What is SLR-like camera?

Question

I asked the following question; 'Are their digital cameras with optical zooms of upto 100x. Want 2 know cameras with d greatest optical zoom?'.

I was given an answer thus, 'The longest optical zoom on a SLR-like camera is the 20x optical zoom Olympus SP570UZ'

I don't understand the answer because I know at least some camera like camcorders with optical zoom of 32x. Or does optical zoom has different meanings. Please I asked to be enlightened. THANKS.

Answer 1

That Olympus has the greatest zoom range that I know of.  The answer you got was correct.  If you are asking about camcorders, ask in that section.  We know about cameras over here.

Answer 2

There are two major factors that need to be taken into consideration when comparing cameras "ZOOM" capability.  

1) Sensor size, which determines the magnification of ANY lens for a specific focal length (the optical length of the lens).  This also determines, to a large degree, the physical size of a lens AND the basic IMAGE QUALITY..

2) The usage of the recorded image which determines the IMAGE QUALITY NECESSARY for a usable image.

SENSOR SIZE: For example: one lens with a focal length of 10mm could be a Very Wide Angle "Fisheye" lens if used on a 24x36 mm ("full frame" 35mm format) camera a "Normal" lens if used on a typical "point and shoot digital" camera with a sensor size of 7x5mm and a "Telephoto" lens if used on a typical cell phone camera.

Digital SLR and SLR Like cameras usually have larger sensors so they give better quality images but that means they use physically larger lenses with longer basic focal lengths.  The 10mm lens would be a moderate to extra wide angle lens for most cameras of this type of sensor.  

To get a 20X optical zoom STARTING at 10mm calculate 10mm * 20 = 200mm.  The lens would need to be a 10mm-200mm lens.  A  fairly large, heavy lens.

If you started with a 5mm lens and wanted to get a 20X zoom the lens would be 5mm * 20 = 100mm.  The lens would be a 5mm-100mm lens.  A much smaller lighter lens than the first example but the image sensor would have to be much smaller to get comparable image size with a significantly lower quality image.

Now, starting with a 4mm lens and at 32X zoom ratio you would get 4mm * 32 = 128mm, a lens close to the same physical size as a 5mm-100mm.

What this demonstrates is that it is easy to "play with numbers" to make a combination look impressive without really providing a significant difference.  The Olympus camera is equipped with a 4.6mm-92mm lens which is fairly compact and provides impressive magnification while maintaining a lightweight design.

USAGE OF IMAGE: Images from DSLR, DSLR Like and "Point and Shoot" cameras are intended to be viewed as individual images so they must be higher quality than camcorders images.  Camcorder images are normally viewed for a moment (usually about 15 images per second) and then replaced with the next image, resulting in an optical illusion that makes the picture appear clearer because details missing in one image are generally picked up in adjacent images in the same second.

Hope that helps.