Sensor dust 'move' if focal length is change ?


Jan 11, 2010
109
0
16
#1
Hi,

Observe a funny situation.
My panny GM5 (with 12-32mm lens) got 6 dust spots, 3 on upper left edge, 3 on lower right edge.

At the widest focal length (12mm), the spots are about 10cm from the edge of my PC monitor. (at 100%)
But when the focal length is at (28mm), the same spots are about 12cm from the edge.
As you zoom in, the dusts 'move' towards the lens center.


Is this possible ?
 

DSolZ

New Member
Mar 6, 2010
784
6
0
#2
The sensor dust on my old Nikon sensor .. Appear at fix position.
 

darrrrrrrrrr

Senior Member
Sep 19, 2006
3,209
5
38
30
Singapore
#3
Hi,

Observe a funny situation.
My panny GM5 (with 12-32mm lens) got 6 dust spots, 3 on upper left edge, 3 on lower right edge.

At the widest focal length (12mm), the spots are about 10cm from the edge of my PC monitor. (at 100%)
But when the focal length is at (28mm), the same spots are about 12cm from the edge.
As you zoom in, the dusts 'move' towards the lens center.

Is this possible ?
Possibly because of the distortion corrections that are automatically applied to the raw image. Many mirrorless system lenses rely heavily on software correction to fix optical issues.
 

shierwin

Senior Member
Dec 29, 2008
3,435
8
38
East Coast
#4
A few good shots with a powerful blower should clear the dust specks off the sensor :)
 

shierwin

Senior Member
Dec 29, 2008
3,435
8
38
East Coast
#5
Hi,

Observe a funny situation.
My panny GM5 (with 12-32mm lens) got 6 dust spots, 3 on upper left edge, 3 on lower right edge.

At the widest focal length (12mm), the spots are about 10cm from the edge of my PC monitor. (at 100%)
But when the focal length is at (28mm), the same spots are about 12cm from the edge.
As you zoom in, the dusts 'move' towards the lens center.


Is this possible ?
When you change the focal length, the field of view changes. The dust you see at 28mm is not the same dust speck you see at 12mm
 

darrrrrrrrrr

Senior Member
Sep 19, 2006
3,209
5
38
30
Singapore
#6
When you change the focal length, the field of view changes. The dust you see at 28mm is not the same dust speck you see at 12mm
If the dust is on the sensor, it should be at the same spot regardless of focal length or lens used no?

Unless there's some software manipulation of the pixels post-capture, which would explain the movement of the spot in the final displayed image.
 

Rocky99

New Member
Jul 7, 2005
218
0
0
#7
i'm not expert but thats what i think.
"Sensor dust" fixed when focussing or zooming = dust speck on sensor
"Sensor dust" move when focussing or zooming = dust back on the glass of the lens.
Try and use a powerful blower to blow the back of the rear glass of the lens as well.

Have you tried using other lenses?
 

Last edited:

shierwin

Senior Member
Dec 29, 2008
3,435
8
38
East Coast
#8
If the dust is on the sensor, it should be at the same spot regardless of focal length or lens used no?

Unless there's some software manipulation of the pixels post-capture, which would explain the movement of the spot in the final displayed image.
My bad...
 

Jan 11, 2010
109
0
16
#9
Hi,


My understanding is that, if the dust is above 'that particular pixel',
no matter which lens/focal length, it still on that same pixel,
dont understand why it could 'move'.
In-camera correct could be a possibility but that 'correction' seems a bit too much.

I'm sure its on the sensor, cos i would see the same dust pattern (inverted) visually on the sensor with a torchlight,
Its quite big, you can see it during LiveView as well.


Anyway, the sensor already cleaned, just trying to understand more.
Unfortunately i only have 1 mft lens at this moment, so cant do a swop.


Thanks
 

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