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Old Oct 20, 2003, 3:38 PM   #1
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Default ISO and TTL ?

Whats ISO ?
Some cams has: Adjustable ISO speeds: 50, 100, 200, 400 and that tells me nothing :?

I also heard: Dont buy a camera with TTL, erm...TTL....??
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Old Oct 20, 2003, 4:53 PM   #2
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ISO as defined by Steve:

ISO - The speed or specific light-sensitivity of a camera is rated by ISO numbers such as 100, 400, etc. The higher the number, the more sensitive it is to light. As with film, the higher speeds usually induce more electronic noise so the image gets grainier. ISO is the abbreviation for International Standards Organization. (In the good old days it was known as the "ASA film speed.")


You can also see the definition of TTL (through the lens) under Digicam definitions.
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Old Oct 20, 2003, 5:42 PM   #3
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TTL means "Through the Lens"
i think" :?:
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Old Oct 20, 2003, 7:28 PM   #4
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you would be right
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Old Oct 20, 2003, 10:15 PM   #5
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Cerb

In what context did someone say "Dont buy a camera with TTL"? In most of the situations I can think of, I'd want TTL. TTL usually applies to something like "ttl metering" or "a ttl viewfinder". So saying "a camera with TTL" doesn't mean a lot.

Eric
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Old Oct 21, 2003, 7:20 AM   #6
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Default Re: ISO and TTL ?

Quote:
Originally Posted by Cerb
....
I also heard: Dont buy a camera with TTL....??
The major reason that might be a good recomendation is price: TTL digitals are the most expensive. They are also the best in just about every category - the only exception I can think of is the lack of a live preview. That means you cannot set up to be able to use an external monitor/LCD as a remote viewfinder.
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Old Oct 21, 2003, 8:10 AM   #7
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Quote:
- the only exception I can think of is the lack of a live preview. That means you cannot set up to be able to use an external monitor/LCD as a remote viewfinder.
Electronic ViewFinder (EVF) cameras are TTL based as well (including their flash metering) and you can preview the image, with a real-time histogram I might add (D7s/A1 etc)... But you're right it's something I really missed in dSLR with an 'optical' viewfinder especially for night scenes! :P

BTW the E10/20, even with a TTL optical viewfinder, use a semi-transparent mirror so you can 'preview' the LCD as well...
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Old Oct 21, 2003, 9:13 PM   #8
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i'm not shure :roll: but i think iso stands for International Standards Organization
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Old Oct 21, 2003, 10:18 PM   #9
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Actually ISO stands for "International Organization for Standardization". Then why is it not called IOS? See:

http://www.iso.ch/iso/en/xsite/conta...go/query1.html
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Old Oct 22, 2003, 12:39 PM   #10
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For thoses of us young (or still in diapers) enough to remember. ISO was conceived to combine two norms: the American Standards Association (ASA) and the Deutsche Industrie Norm (DIN). In the early days at least the ISO showed two numbers 100/21, 200/24, 400/27,.... etc, but the 2nd (German) number is too confusing for most average users since its based on a log scale in degree just went out of fashion instead.

The American number is more easy to remember: double the # and one get twice the sensitivity... good old ingenuity(or luck) I guess depending on which arithmetic one prefers: x2 or +3 math (Remember each additional 3dB is twice the power in a log scale?). :lol: :lol: :lol:

http://www.minoxlab.com/Don_Krehbiel/mpl/dkasa.htm
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