Sensor Dirt

[Cameraboy6476]

Canon EOS M50 Kit Lens 15-45mm  Using the same lens..the first Photo shot at 1/250 shows no dirt...Second shot at 1/50....dirty.....Can anyone please explain this to me. Put the "clean" verion in lightroom and tried to replicate the "dirty" version by adjusting exposure, texture, and contrast and still no dirt. Thank you everyone.

[ebiggs1]

A dirty sensor will show up differently depending on settings. Yours needs to be cleaned. If you have never cleaned a sensor I advise you to take to someone that has experience doing it. It is not hard to do but certain parts inside the mirrorbox do not respond well to careless treatment.

Perhaps you have a local camera store or service center.

[wq9nsc]

I agree with Ernie that your sensor looks like it is due for cleaning.  Subtle differences in lighting or initial exposure conditions greatly impact whether/how much the dust is noticeable in the captured image.

If you are careful, follow instructions, and exercise a light touch then you should have no problem safely cleaning the sensor but if you have any concerns about your ability then take it to a shop that you are confident can do it correctly.  And if you take it to your camera shop, you don't necessarily want the new teenager who works part time behind the counter cleaning it.  Plenty of people are willing to do this sort of work even when they shouldn't.

I travel and shoot a lot under varying conditions and although I have several camera bodies there are plenty of times where I need to change lenses under less than perfect conditions.  I keep proper cleaning supplies with me so that I can do a sensor cleaning during a trip when necessary.  Make sure you use the correct cleaning products and explicitly follow the instructions for cleaning in the manual.  Pay particular attention to starting with a fully charged battery, you definitely don't want it powering down while you have a cleaning swab inside the sensor/mirror box area!  Even with excellent vision, a quality magnifying headset is extremely useful when doing this sort of cleaning.  It will make little specks obvious which might otherwise be missed.

Rodger

[ebiggs1]

"...if you take it to your camera shop, you don't necessarily want the new teenager who works part time behind the counter cleaning it."

I second, third and fourth that advice!

[kvbarkley]

I don't know if it will happen this year (Canon and the Fiesta committee had a falling out over last years canceled fiesta) but if you make your way to Albuquerque during Balloon Fiesta, they would clean it for free!

[kvbarkley]

Here is how my T6S records dust for the dust delete data function:

You can take an image using the preparation steps to see your dust.

[MikeSowsun]

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@Cameraboy6476 wrote:

Canon EOS M50 Kit Lens 15-45mm  Using the same lens..the first Photo shot at 1/250 shows no dirt...Second shot at 1/50....dirty.....Can anyone please explain this to me. Put the "clean" verion in lightroom and tried to replicate the "dirty" version by adjusting exposure, texture, and contrast and still no dirt. Thank you everyone.

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It is not the shutter speed that makes the dust more visible. It is the aperture. Smaller apertures like f/8 f/11 and f/16 are much more likely to show the dust on the sensor. 

If you go back and check the aperture EXIF data on those photos,  I am sure you will see the connection 

[kvbarkley]

I was going to say that about aperture, but I realized that I don't see how it works. How can the aperture of the lens affect the focus of dust on the lens?

[jrhoffman75]

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@kvbarkley wrote:

I was going to say that about aperture, but I realized that I don't see how it works. How can the aperture of the lens affect the focus of dust on the lens?

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My understanding is that smaller aperture results in a more collimated light beam and thus less scattering of the light around the dust specks.

[ebiggs1]

As the aperture gets smaller, larger number, the dust particles tend to appear darker or stand out more. That is why they show up more as the exposure changes. They also get smaler as the aperture gets smaller, larger number.

Also certain shots, like photos of the sky, will make them show up more.