Dust Detection

[Guest Nick932]

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Using the 21mm Super Elmar the camera cannot detect dust (Sensor Cleaning, Dust Detection).

It says that the image is inhomogeneous. Does anybody know if the 35mm Lux work?

[250swb]

I hope you don't mean you are thinking of buying a 35mm Summilux just to detect dust?

 

Stop the 21mm down to f/16, point the camera at the sky and take a picture, increase the contrast of the picture in Lightroom and you will see any dust on the sensor.

 

Steve

[thighslapper]

because of the wide angle you will struggle to get a uniform illumination all over the image field ..... and there will be some inherent vignetting....... even using the sky .... unless uniformly clear or overcast it may not work.

 

use a uniformly coloured and lit interior/exterior wall and take the photo from very close with the camera de-focussed. ISO/shutter speed is irrelevant.

 

only use dust detection at one stop beyond what you would normally use as a maximum.

 

you will never get the sensor 100% clean at f22........

 

I rarely use above f8 ........ so I clean till nothing shows at f11.......... which usually means slightly bigger specks that are easily shifted with a blower......

 

......... and bear in mind that dust is usually only an issue in the sky ....... so bits on the lower image field when using dust detection can often be ignored ......

Edited July 20, 2014 by thighslapper

[Guest Nick932]

Thanks about the lightroom info, I have used this quiet often.

 

It is just convenient to have the detection work in camera. I do not always lug a laptop and I know that if possible, I should clean the sensor

 

I know it works with the 50 Cron. Due to vignetting, I have with difficulty make it work with the 21mm Super Elmar. I am just planning to buy the 35mm Lux but If it does not work add a cheap 50.

Edited July 20, 2014 by Nick932

[250swb]

 

I know it works with the 50 Cron. Due to vignetting, I have with difficulty make it work with the 21mm Super Elmar. I am just planning to buy the 35mm Lux but If it does not work add a cheap 50.

 

Vignetting is usually a feature of uncorrected lenses used wide open, are you sure you are stopping the lens down and the coding is recognised? Even so, you don't need to lug a laptop around as you say, you can set higher contrast and underexpose the sky using a JPEG and then magnify the image of the sky in playback and you will see all the dust just as easily as if you used the idiotic 'dust detection' feature, which after all does in principle exactly the same thing, only it expects you to find a white wall instead of a commonly available sky (with or without clouds).

 

Steve

[Guest Nick932]

Vignetting is usually a feature of uncorrected lenses used wide open, are you sure you are stopping the lens down and the coding is recognised? Even so, you don't need to lug a laptop around as you say, you can set higher contrast and underexpose the sky using a JPEG and then magnify the image of the sky in playback and you will see all the dust just as easily as if you used the idiotic 'dust detection' feature, which after all does in principle exactly the same thing, only it expects you to find a white wall instead of a commonly available sky (with or without clouds).

 

Steve

 

Thanks for the tip this works too.

 

FYI: It works as a charm with the Lux 35mm.

[Guest Nick932]

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Vignetting is usually a feature of uncorrected lenses used wide open, are you sure you are stopping the lens down and the coding is recognised? ...

 

Yes the lens is recognised. I do not know if the 21mm is in the corrected lens list or not definitely is very hard to make it work- it has worked after great effort; even the Leica tech could not do it. It seems to me that this is another bug.

 

Have you tried a Super Elmar 21mm with the "Dust Detection"?

[rafael_macia]

I always have used a 90mm lens, focal turned to it's nearest setting (not infinity), and using a small F stop 16 or 22. Pick an even part of the sky to shoot.

This shows up dust perfectly, on the viewing screen.

[CheshireCat]

......... and bear in mind that dust is usually only an issue in the sky ....... so bits on the lower image field when using dust detection can often be ignored ......

 

... if you only shoot in landscape orientation

[roverover]

I have recently attempted to check the Dust Detection on my 240, which i have previously done with a 50mm M lens, aperture closed down, and i have recently bought a 35mm M lens and have noticed that the Dust Detection is Very hard to get working.

I have experimented with aiming at bright objects such as a blue sky, white wall, bright computer screen etc, only to discover the "Image Inhomogeneous" message...  i got it to work with the 35mm lens 1 time, only after about 20 attempts and it only worked once, the 50mm lens sometimes took a few tries but always did work.

 

I am curious, is there any particular reason why a wider angle lens may not work as well with the Dust Detection setting?

[Exodies]

The wider the lens, the larger the homogeneous area needs to be.

[roverover]

The wider the lens, the larger the homogeneous area needs to be.

 

Thanks for your reply. I am curious, if using a wider lens to check the sensor for dust, is there a way to achieve this?

[jdlaing]

Thanks for your reply. I am curious, if using a wider lens to check the sensor for dust, is there a way to achieve this?

If you're using a wall step closer.

[roverover]

If you're using a wall step closer.

 

Thanks but that has Not worked either. I have been experimenting and testing with close and far attempts but not having luck.  Are You using a 35mm or wider lens and is it working on your M?

[jdlaing]

Thanks but that has Not worked either. I have been experimenting and testing with close and far attempts but not having luck. Are You using a 35mm or wider lens and is it working on your M?

When I tried it it worked fine. I don't use that method. I shoot a clear sky and if spots appear I blow it clean with a rocket blower. The in camera dust detection will just make you obsessive.

[jaapv]

I have recently attempted to check the Dust Detection on my 240, which i have previously done with a 50mm M lens, aperture closed down, and i have recently bought a 35mm M lens and have noticed that the Dust Detection is Very hard to get working.

I have experimented with aiming at bright objects such as a blue sky, white wall, bright computer screen etc, only to discover the "Image Inhomogeneous" message...  i got it to work with the 35mm lens 1 time, only after about 20 attempts and it only worked once, the 50mm lens sometimes took a few tries but always did work.

 

I am curious, is there any particular reason why a wider angle lens may not work as well with the Dust Detection setting?

Hold a sheet of white paper in front of the lens and aim at an evenly lit surface. That should do the trick.

However, once you have it working, you'll find it far too sensitive. Most of the dust will never show up on a photograph and it is nearly impossible to clean a sensor to the point that no dust is recorded.

[david strachan]

The white paper trick is best, as Jaap says.

 

I've just cleaned my M-P after nearly a year of use (bought new, now 4,400 images). Tried the in-camera method and it showed no spots at all. Then tried my preferred method, taking a picture and zoom in around the image...and found a slight grease spot, and a small particle...its very difficult to get a perfectly clean sensor...you'll start getting frustrated if you aim for perfection.

 

Method is ...

+1.5 exposure, set my iso to 200 at f22, set completely OOF to infinity, and make sure the camera is moving to fully blur any texture from the white paper. Carefully examine any sensor marks scrolling at full zoom, on the LCD.

 

 

...

[pop]

In addition, the picture you take must not be sharp. When taking, for instance, the picture of a white sheet of paper or a cupboard door or something, set the lens to the infinity setting. Gently moving the camera might also help in blurring the picture even further.

[Exodies]

This is my method. First resist OCD tendencies.

Scrutinize carefully the sensitive areas (e.g. sky) of any pictures you are going to use (for web or print).

If spots, use the in-camera detector (white wall, clear sky - not always successful; expodisc - works every time).

Clean with a rubber bulb blower, detect, repeat (stop when clean or you get bored).

 

Up to now I haven't had to go any further but I have some drops and soft paddles ready.

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Hallo,

Look here: Leica M

[250swb]

 

I am curious, is there any particular reason why a wider angle lens may not work as well with the Dust Detection setting?

 

A wider lens is fine, just point it at a large area of clear blue or overcast sky but don't be confused by dust that appears to have wings. Dust shows up in photographs when the aperture is small, so it is important to stop the lens down to detect dust, but any lens can be used.