Reading a book (about proper exposure) now I have questions
A little while back I was having some issues with exposure so after some research and recommendations I picket up the book called "Understanding Exposure" by Bryan Peterson.
I'm still a bit unsure about how I feel about the book. In the beginning of the book he talks about the 3 items needed to achieve a correct or creative exposure, shutter speed, aperture and ISO.
As I was reading about each topic I noticed that during his explanations and descriptions of each image all he really described was shutter speed and aperture used and leaving out ISO. At the beginning of the book he talks about ISO and what it is but after that he doesn't mention what ISO he used to compose his shots.
I thought the lack of this information in each instance was a real void in understanding how things tied into each other. Especially for a newbie.
Anyway, one of the questions I have is in the book he makes reference (more than once) of getting his exposure by metering the sky, then recomposing. Is that a normal technique or am I missing something. He never explains in the book.
Thanks
R.
I'm still a bit unsure about how I feel about the book. In the beginning of the book he talks about the 3 items needed to achieve a correct or creative exposure, shutter speed, aperture and ISO.
As I was reading about each topic I noticed that during his explanations and descriptions of each image all he really described was shutter speed and aperture used and leaving out ISO. At the beginning of the book he talks about ISO and what it is but after that he doesn't mention what ISO he used to compose his shots.
I thought the lack of this information in each instance was a real void in understanding how things tied into each other. Especially for a newbie.
Anyway, one of the questions I have is in the book he makes reference (more than once) of getting his exposure by metering the sky, then recomposing. Is that a normal technique or am I missing something. He never explains in the book.
Thanks
R.
Canon 5DMk II | 70-200mm f2.8 IS USM | 24-105mm f4.0 IS USM | 85mm f1.8 prime.
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i've never read his book understanding exposure but based on what I know
ISO, Shutter speed and Aperture are related to get the proper exposure, what is your guide? that's the in built meter in your camera. Basically, one bumps the ISO higher when he/she wants to get faster shutter at a given aperture at the cost of grainy shots.
The best way to learn it, is to try it out.
HTH
its not a normal technique but A technique
you can meter at anything you like ;
the subject , background or .... the sky
different results , check yerself
thats it
ISO is simple ;
lower value = less grain / noise
raise only when necessary [ if shutter speed / aperture is not enough ] [ darkness ]
/ɯoɔ˙ƃnɯƃnɯs˙ʇlɟsɐq//:dʇʇɥ
R.
Another substitute for a grey card is the palm of your hand (since most of us always have one of these with us ) but it usually reads about 1stop brighter than a grey card, so you need to open your aperture 1stop more than metered off your hand. Ziggy has suggested this technique at times.
As to ISO, when folks shot film, to change ISO, they had to yank the film out of the camera, and insert a new roll with a different ISO, not a very convenient way to set an exposure; today, DSLRs make swapping ISO, rather than shutter speed or aperture, a potential way of adjusting exposure. But I really don't swap ISO when shooting, I vary aperture or shutter speed, and only change ISO if really necessary.
Moderator of the Technique Forum and Finishing School on Dgrin
not if you want the sky as subject , and surroundings are unimportant
btw
its just a technique to create different results
no technique is binding , or normal ,.....
and
gray is average .... => not+ , not- .
if you read the mentioned book and see the pictures ,
you see lit sky's with dark / black foreground
[ so , thats why the author measures sky , not foreground or average [grey ]
( i guess )
/ɯoɔ˙ƃnɯƃnɯs˙ʇlɟsɐq//:dʇʇɥ
Moderator of the Technique Forum and Finishing School on Dgrin
You can meter for the sky, then recompose and hit your subject with a bit of flash, and viola - a shot that doesn't look like it was shot in a cave...
or am I thinking of a Joe McNally book? :photo
Now I have to find my copy and look it up....
You might check out "Incident Light Metering"…
- Wil
After using what ever method of metering, A rule odf thumb you should use is: shutter speed should be 1/iso and aperture is f16 for a bright sunny day. Adjust aperture for hazy-maybe one stop-or F16. etc.
Your exposure should be in the neighborhood of these settings.
ISO is like setting a battery checker for a voltage range. If you set the checker to check AA batteries(1.5 volts) but put a 6 volt battery on it, it will peg as full, even if the 6 volt battery is run down. Conversely if you set the meter to check say a 9 volt battery, but check a AA(1.5 volt) it will look low, even if new.
Once you choose an ISO setting, it is in the background of your subsequent selection of aperture and shutter speed.
The best ISO for quality is always you cameras native, or lowest numeric ISO-Canon is 100 I believe, Nikon is 200. Even a long exposure may be better at say 200 on a Nikon than 6400 ISO, in terms of color and contrast. Now using a long exposure time means no movement from the subject so keep that in mind when deciding what ISO to choose.
Hope this helps.
R
I think he's commenting on my comment about reading.
R.
http://sites.google.com/site/inexpensivemacrophotography/home
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Smugmug
Forgive me if this is a duplicate - I can't see my earlier post.
The reason he mentions metering off the sky is because a blue sky (or green grass, or wet tree trunk) are all 18% gray. So you can get an accurate exposure that way, even if your subject is a white boat or a black dog where your camera's built in meter would be fooled.
You can also always get an accurate overall reading of a front lit subject by using the sunny f16 rule. If you meter at the blue sky using that rule you will see that the sky is a neutral for your meter - 18% gray .
Well, sort of. What you are really doing when metering is setting the camera so that your metering sample is treated as 18% gray. Whether that works or doesn't depends on the luminosity of your subject matter. If the sky is a bright overcast, for example, and your subject is a black dog, you will lose all detail by metering from the sky unless you apply exposure compensation. Modern cameras have more sophisticated metering modes (spot, partial, center-weighted average) that give you better control than sunny 16 or meter off the sky, but you need to understand how they work and decide for yourself what's important in the image.
Yes.
Shutter speeds run by the same ratios 1/25th, 1/50th, 1/100, 1/200th, 1/400th, 1/800th etc
Full ISO steps are ISO 100,200, 400, 500, 1600
Thus apertures, shutter speeds, and ISO can all be altered and yet let the total amount of light admitted to the sensor remain equivalent by the appropriate choices of values of each.
Metering is complex because most shooters only use the Reflected light meter in their cameras, which is only able to measure the amount of light entering the lens, but does not know if the subject being measured is a white snow field in bright sunlight, or a black cat in a coal mine. That is why you must interpret the values your camera gives you. A 16% grey card helps because you KNOW it should read in the middle of your histogram, not white and not black, but mid grey.
One way to avoid the difficulties of a reflected light meter is to use what Hollywood uses to shoot movies - an Incident light meter, like the Sekonic L-358 - it reads the actual light falling on the subject, and whether white or black subject, both should be exposed more correctly than with an uninterpreted reflected light meter.
Moderator of the Technique Forum and Finishing School on Dgrin