Dust spots on my sensor

it could also be your lens.

you can send it in for a service, but i think its about R1000
 
Get yourself a blower and a sensor pen, if those dont work you'll want to do a wet clean.

I can't make out what aperture you're using but lenses are rarely their sharpest wide open or stopped down all the way. I suspect you've stopped down quite a bit which also highlighted the sensor dust issue.
 
Yeah, like I said in previous post, I don't know too much about photography and should probably take a course to better understand all this stuff.

Was taken at f32 to get the most detail.

Lens has been changed so probably a dirty sensor
 
JUGGY said:
Yeah, like I said in previous post, I don't know too much about photography and should probably take a course to better understand all this stuff.

Was taken at f32 to get the most detail.

Lens has been changed so probably a dirty sensor
Click to expand...
This might help you understand - http://www.luminous-landscape.com/tutorials/understanding-series/u-diffraction.shtml

And yes, it's almost certainly the result of a dirty sensor. You can always shine a light through the lens if you want to make sure.
 
JUGGY said:
Can someone please advise me how to get rid of these dust spots or do I need to send the camera in for a service? They're all over the place but more prominent in the top center area.

Taken at ISO 200 1/30s @ 50mm with a 450D and a 17-85 lens.
Click to expand...

The easiest way to confirm dust spots is to select a small aperture (at least F16), and take a picture of a blank wall, then pan slightly to the side, and take another.

There are many guides on the web on removing dust from your sensor, but you should always start with the simplest method:
1. Make sure your battery is fully charged, or the camera is on a charger
2. Do a mirror lock-up (check your manual)
3. Use a bulb-blower to try and blow off the dust while pointing the camera down (never ever use canned compressed air, the propellant in the can be deposited on your sensor, making things worse).

If this does not work, then you can move on to the more risky methods. I say risky, because you have to be careful to use the right fluid if you opt for a wet method, or you could damage your sensor (actually, the coating on the low-pass filter, to be precise). The Eclipse fluid is popular, but be aware that the two flavours (original, and Eclipse 2), are different, and you should double-check which one is more suitable for your sensor.

Disclaimer: Follow my advice at your own risk. If you break your camera in the process, you have been warned ...

ps: I know someone who took his Nikon D70 in for a sensor cleaning at the agents, and they did not follow the correct procedure. The battery ran out while they were busy, and the shutter closed on their tools, breaking the shutter in the process. He had to pay for repairs in the end. I would rather break my own camera, than pay someone else to do it :)
 
JUGGY said:
Yeah, like I said in previous post, I don't know too much about photography and should probably take a course to better understand all this stuff.

Was taken at f32 to get the most detail.
Click to expand...

Ouch. You should note that on an APS-sized sensor (which is what the 450D is using, iirc), you will hit the diffraction limit once you go over about F16. In other words, while the depth of field will still increase, your picture will actually become less sharp as you decrease the aperture size.

Explanation: If the aperture is small (around F16), the light starts "fanning out" after passing through the iris (see Wikipedia for info on diffraction). This effectively increases the area over which your hypothetical "single ray of light" will be spread on the sensor. Once the area exceeds the size of a single pixel, the image will become more blurry.
 
At f/32 you will definitely see dust spots. Use a smaller aperture... I cannot look at your image, because I can't see flickr at work, but for my landscapes I normally use between f/8 and f/16. You might not even notice the dust on your sensor (depending on how dirty it is) in that aperture range.
 
Thanks for all the info guys. I've decided to get a sensor wand, lens pen, sensor brush and some air to sort myself out. Most places only do an air clean for R150 and then wet clean in included in servicing at around R500-800

Done quite a bit of reading since posting this, thanks for the links and advice. I found something interesting called the Sunny 16 rule. Interesting stuff

On a sunny day and with ISO 100 film / setting in the camera, one sets the aperture to f/16 and the shutter speed to 1/100 or 1/125 second (on most cameras 1/125 second is the available setting nearest to 1/100 second).
On a sunny day with ISO 200 film / setting and aperture at f/16, set shutter speed to 1/200 or 1/250.
On a sunny day with ISO 400 film / setting and aperture at f/16, set shutter speed to 1/400 or 1/500.
 
JUGGY said:
Thanks for all the info guys. I've decided to get a sensor wand, lens pen, sensor brush and some air to sort myself out. Most places only do an air clean for R150 and then wet clean in included in servicing at around R500-800

Done quite a bit of reading since posting this, thanks for the links and advice. I found something interesting called the Sunny 16 rule. Interesting stuff

On a sunny day and with ISO 100 film / setting in the camera, one sets the aperture to f/16 and the shutter speed to 1/100 or 1/125 second (on most cameras 1/125 second is the available setting nearest to 1/100 second).
On a sunny day with ISO 200 film / setting and aperture at f/16, set shutter speed to 1/200 or 1/250.
On a sunny day with ISO 400 film / setting and aperture at f/16, set shutter speed to 1/400 or 1/500.
Click to expand...
The sunny 16 rule is good to know but the light meter is better :)

I can fully recommend the Sensor Klear II (made by Lens Pen) I mentioned getting here. Less than R200 and so far I've cleaned all four of my cameras which saved me a fortune in cleaning charges. :)
 
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bwana said:
The sunny 16 rule is good to know but the light meter is better :)
Click to expand...

I have another question. Which ISO is best to shoot with? I suppose full daytime then 100, slightly less light then 200 etc, etc, etc?

I had ISO explained to me as follows.

Say you're talking to a room of 100 people, all of them will get what you say. As the room gets bigger the less people will get what you're talking about. ISO works the same in spreading the info you capture over the film. The more it needs to spread the more it's diluted so to speak.

Would that be a good analogy?
 
JUGGY said:
I have another question. Which ISO is best to shoot with? I suppose full daytime then 100, slightly less light then 200 etc, etc, etc?
Click to expand...
The lowest you can get away with is always going the be better but like always it's all about compromise. You have to weigh it against aperture and shutter speed.
 
JUGGY said:
I have another question. Which ISO is best to shoot with? I suppose full daytime then 100, slightly less light then 200 etc, etc, etc?
Click to expand...

For me, the best way to think of ISO is in terms of the amplification factor applied to the output of the individual detectors in the sensor.

Imagine that the value of pixel i in your sensor, v(i), is modelled as:
v(i) = s(i) + n
where s(i) is the signal strength (amount of light) at that pixel, and n is the sensor noise at the time that the value of the pixel was captured. This sensor noise is a combination of thermal and dark current noise, and something which you can not really control. Although the exact value of n will vary over time (it is a random value), one can assume that it will be smaller than some maximum value n_max most of the time. Now we introduce the ISO value, which is modelled as
v(i) = g * (s(i) + n)

For low ISO values (e.g., ISO 100), the value of the amplification factor g is small, and for high ISO values (e.g., ISO 1600) the value of g is large.

If we have lots of sunlight, then the value of s(i) is large, and we can capture bright pictures with low amplification (Low ISO, small g). If we have less light in our scene, and thus a small signal s(i), then we have to increase the amplification factor (High ISO, large g) in order to have a picture with proper exposure.

In practice, the value of the signal, s(i), is not really correlated with the magnitude of the sensor noise, n. This means that a higher amplification factor g will increase the effect of noise relative to the signal. High ISO thus means more noise in your image.

You should therefore aim to use the lowest ISO value that is allowed given that your other exposure parameters (aperture size and shutter speed) are determined by the type of photo you wish to capture.
 
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Below is another interesting explanation I saw on another forum a few months back:

Imagine you have a tap.... this represents the camera. You also have a bucket under the tap..... this represents the photo / image. You also have water (out the tap)...... this represents the light. The object is to fill the bucket exactly ....... correct exposure (don't overfill or underfill). As you open the tap lever, you are opening the aperture and the bucket begins to fill. the wide you open the aperture, the quicker the bucket fills and so your shutter speed (time) reduces. As you increase the pressure (this represents ISO) the bucket will also fill quicker but there are consequences such as splashing (represents noise). Conversely if the lever (aperture) is closed, and you still need to fill the bucket quickly (shutterspeed), then you need to increase the pressure (ISO). If there is not much water (light), then one has to open the aperture all the way and it may take a while for the bucket to fill.
Click to expand...

It can probably be re-written to be slightly clearer, but I thought it was pretty good anyway.
 
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