fool question about long exposure and 30 sec limit

Hi
I am ashamed
but yesterday i was shooting long exposure in the dark

and i did notice the shutter speed did blink 30"

well I realized that 30 seconds is the max, i knew it after there is bulb in manual
i was set to aperture and iso 100

well i could lower the aperture and/or raise the iso

but the question is
i'm talking about long exposure and darkness
in the darkness how could i calculate the exposure ?

i mean i want to keep aperture 9 and iso 100

the camera is limited to 30" , and for example a right speed is 45"

i can go in manual , but again how can i know the shutter speed to obtain a correct exposure?

ps i was shooting with a 5d mark 2 , burst mode AEB +2 ,0 ,-2 but my camera did not perform 3 shots in raw , but i had to press the shutter every time(3 times) , weird because i pointed the camera at a strong light and it was enough press the shutter once to have 3 shots


thanks
cheers

With exposure that long I have found that the best way is trial and error. With exposures that long individual point sources of light may start to overexpose a lot even though the entire frame is very dark.

gjl711 wrote in post #13935070
With exposure that long I have found that the best way is trial and error. With exposures that long individual point sources of light may start to overexpose a lot even though the entire frame is very dark.

thanks gjl711

and what about an external exposure meter ?

Set ISO to 1600, take meter reading, set ISO to 100, multiply time by 16.

Not sure what you might be shooting but you might give this handy make it yourself night calcualtor a go. It is based on The Jiffy Calculator by S. P. Martin and first published in Popular Photography in April 1968. The calculator has a range of 20+ scenes such as burning buildings, neon signs, display windows, landscapes under moonlight, fireworks, etc. You cut it out in two pieces, one which slides within the other to align scene number with ISO in a window; the other window gives f/stop and speed combinations. A "new" Jiffy Calculator is available at http://photocamel.com …-calculator-can-help.html.

Seriously, it work well for getting a great starting point for exposure but bracket, bracket, bracket...

tzalman wrote in post #13935147
Set ISO to 1600, take meter reading, set ISO to 100, multiply time by 16.

good tip
but i need a calculator
thanks tzalman

tzalman wrote in post #13935147
Set ISO to 1600, take meter reading, set ISO to 100, multiply time by 16.

16? Shouldn't it be 4?

No it is 16, it is 2 to power of 4[Stops] .

Trial and error and a good stopwatch are the way to go I think.

Best way is to put your ISO as high as possible and calculate the exposure in relation to ISO 100. 1s at 3200 ISO is 32s at 100 ISO. Use your cell phone to calculate, if you need.

This is not directly related to your question, however you might find it of interest.

You can get past the 30 second max exposure, with Magic Lantern.

http://magiclantern.wi​kia.com/wiki/Unified/U​serGuide

John from PA wrote in post #13935157
Not sure what you might be shooting but you might give this handy make it yourself night calcualtor a go. It is based on The Jiffy Calculator by S. P. Martin and first published in Popular Photography in April 1968. The calculator has a range of 20+ scenes such as burning buildings, neon signs, display windows, landscapes under moonlight, fireworks, etc. You cut it out in two pieces, one which slides within the other to align scene number with ISO in a window; the other window gives f/stop and speed combinations. A "new" Jiffy Calculator is available at http://photocamel.com …-calculator-can-help.html.

Seriously, it work well for getting a great starting point for exposure but bracket, bracket, bracket...

thanks John , nice found , i printed the pdf

mafoo wrote in post #13935841
This is not directly related to your question, however you might find it of interest.

You can get past the 30 second max exposure, with Magic Lantern.

http://magiclantern.wi​kia.com/wiki/Unified/U​serGuide

do you use it? is safe?
thanks mafoo

but about the feature AEB of the 5d mark2

i wanted to take 3 shots for an hdr

i set up the camera in burst mode , and AEB to -2 0 +2

so the camera should take 3 shots automatically


but i found out that in the darkness , night , it does not
i had to press the shutter 3 times to take 3 shots -2 , 0 and +2
and the shutter speed was about 5 seconds , max 15 seconds

is normal?
i have the last official firmware


thanks a lot to everyone

cheers

mantra wrote in post #13936328
but about the feature AEB of the 5d mark2

i wanted to take 3 shots for an hdr

i set up the camera in burst mode , and AEB to -2 0 +2

so the camera should take 3 shots automatically


but i found out that in the darkness , night , it does not
i had to press the shutter 3 times to take 3 shots -2 , 0 and +2
and the shutter speed was about 5 seconds , max 15 seconds

is normal?
i have the last official firmware


thanks a lot to everyone

cheers

I'm assuming you had burst set and held the shutter button down for 1 minute 30 seconds.

mantra wrote in post #13936294
do you use it? is safe?
thanks mafoo

I have not used it, but only because I have no current need for it. There has never been a reported case of this software damaging a camera in any way.

It sits on your memory card, and only loads if you have the app on that card. It does not replace your firmware.