Astrophotography on EOS 650d : problem with 9 min exposures

[wbhart]

I'm having an issue taking 9 minute exposures, which I initially thought was a bug, but now think could be because I'm doing something incorrectly.

I set the camera to M and Bulb mode. In ML I set the bulb timer to 9 mins, and the intervalometer to something bigger than that, e.g. 9 mins 15s. The issue is that after the first exposure, it sits there busy for a further 9 minutes before saving the image to my SanDisk card. It's not possible to do anything, even shut the camera down, during this time. It does eventually save the file.

I don't think there is a problem with the SanDisk card, and I've formatted it both in and out of the camera and reloaded ML.

The problem also occurs sometimes with shorter exposures, e.g. 4 mins, but I haven't seen it happen with 1 minute exposures. I have only seen the problem when saving images in raw mode.

Do the steps I am going through above sound correct? Is there anything I'm missing? Has anyone else seen this problem?

[dmilligan]

Turn off long exposure noise reduction in the Canon menu.