Long exposure test shots.

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R32-Simon

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Simon
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Afternoon all :)

I've been reading a magazine in my lunch and it suggests for long exposures at dusk/night etc to do a quick test test shot. They suggest put my ISO at the top and my lens wide open. Then take the shot. Check exposure. If it looks ok then to drop both the aperture and ISO one at a time whilst upping the shutter speed one at a time. Well that was how i understood it anyway. Now I think I understand what they are saying but has anyone else got a better way to explain it so I camels it sink in abit better.

Many Thanks Simon.
 
Exposure can be put a simple value

Aperture x iso x shutter speed = "correct exposure"

(please notice it is the correct exposure, not the right exposure)

So if you want the same exposure and you are reducing the iso, you must inturn change another value (shutter speed and aperture here) so that the "correct exposure" is constant.

You can get exposure calculators for android and iphones. The one I use, you type in the exposure settings for the test shot at the top, it will then calculate the shutter speed based on the ISO and aperture you want to use for the shot. It will even work it out if you use ND filters to increase the shutter speed.
 
Ah, but have you got your 1,000,000 candle power torch to go with your app when you get it?

(Digital camera magazine?)
 
I believe that your test shot is to test your focus. It's basically suck the light in (low f + high iso) and see how it looks. If you feel you've framed it well and it's in focus, then start the long exposure shot (by dropping the ISO and upping the shutter & f)
 
you might of done as it did right a bell when I read you typed, but not very loudly :lol:

I got the idea for using an exposure app from one of the magazines
 
^Joe said:
I believe that your test shot is to test your focus. It's basically suck the light in (low f + high iso) and see how it looks. If you feel you've framed it well and it's in focus, then start the long exposure shot (by dropping the ISO and upping the shutter & f)
Click to expand...

:plusone: :D I will do exactly this :lol: I don't get all this using of app to calculate exposure

Matt
MWHCVT
 
There were a couple of articles in there both of which were about night shots one was painting with light, I'm guessing that was the torch comment?? I made a note of that to try :D. However my comment was on another piece after on general night shots.
 
^Joe said:
I believe that your test shot is to test your focus. It's basically suck the light in (low f + high iso) and see how it looks. If you feel you've framed it well and it's in focus, then start the long exposure shot (by dropping the ISO and upping the shutter & f)
Click to expand...

Ah right. I got the impression you did the quick test shot to check the exposure was to your liking (but creating a noisy shot etc), then if it was you would adjust accordingly to get a better picture. Rather than do a 3 minute exposure to find it was wrong. I must have misread tho :(
 
R32-Simon said:
Ah right. I got the impression you did the quick test shot to check the exposure was to your liking (but creating a noisy shot etc), then if it was you would adjust accordingly to get a better picture. Rather than do a 3 minute exposure to find it was wrong. I must have misread tho :(
Click to expand...

Nope you read right.

Your camera cab do the calculations up to the shutter being open for 30 seconds. After that you need to work out the exposure yourself and use bulb mode. You will need to time the exposure with a stop watch or use a programmable remote shutter.
 
DorsetDude said:
Ah, but have you got your 1,000,000 candle power torch to go with your app when you get it?

(Digital camera magazine?)
Click to expand...

I've that torch that powerful but lost the charger some time again, and when it was fully charged it only lasted 20 mins max :(
 
Last edited:
^Joe said:
I believe that your test shot is to test your focus. It's basically suck the light in (low f + high iso) and see how it looks. If you feel you've framed it well and it's in focus, then start the long exposure shot (by dropping the ISO and upping the shutter & f)
Click to expand...

This sounds really interesting as one thing Ive struggling with is focus.
 
Dale_d3100 said:
Nope you read right.

Your camera cab do the calculations up to the shutter being open for 30 seconds. After that you need to work out the exposure yourself and use bulb mode. You will need to time the exposure with a stop watch or use a programmable remote shutter.
Click to expand...

Would I be right in thinking the following

30 second shot at 1600 would be a
60 second shot at 800
120 second shot at 400
240 second shot at 200??

Thanks for all the responses everyone.
 
R32-Simon said:
Would I be right in thinking the following

30 second shot at 1600 would be a
60 second shot at 800
120 second shot at 400
240 second shot at 200??

Thanks for all the responses everyone.
Click to expand...

Yes.
 
Simon.. this may help you or confuse you further, it's something that I find useful.

The Ultimate Exposure Computer uses EV (exposure value) numbers to represent the overall exposure. You can look up an ISO, shutter speed and aperture combination and come up with the EV number. Any combination with the same EV number will have the same exposure.

The above just uses part of the UEC, it's a bit marmite with folk on this forum but personally I find it very useful for generating a starting exposure for the first test shot in low light and after some practice I find it's usually pretty much spot on (good enough for a film shot in low light without a meter). I keep a printout in my camera bag, although I've adapted it to give a quick look-up for filter compensation, etc.
 
HoppyUK said:
Yes.
Click to expand...

Thanks :)

Alastair said:
Simon.. this may help you or confuse you further, it's something that I find useful.

The Ultimate Exposure Computer uses EV (exposure value) numbers to represent the overall exposure. You can look up an ISO, shutter speed and aperture combination and come up with the EV number. Any combination with the same EV number will have the same exposure.

The above just uses part of the UEC, it's a bit marmite with folk on this forum but personally I find it very useful for generating a starting exposure for the first test shot in low light and after some practice I find it's usually pretty much spot on (good enough for a film shot in low light without a meter). I keep a printout in my camera bag, although I've adapted it to give a quick look-up for filter compensation, etc.
Click to expand...

Wow thanks. I'm only on my phone at the moment but I'll defiantly take alook at that later.
 
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