I tried using my prime lens using F2.8 exposure and the dust is still there. Is this something common - dust appearing when a big aperture is used? I'm afraid if I take it to service centre, they will just add more dust to my sensor. Really need your advise :s

PS- ill post more pics later, 2 different lens and also including small apertures. Thanks for reading!
 

daredevil123

Moderator
Staff member
Oct 25, 2005
21,662
68
48
lil red dot
#9
If I take a F2.8 exposure and check the lcd screen of my camera zoomed in at 40-100%, the dust is visible. I checked my raw files in lightroom using my laptop and the speck of dust (can only see 1) is still there. I did one final check and viewed the raw files in my 27inch imac and dust is there. I hope its just dead pixel but its not. I tried using my prime lens using F2.8 exposure and the dust is still there. Is this something common - dust appearing when a big aperture is used? I'm afraid if I take it to service centre, they will just add more dust to my sensor. Really need your advise :s

PS- ill post more pics later, 2 different lens and also including small apertures. Thanks for reading!
Actually, you should be more worried that it might be dead pixel. Dead pixel cannot fix, can only remap the sensor. Dust can clean.

And no, it is not common. Usually dust can only be seen at small apertures. And if dust is in the lens, it is usually invisible unless it is near the aperture blades, and the aperture is smaller.

If it shows on 2 different lens, then it has to be either a dead pixel, or dust on sensor. Give your sensor a good blow and see if the problem persist.
 

Dec 1, 2009
125
2
18
#11
Thanks Francis, won't happen again :eek:

Is it possible that a pixel suddenly died? My camera is less than a year - only 8months with less than 5k shutter count.
If I go for sensor cleaning, is there a way for them to check if i have dead pixels in my sensor too? If the 'dust' cant be
removed after the sensor cleaning, is it safe to assume that it's a dead pixel and not a stubborn dust? Is dead pixel part of the warranty?
 

Dec 1, 2009
125
2
18
#12
Dead/hot pixels are show as dark/black spots. Mine looks like a golden cross when zoomed at 100%, hopefully it’s just stubborn dirt (hopefully :) )
 

Fotophilic

Senior Member
Jun 18, 2006
2,388
0
36
big tree town
#13
as far as i know of, the defective pixels can appear as bright spots as well.
if it is still under warranty, maybe you can try paying a visit to the service center to see what they can do for you. most likely they will do some pixel mapping so that it does not show up again.
it is common to get dead pixels on sensors (IIRC).

yes i do agree that u should give ur sensor a good "blow" and test again. visually inspect the sensor for dirt first. if a young person's eyes can't see it, most likely it should not be a problem.

just don't get too upset at this point of time. update us again.
 

Limsgp

New Member
Dec 16, 2005
1,128
0
0
Singapore, Bedok
#15
For dead or hot pixels, it depends on the percentage. Greater than a certain percentage and it will be covered under warranty as it is considered manufacturing defect.

For 1 or 2 pixels, maybe they'll just remap for you.
 

Dec 1, 2009
125
2
18
#16
@fotophilic 0 - i've checked the mirrors (center and top) and it looked clean besides some small particles which I think
may not cause the 'dust' in my pictures. i also checked the thing that covers the sensor and it looked clean too. So i guess,
ill ask the service centre to check for dead pixels and have it remapped. By the way, is there a software that we can use
to check for deadpixels? have any idea how much to do remapping for 1 or 2 pixels?

@ovaltinemilo - will try to post bigger pictures tonight.

@limsgp - didnt know theres a certain percentage to be covered under warranty. thanks for the info!
 

Dec 1, 2009
125
2
18
#17

ovaltinemilo

Senior Member
Sep 12, 2009
2,819
0
0
Sin jia Po lah
#18
hi guys, please check these 2 pics (those inside the circle). It looks like a golden + sign. So i'm guessing it's a dead pixel and not a stubborn dust. So camera will go to service center for remapping... any idea how long it takes for the remapping? Thanks for reading!


http://i302.photobucket.com/albums/n...s3y/dead_1.jpg

http://i302.photobucket.com/albums/n...s3y/dead_2.jpg
The links are dead too....
 

Top Bottom