High zoom lenses preferred by lousy photographers

Photography equipments are full of trade-offs, and amongst them, cost, optical quality, speed (aperture). When you have a cheap lightweight zoom lens, you're giving up other things: amount of light it outputs for the film, image quality, and variety of pictures.

Amount of light:

For a given focal length, a fast lens (I'm not talking about focus speed, but "how much light it can send to the film/sensor") is usually larger and heavier because it needs more optics to take in light, and to output more light. Fast lenses today range between f/1.2 to f/2.0. Almost all the professionals I know prefer at least f/2.8 or less. Each f-stop is the difference between twice or half the light output (e.g. going from f/1.4->2.0 is one stop, and 2.0-2.8 is another stop). A f/1.4 lens is twice as bright as a f/2.0 lens, and four times as bright as a f/2.8 lens. Given the same focal length a f/1.4 lens will almost always be heavier and bigger than a f/2.0, and much much heavier and bigger than a f/2.8. Not surprisingly the cost of lenses go up exponentially as the f-stop number decreases only slightly. For day time pictures, none of this will matter because there is so much light that using f/5.6 to f/8 to f/11 will suffice. But for night time, or for fast action, you'll need to open up the aperture to allow more light. Let's say it is sunset and you need to shoot your kid's soccer game (approx EV 10). You have the following choices (given that you want at most 400 ISO for a 11x16 picture):

• ISO 400, f/5.6, 1/100 sec
• ISO 400, f/2.8, 1/500 sec

The two exposures above are almost equivalent, but you really need faster than 1/100 sec for sports. Let's say you'll accept 1/500 sec f/2.8 for a sharp-enough of sports motion (f/2.8 allows FOUR TIMES more light than f/5.6). Since most cheap zooms at the longest length START at f/5.6, you won't be able to take the shot, and even if you try to take the shot 1/100 sec will result in blurred motion. Another option is to boost up to ISO 1600 (400->800->1600 is 2 stops or FOUR TIMES more sensitive film), but now you're increasing grains that is not acceptable for 11x16 picture). In this situation the cheap zoom is too difficult to use due to motion blur, and almost useless at night time even when flash is used.


Zoom image quality:

Cheap plastic zoom lenses (aka "kit-lens") usually produce very soft pictures. Even at f/5.6, they tend to be too soft. Compared to a professional f/2.8 lens, at f/2.8 it can yield sharp pictures usable on magazines, and when they go to f/5.6, the quality of the pro lens will surpass the consumer lens by leaps and bounds.

Frequently cheap plastic zoom lenses exhibit a lot of undesirable traits such as vignette, chromatic aberration, etc. The bokeh on cheap lenses tend to be very busy, and ugly. There are those new "super convenient zoom" lenses out there with 11X or more ratio (e.g. the 18-200mm zoom). These may be convenient to use, but their image quality is very soft, the colors are subdued, the bokeh is horrible, and people are now just discovering that these super-zooms take horrible pictures; you'll see a bunch of them used, marked down, on eBay.

In short, you may end up with an affordable long zoom, but you may not end up using it much because you'll be disappointed with the images it produces. Everything is a trade-off of cost, zoom, and image quality.


Substitute for cheap plastic zoom lenses:

The target audience for cheap plastic zoom lenses are beginners, or people who simply don't know any better.

For people who just started in photography, prime lenses (no zoom) are great substitutes because they cost just as much as cheap zoom lenses, but more importantly their image quality rivals that of professional zooms that cost thousands of dollars. They are usually lighter or have bigger aperture. Equally important, they are great pedagogic tools for students to learn about exposure and composition. Prime lenses force the beginner photographer to WALK AROUND to get the composition they want. The act of simply walking around will yield a wide variety of unique shots, and people tend to like variety over pictures that look the same. Variety is the spice of life. You know some people sit in the same location and take hundreds of shots? They will have boring looking pictures; their pictures are very 1 dimensional because they lack varieties.

Moral of the story:

Camera engineering is all about trade-offs. A lens with lots zoom is sacrificing image quality. Camera companies want you to think that you're getting a lot for your money, when in fact they're also taking away other things. Don't fall for the zoom numbers. They mean very little.

High megapixel cameras preferred by lousy photographers

Photography equipments are full of trade-offs, and amongst them, cost, optical quality, speed (aperture). When camera companies pack many megapixel in a little sensor, the sensor will gain an undesirable trait: noise.


Megapixel race:

A lot of beginners think megapixel is a desirable attribute. There's a brand that starts with "C" that is very good at marketing to consumers; they tend to produce plastic cameras with high megapixels bundled with cheap plastic zooms (e.g. 55-250mm IS). Don't get me wrong, I use this brand, and I love the 55-250mm IS as a lightweight substitute for the 70-200mm f/2.8 monster. But I digress...

High megapixels are great if you need to print big sized pictures (16x20"), or if you tend to crop frequently. For most people, this is irrelevant because they only print up to 4x6, or upload to the internet at 1600x1200 (only 2 megapixel). A 12 megapixel APS-C (cropped sensor DSLR) is way more than enough to print a nice 12x16 wedding album. Heck even a 8 megapixel APS-C is more than adequate.

Thanks to marketing, common people now want lots and lots of megapixels (kind of how the layman cares about a CPU megahertz but doesn't care about cache+RAM). Company "C" loves to pack lots and lots of megapixels to consumers. But here's a catch. Noise. The moment you pack a lot of megapixels (and given the same sensor and processing technology), more noise occurs. The noise becomes much more apparent at high ISO, which makes it difficult to use at night. Technology is about trade-offs; nothing is free.

Let me ask you this. Given the following two choices (without using flash), what would you buy?

1. 15 megapixel that looks great when shot during the day and you can print up to 16x20. Good grains up to ISO 800.
   
2. 8 megapixel that looks great when shot during the day but you can only print up to 8x10. Good grains up to ISO 3200.
   

It really depends on your style. For me personally I shoot at night-time frequently. I love shooting at night not because it's easy, but because it's extremely difficult as it is very demanding on the capabilities of the camera sensors and the lens, and the skill of the person behind. Despite years of experience I still make crappy pictures at night, and occasionally good ones; I do it because it's tough, and because it's always an educational and fun learning process. Most people can take technically good pictures (proper exposure) during bright day time using full auto-mode, but very few can shoot well at night. Personally I go for the second option. In fact, since I never print 16x20 and almost all of my pictures are internet sized (1600x1200 or less, or 2 megapixels), choice 2 is more than enough for me. In fact, if I can pick 5 megapixel with super high ISO (3200-256000 ISO) for night time, I'll take it over a 15 megapixel sensor with only 800 usable ISO.



Newest low-end Brand A vs. Brand B at 100 ISO. The two classes are quite equivalent, and look great at ISO 100.



Top Brand X 15MP vs. Bottom Brand Y 12MP, ISO 3200. Pictures saved as GIF instead of JPG since JPG has a way of "smudging" over noise. Note the blue "chroma" noise for Brand X, despite having more megapixel.

Wasted megapixels:

The other interesting thing about camera companies these days is they pair up a high megapixel camera with a cheap kit lens. What consumer end up is having a sensor with resolving power much higher than that of the lens, so the extra megapixels end up being wasted. Pairing up a high megapixel camera with a kit lens is an engineering mismatch, but apparently, it is brilliant from the marketing perspective.

For example if the lens can barely project 15lpmm (lines per milimeter) but the sensor can record up to 30lpmm, then the sensor will still only record 15lpmm from the lens. With this combination, it is no different than buying a sensor that has 1/2 the megapixels, then upsizing it. By doing so, no extra details will be recorded, and the only thing a consumer will end up is having a bigger image and a bigger file, and an underutilized camera.

One similar analogy I can think of is a car company that pairs up a super expensive Y-rated sports tire with a car that barely has 50 horsepower. The Y-rated tire can go up to 186mph. But seriously, I don't know any sportscar with 50 horsepower that can go up to even 100mph. It's wasteful and a plain mismatch to put such a high quality tire on a slow car. However, marketing knows better, and marketing knows that consumers will buy based on meaningless numbers and slogans alone (megahertz? megapixels? 16X CDROM speed? MMX! IT'S A PENTIUM INSIDE!)


Moral of the story:

Camera engineering is all about trade-offs. A camera with high megapixel is sacrificing the ability to shoot well at night. Nothing is free. Don't fall for the megapixel numbers. They mean very little by themselves. One needs to evaluate a camera system as a whole.


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High ISO shoot-out comparisons:

Nikon D5000 (12.1MP) vs. Canon T1i (15 MP)
http://www.cameralabs.com/reviews/Nikon_D5000/noise.shtml

Nikon D700 (12 MP) vs. Canon 5d mk 2 (21MP)
http://www.xtremephotography.ca/Canon-5D2-Vs-Nikon-D700/