Zoom Lens' ... some extend, others don't? (Page 2): The only thing that I can think of that makes a really big difference, and probably not that big.... is that the external zoom and...

bkyser Loc: Fly over country in Indiana

The only thing that I can think of that makes a really big difference, and probably not that big.... is that the external zoom and focus lenses have to move air in and out to expand and contract. That draws in dust, which can get inside the lens, and possibly makes it easier for mold issues as well. Internal focus lenses don't have these "issues"

I have a combination of both, and don't worry about it myself.

Bill Emmett Loc: Bow, New Hampshire

I shoot the Tamron SP 24-70mm f2.8 USM lens and it does expand as you zoom.

B

TriX Loc: Raleigh, NC

imagemeister wrote:

The more expensive/better zooms are non-extending "internal ZOOM" - and as far as I know, they are all constant aperture.

Extending Zooms are all variable aperture with the exception of the Nikon 200-500 - and I do not know ( a mystery) how they can make it constant aperture ??

My Canon 24-105L f4 extends and is also constant aperture.

imagemeister Loc: mid east Florida

TriX wrote:

My Canon 24-105L f4 extends and is also constant aperture.

I knew there must be another one somewhere !

amfoto1 Loc: San Jose, Calif. USA

Drdale55 wrote:

Hi,
Wasn't sure if there is a term that describes this issue. Some like my Nikon 200-500 extend when zooming. Others like my Nikon 70-200 and my 2 Tokinas (12-24 and 20-35) do not. Can't find a term in the lens description that describes that. Was actually wondering about the Tamron 24-70 f2.8. Thanks.

Some lenses are internal focusing/internal zooming... they don't increase in length when you change the focal length or focus distance. Your 70-200mm is an example. This type of lens might be easier to seal against dust and moisture and maintains balance better... but starts out larger/heavier, is more complex and typically costs more.

A lens that isn't internal zooming and/or isn't internal focusing is allowed to physically grow longer when zoomed and/or when focused closer, but can be more compact in the retracted position, possibly less complex and less expensive... but may be more susceptible to moisture or dust getting inside. Some lenses of this type even rotate the front barrel when focusing, which is a pain in the arse when trying to use a filter like a C-Pol, which is adjusted by rotating the filter.

jackm1943 Loc: Omaha, Nebraska

Drdale55 wrote:

Hi,
Wasn't sure if there is a term that describes this issue. Some like my Nikon 200-500 extend when zooming. Others like my Nikon 70-200 and my 2 Tokinas (12-24 and 20-35) do not. Can't find a term in the lens description that describes that. Was actually wondering about the Tamron 24-70 f2.8. Thanks.

I have that Tamron and use it on my full frame camera. It does extend a bit, maybe a couple of inches at most. I love this lens, very sharp and it has vibration control. A great all around lens IMO.

Boris77

Drdale55 wrote:

Hi,
Wasn't sure if there is a term that describes this issue. Some like my Nikon 200-500 extend when zooming. Others like my Nikon 70-200 and my 2 Tokinas (12-24 and 20-35) do not. Can't find a term in the lens description that describes that. Was actually wondering about the Tamron 24-70 f2.8. Thanks.

Has anyone mentioned that the 24-70 extends when zooming? Info is in the review details; I do not think it is part of any lens name.
Boris

Kevin Sauer Photography

You're starting to get it but are still missing half.

Internal Focus and Internal Zoom are NOT interchangeable descriptions of a lens moving.

Internal Focusing means that there is no lengthening or shortening of the lens when you are focusing.

Internal Zoom means there is no lengthening or shortening of the lens when you are zooming.

The Tokina 24-70mm 2.8 does have internal focusing, meaning that when you are adjusting the focus on a subject the front of the lens will not move.

But that is only for focusing it DOES NOT zoom internally meaning that when changing focal lengths or "zooming" the front element of the lens will move.

Delderby Loc: Derby UK

Just for the sake of interest and to add another "different" lens type - I have a Panasonic 35-100 MFT lens (2x crop) which collapses to make it very small. To use it, the zoom ring has to be turned a bit to extend the lens about an inch for it to operate. Then, when zooming, the lens extends / contracts further. When focusing the lens does not extend / contract. Made of metal, it is very sharp and has great IQ - making for a good and unobtrusive walk around lens.

Drdale55 Loc: Prescott, AZ

cthahn wrote:

You seem to think purchasing all these lenses is going to help your photography. Take some photography classes and learn about the basics of photography. Start taking pictures and quit worrying about what new zoom lens to purchase.

I remain baffled by bozos in this group. WTF!! What, in my question gave you the idea that I wanted to buy lens' to improve my photography. And what in that message encourages you to tell me to take photography courses and to "Start taking pictures and quit worrying about what new zoom lens to purchase." You know nothing about me or my photography skills, etc. All I was looking for was a term for a "phenomenon" ... zoom lens' that lengthen when zooming and those that don't.

So, before you crawl back in your hole, the answer was internal focus and/or internal zoom. Geeze!!!!!

Drdale55 Loc: Prescott, AZ

Kevin Sauer Photography wrote:

You're starting to get it but are still missing ha... (show quote)

Thanks, appreciate the clarification!

Dale

TriX Loc: Raleigh, NC

Drdale55 wrote:

I remain baffled by bozos in this group. WTF!! Wh... (show quote)

Ignore him... just his usual useless, negative sh*t

jackm1943 Loc: Omaha, Nebraska

To clarify my earlier comment re. my Tamron 24-70, the movement occurs only during zooming, not focusing.