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Two pocketsfull

Doug Kerr

Well-known member
Most of our photography is done now with two compact cameras, a Canon PowerShot G16 and a Panasonic Lumix DMC-ZS100. Both have permanent zoom lenses with "eyelids" to protect the lens when in a pocket, and indeed either of these will go easily in a pocket in the dock pants I wear most of the time (or handily into Carla's purse).

They are very close to the same size, give or take a couple of millimeters in one dimension or the other:



Canon G16 and Panasonic ZS100​

Here I want to do some very primitive (perhaps presumptuous) "theoretical" comparisons between these cameras as to the matter of photometric performance. Here are some of the pertinent specifications of the two cameras:

Canon G16
Sensor: 7.44 mm × 5.58 mm ("1/1.7 inch"), 12 Mpx
Lens: Focal length 28-140 mm ff35 equivalent, f/1.8-2.8

Panasonic ZS100
Sensor: 13.2 mm × 5.58 mm ("1 inch"), 20.1 Mpx
Lens: Focal length 25-250 mm ff35 equivalent, f/2.8-5.9​

Now I will make the comparison based on our normal usage, which is a deliverable image about 800 px maximum dimension. I will assume the use of teh JPG output from the cameras. To make the comparisons consistent, I will assume deliverable images 800 px × 600 px, assuming for the G16 downsizing of the full-frame image, and for the ZS100 downsizing of a crop in width only, to a 4:3 aspect ration. And I will assume use of the

Now, of course the noise performance of the cameras "full-size" image is not directly a function of the pixel dimensions (because among other things of probably different strategies of in-camera noise reduction). And of course the noise performance with respect to downsized images is not directly a function of the size (on the sensor) of the pixels of the downsized images.

But that having been said, I will make some comparisons that essentially assume that relationship.

If we go through all the bush-league algebra, we find that the size of the delivered image pixel on the camera sensor is 2.79 times larger for the ZS100 than the G16. So we can realize for the same photometric exposure, there will be 2.79 times as much phtometric energy per (delivered) pixel for the ZS100 as for the G16.

Now we look at the lenses. Consider a shot at a ff35 equivalent focal length of 28 mm, which is the "widest" available on the G16. At that focal length, the largest aperture available on the G16 is f/1.8. and for the ZS100 it would be f/3.0.

For the same scene and the same shutter speed, this would mean about 2.8 times as much phtometric energy per unit area for the G16 as for the ZS100.

So for what such a comparison is worth, we find that the smaller maximum aperture on the ZS100 almost exactly negates the benefit (in this primitive comparison) of the ZS100's larger sensor.

At an equivalent focal length of 140 mm (the "longest" available on the G16), the maximum aperture available on the G16 is f/2.8, and on the ZS100 f/5.8, a ratio of photometric exposure of 4.3 times. Here, the smaller maximum aperture of the ZS100 well more than negates (again, under this primitive comparison) the advantage of the larger sensor of the ZS100.

Now of course, even if the assumed effects on noise performance were valid, this doesn't overall negate the advantage of the larger sensor of the ZS100. For example, "all other things being equal", we should be able to get comparable noise performance in any given situation with the ZS100 by using a smaller aperture, giving an advantage in depth of field.

But of course this is all conjecture. What will turn out to be the actual difference in performance of the two machines in different situations will only turn up over a long time of use.

In any case, they are both lovely machines.

Now as a matter of interest, our Panasonic Lumix DMC-FZ1000 uses the same sensor as the ZS100, but its lens is 25-400 mm ff35 equivalent, f/2.8-4.0. So we might expect with it to be better able to exploit the larger sensor where a larger aperture is workable from a depth of field basis. But this camera is gigantically larger, and rather heavier, than the ZS1000:





Panasonic FZ1000 and Panasonic ZS100​

Woof!

The weight difference isn't as much as you might think, 519 g for the FX1000, 312 g for the ZS100. (Both the G16 and the ZS100 feel like little bricks!)

Best regards,

Doug
 
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