long exposures. how?


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noob117

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Oct 16, 2006
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#1
hey guy/girls.
i hav seen sum pix in the night shots forums.
they expose the pix for like 500 over secs to make a super dark area bright.
how they know the timing to get a ok exposure? not under or over expose?:dunno:
 

Artosoft

Senior Member
Aug 31, 2005
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#4
Agak-agak.

Film is best for long exposure. try long exposure with dSLR, and you will see hot-pixels come out.

Regards,
Arto.
 

lastboltnut

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Mar 23, 2006
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#5
Yah, I have the same question too....read book that says the formular Exposure=Aperture X Shutter Speed is only applicable to shorter shuter speed.....if like <10 sec this formular is not accurate liao....so, need to agar-agar...:dunno:
 

unseen

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Dec 14, 2004
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#6
hey guy/girls.
i hav seen sum pix in the night shots forums.
they expose the pix for like 500 over secs to make a super dark area bright.
how they know the timing to get a ok exposure? not under or over expose?:dunno:
Well I don't know about the rest.. for me I calculate the amt of light..

if ISO 1600, f2.8 = 10 seconds to get proper exposure..
1600 => 800 => 400 => 200 => 100 = 4 stops, so take 10 x 2 x 2 x 2 x 2
then ISO 100 F2.8 = 160 seconds..
F2.8 => F4 => F5.6 => F8 = 3 stops, so take 160 x 2 x 2 x 2
then ISO 100 F8 = 1280 seconds needed for an exposure..
 

blazer_workz

Senior Member
May 8, 2006
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ClubSNAP Community
#8
my explaination is like this..i think the stop system still plays a part..
at 30sec to increase 1 stop its 1min..and for 1min to increase 1 stop its 2min..and for 2min to increase 1 stop its 4min..so on and so forth..hence as the longer ur exposure becomes, the accuracy of seconds becomes insignificant..just my 2cents..
 

blazer_workz

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May 8, 2006
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#9
Well I don't know about the rest.. for me I calculate the amt of light..

if ISO 1600, f2.8 = 10 seconds to get proper exposure..
1600 => 800 => 400 => 200 => 100 = 4 stops, so take 10 x 2 x 2 x 2 x 2
then ISO 100 F2.8 = 160 seconds..
F2.8 => F4 => F5.6 => F8 = 3 stops, so take 160 x 2 x 2 x 2
then ISO 100 F8 = 1280 seconds needed for an exposure..
this is nice way of calculating too:thumbsup: ..will try it out:)
 

lastboltnut

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Mar 23, 2006
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Where the wind blows...
#10
I think TS is asking how you know the initial setting, like you need ISO1600 f2.8 form 10s in the first place?

By the way, when time is >10s (IIRC), your formular is not correct....this is what I read from a book.:dunno:

Well I don't know about the rest.. for me I calculate the amt of light..

if ISO 1600, f2.8 = 10 seconds to get proper exposure..
1600 => 800 => 400 => 200 => 100 = 4 stops, so take 10 x 2 x 2 x 2 x 2
then ISO 100 F2.8 = 160 seconds..
F2.8 => F4 => F5.6 => F8 = 3 stops, so take 160 x 2 x 2 x 2
then ISO 100 F8 = 1280 seconds needed for an exposure..
 

lastboltnut

Senior Member
Mar 23, 2006
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Where the wind blows...
#11
Yah, it's call the reciprocal failure that makes the Exposure=timexaperture inaccurate...:thumbsup:

for film u need to take care of reciprocal failure....
Sorry, I have finally got the time to rectify my statement. the formular is only accurate from 1/1000s to 1s. So anything more than 1s shutter speed is not accurate (but I think it wont affect many of us lah). And it is call Reciprocity Failure, not Reciprocal Failure.

Check out this site on how to compensate for the difference.

However, I am not sure if it affects digi cam....Canon says it doesn't affect their cam...
 

noob117

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Oct 16, 2006
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#12
wah so leceh.
will it like spoit the shutter if its open for too long?
 

dreamerz

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Aug 13, 2005
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www.sherman-photography.net
#13
Yah, it's call the reciprocal failure that makes the Exposure=timexaperture inaccurate...:thumbsup:



Sorry, I have finally got the time to rectify my statement. the formular is only accurate from 1/1000s to 1s. So anything more than 1s shutter speed is not accurate (but I think it wont affect many of us lah). And it is call Reciprocity Failure, not Reciprocal Failure.

Check out this site on how to compensate for the difference.

However, I am not sure if it affects digi cam....Canon says it doesn't affect their cam...
oops...remember the term salar...:sweat:

digital is nt affected as much as film...
 

noob117

New Member
Oct 16, 2006
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west
#15
ic ic
any ideas on any thing to start wif?
i can onli use max of 30secs wif timer.
i dun have remote release. i hold then later cam shake.
 

noob117

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Oct 16, 2006
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#17
may i know how much is a reasonalble priced one for a canno 350d?
 

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