Tag Archives: zoom lenses

A lens experiment

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On my just-finished Caribbean holiday, I decided to try an experiment.

For most of my travel shots I use the super-wide lens, but I always bring a long lens as well. Normally, the Canon 70-200 f/2.8L IS. A superb lens, but heavy and big.

So this time I used an all-round consumer lens on my second camera- namely, a Tamron 18-270 mm f/3.5-6.3 Di II VC PZD stabilized lens for Canon. Here it is:

And here it is, pulled out to its full length:

I decided to try this lens for three reasons:

  • To see the differences (I have only used expenive lenses for many years)
  • For convenience – 18-270mm in one small, light package.
  • For length: 270mm on my crop camera, the 7D, is 432mm!

So how did it do?

Obviously, the convenience stands out. One lens, not three. And the lower weight. I certainly appreciated that. And the longer effective length. And if I had bought this lens, instead of borrowing it from the importer, I would have also appreciated the great price point.

Through the vacation, the lens performed well. No issues, no trouble focusing, no noisiness, no trouble of any sort. It did what it was supposed to do. I used it in one-shot focus mode, and in that mode, focus worked fine. Vibration Control (“IS” in Canon terms) also worked well – and this function is essential on a long lens.

Sint Maarten Gull (Photo: Michael Willems)

As a regular and intelligent reader, you know there is a price for everything.

In this case, that price is mainly the smaller aperture (f/6.3 when zoomed out, as opposed to f/2.8 on my “regular” pro lens), with additional “small reasons”. Many people would not even notice these, but as a spoiled pro lens user, I do.

So you do need to keep in mind I am comparing apples with oranges here… given that, I see little things like:

  • The lens drops when you aim it down – hence the need for a “lock” button to prevent it doing that.
  • Turning the zoom is fairly smooth, but not as smooth as on my 70-200. The zoom smoothness is also not the same all through the zoom range.
  • Having used pro lenses for so long, the fact that the lens would not go down to f/2.8 kept making me think I was in the wrong mode – each time it took me a moment to realize why the numbers weren’t doing what I expected them to!
  • Especially when zooming in all the way, this lens is not quite as sharp as the oranges it is being compared to. Don’t be put off by that – as said, I am comparing it to a dedicated, heavy, $2.500 lens. The real question is: is it sharp enough? You judge: click on images and then click on “show full size”. This is not full size as it came out of the camera, of course, but it gives you an idea. Of course a tad of Lightroom sharpening takes care of most issues – don’t “pixel peep” too much. (Also – longer lenses are less sharp because of the air moving in between yo and your subject – do not mistake that for lens sharpness!)
  • More barrel and pincushion distortion at the wide and long ends.

A few sample shots:

Sint Maarten (Photo: Michael Willems)

Sint Maarten (Photo: Michael Willems)

Sint Maarten (Photo: Michael Willems)

A wide angle shot; note the pincushion distortion:

Sint Maarten (Photo: Michael Willems)

I was happy (and surprised) to see no appreciable amount of chromatic aberration: I would have expected more on this lens.

Image quality seems a little less when you zoom in all the way – but that is to be expected, and in my view, 270mm is a bonus gift horse that one should not look in the mouth.

So when would I use a lens like this?

  • When I want 270mm – a great long focal length.
  • When I want convenience, and an “all in one” package.
  • When weight and size are an issue.
  • When price is important.
  • When I want to minimize lens changes, eg in dusty environments.
  • When I can only bring one camera.
  • When I expect to quickly need to change from wide to telephoto.
  • When there is plenty of light.

When would I not use it?

  • When shooting in low light environments. f/6.3 is enough in the sun or in a studio – perhaps somewhat less so in low light.
  • When quality is utterly paramount, like when shooting stock photos.
  • When shooting sports (I did not test continuous focus but I expect it would not be as good as the Canon lenses here).

This experiment was successful – I would consider carrying a “one lens does it all” again in the right circumstances, and if so, if only because of its excellent 18-270mm range, this Tamron is high on the list.

Note: As is the norm with my reviews and product mentions, I have not been paid anything for writing this review.

Sharpness strategies

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Today, I helped a student get to grips with shooting with a long lens.

So….was it really all that long? 70-200mm. And 200mm is not actually long when you are shooting small birds, some 10m away:

This was shot at 1600 ISO – it was a dull cloudy day and with birds you want high speed, which means high ISO even when you have a good lens opened up to f/2.8.

So the lens is short. So we have to crop. And when you crop, you see the limitations (click to see this part of the image at full size):

So.. what are some strategies you can use to get sharp pictures?

First, do not shoot through obstructions. Through a clean window pane, and with a filter on the lens, we got this (a small crop out of the image):

Without the filter and window, this becomes:

Better!

Other strategies:

    1. Use a good quality lens. Lenses are not what you should be saving on!
    2. Shoot at a fast enough shutter speed. “1 / lens length” or much better. I prefer to do this by using aperture mode at aperture wide (or nearly wide) open.
    3. Now set the ISO high enough to get a good shutter speed.
    4. Use VR/IS stabilization.
    5. Consider using a monopod (or even a tripod): one with a quick release.
    6. Focus on the background, then focus on the bird, then shoot.
    7. Use One Shot/AF-S focus, unless the subject moves. In that case use AI Servo/AF-C.
    8. Focus on contrasty bits!
    9. Use one focus spot, and avoid mis-focusing.
    10. Light well, if you can – meaning “light bright and expose to the right”. My dictum: “Bright pixels are sharp pixels”.
    11. Take multiple images and use what works. Your lens will mis-focus occasionally.

      Also, consider stopping down the aperture a bit when you have to. Like when the bird is inside a tree… f/2.8 gives you this:

      While f/4 gives you this:

      That depth of field is much better.

      And one more, where a bird is “bright pixels”:

      Concluding, there is not one way to get sharp pictures. The best technique is to try to stack the odds in your favour by using as many of the techniques described above.

      Zoom Power

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      A friend asked me the other day:

      Mike – I don’t understand how to compare the zoom power of my Nikon P100 26x zoom to the Canon 28-300mm zoom with my Canon 5d MkII.

      Good question. But I think it is the wrong question. Or at least, the way the question is asked shows me that it might be based on the wrong premise.

      The term “zoom power” seems to indicate that the ability to chance focal length settings through a wide range is a good thing. Like, a 10-500mm lens would be a good thing. Some even call this “ultra zoom technology” – you know, as in: just add the word “technology” to a term and it somehow gains in value. But only to the ignorant: when someone says “technology” like that, I just hear “marketing”.

      Here’s why I think a wide zoom range (i.e. a wide ability to change from one focal length to another) is not necessarily a great thing.

      First, it is a compromise. The wider the adjustment range, the more this lens will be a compromise at all lengths. A wide zoom range lens will neither be a great wide, nor a great standard, nor a great telephoto lens. Its aperture will be small, and it will vary. It will show pincushion and barrel distortion at both ends. It will not be sharp. The more a lens is like a prime lens, on the other hand, the clearer, faster, and sharper it will be.

      The other reason is that of discipline. With a lens that can go from very wide to very long. you will never have a reason to be consistent in your images. Your pictures will not take on any particular look and feel: rather, each image will be different. Neither fish nor fowl, you might say.

      The reason we have these super zoom compacts is for convenience, of course. But a lot of the time, this is wishful thinking kind of convenience. I hear it often: “yes, but I don’t want to own multiple lenses to get from 10mm to 500mm”. Sure, like I don’t want to die or pay taxes. Both are, alas, inevitable.

      So only you can decide whether you want a wide range zoom camera or lens. To me, the wider the zoom range, the more everything will be a compromise, and the worse my pictures will be. But you may have different thoughts if size and convenience are more important to you than quality.

      My lenses are a 16-35 (“2.2x zoom”), the 100mm, 50mm and 35mm primes (“0x zoom”), a 70-200 (“2.9x zoom”), and a 24-70 (“2.9x zoom”), and they are among the best on the planet. In fact my entire range of lenses from 16 to 200mm is equivalent to one 12.5x zoom, in those terms. This shows you how little those terms really mean.

      But since you ask: a 28-300 mm zoom would be a “10.7x zoom” in marketing-speak. So the compact 26x zoom has a much wider range. 2.43 times wider, in fact!

      Zoom zoom zoom.

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      A beginner’s question this time:

      What does zoom have to do with wide angle? I thought they were two opposite things!

      Not necessarily. A “zoom” lens is simply an adjustable lens. As opposed to a prime lens.

      What you are perhaps confusing with a “zoom” lens, dear student, is a telephoto lens.

      Let me explain.

      There are two main types of lenses:

      1. Zoom – this means adjustable focal length.
      2. Prime – this means not adjustable: you have to zoom in by stepping forward.

      And, an entirely unrelated classification, there are various lengths of lenses:

      • Wide angle – roughly, less than 24mm on a crop camera
      • Standard – roughly, 30-40 mm on a crop camera
      • Telephoto – roughly, longer than 50 on a crop camera

      So a 10-20mm zoom lens is a wide angle zoom lens. A 24-105 zoom lens is a wide-to-telephoto zoom. A 24mm prime is a wide angle prime lens. And so on!