effect of light correction on night photography

[rmphoto]

im really into night photography..

i found a hoya 80 B light correction filter laying around...

just wondering what the effect would be to shoot some night photos with it?

 

[doxx]

An 80B is basically a cooling filter, to be used with daylight
balanced film (or digital)

so street lights (and other Tungsten lights for that matter)
will be not as yellow/orange like they usually are...
BUT the 80B filter slows the exposure down by one stop.

 

[rmphoto]

i think that will be nice...


if it slows it down by one stop, then i should be leaving it open a little longer than normal?

 

[Hertz van Rental]

i think that will be nice...


if it slows it down by one stop, then i should be leaving it open a little longer than normal?

Yes. Open up the aperture 1 stop or go down I stop on shutter speed.

 

[rmphoto]

but im talking exposure times.. on bulb

its always left at f8 with night photos, so say a regular shot i would leave open for 20 seconds... with the 80b filter i would leave it 25?

would that make sense?

 

[Unimaxium]

Well a stop is defined as a doubling or halving of exposure time or aperture area. So theoretically, a 1 stop difference would mean you would have to go to 40 seconds with the filter on if you were to do 20 seconds without it. However, there is a characteristic of film and I think also CCD sensors (for digital cams) called reciprocity failure, which is something that I don't completely understand. Although what I do understand about it is that at very long (or fast) shutter speeds, a doubling/halving of exposure time does not actually double or halve the brightness recorded on the film or sensor, as it would at more normal shutter speeds. This means that you might have to make the exposure even longer than 40 seconds (I think). For more info you can probably google it or search on this forum for a better description.

 

[rmphoto]

hmm thanks for the info.

i think the best way to find out is to just try it.

ill just slap it on for a second shot and leave it open a little longer..
testing is the best way!

thanks