zoom lens a dumb question

<p>I was really happy till last week. During a conversation, someone told me that any zoom lens above the number of its lowest zoom in multiple of 10 will be a scrap. For example, 18-200mm lens is a scrap according to him 10 multiple of 18 is 180 but the highest number is 200 in this case and so lens do not perform at its best. I did some search for this but not convienced by this argument.<br>

If it is true, why 18-200 mm lens are so popular in the market. (my lens is 18-200). </p>

<p>Well, it used to be more glaringly obvious than it is today, so a lot of these "highly negative" comments are from folks who have been doing this for twenty years and they formed their opinions back in the day.</p>

<p>The truth (according to me) is that modern optical design has come a long long ways, and a (Nikon) 18-200 that's performing correctly is "almost as good" as its less zoomy cousins. (I mention Nikon because that's the only one I've played with.) They're several giant steps above "crap".</p>

<p>Having said that, I will predict that one day you'll see images from a 3x "pro zoom" or a non-zoom prime lens and notice that they have a little more snap, a tad sharper image. Then you'll have to ask yourself whether it's worth the money / loss of convenience to trade up. Many of us who have way too much equipment would rather take the lightweight "kit zoom" or ultrazoom on vacation and leave the heavy artillery at home.</p>

<p>I would have called it less then optimal and f5.6.</p>

<p>The 18-200/3.5-5.6 is actually a very good lens. It is sharp, has low chromatic aberation and the distortion is acceptibe. Its main disadvantage is slow speed (aperture) and that it is not sealed against the elements very well. At nearly $1k, it is hardly a cheap lens. A plastic 28-80 Nikkor kit lens can be had for $80 or so on the used market.</p>

<p>Allowing the aperture to vary with zoom allows the designer to create a much longer zoom range with good optical properties, keep the weight and cost to a minimum. Its performance overall is comparable to prime lenses in its range, only slower. "Professional" quality, f/2.8 zoom lenses are generally better than the prime lenses they replace, at least in the wide to normal focal lengths, but cost (and weigh) two or three times as much as a consumer zoom lens.</p>

<p>Much of the distaste for zoom lenses originated with early models (e.g., the 43-86 Nikkor), which had really poor image quality. These opinions linger partly out of nostalgia for the "old days". There are a few real gems in prime lenses amid a vast array of dogs. The most strinking examples are in the long lenses, from the 300/4 AFS to super-telephotos. I use a 55/2.8 "Micro" for its sharpness and high resistance to flare, and occasionally a 50/1.4 for its extremely shallow depth of field. With ISO 25400 at my fingertips, lens speed is a moot point.</p>

<p>Ten years ago when I got my first camera and took my first course I was told anything over 3X was crap. As stated years ago these might have been true. At the time I had the standard 28-80 kit lens and the 80-200 zoom. I had a friend that had one of the 28-200 'wonders'. At that time when we compared photos we both agreed mine were generally better.<br>

However, he was happy with his results, as all he was looking for was vacation snaps and liked the convenience of one body with one lens. Instead of broad condemnations you have look at the performance of each lens and decide if it meets your needs.</p>

<p>Canon 35-350 in my bag - lots of fun and lots of sharp contrasty images:</p>

<p><img src="http://www.john.macpherson.btinternet.co.uk/Resources/img00103a.jpeg" alt="" width="654" height="440" /></p>

<p><img src="http://www.john.macpherson.btinternet.co.uk/Resources/beinn314a.jpeg" alt="" /></p>

<p><img src="http://www.john.macpherson.btinternet.co.uk/Resources/rum00867a.jpeg" alt="" /></p>

<p><img src="http://www.john.macpherson.btinternet.co.uk/Resources/rum00872a.jpeg" alt="" /></p>

<p><img src="http://www.john.macpherson.btinternet.co.uk/Resources/asd211a.jpeg" alt="" /></p>

<p><img src="http://www.john.macpherson.btinternet.co.uk/Resources/alamy12a.jpeg" alt="" width="654" height="440" /></p>

<p><img src="http://www.john.macpherson.btinternet.co.uk/Resources/stock21a.jpeg" alt="" /></p>

<p> </p>

<p>Long excursion lenses (18-200) (18-270) etc, can not hold a candle to lenses with far less excursions (80-200) (70-200) (17-35) etc..etc...</p>

<p>Keeping so many lens elements in proper collimation is no small feat optically; not to mention the inherent light sponge these many elements create...can't fight physics.</p>

<p>Where the multiple of 10 came from I have no idea.</p>

<p>I (had) the Nikon 18-200 for about a year. I purchased it out of curiosity and hope springing eternal.</p>

<p>This lens optically speaking is far from what I require in IQ.</p>

<p>As a hobby lens or for the casual shooter, it fills the bill nicely.<br>

Plenty has been written about this particular lens, so I won't belabor the point.</p>

<p>All lenses involve some compromises in their design, even prime lenses. The fact that an 18-200mm has a lot of compromises in order to reach that utility in terms of reach does not make it "crap". If absolute sharpness is the <em>only</em> criterion used to judge lenses then almost any zoom lens ever made is going to come up short when compared to a series of modest aperture prime lenses. We used to get by changing the lens every time we wanted a different focal length, to be sure; but relatively few people these days are willing to not accept the results of a few contradictions in order to have the convenience of a zoom.</p>

<p> I would imagine the 10x factor was an old standard for full frame zooms. As the format, or image sensor decreases in size, that number should go up. I have the 18-200 Nikkor, which is not as good as my 80-200 2.8, but is a wonderfully useful all around lens. Tell your friend to put away his parachute pants and move into the new century. : )</p>

<p>This little math formula for determining quality without seeing the picture sounds like a real thin hypothesis to me. I can feel the idea; I could expound; yet, I feel there's already too much marketing BS in that 10X whatever bit that it'd be wrong to accept the premise of the question.</p>

<p>I'd skip that formula and use a lens that you like.</p>

 

<p>Conceptually, the factor of 10 was a sort of useful guide in the old days due to design compromises manufacturers had to make. As computer aided design and lens production methods have improved from manually grinding lenses to computerized grinding to fine specs, so has the optical quality of many zooms to where this old idiom is no longer necessarily accurate. You do get what you pay for, so when looking at zooms with a wide zoom range, make sure the other characteristics of quality are there and understand the potential shortcomings and usually the need for increased post production work at some point in the zoom range - especially barrel and pincushion distortion.</p>

If you're happy, that's what counts.

<p>A lot of people are prone to exaggeration and/or pomposity. An 18-200 will not be as sharp as a good 17-50 f/2.8 and 70-200 f/2.8. That's a fact. It's also a long way from saying that the 18-200 is crap. A Corvette may not be as good as a Ferrari, but it certainly isn't crap.</p>

<p>Sharpness can be measured objectively. "Sharp enough" is totally subjective. To some people a single-use camera is sharp enough. To others only a large format view camera is sharp enough. Judging by the sales of superzooms, lots of serious photographers find them sharp enough. I do.</p>

<p>The exception is that if one is a pro, sharp enough is up to the client.</p>

<p>Thanks for all these information, especially Todd, Edward, Jim, JDM, Stephen and Mark for important points to be considered.<br>

Other thing with my zoom experience is, I was always using autofocus and the pictures were never satisfying. Recently I tried with manual focusing and also by bracketing and well, I got good results and happy.<br>

here is one pic shot from the top of small mountain at 200mm. I am really happy with this result.<br>

Thanks again </p><div></div>

<p>The lens should auto focus without a problem. What camera are you using it on? Are you using AF-S, AF-C, or AF-A? AF-S is best for stationary subjects. AF-C (continuous) is best for moving subjects. AF-A works like AF-S until it senses motion and then it switches to AF-C. There are also several AF Area Modes. Using the wrong AF mode can result in unsharp focus.</p>

<p>Try using AF-S (or AF-C with a moving subject) with Single Point AF and use the center focus point until you learn how to use the others. That is in effect what you are doing when you use manual focus. It's all explained in your manual.</p>

<p>It's just an old rule of thumb, used to describe what should be evident anyway. Rule of thumb are not "rules", but they more or less describe reality. There's no way that a zoom with such a range is going to be as good a lens as one with a shorter range. It has to be too complicated, with too many compromises. You don't even need a rule of thumb to tell you that. Such lenses are popular in the market only because beginners and snapshooters as a group tend to like big, wide-ranging zooms that will cover all the needs they think they have - one of which they perceive as the coolness of being able to take pictures of far away scenes from wherever they are standing. When taking pictures of things from a long distance, there's too much stuff in the air between you and the subject, even if the lens was the best lens in the history of the world. So, in essence, you would have been better off starting out with a shorter wide to medium zoom, and a medium to long zoom.</p>

<p>Thanks Mark.<br>

Pierre you made a very good point.</p>

<p>Pierre is entitled to his opinions, but his statement that these lenses are limited to beginners and snapshooters is just plain wrong. I got my first SLR in 1967 so I am hardly a beginner or a snapshooter. I personally know several other experienced outstanding photographers who use them at times. If you look at the reviews of the Nikon 18-200 VR at B&H you will find that of 131 reviewers 51 are enthusiasts, 21 semipros, 8 pros, and only 28 are casual users. They give the lens 4.5 of 5 stars. If you look at the Tamron 18-270 VC you will see similar results.</p>

<p>Mark<br>

Sorry, I mean, even I am not convienced by Pierre's words about beginners and snapshooters but I was impressed with his words "When taking pictures of things from a long distance, there's too much stuff in the air between you and the subject, even if the lens was the best lens in the history of the world"</p>

 

<p>It's a rare situation indeed when your choices of perspective for shooting a given scene or subject would require such extremes as going from super wide angle to 200mm telephoto. The only reason I can see for having a zoom like that is for being able to shoot anything you might encounter on some vague walkabout without ever having to changes lenses, or having to use your legs. If that's your reason, fine... but for the price of a really good 18-200 zoom, you would have lots of money to explore other ways to spend it... and if it's a cheap super zoom, it's not worth owning anyway given the other possibilities.<br>

<br /> But look, even if you don't agree with me on that (and I know I'm a minority of one), your photography will be infinitely better if you zoom with your feet rather than relying on a super wide to telephoto zoom lens. In my humble opinion, a fast lens is a lot more useful and fun than such a zoom... The latter are why you all need cameras that can work at ISO 3200.</p>

<p>Pierre<br>

LOL, ya its absolutely true that zooming with foot is far better option than zooming with a telephoto for sure and also fast lens is a lot more better, but that was not the issue I raised.<br>

The fact that, why I choose 18-200 was, its really dusty in India and one cannot change the lenses more often. For this reason I went to this lens (I think I posted a thread in PN before buying this lens asking for suggestions). Also ease of this lens made me crazy in handling ie., no need to carry additional bag for extra lens. Most of the time I just take my camera, thats it, even no bag or anything which is connected with my photography. Thats why I like this lens a lot. But as you said I need to compromise a little for this but you know I am happy because I am not a prof.</p>

 

<p>Pierre, I live in NYC and I do a lot of shooting on the street and in the parks. I find the superzoom invaluabe for this kind of shooting. I could be shooting the Bethesda Fountain in Central Park at 28mm and then see an interesting individual near the fountain. By the time I change lenses the moment's gone. I've been doing this for 40+ years. I've used primes and short ratio zooms and missed a lot shots until I started using superzooms.</p>

<p>A second reason I like superzooms is that I'm 66 and traveling light is a necessity. I'm in pretty good shape, but I'm not a kid anymore. I spent yesterday walking around Battery Park and Lower Manhattan in 87 degree heat. I carried three lenses, a Nikon 10.5mm FF FE, a Sigma 10-20, and a Tamron 18-270 VC. Carrying the 18-270 VC instead of my Tamron 17-50 f/2.8 and Nikon 70-300 VR makes a big difference after a few hours. Later I'm going to the boardwalk and I'll carry just the D90 or D60 with the 18-270 VC.</p>

<p>On the other hand when I go to the zoo or aquarium I carry my 17-50 f/2.8, Sigma 50-150 f/2.8, and Nikon 70-300 VR. I have time to change lenses and plenty of chances to sit and rest. I also go on cooler overcast days.</p>

 

<p>I don't want to come off giving the impression that I think that strongly about it, Mark. I'm sure you know what works well for you. I'm an easy-going guy, and I certainly wouldn't be one to argue about it.</p>

<p>I just think these are issues that new camera and lens buyers should at least think about before they plop the credit card down on the counter. If we all had the same opinions, there wouldn't be much point in having a forum :-)</p>

<p>Pierre, you're right to point out the weaknesses of superzooms. They are pushed by the lens makers and potential buyers should know their weaknesses as well as their good points.</p>

<p>Well just as Pierre is, as he describes himself, "a minority of one" - I'm perhaps the other end of the scale.</p>

<p>The images I posted above were all taken with a so-called superzoom, and in truth one that is pretty often given a rubbishing on the web.</p>

<p>Often I suspect by either people who've not used it, or only briefly and whose unrealistic expectations exceeded the lens ability.</p>

<p>Image 2 I posted above was taken in arctic conditions, in midwinter at several thousand feet in Scotland's mountains, working on contract for our country's environment agency - so I was being paid for this and there was an expectation of quality. The conditions were severe, strong winds with 60mpph gusts, wind-blown snow, and ice-pellets that would lose your eye, one of which smashed a lens filter such was its velocity. In such conditions changing lenses is difficult if you want to keep snow out of the mirror box. So the ability to go from 35mm wideangle, to 1/4 life size close-ups, to 200mm tele detail shots, and even longer, quickly and easily with no lens changes is vital to getting the work done.</p>

<p>The following year, working for the same organization, documenting a remote island nature reserve I ventured out in gale force winds, that were verging on hurricane force at times, and grabbed image 3 - a view of a neighbouring island with what looks like smoke at its left end but which is a huge waterfall going vertical in the gale, and then zoomed back for image 4 - a view over the bay below me in stormy light. I'm being buffeted by wind, rain and piles of debris, much of which would end up inside the camera if I tried changing lenses, so again the big zoom saves the day.</p>

<p>Later that same year I photographed whales as I crossed to the island, and was able to capture wide shots of people gawping beside me with whales in background at 35mm and then quickly zoom to 250mm for close-ups of the whales, with no worries about getting a camera full of salt spray or whale snot (which folks further up the boat got in the face) if changing lenses. But as happened to people beside me - by the time they changed the lens the whale was gone.</p>

<p>Is the quality as good as a 70 or 80-200 zoom? Of course not, but its good enough for up to A4 and a bit more towards A3 if it all works.</p>

<p>Mark hits the nail on the head - know their weaknesses and strengths and use accordingly. Mine is over a dozen years old, works flawlessly still, and has paid for itself several times over, many images sold through Getty, whose standards are not low. Can you ask any more of a tool?</p>