Sensor or lens dust?

Started 4 months ago | Discussions
mmpd3 Regular Member • Posts: 106
Sensor or lens dust?
1

The below two images were taken within a few minutes of each other with the 80D + 100-400L MkI combo. Both were shot in Tv mode but due to the changing light conditions the first one ended up at F22 & the second at F10. The first picture has a load of spots on the left hand side that are not present in the second image.

I couldn't see any dust on the sensor but gave it a good going over with an air blower so I'm inclined to think it must be dust in the lens (even though I can't see anything). Would this make sense and the spots are only visible due to the much brighter conditions in the first image?

Thanks for any advice.

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shawnwood.smugmug.com

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Distinctly Average Senior Member • Posts: 1,209
Re: Sensor or lens dust?
5

These are more likely to be on the sensor. You can check that by taking off the lens and firing a shot at a white wall. You should see them. Spots on the sensor show up more as you stop down going from barely visible to horrible.

Dust on the lens rarely shows in images. Even splats of mud on the front barely show or show as flare rather than a spot. On the back of the lens it takes a very big spot to show on the image so you would notice it. However, try and keep the back of your lens as dust free as possible as any dirt there will find it’s way onto your sensor.

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BG454 Veteran Member • Posts: 7,331
Re: Sensor or lens dust?
4

Distinctly Average wrote:

These are more likely to be on the sensor. You can check that by taking off the lens and firing a shot at a white wall. You should see them. Spots on the sensor show up more as you stop down going from barely visible to horrible.

Dust on the lens rarely shows in images. Even splats of mud on the front barely show or show as flare rather than a spot. On the back of the lens it takes a very big spot to show on the image so you would notice it. However, try and keep the back of your lens as dust free as possible as any dirt there will find it’s way onto your sensor.

Agreed.
Dust on lens rarely shows on an image.
The smaller the f-stop, the more likely sensor dust will show up.

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OP mmpd3 Regular Member • Posts: 106
Re: Sensor or lens dust?
1

Distinctly Average wrote:

These are more likely to be on the sensor. You can check that by taking off the lens and firing a shot at a white wall. You should see them. Spots on the sensor show up more as you stop down going from barely visible to horrible.

Thank you, that's very helpful. I'll definitely try this when I get home tonight.

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 mmpd3's gear list:mmpd3's gear list
Canon EOS 60D Canon EF 50mm F1.8 II Canon EF-S 18-135mm F3.5-5.6 IS Canon EF-S 55-250mm f/4-5.6 IS Canon EF 100-400mm f/4.5-5.6L IS USM +1 more
The_WB Regular Member • Posts: 483
Re: Sensor or lens dust?
1

Looks like sensor dust to me too.  A bad case, I might add.  Pics shot at f/10 will start to show this problem.

Sensor cleaning time.

Sue Anne Rush
Sue Anne Rush Senior Member • Posts: 5,233
Re: Sensor or lens dust?
1

Either way - awesome photograph. 

mmpd3 wrote:

The below two images were taken within a few minutes of each other with the 80D + 100-400L MkI combo. Both were shot in Tv mode but due to the changing light conditions the first one ended up at F22 & the second at F10. The first picture has a load of spots on the left hand side that are not present in the second image.

I couldn't see any dust on the sensor but gave it a good going over with an air blower so I'm inclined to think it must be dust in the lens (even though I can't see anything). Would this make sense and the spots are only visible due to the much brighter conditions in the first image?

Thanks for any advice.

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Sue Anne Rush

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OP mmpd3 Regular Member • Posts: 106
Re: Sensor or lens dust?
1

Sue Anne Rush wrote:

Either way - awesome photograph.

Thank you.

Taking a photo of a wall without a lens on didn't show up the spots but using my 18-135 and shooting the wall at anything between F13-F22 clearly showed them. Given the air blower didn't make much difference its definitely time to get a cleaning kit.

Thanks for all the replies.

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shawnwood.smugmug.com

 mmpd3's gear list:mmpd3's gear list
Canon EOS 60D Canon EF 50mm F1.8 II Canon EF-S 18-135mm F3.5-5.6 IS Canon EF-S 55-250mm f/4-5.6 IS Canon EF 100-400mm f/4.5-5.6L IS USM +1 more
Distinctly Average Senior Member • Posts: 1,209
Re: Sensor or lens dust?
2

mmpd3 wrote:

Sue Anne Rush wrote:

Either way - awesome photograph.

Thank you.

Taking a photo of a wall without a lens on didn't show up the spots but using my 18-135 and shooting the wall at anything between F13-F22 clearly showed them. Given the air blower didn't make much difference its definitely time to get a cleaning kit.

Thanks for all the replies.

I’ve often just added more dust with a blower. A cleaning kit is the best way to go. Best of luck.

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