Digital Lens Range Compared to SLR Range

[Gas Man]

I've read that SLR lenses on Digital SLR cameras have more zoom or something, is this right ?

[OwenS]

I think youre referring to DX body cameras. The crop factor on the image sensor gives a 1.5x amplification to the lens focal length. e.g. a 200mm lens on a DX format digital camera would give a 300mm equivalent.

[Kym]

I've read that SLR lenses on Digital SLR cameras have more zoom or something, is this right ?

A 300mm lens is always a 300mm lens.
The difference is the cropping - it is not additional magnification as such; although it appears the way in practice.

The explains it quite well... (at least the first half of the article)
http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm

Another explanation:
http://www.luminous-landscape.com/tutorials/understanding-series/dslr-mag.shtml

[JM Tran]

in a nutshell, the focal length, say 300mm will still be 300mm

but the FIELD of VIEW changes, not the focal length

a 200mm lens on a 1.5x crop sensor will provide a 300mm image due to the change in field of view

[ricktas]

As the others have said, a 300mm lens is a 300mm lens, It is a set physical size and cannot magically become a different size cause it is placed on a cropped sensor body. The factor that is different is the sensor size.

To get an understanding have a look at this diagram (http://a.img-dpreview.com/reviews/NikonD3/Images/viewfindercrop.jpg)

It shows how a smaller sensor grabs the image that comes through the lens. Cause it grabs a smaller area (cropped) it appears to be zoomed in more, but really all it is doing is missing all the date the lens can capture that is outside the sensors 'view'.

Note the diagram in this instance uses Nikon Nomenclature:

Fx - Full frame - 35mm sensor
Dx - Cropped sensor
5:4 - The Nikon D3 allows capture in a 5:4 format as well.

[davidd]

I've read that SLR lenses on Digital SLR cameras have more zoom or something, is this right ?

The other thing to mention is that it doesn't matter if it's a DX or FX lens, you will get the same effect. ie a 200mm DX lens will give the same effective length as a 200mm Full Frame lens on a DX body.

DX lenses are smaller in diameter, so they don't cover the full size sensor.

[IngridM]

The other players in the field are Olympus/Pany Leica, which have a 4/3 system that has a smaller sensor again, with a 2x conversion factor. So an Oly 50-200 zoom will give you the same effective distance as a 100-400 on a 'full frame' (35mm) sensor. A smaller, lighter system but not as good under really low light. Outstanding quality glass, edge to edge sharpness, weathersealed (mid - pro range) - but it is what they call a 4/3 system. Horses for courses.

[cherryw]

There is also the fact that the 4/3rd lenses are specifically made for digital cameras as in the light falls onto the sensor is at a 90 degree angle, where as other lenses the further away from the centre of the lens the angle the light hitting the sensor is increased.