Longest exposure time possible with digital cameras?

[anonymous]

What I would like to know is the longest exposure time in digital cameras (never mind the models themselves, they are being constantly crammed into my head by a colleague of mine). For the answer, which need not be made in the timely fashion (I don't care much about the fashion), I thank you in advance.

[McQ]

With most compact digital cameras (such as the Canon PowerShot series), the exposure time is limited to about 15 seconds. However, most digital SLR cameras can theoretically take an exposure all the way until the battery dies (hours and hours) using "bulb mode", however other factors are likely to be more limiting.

This includes fixed pattern noise, and is highly dependent on temperature (lower temperatures allow for longer exposures with less pattern noise). This usually gets bad beyond a few minutes, depending on camera model and temperature. On the other hand, one could always take several shorter exposures in sequence and combine these to create a single long exposure. Keep in mind though that a few minute exposure in digital is often the equivalent of a much longer exposure in film (because the former is not susceptible to reciprocity failure). Hope this answers your question.

[dougpetersonci]

What I would like to know is the longest exposure time in digital cameras (never mind the models themselves, they are being constantly crammed into my head by a colleague of mine).

Compact cameras are often limited to 15-30 seconds by both software (i.e. you can't set it any longer) and image quality (it looks terrible if you go beyond it).

Medium format digital backs like the phase one digital backs can expose for up to an hour without significant noise build up. Here is a chart of temperature versus max exposure for phase one digital backs..

[brianchapman]

I have done exposures up to about 80 minutes (temperature about 50F) with my Rebel XT but as Sean mentioned there was significant fixed pattern noise...enough that the image was not really usable. In Hawaii at 80F even exposures of 8 minutes had significant noise. At Lake Tahoe at 15F I managed a 25 minute exposure which was completely usable...it took my fingers another 25 minutes to thaw though.

I'll look for some samples when I get home and post them here...