Artefacts at slow shutter speed - on sensor?

[John Mono]

Hi all,

I'm a complete newcomer to photography, after recently purchasing my first DSLR in the form of the D40. My first post on these forums is a query regarding artefacts showing in some images.

If I take photos with a slow shutter speed or, in the example below, using the bulb setting, I appear to get a couple of strange artefacts in the image. The Flickr link below shows two images, the left one being the bulb setting, showing two artefacts, and the right one being a much faster shutter speed that shows no artefacts.

http://www.flickr.com/photos/35909012@N05/

My query is - are these being produced due to some dust on the sensor? I have a feeling they might be however I wanted to check, as I was confused to only see the artefacts appear with slow shutter speeds. Perhaps somebody could explain why I'm only witnessing it in these conditions?

Thanks in advance for your time!

 

[mmcp42]

slow shutter speed means small aperture
small aperture will show sensor artefacts

looks like dust so a good blow (with a pocket rocket - not damp breath!) ought to shift it

your camera instructions will tell you how to lock up the mirror first

 

[John Mono]

Thanks so much. Artefacts have cleared just fine now after using the blower.

I just needed to check with somebody to give me the confidence to start fiddling so early on in my cameras life (3 days!).

Much appreciated

 

[mmcp42]

Thanks so much. Artefacts have cleared just fine now after using the blower.

I just needed to check with somebody to give me the confidence to start fiddling so early on in my cameras life (3 days!).

Much appreciated

you'll probably need to repaet on a regular basis
trouble with SLRs - every time you change a lens another gremlin sneaks in and hides!