Zooming in on Type 2

I want to start out this blog on why today’s camera phones actually do a pretty good job.  If you go by the ‘size matters’ analogy, quality should be poor at best since a full frame camera is about 50 times larger.  The better cell phones have sensors that are just a little smaller than the green 1/2.5″ rectangle below at 1/3″.  I should point out that this diagram is not to scale.  Depending on your screen, maybe 3x larger than life.

Relative sensor sizes.


One of the smaller negative films, disc camera, had an image size of about the 2/3″ rectangle, but image quality was less than what a modern cell phone can do today.

To keep things a bit simpler, let me wave a hand and describe the factors that level the playing field between a large sensor and the smaller sensors.  Basically picture quality relates to a signal to noise ratio.  In general, a larger sensor will create more noise.  The relationship isn’t linear, but it levels the playing field some.  Also, another development in the last few years is BSI, back side illumination.  This has improved low light performance greatly in the cell phone world.

As we are talking about leveling the playing field, it should also be noted that the cost of making a fast lens for a small sensor is cheaper.  It is also easier to design a zoom lens with a smaller sensor.

Ok, so we have the basics down, right?  Let’s talk about the person who would like a camera with a better zoom, Type 1.

A point and shoot camera with a 1/2.3″ (6.17 x 4.55 mm) BSI sensor (just a little bigger than the 1/2.5″ sensor) and a 30x zoom can be bought for around $350.  In other words, it covers a 24-700mm full frame equivalent focal length.  It has a minimum f-stop of f3.5 to 6.4.  It will take good pictures in sunlight when zoomed in for your kids ball games… but it will struggle for an indoor shot at graduation or something like that.  Most of these cameras have a minimum f-stop around 3.5, so while the sensor is larger the f-stop doesn’t let in as much light… so shooting a group picture in a dimly lighted restaurant won’t be any better than your cell phone.  Your cell phone does well because it has an f-stop of about f2.2 or f2.4.

Canon Elph 190
Canon Elph 190 IS, f3.0 to 6.9, 10x zoom, about $150

Or a Canon with the same size BSI sensor and a 12x zoom (25-300mm) for about $200.  This camera has an f-stop of 3.6 to 7.0, so it has considerably less zoom, and on average it will probably perform less well in low-light situations compared to your cell phone.  But, the low light performance difference may not be noticeable by most people.  The picture above is of a another Canon that was released at the same time, 10x instead of 12x zoom, f-stop of 3.0 to 6.9, and not BSI sensor for $50 less.

These cameras are small enough to put in a large pocket or purse, so they are easy to take with you.  Pretty much every brand has a camera or two in this range.  But, due to the quality of the cell phones today, the market for these simple point and shoot cameras has decreased in the last few years.  But, if you are Type 1 and want some real zoom on your camera, this is the least expensive way of doing it.

Questions?  Please feel free to ask in the comments or e-mail me.

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