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How do you calculate long night exposures?

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LesMizzell

LesMizzell

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There's a fire hydrant about a block from my house. I walk my dog by it every evening around 1:00 AM. It's leaking (the hydrant, not the dog), water splatters everywhere - and it looks pretty cool with the street light filtering down through a tree onto it. After stopping and looking at it a few nights in a row, I've worked out an angle for a photo that I think would look really nice.

So...

How do you calculate exposure for something like this? ISO 100, f8 or so ... guess that maybe 30 seconds will do, try it, if not, try 40, if not, try 60 and just keep going until it looks right, or is there a more scientific method with less guessing?

How would the rest of you do this?

--

'Not everybody trusts paintings, but people believe photographs.' -- Ansel Adams
 
Err... why not just let the camera calculate the exposure(shoot Av for instance)?
Nols
--
'Ask not what your camera can do for you...' (oh well, you know how this ends)

 
Trail and error.

Digital cameras stay sensitive on long exposures unlike film. But still, at night you got lots of room to work with. You can take 2 shots with pretty different exposure times and not notice much of a difference.
 
LesMizzell said:
There's a fire hydrant about a block from my house. I walk my dog by
it every evening around 1:00 AM. It's leaking (the hydrant, not the
dog), water splatters everywhere - and it looks pretty cool with the
street light filtering down through a tree onto it. After stopping
and looking at it a few nights in a row, I've worked out an angle for
a photo that I think would look really nice.

So...

How do you calculate exposure for something like this? ISO 100, f8 or
so ... guess that maybe 30 seconds will do, try it, if not, try 40,
if not, try 60 and just keep going until it looks right, or is there
a more scientific method with less guessing?

How would the rest of you do this?
Click to expand...
To be honest I'd take an educated guess and work from there. The nice thing about our cameras is the review function. ;-) It also depends on if you want to freeze the water or blur it. For static night scenes I like to use a tripod, high f stop and long shutter speed. But that is for "scenery" shots. Since it sounds like you have the image in your mind already, I think your experimentation will be the only way you'll "get this right" so you are satisfied with it.
LesMizzell said:
--
'Not everybody trusts paintings, but people believe photographs.' --
Ansel Adams
Click to expand...
--
LaRee
http://www.laree.smugmug.com/
http://laree.zenfolio.com/
 
Like others have said, trial and error will get you the answer you need. One other thing you could try, to speed up the trial and error process woudl be to up the ISO to 1600, find an exposure that works and then adjust back down to ISO100 while adjusting your shutter speed (or aperture) accordingly. Takes a little math, but should save time.

--



http://www.trekearth.com/members/Darren/photos/
http://www.darrenmelrose.com
http://dailysomeone.blogspot.com

My name is Darren, I shoot people.
Have camera, will travel
 
Run the camera at the most open aperture and ISO you can and see if the camera will meter for it. Try spot metering on the subject itself. If not, open yourself up to the largest that the camera can meter for and see what comes out. You should be able to work it from there.

If you can simulate the ambient light level at home, then try it in the comfort of your own living room so that you can find the sort of ball park you're talking about. Be aware of slightly strong reflected or ambient light possibly blowing areas of the shot and don't discount throwing a little artistic lighting in to the scene yourself if you have to. Just be aware of the neighbourhood and take a friend if you could be at risk.

--
'No Comment.' It's my quote; so popular that many use it.
http://www.msknight.com/places/oddshots/1.htm
 
Yep, I have done just that before. You get a noise as all heck test shot, but you can get close on exposure.
 
Just to pile on, I'll say trial and error too. Seriously, thats how it's done. For a night shot were I believe it's nearly pitch black but with some ambient light of street lights or lights from surrounding buildings , I'll start out with an exposure of 15 secs, ISO200 @ F/5.6 and go from there, you will find that with long exposures that the exposure time is quite forgiving, a few seconds up or down won't make much of a difference.

Also, and when it is dark, forget using the camera's light meter, switch to "M" mode, use manual focusing, and of course since you are using a tripod, use a wired remote with the 2 second timer (Pentax's implementation of mirror lock up).

--



Kristian Farren
 
Remember if you want the blacks to come out black you'll need to dial in some EV compensation about -1-1.5 stops or so. Because the 'ideal' exposure is that 18% grey (or 12-14%, whatever), auto metering will make blacks overexposed and whites underexposed.

This is important if a large part of your scene is dark or light (night sky or snowy expanses). The opposite is true in bright situations, you may need to OVEREXPOSE to keep the whites from being washed out to a duller tone.

If you can meter off a grey card (using spot or centre weighted), you'll probably be able to get a good start from there. I find that most exposures at night in the city rarely exceed 30 secs with apertures between 5.6-16.
 
A course I did a while back had us photographing Niagara Falls at night. Try one, then increases by 100%.

Double or Half otherwise there just won't be much difference. 1/2 or 1/3 of a stop just don't affect the final product that much.
 
LesMizzell said:
There's a fire hydrant about a block from my house. I walk my dog by
it every evening around 1:00 AM. It's leaking (the hydrant, not the
dog), water splatters everywhere - and it looks pretty cool with the
street light filtering down through a tree onto it.
Click to expand...
My cable remote finally showed up yesterday, so what better to try it out on than the planned shot above? So around 12:30 this evening I made sure I had exactly what I needed in my bag, got my tripod out, woke up my poor cocker spaniel and walked around the block to see what I could come up with.

Above half way there I realized I had made a goof in clothing. It never got below 60f last night - tonight it's 33f. I'm wearing a short sleeved shirt and it's freaking COLD! Whoops! But, this might be even better because the water spewing out of the hydrant will be warm enough to steam and stuff and now the shot I'm planning is going to be even better.

I make it to the other side of the block and stop in disbelief. Oh great, they didn't just fix the hydrant - it's GONE. Nothing there at all. Just a hole in the ground.

I'm glad my dog is deaf. She can't hear me cursing on the way back to the house...

--

'Not everybody trusts paintings, but people believe photographs.' -- Ansel Adams
 
...and don't plan the shot too long.

To be honest, I feel for you. I would have like to see the outcome. Create a new route and find something event more thrilling round the corner.

Good luck!
--
J-A
  • Photography records life
 
I let the camera make the first choice, i then refine it to what i prefer, usually on the first or second shot after the original i have it down to a science, from then on as long as the conditions are simial i manually set the exposure accordingly
--
Mike from Canada

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'



http://www.airliners.net/search/photo.search?sort_order=views%20DESC&first_this_page=0&page_limit=121&&emailsearch=mighty_mike88%40hotmail.com&thumbnails=
 
Why the wired remote vice a infrared remote? This is sort of a general question, the infrared remote has longer range that the wired, so i'm wondering why the preference for wired.

thanks.
--
Phil
 
the wired remote allows you to lock the shutter open for as long as you want ... the infrared remote button has to be held down ...
Philnw2 said:
Why the wired remote vice a infrared remote? This is sort of a
general question, the infrared remote has longer range that the
wired, so i'm wondering why the preference for wired.

thanks.
--
Phil
Click to expand...
--

Shane,Gold Coast Aussie. Lens list in profile. http://www.bigred4x4.com/pic-a-day-2007

 
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