mwsilvers wrote:
...The SX60 has a 35mm equivalent angle of view of 21-1365 as a result of it's small sensor size with a crop factor of 5.62. However, the actual focal range of the SX60 lens is approximately 3.7- 243mm.....
This is correct.
In fact, to achieve that extreme range of focal length "equivalents", the sensor in the typical "bridge" camera is VERY small.... such as a so-called 1/2.5" that measures 4.29x5.76mm for a total of about 25 square millimeters. To fit 16MP worth of pixels on such a tiny sensor requires each pixel be extremely small and as a group that the pixels be very closely crowded together.
In comparison, an "APS-C" DLSR that can use a 150-600mm lens has an image sensor roughly 15x23mm with an area of 345 square mm.... close to 14X larger than what a typical "bridge camera" uses.
It's even greater difference with a so-called "full frame" DSLR, with an even larger 24x36mm sensor that has an area of around 864 square mm... more than double the size of the APS-C and almost 35X the size of the sensor in the bridge camera.
SIZE MATTERS when it comes to image sensors and the quality of the images they can produce. Larger sensors can be higher resolution (many are 24MP, some as high as 50MP) without being nearly as crowded, which reduces problems with noise caused by heat and cross talk. The higher ISOs you're able to use with tiny sensors are very limited. Where you might only be able to use ISO 400 or 800 with a bridge camera, you may be able to get as good or better image quality at ISO 12800 or 16000 or even higher with an APS-C or especially a full frame camera.
The larger sensor cameras are also able to use much larger individual pixel sites that do a better job catching light for more fine detail and may be able to use weaker or no "anti-alias/low pass" filter, which is used to slightly blur images to reduce moiré problems in images.
Longer focal length (whether real or "equivalent") also are harder to hold steady for a sharp shot. Most camera systems today of all types offer some sort of image stabilization.... but it can only do so much.
Finally, an extremely long focal length may allow you to photograph subjects from a much greater distance... But that means shooting through more atmosphere, which often degrades image quality significantly. It's always better to simply get closer to your subject (and there are
always subjects just out of your reach anyway, no matter how "long" your lens).
So, for many reasons you will find that an APS-C or full frame interchangeable lens camera with a 150-600mm lens on it will make for MUCH better images than are possible with a bridge camera. Depending upon how you use your images, you might not see the difference.... for example if you only share your images online in typical sizes and at low Internet resolutions. But if you make prints much larger than 4x6 (or crop your images at all), you'll definitely be able to see advantages of the larger sensor cameras.