attack_donut
enthusiast
Reged: 16/12/2006
Posts: 284
Loc: East Coast
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I have a Nikkor 35-70 push-pull 'zoom' lens, which I like very much. I know it's good quality and sharp.
I have some that are twist to zoom which are also good.
Just curious, is one design superiour to the other, or is it simply a matter of cost-to-produce?
Cheers!
AD
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So rise up, o ye lost ones
As one we will claw the clouds
Rise up, the forsaken and dethroned
A legion wronged, to claw the clouds
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mediaman
Nearly Laid Back
Reged: 28/07/2008
Posts: 1057
Loc: edinburgh
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Some "push/pull" types,if "weighty" can creep from one focal lenth to another, while the camera is still hanging around your neck.
The more a lens is used, the more chance of this type of "zoomcreep"
Optically, I don't think either lens type automatically makes it a "better" lens
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Kenny.
The tears of laughter were running down my legs.
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GeoffR
Reged: 31/05/2003
Posts: 5068
Loc: Bucks
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Either type can "creep" it really is just a matter of personal preference for the user and convenience for the manufacturer. Though some physically long zooms could become almost impossible to use if they aren't of the "two touch" variety.
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Benchista
Which Tyler
Reged: 11/08/2000
Posts: 42233
Loc: Everywhere and nowhere, baby
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Back in the late 70s, the trombone type were generally much preferred for their speed of use. In the AF era, the two touch type are dominant because of greater precision. I was playing with an old Nikkor 100-300mm f5.6 yesterday, a trombone type, and it's very nice.
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Nick
www.nbrphoto.com
Light and Shade II - the new blog
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El Sid
Going potty
Reged: 14/04/2003
Posts: 10755
Loc: Sussex-by-the-Sea
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I have several zooms in both types and I think I'd just plump for the two touch type as better overall. Most of my one touch (push-pull) types are a bit stiff in operation and a bit tricky to zoom with precision while on the whole the two touch types are better in this respect - although as with most things the original cost, and thereby build quality, tend to have a bearing on ease and precision of use.
Perhaps the exception to this is my 70-210 f4 Series E Nikon which has a very nice and easy-to-use slide - although inevitably it can creep quite a lot if angle up or down too much and not held in place...
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Nigel
Completely BSRIPN 
ElSid Gallery
Terrorist?............or potential photographer?....... 
There are no people more opressed than those who willingly opress themselves
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Malcolm_Stewart
Carpal \'Tunnel
Reged: 11/07/2005
Posts: 4460
Loc: Milton Keynes, UK
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All zooms which change length must act as dust suckers to some degree - the only zoom I have which is fixed in length is my EF 70-200 f4L. Does it matter, probably not in the UK, but in countries where there's dust storms with fine sand, it's a serious issue. (Gets into the USM mechanisms as well if they're not adequately sealed.)
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Malcolm Stewart
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swanseadave
veteran
Reged: 05/10/2007
Posts: 1586
Loc: Swansea, Gateway to Gower
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I have a Sigma 70-210 f4 one touch zoom,which is in Fuji x mount,now unusable since I have no functioning camera on which to mount it.While optically sound,it has always suffered from zoom creep.It must be a design fault.
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Dave CRIPN
If it wasn't for bad luck, I wouldn't have no luck at all - Albert King
Blues is a healer - John Lee Hooker
my flickr
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El Sid
Going potty
Reged: 14/04/2003
Posts: 10755
Loc: Sussex-by-the-Sea
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Quote:
It must be a design fault.
The problem with zoom mechanisms is that they have to be a compromise design to some extent. Too tight and the lens is difficult to zoom smoothly and with precision, too loose and it creeps. As I said above my Series E Nikon zooms very smoothly but does creep quite easily while my much tighter Tamron 200-400 doesn't creep much if at all - but is very difficult to zoom precisely. It's all a matter of swings and roundabouts though, as with much else, I suspect that the more expensive and well constructed a lens is the closer to ideal the compromise becomes.
PS the Nikon E isn't the lens with the worst creep that I have - that honour must go to an aged 35-135 USM Canon which I have previously described as not suffering from zoom creep so much as zoom sprint... In this case I suspect it's a combination of poor design, mediocre build quality and sheer age - boy is it loose... 
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Nigel
Completely BSRIPN
ElSid Gallery
Terrorist?............or potential photographer?.......
There are no people more opressed than those who willingly opress themselves
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parisian
Over the hill and far away...
Reged: 10/02/2002
Posts: 9299
Loc: Môn mam cymru
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Quote:
boy is it loose...
I had an ex-wife like that!
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Hells pensioner - born to be mild
JustMono
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PeteRob
Reged: 30/03/2004
Posts: 71
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Yes you are right. I had not thought of it before but in manual focus days the 2-touch zoom was deprecated. I had a 80-200 f2.8 that I bought s/h mint for next to nothing because it was 2-touch (ok it was a konica mount) so I never used a one-touch and was happy to be different. Now with AF the 2-touch is a de facto 1-touch. Thank you for the insight!
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Zou
Carpal \'Tunnel
Reged: 05/02/2007
Posts: 3040
Loc: Edinburgh
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I have a one-touch 70-200. It works fine when at either extreme (either 70 or 200) but inbetween fine focus is difficult without accidently changing the focal length. I much prefer a two-touch if it has to be a zoom.
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Zou's Flickr Page
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attack_donut
enthusiast
Reged: 16/12/2006
Posts: 284
Loc: East Coast
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Can you kindly explain what the term "one touch" and "two touch" mean? Thanks
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So rise up, o ye lost ones
As one we will claw the clouds
Rise up, the forsaken and dethroned
A legion wronged, to claw the clouds
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Wheelman
Reged: 23/11/2002
Posts: 1017
Loc: Kent/Sussex border
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Term used on manual focus zooms that have sort of carried over......
One touch is a push-pull zoom as you hold it in one position and twist to focus and push/pull to zoom
Two touch is where there are two rings, one twists to focus the other twists to zoom
nowadays with auto focus they are both theoretically one touch as you either twist or push/pull to zoom and the camera sorts out focussing. (unless you turn AF off of course )
Hope this helps
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Colin
IRIPN
When you don't know where you are going then any road will do
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Still_Togging_Along
old hand
Reged: 24/09/2008
Posts: 893
Loc: Reading, Berkshire UK
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I would guess that both 'systems' have their plus and minus points;
The Push-pull versions offer focus-override (when it's an AF version) and zoom adjustment via a single control and some of these also have a DOF markers on the barrel assembly. However, I would guess that over a period of time these optics become 'dust-suckers' due to wear and tear upon the seals used.
The versions with 2 twist rings, may well be 'ergonomically' less satisfactory to some people, because it uses two rings and users could well end up accidentally rotating the 'wrong' ring. However, they may well be less prone to dust-sucking because the mechanism moves around inside the main barrel.
The internal design of the 2 ring zooms, are likely to be more complex, but I would guess only a lens designer would be able to tell you which of the 2 systems, imposes the least compromises due to the accuracy required in positioning the various elements where they need to be.
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40+ years of togging, but still learning!
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beejaybee
Marvin
Reged: 18/07/2007
Posts: 6283
Loc: Really Here In Name Only
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Quote:
However, they may well be less prone to dust-sucking because the mechanism moves around inside the main barrel.
This is a question of how much the volume changes when the zoom is operated, not the mechanism for working it. Many two ring action zooms suck in or blow out a considerable volume of air when the zoom is operated, and some push/pull & twist action zooms don't.
The basic issue is that push/pull & twist action doesn't work with AF motors unless a "continuous MF" clutch mechanism is used, and using the same ring for zoom & focus with a USM type AF drive is asking to get the focus wrong when users don't realise that they're inadvertently over-riding the AF focus mechanism when zooming whilst half pressing the shutter release. Push/pull & twist makes lots of sense when focusing manually, to the extent that two ring action zooms looked like becoming an endangered species until AF became dominant.
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