Canon 350D Problem

Ballyman

I had a problem today that has been reoccuring recently on my camera. It only seems to happen during long exposures (>1 sec) as well but it definitely doesn't happen all the time on long exposures.

Basically what is happening is I press the shutter release to take the pic and then wait for it to close. When it closes the picture counter on the viewing screen starts flashing and all other numbers on the screen disappear. The picture counter (number of photos left on the memory card) keeps flashing then for ages. Even when you turn off the camera it keeps flashing. Some times after about 10 seconds it stops and the camera then turns off properly. When you turn the camera on again the photo taken is stored correctly.

This evening however the it kept flashing for ages, >30 seconds even with the camera turned off so eventually I removed the battery to stop it as you cannot use the camera while it is flashing. When I put the battery in the camera worked fine again but the photo I had taken wasn't recorded on the memory card this time.

Now initially I presumed that it was the camera writing to the card but as it doesn't happen all the time after long exposures I have kinda ruled that out. This evening threw a new one into the works by not saving the photo onto the card, although it was a 4 min exposure.

Anyone have any idea what this is and what might be causing it? The camera is a 350D and I was using a Sigma 18-125mm lens. It has happened with other lenses though as well so probably no significance with the lens.

Any help really appreciated.

nilhg

Could it be taking a dark frame for noise reduction?

AnCatDubh

I'm not in the canon camp but I don't know how unsual the behaviour you describe is. I find with my gear that the longer the exposure - the longer it appears to take to create the image and flush it to disk. At a guess, it wouldn't be unusual if I gave it a long exposure to take up 20 seconds or more to stop flashing. So, can't say for definite but it mightn't be a problem at all. i'd expect maybe for the 350d to have slower processing than some of its bigger close relations so it may labour more than some but again mightn't be unusual.

Calina

Are you shooting in RAW? My past experience with long/low light exposures with a 350D is that it took ages to write down the file. You just have to let it do the work. How long it takes depends on what you're shooting AFAIR. I don't have a 350D any more.

The fact that it didn't write the image when you took the battery out before he finished writing out the image points to....it writing out the image.

Ballyman

Thanks for the responses. I put this prob on another site also and it may be that I have the long exposure noise reduction turned on and thats whats causing it. I'll try it again tomorrow with this turned off. It makes sense really that the camera is still writing to the card. The card btw is one of those nameless cheapos off ebay so it probably takes forever to write to it.

Calina

Took a while with the Sandisks I was using too.

Ballyman

Turns out that LE Noise Reduction is the problem. On another site somebody said that

Other Site wrote:

Long exposure noise reduction was my first thought as well. If you do a 4 minute exposure with long exposure noise reduction on, the camera will do a further 4 minute exposure with the shutter closed in order to record the noise generated and then remove it from the original exposure.

What is the benefit of using this function in camera? Would it be easier to just remove the noise after through noise ninja or something or would the camera make a better job of it in the first place?

5uspect

Noise Ninja can't recreate the pattern noise inherent in to the camera. So by taking a dark frame you can replicate the noise pattern.

AnCatDubh

I think that there is a trend to push more 'features' in to the cameras which i'm undecided as to if its a good thing or not. I mean in camera at the moment I can churn out a HDR, a selective colouring, apply lots of digital filters, produce a sketch like image as well as a stack of other features. Is it a good idea? Well i suppose if you don't have processing software it could be handy, or if you were doing an event and didn't have processing capability on site, but it is also comparable to what many of the computer operating systems have done and drawn 'bloat' into the core operating environment in an effort to be 'better' than the rest or gain competitive advantage. I've gotten to a point with computers where i don't want the bundled rubbish to be in there and would rather an OS producer would just give me something that runs the machine and allows me to load anything that i need rather than what the manufacturers think is required by the average joe. I wonder will DSLR's become the same?

5uspect

But that's very different to recording a dark frame. By doing so you're measuring a noise signature unique to your camera's sensor. No software can replicate this unless you take a dark frame manually and then subtract the noise manually afterwards in Photoshop.