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Old Dec 30, 2006, 1:10 PM   #1
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Can some one help clear something up for me?

A "prime lens" is a "fixed focal length" lens. That means it only has 1 focal length correct? If we're talking about an 85mm f/1.8 prime then it will only focus at the 85mm focal length right? Not at 80mm, 75mm...etc.

What about a "tele prime" lens like the 180mm from Nikon? In this case can this lens focus at all lengths up to 180mm? While maintaining the same "angle of view"? And how would it be different from a standard "telephoto lens"? Or are they really one in the same?

Thanks guys! And Happy New Year!!
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Old Dec 30, 2006, 2:28 PM   #2
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There are prime lenses and there are zoom lenses. Prime lenses are of one focal length. Zoom lenses cover a range of focal lenses. To answer your question,

"In this case can this lens focus at all lengths up to 180mm?"

No, only 180mm. A telephoto lens only has a single focal length. A wide angle lens only has a single focal length. If you want more than one focal length in a lens, you need a zoom lens.

Happy New Year!

the Hun
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Old Dec 30, 2006, 2:57 PM   #3
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rinniethehun wrote:
Quote:
There are prime lenses and there are zoom lenses. Prime lenses are of one focal length. Zoom lenses cover a range of focal lenses. To answer your question,

"In this case can this lens focus at all lengths up to 180mm?"

No, only 180mm. A telephoto lens only has a single focal length. A wide angle lens only has a single focal length. If you want more than one focal length in a lens, you need a zoom lens.

Happy New Year!

the Hun
Thanks dood. Happy New Year to you too!

That answered my question. On to other things...
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Old Dec 31, 2006, 11:18 AM   #4
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rinniethehun wrote:
Quote:
A telephoto lens only has a single focal length. A wide angle lens only has a single focal length. If you want more than one focal length in a lens, you need a zoom lens.

Happy New Year!

the Hun
Not entirely true. There are telephoto zooms and wide angle zooms. The terms 'telephoto' and 'wide angle' simply refer to what focal length is available - typically anything with 28mm or less is considered wide-angle (although not on a DSLR since a 28mm lens becomes 42mm or more - so on a DSLR you need an 18mm lens to really be a wide angle).

Telephoto lenses simply have a longer focal length - usually 150mm or more.

So, an 18-200mm zoom lens is both wide angle and telephoto.


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Old Dec 31, 2006, 12:04 PM   #5
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What part wasn't true John, the part where I said, "If you want more than one focal length in a lens, you need a zoom lens.", or the part where I said, " Happy New Year!"?

the Hun

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Old Dec 31, 2006, 1:03 PM   #6
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Quote:
What part wasn't true John, the part where I said, "If you want more than one focal length in a lens, you need a zoom lens.", or the part where I said, " Happy New Year!"? the Hun
Both those parts were true!

The part that wasn't true was:

Quote:
A telephoto lens only has a single focal length. A wide angle lens only has a single focal length.
Happy new year! (true) :-)


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Old Dec 31, 2006, 5:34 PM   #7
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Where is the untruth?

Ok, I just bought a 600mm telephoto lens...how many focal lengths can I expect to get out of it? Can I expect to get every focal length from 1mm to 600mm? No - Can I expect to get 75mm to 600 mm? No - Can I expect to get 300mm to 600mm? No - I can only expect to get 600mm. Therefore, a telephoto lens has only one focal length.

Am I missing something?

the Hun

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Old Dec 31, 2006, 6:15 PM   #8
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I think you guys all know what you're talking about here. It's just wording issues.

A PRIME telephoto lens only gives you one focal length.
A PRIME wide angle lens only gives you one focal length.

A ZOOM telephoto gives you multiple focal lengths where one is great than about 150mm.
A ZOOM wide angle gives you multiple focal lengths where one is less than about 18mm.

So a wide angle can be either and a telephoto can be either, if you just say wide angle or just say telephoto, then you really arn't giving enough detail to know more than that the lens IS capable of giving a shot at one of those focal lengths.
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Old Dec 31, 2006, 7:36 PM   #9
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Thanks Morag...I forgot to say "prime". What did I say in my reply to the OP?

"There are prime lenses and there are zoom lenses. Prime lenses are of one focal length. Zoom lenses cover a range of focal lenses."

Shouldn't have to say "prime" - the default is "prime". You go online and buy a 300mm telephoto lens for $500.00...The website doesn't say "prime" telephoto and it doesn't say "zoom" telephoto...it just says 300mm telephoto. What do you think they are going to send you - a prime telephoto or a zoom telephoto? You are going to get a 300mm telephoto - one focal length, and one focal length only. If it makes you feel better calling that a PRIME telephoto, then be my guest.

The only guy who's smart around here is the OP of this thread - he got his answer and left happy - without going off into all the semantics.

I'm going with him...on to other things.

the Hun

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Old Jan 1, 2007, 10:43 AM   #10
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Hun,

Quote:
A telephoto lens only has a single focal length

Does that highlight it well enough for you? A telephoto lens does NOT NECESSARILY have just one focal length.

300mm 2.8 prime and 100-400 are both telephoto lenses. One is a zoom and one is a prime.



Just yankin' your chain

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