slr lens on dslr and zoom length...

[strumstrum]

...Hi, in noob understandable terms when you see dslr compatible lens from slr days for sale and description says '28-100mm(42-150 on a digital)' is this true? and how? and any noticable difference in quality from an actual 150mm lens?

Ta

 

[andyred]

To try to keep it simple and short, it's an "effective" focal length given due to the crop factor on some DSLR's. Full frame DSLR's are like te old 35mm SLR - a 100mm lens has a focal length of 100, on a cropped sensor, this effectively becomes 160mm

Hope that helped

 

[heidfirst]

- a 100mm lens has a focal length of 100, on a cropped sensor, this effectively becomes 160mm

on a Canon crop body.
Nikon, Pentax/Samsung & Minolta/Sony crop bodies use a 1.5x factor.