another night photograpy exposure question...

[moni_patil]

Hi, tonight I was trying to shoot a building with lights using my

Maxxum 5 and ISO 100 film. The problem was that the scene was beyond

the camera's exposure limits..i.e. required more than 30 second

exposure at f/5.6 . My question is how do I calculate the exposure

when the on-camera meter cannot do this for me? I am confused...i

have read up on night photography and they give a guide with several

situations telling us to use -1 to -10 EV etc...how do i calculate

what EV is required for that particular photo and translate it into

shutter speed? the camera meter only shows from up to +/- 3...i have

seen EV numbers going up to 20 and so on.

 

This is definately a dumb question but i need to learn...

 

thanks,

moni

[stephen hazelton]

The +/- 3 EV numbers you refer to probably mean an adjustment of +/- 3 EV, or over/under exposure by +/-3 EV, not 3 EV absolute.

 

1 second at f/1 is EV 0. Count up or down from there. Each EV number is half the light of the previous number; so EV 1 is half the exposure of EV 0. On the f/stops, each stop from f/1, 1.4, 2, 2.8, 4, 5.6, etc., is a halving of the light. On the shutter speeds, each shutter speed, 1, 1/2, 1/4, etc, is a halving of the light.

 

So say, someone recommends exposing at EV -1. That would be f/1 at 2 seconds. Or f/1.4 at 4 seconds. Or f/2 at 8 seconds, or f/2.8 at 16 seconds, etc.

[cole_petersburg]

First of all, the EV system is based on factors of two. Doubling the exposure is done by doubling the exposure time or doubling the aperture area. Because relative apertures are calculated from the diameter, a setting of f/5.6 gives twice the exposure of f/8 at the same shutter speed. A=pi*r*r=pi*diam*diam*0.25 and +1/2 stop shutter speed is 2^(1/2) = 1.41 times the previous time.<BR>

EV 15 corresponds to the Sunny 16 Rule: 1/ISO, f/16. The sun itself, I have found, is somewhere above 27 because I can't make exposures any shorter. Reflected starlight is around -5 EV.<BR>

Here's what I do: write down a table of numbers. Change only one number at a time. I find myself repeating "More light, less light, more light, less light" in my head if I don't have paper handy. Soon you won't need paper most of the time.<BR>

(EV) (ISO) (Shutter) (Apert)<BR>

15 200 1/250 f/16<BR>

15 200 1/500 f/22<BR>

14 200 1/500 f/16<BR>

14 100 1/250 f/16<BR>

(less)100 30 f/5.6<BR>

Simply set your camera to ISO 3200 or however high it will go, and convert from there. Look up The Ultimate Exposure Guide online. It provides some great tables and lighting examples. A building illuminated by street lights should be between 0 and 5 EV.<BR>

Then adjust for reciprocity failure; film manufacturers make this info available in their technical publications. ISO 100 film shouldn't be too bad. Maybe 1/2 stop for 30 seconds; no big deal.<BR>

The great thing about negative color film and reciprocity failure is that your exposure can be almost indefinitely long, and an extra thirty seconds won't even correspond to one stop. When in doubt, keep the shutter open longer.

[cole_petersburg]

Make that change two numbers at a time... That keeps the total exposure the same each time.

[scott_lewis3]

Hi Moni. If you want realy long exposure times then you might want to invest in a good light meter and remote cable RC-1000 (s or l). Then its as easy as taking a light reading, setting the camera to bulb, set the f. then you can shoot the shot. With the rc-1000 you can lock the shutter open as long as you want (think its up to 8 hours with new batteries).

[manuel_garcia5]

Moni,

 

Here�s the quick & dirty way to get your photo depending on your comfort level with your Maxxum 5. Set the camera to Manual mode (shutter, aperture, focus). Once in Manual mode set the focus, set the aperture to the widest your lens can handle (like f/22) and set the shutter speed for 8-10 SECONDS, not hours. Your EV scale in the viewfinder many start to blink + or � 3 depending on how long you have the shutter open for. That�s OK because it doesn�t understand your metering. Mount on a tripod and set the self timer, press the shutter and step back, you�ll hear the camera beeping. The faster it beeps the sooner the photo will be taken. You will then hear the shutter open and then 8 seconds later you�ll hear it close. Play around with the shutter speed and take notes on how long you had it open for reference. Take it up to 2 minutes, have fun with it. This is pretty much what I did two weeks ago when I wanted to capture a bright moon over my house. Except I didn�t think of setting my camera to Manual mode and wished I would have to get a better depth of field. Hind sight is 20/20. Good luck!

[steve foster]

Manuel,

 

The widest aperture is the lowest f number not the highest.

[moni_patil]

I found this website with an article titles The Ultimate Exposure Computer...this explains a lot!!!