Does anyone know what a digital SLR camera lens of 40mm-150mm is equal to in a optical zoom?

Question

Does anyone know what a digital SLR camera lens of 40mm-150mm is equal to in a optical zoom in a digital point and shoot camera?

Answer 1

You are comparing to things that have little relevance.  The 40mm - 150mm lens IS an Optical Zoom of  150 / 40 or 3.75x zoom ratio.  However the sensors on DSLRs are many time larger so the recorded image is much bigger while the equivalent magnification is lower.  For example a 4mm-40mm lens on a P&S would be a 10x Zoom (40 / 4 = 10x) but the image would be tiny compared to one made with the DSLR 40 - 150 zoom.

Without knowing the sensor size of the P&S there is no way to determine what the equivalent effective MAGNIFICATION is but typical P&S sensors are about one quarter of the size of those in DSLRs so magnification would probably be about 4 times greater.

The only valid way to compare the lenses recording capability would be to check the Angle Of View at the minimum and maximum zoom ranges of each lens.

Answer 2

It will depend on the point and shoot.  Most point and shoots start at around 36mm or 38mm wide (35mm equivalent).  To be able to cover the equivalent of 150mm, they would need to be about a 4x zoom.

However, some point and shoots are a little wider to start off with, at 28mm.  To be able to cover 150mm, you'd need over a 5x zoom (5.36x).  Thus, a 6x zoom would be needed on those cameras.  Note also that a 4x zoom on these wider cameras would only cover to 112mm vs. a 4x zoom on a camera not as wide, which will cover to 150mm. (ex: 4x28mm=112mm vs. 4x38mm=152mm).

You need to check the point and shoot specs, specifically for the lens and see what the 35mm equivalents are.

Hope this helps.