# How do you calculate shooting in bulb mode?!



## sam_justice (Oct 3, 2010)

Was having a browse earlier on flickr and came across a photo which had a near perfect water reflection (and was taken at night) it was a set of buildings which had quite a lot of lights on as well. The photographer said he used an ND filter (iso 100 and f25) to capture the near perfect relflection. I thought I'd have a crack at it tonight shooting a pier (with bright lights) reflecting into the sea.

Slipped on my ND8 filter bumped up the camera to iso 100 and about f22, stuck it in bulb and started shooting. I was waited about 2 minutes and then stopped, the image was so so underexposed I was quite surprised. So, I tried again for 4 minutes, same again. At which point the heavens opened and I gave up.

I looked up the photo again and the exposure time said 173. 173?! 173 minutes?! No wonder my image was so underexposed, but seriously, how can you be so exact when you're shooting in bulb mode when you have nothing to work from?! Another big thing I was worrying about was that the lights would completely blow out the image, seemingly not I gather! Any tips?


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## Josh66 (Oct 3, 2010)

What I do:

Aperture wide open.  Adjust shutter speed and ISO until the in-camera meter tells me *something*.  If I can get the needle to even be visible on the meter, I can figure it out from there.

Once I have the 'right' settings, using all of the settings I don't want - I use that as the baseline and figure out the 'real' settings from there.

Need to stop the ISO down 4 stops?  Raise the shutter speeds 4 stops.  Another 3 stops on the aperture, 3 more on the shutter.

It takes a little math in your head to figure out the shutter speeds, but if you can handle that it works out perfectly.

Usually, I can even figure this stuff out when I'm so drunk I can barely walk, lol.
All it takes is simple addition and multiplication.

The hard part (for me) is converting seconds to minutes and seconds so I can time it with my watch.  780 seconds divided by 60 ... try doing that in your head while you've been drinking, lol.  Somehow, I still do it - and it's right.


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## sam_justice (Oct 3, 2010)

O|||||||O said:


> What I do:
> 
> Aperture wide open.  Adjust shutter speed and ISO until the in-camera meter tells me *something*.  If I can get the needle to even be visible on the meter, I can figure it out from there.
> 
> ...


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## Josh66 (Oct 3, 2010)

Just an example -

Say my meter is telling me ISO 1600 (I want 100), 30 seconds (this will be whatever it has to be), and f/2 (I want f/8)...

Lower the ISO to 100 - that's 4 stops, shutter speed gets bumped to 8 minutes.
30 seconds x 2 = 1 minute; times 2 = 2 minutes; times 2 = 4 minutes; times 2 = 8 minutes.

Stop the aperture down to f/8 (2 stops); another 2 stops on the shutter speed - 32 minutes.
8 minutes x 2 = 16 minutes; times 2 = 32 minutes.

So - f/8, ISO 100, 32 minutes.  Figure in reciprocity failure if you're using film.

It's harder if the baseline shutter speed you're using doesn't double to an even minute...


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## Josh66 (Oct 3, 2010)

I try to use settings that are easy to figure in my head (whole stops), but that isn't always possible...


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## Josh66 (Oct 3, 2010)

If there is an easier way, I'd be interested...

What does everyone else do?

Short of packing a calculator in my camera bag (that's actually not a bad idea), this is all I can come up with...  My cell phone has a calculator on it, so I could use that too, assuming I had it with me.


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## sam_justice (Oct 3, 2010)

O|||||||O said:


> Just an example -
> 
> Say my meter is telling me ISO 1600 (I want 100), 30 seconds (this will be whatever it has to be), and f/2 (I want f/8)...
> 
> ...



That does make sense, I think some test shots are in order tomorrow night.

You should develop some kind of chart, could make a fair amount of money from it.


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## rpm (Oct 3, 2010)

HOLY CRAP!....

>_< well i know who's going to hold off on those uber-long exposures until i break all of that down into it's elements


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## Derrel (Oct 3, 2010)

Long Exposure Photography: 15 Stunning Examples


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## Newcastle Shooter (Oct 3, 2010)

Hello.

If its ok I would like to offer some info/advice. You mentioned going out to give it a bash at night - to be honest, with the camera settings you mention I would skip the filter if you are shooting at night. It gets to the point where there is not enough ambient light to enter the cameras sensor not matter how long you leave the shutter open. Give it a bash with all the settings you said but minus the filter - try 10sec 30sec 1min and judge from there. If you want to use your filter I would go and shoot at either sunrise or sunset. 

Although I am wedding photographer now, for a long while I was a long exposure sunset/sunrise addict so I know a little of what works. The 173 you saw will be secs and def not mins. My shot below was entitled "phenominal lie" simply because the ocean was pretty pretty scary looking. 182 seconds turned it into this below. I also use a ND110 screw on filter but only while there is light. I also like to take shots in the pitch black with no filters. 






Have a look at my stuff on flickr - there is lots of long exposure stuff on there. Although I used 182 seconds - there is no scientific calculation behind this. It would have looked much the same at 150 secs and 220 secs. The reason I stopped was prob to crack open another can of beer  But you would be amazed at how flat and calm ypou can make water with just a 10 sec exposure. Keep practising.


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## rpm (Oct 3, 2010)

nice find Derrel....

thought id add

The Longest Photographic Exposures inHistory - The Latest - itchy i


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## BLD_007 (Oct 3, 2010)

how do you keep the shutter open for an hour? Do you need a special release cable?

I have a pocket wizard and the pocket wizard release cable that has the switch to keep the camera awake. I guess i can use that.


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## Josh66 (Oct 3, 2010)

sam_justice said:


> You should develop some kind of chart, could make a fair amount of money from it.


Probably not as much of a market for that sort of thing as you would expect.  But ... some kind of spreadsheet with the relevant values plugged in shouldn't be too hard to make, I might have to work on that tomorrow...

There's nothing really 'hard' about it, the only 'hard' part is doing the math in your head.  Depending on what settings you get for the baseline, even that isn't very hard.

Try to select a shutter speed that will eventually multiply into a whole minute - 30 seconds (+ 1 stop), 15 seconds (+ 2 stops); ... Then extrapolate from there.

I try to make sure the numbers my meter gives me are easy to work with.  To do that, sometimes you won't get the meter zeroed out...  But, if I can get it to tell me that those settings are 1 or 2 stops underexposed, I can figure it out from that.

Say in the example I gave above, the meter said I was 2 stops under - just double the shutter speed, then double it again - now you're where you want to be.


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## Josh66 (Oct 3, 2010)

BLD_007 said:


> how do you keep the shutter open for an hour? Do you need a special release cable?


Bulb mode with a remote - wired or wireless.  Either works.  You'll need some way to time the exposure too (a watch works good for this).  Some cameras display a timer when in bulb mode.

With film, all-night exposures are no big deal...  Digitally, you have to worry about the sensor heating up (and introducing noise)...


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## dhaval (Oct 3, 2010)

Has anybody tried something like this?
PhotoBuddy - Ambertation.de


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## sam_justice (Oct 4, 2010)

Newcastle Shooter said:


> Have a look at my stuff on flickr - there is lots of long exposure stuff on there. Although I used 182 seconds - there is no scientific calculation behind this. It would have looked much the same at 150 secs and 220 secs. The reason I stopped was prob to crack open another can of beer  But you would be amazed at how flat and calm ypou can make water with just a 10 sec exposure. Keep practising.



Really? But there must be some kind of starting point? Especially when shooting sunset since time is limited.


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## sam_justice (Oct 4, 2010)

dhaval said:


> Has anybody tried something like this?
> PhotoBuddy - Ambertation.de


Certainly seems to be detailed! I'll have to try it


Thanks for the 15 examples, certainly helps. The only thing I worry about when shooting low light is that the street lights and other lights will blow out the image etc. How do you control this?


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## Newcastle Shooter (Oct 4, 2010)

Hey Sam. Somebody said you could produce a chart to calculate long exposure times. I preferred to practice and get an understanding of how long to expose. Charts would not work as there is too many variables - moonlight vs electric light gives different exposures / distance from light / and whats the perfect exposure time when looking at a rock in the sea under moonlight, my perfect exposure is down to the effect im trying to create. 

General rule of thumb based on experience is:

1. If I go out shooting long exposure sunsets and if the actual sunset time is say, 6.00pm - then I will be there from 5.30pm onwards trying a few exposures to see what works best and I will still get lots of light until well after 6.30pm. For all of this I will use a ND110 filter and exposures of 170+sec @ f9 @ iso 200 will be common.
2. Night dark exposures - no filters. If im on a beach in the complete dark and the only light is the moon then exposures of around 170+secs will also be seen. however if Im shooting piers or traffic or city in dark then 30-60secs at f11 iso200 may work.



2010 Monolith Moonrise by Paul Santos Photography, on Flickr
Above 185secs @ f7 @ iso200 no filters pitch black under moonlight

[url=http://www.flickr.com/photos/paulsantos/3762946921/]
	
Branch Out by Paul Santos Photography, on Flickr[/URL]
Tripod stuck out of the window for 60 sec @ f13 to make the lamps star.

Too much mathematics tens to spoil it - just practice, make mistakes, and learn 

Also try shooting in RAW and the tweakability on your image will help you learn too. (if you dont already shoot in RAW)


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## sam_justice (Oct 4, 2010)

Newcastle Shooter said:


> Hey Sam. Somebody said you could produce a chart to calculate long exposure times. I preferred to practice and get an understanding of how long to expose. Charts would not work as there is too many variables - moonlight vs electric light gives different exposures / distance from light / and whats the perfect exposure time when looking at a rock in the sea under moonlight, my perfect exposure is down to the effect im trying to create.
> 
> General rule of thumb based on experience is:
> 
> ...



The thanks button seems to have disappeared, but thanks loads for this. It's my last "hurdle" per se in shooting landscape photography.


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## Newcastle Shooter (Oct 4, 2010)

No probs - happy to help


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## KmH (Oct 4, 2010)

O|||||||O said:


> With film, all-night exposures are no big deal... ...


It depends on the film. Many print films shut down after a period of time and quit reacting to light.

It's called reciprocity failure. Reciprocity (photography) - Wikipedia, the free encyclopedia


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## KmH (Oct 4, 2010)

Newcastle Shooter said:


> Too much mathematics tens to spoil it - just practice, make mistakes, and learn


Absolutely....In time, because of your experience, you can look at a scene and keep your ballpark exposure triad estimated values in the infield - day, night, indoors, outdoors, flash, etc.


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## jwbryson1 (Aug 22, 2013)

Does anybody else have a handy-dandy way to compute exposure time for bulb mode images?


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## runnah (Aug 22, 2013)

jwbryson1 said:


> Does anybody else have a handy-dandy way to compute exposure time for bulb mode images?



Trial and error.


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## KmH (Aug 22, 2013)

jwbryson1 said:


> Does anybody else have a handy-dandy way to compute exposure time for bulb mode images?


You calculate the length of the exposure based on how much light there is in the scene, factoring in the ISO and lens aperture you want to use.

Basically if there is so little light you need to use bulb mode you will need to use a hand-held light meter.
 The concept of 'a stop' of light comes into play.

It's not used here often but the amount of light can be referred to as an f/stop. - "Yo, Ralph! We got f/16 (or f/8, or f/2, or f/64) for the light!"


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## runnah (Aug 22, 2013)

KmH said:


> jwbryson1 said:
> 
> 
> > Does anybody else have a handy-dandy way to compute exposure time for bulb mode images?
> ...



I like my method better, less calculations.


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## cynicaster (Aug 22, 2013)

The few times I&#8217;ve done shots like this, I did the following and it seemed to work quite well:



Set camera to Av mode
Set ISO 100 and whatever aperture I want for the scene
Grab a test shot and if I like the exposure, make note of the shutter speed
Compose my shot, grab focus, switch focus to manual (if not there already)
Multiply the previously obtained shutter speed by 256 to get good approximation of the required long exposure shutter speed
Switch to M mode, set same ISO and aperture as before, but change shutter speed to value calculated in last step
Carefully thread on 8-stop ND filter
Activate shutter with remote release
 
If the long exposure shutter is more than 30 seconds, then obviously bulb mode is necessary.  If your camera supports mirror lock-up, use it, but it probably won&#8217;t matter much for exposures longer than ~1 sec or so. 

Of course, trial and error is a perfectly reasonable way to do this as well.  After you do this enough times then hopefully you&#8217;ll just &#8220;know&#8221; what settings to use, but if you&#8217;re at the sunset of your life and you&#8217;re afraid you might only have time for one or two kicks at the cat before the lighting changes too much, then this method would probably be a good way to make sure you at least get an exposure that falls within the &#8220;tolerance window&#8221; of RAW.


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