Really Long Shutter Times

[Dionysus]

pardon the noob question..but often times, on some pictures, I see a shutter time up to 30 minutes. I was playing around w/ my new XSi, and it seems it can only go up to 30 seconds in shutter priority mode, and in manual mode, after 30 minutes, theres an option for "bulb"..no idea what that is, but how do you set really long shutter times? or is it just a limitation of the camera?

 

[realitycheck3907]

Hey bud, the word bulb comes from a long time ago when they used a bulb to hold the shutter open it would push into the release tripping it and holding it until they let go of the bulb. Now, you just need a remote shutter release to hold it as long you want to. Yours will probably be a switch type remote.
like this one, http://www.tvsdepot.com/product.php?id=181146&ref=froogle

 

[ANDS!]

For the XSi you need [ame=http://www.amazon.com/Canon-Wireless-Remote-Control-Digital/dp/B00004WCIC]RC-1[/ame] to use BULB mode effectively. You CAN simply dial your shutter speed to "BULB" (if its the same as the Nikon, its one past 30-seconds), and keep the shutter depressed - but for 30-minutes; of course not. So for 20 bucks you get the wireless remote, which also helps with group shots or shots of landscapes that you want to be (stand in front of camera and push button).

 

[Joves]

With digitals you must remember that hold the shot for 30 minutes is not good on the sensor. It will heat up alot. When I used to do astrophotgraphy my CCD camera was nitrogen cooled to keep me from frying the sensor and, that was for 10-20 minute exposures.

 

[Dionysus]

awesome guys..thanks...i was wondering how that was done. appreciate the help.

 

[Dionysus]

With digitals you must remember that hold the shot for 30 minutes is not good on the sensor. It will heat up alot. When I used to do astrophotgraphy my CCD camera was nitrogen cooled to keep me from frying the sensor and, that was for 10-20 minute exposures.

good to know...what is a safe time range to avoid frying the sensor?

 

[KD5NRH]

So why didn't the "T" mode catch on? (i.e. push to open, push again to close) It seems so easy to implement on anything with an electronically controlled shutter. Is there just too much chance of leaving the shutter open accidentally?

 

[ann]

they can both be used.

with bulb the "bulb" was actived with air and one had to hold the bulb down , once released the shutter would close. was used quite often for taking pictures where the photographer was standing away from the camera.

t mode is used for long time exposures for the basic reason you have mentioned.
when all cameras had cable release sockets, it was an easy and cheap technique. Now remote devices must be used and based on which body one is using the remotes can become very expensive.