of digital cameras and sensor dust

[Overconfidence]

I have a few questions for those of you who may be more experienced in this area.

We all know that sensor dust is an issue on interchangeable-lens digital cameras. However, I think that it is even more critical on digital rangefinders.

When using an SLR, you will often shoot wide open (or nearly wide open) and autofocus on your subject. On my digital SLR, sensor dust is invisible up to about f/11, but it is noticeable at f/16 and f/22. This is no big deal for me because for the type of shooting I do, I rarely go about f/8. But when I shoot film (particularly street photography), I like to stop down to f/16 and zone focus.

I'm scared that if I were to get a digital rangefinder in the future, sensor dust would limit me and I would be forced to use larger apertures to avoid sensor dust.

In a digital camera, is the sensor actually always exposed to the mirror chamber/lens chamber/that area between the lens and the sensor? I would assume that the shutter would be covering it (except for the 1/250th or however long it takes for the shutter to travel) and that you wouldn't really get all that much dust on the sensor (I rarely see any kind of dust on my film, and obviously the shutter is covering the film).

Also, shouldn't there be a pretty easy way to avoid this dust? We already have the dust "shake-off" systems, but these are pretty inefficient. I would think that it would be easy enough to have some kind of sacrificial static or otherwise strips in the camera body that would attract dust, but I don't know the technical implications of that.

Another issue with rangefinders in particular is the angle at which the light hits the film/sensor - would it be impossible to include the basic shake-off systems or filters if you're trying to build a thin/sensitive/whatever sensor with a complicated microlens structure?

These are just my curious ramblings, please give any insight you can or explain the obvious to me. Cheers!

 

[payasam]

We already have the dust "shake-off" systems, but these are pretty inefficient.

I have had an Olympus digital SLR for almost a year without dust problems, and India is a damned dusty place. Olympus give their system the absurd name Super Sonic Wave Filter.

 

[Olsen]

I have used my M8 together with, first, my 1Ds II, and later with my new 1Ds III. To get good pictures I stop down my DSLR shots just as much as the ones I take with my M8. To my experience, the M8 is just as vulnurable to dust as 1Ds II. I only used a blower to clean the sensor. Which is only limited efficient. But I never touch the sensor with anything myself. I leave that to a local Canon serice shop here in Oslo.

The 1Ds III is a totally different animal altogether. This is the first camera I have with this sensor 'shake' system. It works wonders. Along comes also a software solution with further a possibility to eliminate spots. I have not had to use yet, which shows how effective the sensor shaker is.

One more thing; the M8 is easier to clean than the 1Ds II because it is not Full Frame.

 

[philippereyniers]

Very useful info !

I had dust on the sensor of my M8 very soon after I bought it. I read somewhere on the forum that the aperture mechanisms "spits" tiny spots of oil on the sensor 🙁 Consequence : my dealer sent it back to Solms !

The M8 is a diva...

 

[Olsen]

I found my M8 to nor better or worse than my 1Ds II regarding dust. On both sensors there occured from time to time 'dots' that would not be blown away. - I have no idea why or what that might be. Both Canon and Leica, along with the rest of the camera business, uses carbon lubricated shutter mechanisms. That Leica's 'spits' more than competition is a theory I don't believe in.

By the way....

I looked up some of my old 6 x 6 cm slides and ran them through a scanner. Sweat was dripping down my back when I saw all those scratches and dust spots. So, the world has become a better place - regarding clean images, with digital photography after all...

 

[gavinlg]

Yeap, pretty much. I guess I sort of prefer the way dust/scratches work on film because it's not always the same, meaning it's not the $1500 instrument you're using that's faulty, it's the $5 roll of film. But that's not really logical thinking.

I am (excuse my noobishness) still confused about how the dust gets on the sensor in the first place... is it only during exposure (when the shutter is open and the picture is being taken) or is the sensor left bare in the body cavity with the shutter somehow open and when you change your lens, dust gets in and can stick to the sensor? I understand it may have something to do with the sensor being charged (inherent of CMOS/CCD) and that attracting the dust to it... but if the shutter is closed, then how does the dust get to the sensor? Would it then not be possible to just, like, blow out the dust that has accumulated in the body with a lens off and then put the lens on, getting rid of dust in the body?

The shutter itself covers the sensor normally unless you either open it to taken a shot or activate manual sensor cleaning. What happens is that dust gets into the cavity in front of the sensor around the mirror (in an SLR) or around where the mirror would be if it were an SLR (m8). Generally whenever you change lenses you expose the cavity to dust in the air and when you close a lens on it it gets trapped in there. The other thing that happens depends on wether the body and lens is sealed or not. In the case of a body and lens with no or minimal weather sealing (eg - 40d/m8) dust can enter pretty much willy nilly through places like the card slot, usb slot, lens mount, popup flash, battery chamber etc. Specifically in the case of DSLRs, using a zoom lens creates a vacuum behind the lens where the mirror is which sucks air/dust through any cracks/crevices it can find wether that be the lens mount, the camera body/card slots or in-between the zoom/focus rings on the lens.
So that is pretty much how it gets in there. Olympus/zuiko digital lenses are generally an exception to the whole "sucking dust in like a vacuum" as they're extremely well sealed. I noticed when I first got my e-3 and 12-60 that when zooming the lens in and out, I can actually hear the seals in the lens barrel, and the air struggling to get past them.

The reason why it sticks and clings to the sensor itself is because the sensor is an electromagnetic device which tends to emit a static charge. This charge magnetizes dust particles in the vicinity which then are attracted/magnetized to the sensor. This is also why a bulb blower wont always work when trying to blow the dust off manually.

Now, ways to prevent it or minimize it:
Try to buy weather sealed bodies and lenses (sorry m8 users). The top nikon and canon lenses and bodies are pretty well sealed. The olympus e-1/e-3 are the best sealed cameras on the market, and the zuiko digital lenses are extremely well sealed as well.
Secondly try to change lenses in areas with minimum dust. For instance you wouldn't do it in a dust storm or on a windy day on a gravel track.
As far as trying to prevent it from getting into the camera thats about as much as you can do...

For a low/no risk way to try and clean it, go to your bathroom, turn the shower on (hot water) and run it for a few minutes so there's a little steam in the room. This tends to de-magnetize the airborne particles in the room (and the bathroom is the most dust free room in most houses).
After you've turned the shower off and waited a few minutes get a big bulb blower, activate manual sensor cleaning on your camera, and hold the camera, lens mount facing down at the ground, and stick the tube of the bulb blower into the lens mount. Give about 5-8 big puffs of air and then turn the camera off/mount the lens back on (closes shutter). Go outside and shoot the sky at f22 or smaller, and see if it helped.

As for the mentioned dust vibrators on the sensors of some of the new canons/nikons - basically they don't do so much. My d300 had sensor cleaning go everytime it was turned on and off, and after 3 months of using just 2 lenses, the sensor had a large amount of dust showing up above f8. My old 5d was the same, and a friend with a 40d and it's vibrating sensor cleaner has the same problem.

On the other end of the scale, the olympus "super sonic wave filter" actually is VERY effective. Silly name, but after just over a year with my E-410, there is literally NO dust on it. My E-3 also has no dust on the sensor at f22 after about a month. I've used it in the rain and on the beach as well.

So to sum up, be smart about where and when you change lenses, buy a sealed camera/lens if possible, and if you really don't want to have to worry about your digital camera being a dust magnet, buy an olympus.

 

[gavinlg]

Sensor dust is not on the sensor; it is on the glass cover in front of the sensor. Because there is a physical distance between the sensor and the dust, aperture makes a huge difference.

Yep. The dust sits on the anti aliasing filter which is a thin piece of glass in front of it. Technically it's a part of the sensor itself but it still creates distance between the dust and the actual sensor itself. Having a lens wide open or say f1.2-f4 means that the dust is so out of focus it wont show - much like shooting through a wire fence at f1.4 - the fence won't show up in the picture. Shooting at f22-f32 brings the DOF closer to the sensor so it brings the dust more into focus.

Generally speaking you won't be able to see dust in pictures on an m8/5d/d3 at around f8 or wider unless you have some serious crap on the sensor.

 

[Keith]

My sensor on my M8 is a little on the nose regarding dust spots but they're only ever noticable in certain shots .... it takes a few seconds to clone them out so I don't bother cleaning the sensor.

One day I'll get around to doing something about it but the whole sensor cleaning thing scares me a little so I take the option of just leaving it. They've been there since I bought the camera! 😛

 

[gavinlg]

My sensor on my M8 is a little on the nose regarding dust spots but they're only ever noticable in certain shots .... it takes a few seconds to clone them out so I don't bother cleaning the sensor.

One day I'll get around to doing something about it but the whole sensor cleaning thing scares me a little so I take the option of just leaving it. They've been there since I bought the camera! 😛

When I had a canon 30d a few years ago the very first one I bought had multiple smears on the sensor at around f16. Not just dust - literal smears of oil.

The shop replaced it straight away.

 

[kuzano]

Ah,... the old Apples/Oranges problem.

Ah,... the old Apples/Oranges problem.

1) Dust on the image sensor has the same effect as if you had dust on the surface of the film. Rarely a problem with 35mm cassettes. Large Format sheet film people know about this problem. The spots are there in the image, regardless of optics.

2) Dust in the lens changes the image based on f stops. It is true that if you look closely at the two blue sky images, the one that supposedly shows no dust actually does. There is one big spot on the right center of the image that corresponds to the worst of the many spots on the second image.

Number one and two images are representative of dust specs in the lens or on the lens.

Those dust specks would look identical if the dust were on the digital image sensor (or on the film)

Furthermore, cleaning the image sensor is not for the faint of heart. Using incorrect brushes or blowing dirt in a way that scratches the surface of the sensor can ruin a digital camera. Have any of you considered the replacement cost for a "SORRY but your handling of the sensor damaged it... No Warrantly coverage!" M8 sensor.

 

[Highway 61]

Another nice mystifying issue.

Best thing is to just not think of that dust spots/stains problem unless you are that exceptional photographer who shoots artwork masterpieces everytime you depress your digital camera shutter button.

If you are one of the average photographers around occasionally taking an excellent photo from time to time, well, PhotoShop will get you rid of the dust /dirt spots for this very photograph after a 10 minutes job in front of your monitor.

Option 1 should get you in a very bad mood OTOH chances that you obbey the Option 2 rules are 99.99%.

And if you are in a mix between Option 1 and Option 2, you're one of the Eclipse and Sensor Swabs manufacturers potential customers.

Till the Apocalypse settles in.

😀

 

[delft]

I find the 'Arctic Butterfly' a very usefull tool to clean my 20D's sensor whenever I can't stand the dust anymore. It's a nylon brush that gets a static charge by spinning it around with the built-in motor, and it brushes off the dust particles from your sensor quite effectively. It should work on an M8 too.

Light on your path,

Dirk

 

[victoriapio]

I find the 'Arctic Butterfly' a very usefull tool to clean my 20D's sensor whenever I can't stand the dust anymore. It's a nylon brush that gets a static charge by spinning it around with the built-in motor, and it brushes off the dust particles from your sensor quite effectively. It should work on an M8 too.

Light on your path,

Dirk

Get my sunglasses out Dirk 😀 Yes Dirk is right, no one needs to be afraid of cleaning their sensor. Get the Visible Dust or any other good sensor cleaning system and clean them. Takes under a minute for the Leica or DSLR.

O.C.