The term for "lens does not extend during zooming"?


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wongjunhao

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#1
Hi, some of the zoom lens have this feature that the lens barrel does not extend during zooming. May I know what is the term use for that?

Pardon if the question sounds stupid because I'm new to photography.
Please be nice.

Thanks.
 

ahbian

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May 23, 2006
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#2
I think should be internal focusing.
 

Jed

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#5
It's definitely not internal focusing because that pertains to not extending when focusing.

I don't think there is a phrase, which is why lens marketing blurb has more or less the same text as you used.
 

Diavonex

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#6
It's call internal zoom.

I read somewhere that a mirror is use to turn the light at right angle to achieve a reasonable zoom level in a compact/slim enviroment.

Use mainly in ultra-compact camera.
 

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wongjunhao

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#7
Thanks for the replies. "Internal zoom" sounds right.

If only every lens has internal zoom, that would be great.
 

sf_kang

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#8
This has to do with the design of the zoom lens. On some zoom lens, the lens barrel actually extends further and further during the 'zooming', i.e. the overall lens become longer. For the better zoom lens, the designers have managed to achieve the zooming effect while keeping the length of the lens constant (meaning lens barrel does not extend) during the zooming. This is prefered and makes handling more pleasant. For closeup work, it keeps the lens to subject distance unchanged throughout the zoom range. Most of the better and pro zoom lens would have this feature, e.g. the Nikkor AF-S VR 70-200mm/f2.8G, the physical outer dimensions of the lens remain unchanged throughout the zoom range. Hope this helps.
Fred
 

night86mare

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#10
yes the term is internal zoom.

nikkor 70-200mm f/2.8 VR is one example of an internal zoom lens.
 

neech7

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Dec 17, 2009
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#12
Internal zoom + internal focus + non-rotating front element = :thumbsup::thumbsup::thumbsup:
 

#13
i'm using tamron 17-50, when focusing, the length of the lens barrel does not change. Unlike my previous kit lens or 50mm prime lens, when focusing, then len barrel extend in & out.

So i suppose the features you mentioned is the same concept, but zooming(also including focusing) instead of focusing?
meaning the len barrel won't be extended when u do zooming or focusing, everything is internaly within the len barrel.
 

CamInit

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Nov 3, 2009
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#14
Is internal focusing same as parfocal ???
 

CamInit

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#16
So in summary,

Internal focusing = no change in physical length of lens barrel at different focus

Internal zoom = no change in physical length of lens barrel at different focal lengths

Parfocal = no change in focus at different focal lengths

so, i gather that a lens with internal zoom + internal focus + non-rotating front element can theoretically be made by encasing any zoom lens in a large enough barrel? :think:
 

Rashkae

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Nov 28, 2005
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#17
so, i gather that a lens with internal zoom + internal focus + non-rotating front element can theoretically be made by encasing any zoom lens in a large enough barrel? :think:
Nope. You need to factor in the wide angle requirements too.
 

Sep 17, 2008
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#19
cant help it. if u want good stuff its big one:x
 

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