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Photography Question 
Darren S. Thomas
 

Aperture and shutter speed question.


Hi, can anyone help me figure this out please.

I bought a film camera a few weeks back and I am still understanding the settings and whatever.

My question is if I get a light meter reading of:

500-8 250-11 125-16 6--22 3-32

What shutter speed setting would I use to take a picture with a aperture speed set to 2 or 2,8. The lowest I can set according to my light meter is 500-8.

The shutter speed on my camera goes from B 30x 60 125 250 500.

Thanks, and I hope that makes sense.


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12/21/2007 3:42:47 PM

 
Darren S. Thomas   I mean my light reading is:

500-8 250-11 125-16 60-22 30-32

Sorry


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12/21/2007 3:45:50 PM

 
Alan N. Marcus   Hi Darren,
The values you provided are:

1/500 second @ f/8 - 1/250 second @ f/11 - 1/125 second @ f/16 - 1/60 second @ f/22 - 1/30 second @ f/32

All fiver of these yield the same exposure as to light energy reaching the digital chip/or film inside the camera.

The first is one five hundredth of a second (very fast to stop subject motion at a sporting event or track and field event. The f/number or aperture is f/8 about the middle of your lens opening settings.

The second one two hundred fiftieth of a second at f/11 is the nest slower speed but still quite fast to arrest moderate subject movement. The f/number f/11 allows half as much light to enter as f/8. Thus f/11 is a smaller aperture that provides increased depth-of-field.

The third is one one-hundred twenty-fifth of a second at f/16. This is a moderate shutter speed good for most occasions. The aperture setting of f/16 provides widespread depth-of-field.

The fourth is one sixth of a second at f/22. a moderate shutter speed for subject void of fast action. The aperture f/22 yields a very wide span of depth-of-field.

The fifth is one thirtieth of a second at f/32. This is the slowest safe shutter speed that can be hand held. Slower and you will need a tripod mount to steady the camera. The f/32 supplies enormous depth-of-filed.

Alan Marcus (marginal technical gobbledygook)
ammarcus@earthlink.net



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12/21/2007 4:10:59 PM

 
Alan N. Marcus   AMENDMENT

The fourth is one sixtieth of a second at f/22. A moderate shutter speed for subject void of fast action. The aperture f/22 yields a very wide span of depth-of-field.


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12/21/2007 4:16:48 PM

 
Darren S. Thomas   Hey, thanks a lot for the answer. I been taking my pictures with the opposite settings. I thought lower the f stop, the more increase in field of depth I had. Duh!

My light meter makes more sense now too. Thanks again for taking the time to explain it to me, I appreciate it a lot.

Merry Christmas.


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12/21/2007 5:24:35 PM

 
Alan N. Marcus   We go just a little deeper into the subject:

The f/numbers explained:
The camera lens gets its name from the lentil seed it resembles. The lens projects an image of the outside world, focusing it at the focal plane which is the position occupied by the surface of the film or electronic chip. This image is allowed to play briefly on this surface by the shutter which acts as a gate. A lens is much like a funnel in that it gathers light. The larger its diameter the more light it gathers. Thus the diameter of the lens is a key controlling factor regarding how bright the projected image will be. In addition to diameter, image brightness is a product of scene brightness and lens focal length.

Needed is a precision way to control image brightness. The optical solution is an adjustable control over the working diameter of the lens. This takes the form of a washer shaped restriction or stop called an aperture. This mechanism is technically known as the Iris, so named after the Greek god of the rainbow (colored portion of the human eye). Sometimes it’s called a stop, so named after a set of thin metal slides, with different size holes, invented by John Waterhouse in 1858, they were inserted into the lens barrel, and each stopped a different amount of light allowing repeatable adjustments over image brightness.

Photo scientists concluded the logical sequence of adjustment should be in 2 x increments i.e. twofold brightness change stop-to-stop. To accomplish, this, the diameter of the aperture hole can be enlarged or reduced by a calculated amount thus causing a shift in the area (square measure) of the hole in twofold increments. Scientists recognized that when dealing with a circle you must vary the diameter multiplying it by the square root of 2 which is 1.414. This math calculates a revised diameter that generates a circle with a twofold area increase. Conversely if you multiply the diameter of a circle by 0.707, you calculated a revised circle with a twofold area decrease.

Using 1.414 (rounded to 1.4) a number set emerged:
This is set is called the full stop set or the f/stops:
1 – 1.4 – 2 – 2.8 – 4 – 5.6 - 8 – 11 – 16 – 22 – 32 – 64
Note each number is its neighbor on its left multiplied by 1.4
Note each number is its neighbor on the right multiplied by 0.7

Your camera lens will not envelope all the numbers in this number set. Likely the widest will be f/2.8. This aperture allows lots of light to enter but you sacrifice depth-of-field. Likely your camera will stop at f/22, a tiny aperture that greatly restricts light but provides a great span of depth-of-field.

Alan Marcus (marginal technical gobbledygook)
ammarcus@earthlink.net


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12/21/2007 5:48:32 PM

 
Andy 
BetterPhoto Member Since: 5/28/2002
  I always enjoy Alan's lecture ;)

Anyway, go back to your original question. The fastest shutter speed on your camera is 1/500 second at f8. If you want to use f2.8, that's 3 stops faster, that is, the shutter speed should be 1/4000 second. In order to use f2.8, you have to reduce the amount of light entering the lens. A simple solution is to use some kind of filter to reduce the light, like a polarizer. That's about 2 stop of light lost so you can use f4. Or you can use a 3 stop neutral density filter. Hope this helps.


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12/22/2007 4:22:06 AM

 
Darren S. Thomas   Thanks for the help Alan and Andy, I'm sure this will help me take better pictures. Thanks a lot, I appreciate it.


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12/22/2007 5:45:30 AM

 
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