# When 30 sec Exposure isn't enough, how do you metering?



## duydaniel (Sep 8, 2013)

Hi there,

Yesterday I was shooting a city at night in AV mode.
The camera required more than 30 seconds so I hook in a third party shutter release cable.
But I couldn't find a way to determine how long should I expose the scene because the camera 
doesn't give any number at B mode.

So how do you do this correctly?
I was just guessing the number around 40-60 seconds.
But would love to know how you approach this.


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## wayno (Sep 8, 2013)

Trial and error. Eventually you will just know. Use your histogram after the first test and then work downwards or up. I shoot Bulb 70% of the time for the stuff I do and after awhile, it all becomes surprisingly easy to predict.


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## polarhannes (Sep 8, 2013)

I usually crank up the ISO. If ISO 6400 and 30 seconds deliver the exposure I intended, I lower the ISO to 3200 and expose for 60 seconds. Or ISO 1600 and 120 seconds... You get the idea.
Just use a very high ISO and then calculate the necessary shutter speed for getting the same exposure with a lower ISO.


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## duydaniel (Sep 8, 2013)

polarhannes said:


> I usually crank up the ISO. If ISO 6400 and 30 seconds deliver the exposure I intended, I lower the ISO to 3200 and expose for 60 seconds. Or ISO 1600 and 120 seconds... You get the idea.
> Just use a very high ISO and then calculate the necessary shutter speed for getting the same exposure with a lower ISO.



A+
Nice never thought of that


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## Mt Spokane Photography (Sep 9, 2013)

Don't expe4ct the camera to do a very good job exposing in that kind of light. The light meter is easily fooled.

Estimate the exposure and then take three or 5 frames bracketing it. Cranking up ISO increases noise.


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## risc32 (Sep 9, 2013)

polarhannes said:


> I usually crank up the ISO. If ISO 6400 and 30 seconds deliver the exposure I intended, I lower the ISO to 3200 and expose for 60 seconds. Or ISO 1600 and 120 seconds... You get the idea.
> Just use a very high ISO and then calculate the necessary shutter speed for getting the same exposure with a lower ISO.



This is what i do also. i don't know what camera your using, but on the 5dmk3 when in bulb mode the top LCD counts the seconds you've had the shutter open. Actually, for all i know all canons have had this feature for a while, or not, i just don't know. anyway, sometimes useful. i used to use a kitchen timer, and still do when the camera is positioned in such a way that i can't see the LCD. unfortunately even doing this, you will probably need to just check the LCD and disregard the camera"s meter. it's just not designed for this stuff.


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## dr croubie (Sep 9, 2013)

Gossen Digisix. Once you start using a handheld meter, you'll wonder why they still bother putting all those fancy TTL meters in cameras at all. (OK, it's not a spot meter, but the digisix is smaller than my shorty mcforty and does the job). Meters nominally 0 to 18EV, but does -9EV to +27EV with a trick, by comparison the 1DX only meters 0EV to 20EV.


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## m (Sep 9, 2013)

The lights tend to burn out.
Take two exposures.


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## jdramirez (Sep 9, 2013)

It is like shooting a canon (with canon balls). 3 Shots is all it takes. Shoot the first one... figure out if it is under or over... shoot the next so you bracket the middle... and then eyeball whether it needs to be closer to the first or closer to the 2nd shot.


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## keithfullermusic (Sep 9, 2013)

it seems like its been suggested, but here is what i do:

I put the camera in Tv mode, and set my ISO to whatever I want (usually 100-400), then let the camera decide what it thinks the aperture should be at a 30 second shot. Then, I take the shot. If I like what the camera chose I then switch it to Bulb mode and match the settings. 

Let's say I was at 30 seconds, ISO 200, f/7.1 and I want a 60 second shot- the easiest thing to do would just be to lower the ISO to 100, which would mean that a 60 second shutter would give the same exposure as the first shot. If ISO isn't an option (if I was at 100 initially) and I wanted the 60 second shot, I could go 60 seconds, ISO 100, and f/10 - this would give the same exposure as 30 seconds, ISO 100, f/7.1.

Now, let's say I was at 30 seconds, ISO 200, f/7.1, but now I wanted a 2 minute shot. I could go to Bulb mode, hold the shutter for 2 minutes, drop the ISO to 100, and go f/10. That would give me the same exposure as before.

My point is simple - just find an exposure you like at a time where the camera is able to meter. Then, just do the math.


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## wayno (Sep 9, 2013)

I've done that whole high ISO to test business but in reality, a couple of attempts, using your histogram as a guide is all I need. No need to over complicate it. Lights do blow out but that's the point. They're lights and the key is just to be sure they don't blow out excessively. I use a stopwatch to keep track.


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## duydaniel (Sep 9, 2013)

Thank everyone for your input.
I hope to do better next time.
Here was a pic I shoot earlier

f13
iso 640
32mm (24-105)
35 sec
5D3


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## wayno (Sep 9, 2013)

Nice shot! Well handled light.


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## wickidwombat (Sep 12, 2013)

polarhannes said:


> I usually crank up the ISO. If ISO 6400 and 30 seconds deliver the exposure I intended, I lower the ISO to 3200 and expose for 60 seconds. Or ISO 1600 and 120 seconds... You get the idea.
> Just use a very high ISO and then calculate the necessary shutter speed for getting the same exposure with a lower ISO.



I do it this way too


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## Lichtgestalt (Sep 12, 2013)

i normaly metering at a shorter exposure time and then do the math in my head.. it´s not that complicated.

or today there are apps who do the math for you.


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## GMCPhotographics (Sep 12, 2013)

Lichtgestalt said:


> i normaly metering at a shorter exposure time and then do the math in my head.. it´s not that complicated.
> 
> or today there are apps who do the math for you.



Yep, and if you need a longer exposure than 30 secs, then it's time to pop on a remote release cable, dial the camera into Bulb and use a timer...while being careful to black out the view finder and mask the lens AF window against stray light. 
I usually meter wide open and then workout what aperture I need. Do the maths....it's not hard...for every three clicks on the aperture dial is one stop. f1.4/2.0/2.8/4.0/5.6/8/11/16/22/32/64....each stop (three clicks on one dial) causes a stop the other way on the shutter dial (three clicks). 
If you are tired and suffering from brain freeze....use an iphone app....just becareful of the phone's backlight during the exposure


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## RGF (Sep 14, 2013)

open up a stop or increase ISO by +1 stop. Then reduce F stop or ISO and halve previous value.

Can use trial and error, High ISO and wide open till you get it correct. Then set the desired setting and your exposure should be reasonably correct.


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## Valvebounce (Sep 15, 2013)

Hi GMC
I get the blackout view finder but where is the lens AF window please? I thought AF was done down the big hole in the end facing away from the body! ;D
Last looooong exposures I took were off Hartside near Alston Cumbria, looking back over Penrith, it was so dark I needed the iPhone torch to do the setup, I find the little light in the camera goes off too quick. With snow on the ground and the wind it was bloody cold too, had to work quickly which is difficult when the exposure is 90 seconds or so!
I wish I had some of these tips then as I just guessed, tried it, doubled it, tried it add 50% tried it until I got a reasonable result. I will have to try some of these tips soon. 
Thanks for sharing folks.

Cheers Graham.




GMCPhotographics said:


> ...while being careful to black out the view finder and mask the lens AF window against stray light.


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## bycostello (Sep 15, 2013)

as said above.... get a meter reading at some exposure, iso or aperture and then do the math to get if for the settings you want...


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## alexanderferdinand (Sep 15, 2013)

duydaniel said:


> Thank everyone for your input.
> I hope to do better next time.
> Here was a pic I shoot earlier
> 
> ...



Wow! And I dont see anything blurry because of movement, especially the ships in the water.


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## RGF (Sep 15, 2013)

nice shot. Might try HDR to help reduce highlights from buildings overly bright lights


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## duydaniel (Sep 16, 2013)

RGF said:


> nice shot. Might try HDR to help reduce highlights from buildings overly bright lights



My problem with HDR is that they look faked and not very sharp.
For such a long exposure, the chance of getting blurry images is so high


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