03-24-2011, 05:54 PM
Thank you Photozone for starting to include "Equiv. max. f-stops" in the reviews.
It brings attention to the fact that it is misleading to specify equivalent focal length along with non-equivalent relative apertures (thus breaking simple proportion: ApertureDiameter = FocalLength / FNumber). It is great that you specify both.
In recent Nikon 18-55vr review:
[indent]Equiv. focal length: 27-82.5 mm (full format equivalent)
Equiv. max. f-stops: f/5.0-8.0 (full format equivalent, in terms of depth-of-field - not speed)
[/indent]
Only slight detail: values should be f/5.3-8.5 since crop factor for Nikon DX cameras is 1.52, not 1.4.
It could be also improved by linking to this excellent article (or write some shorter explanation on your site): http://www.josephjamesphotography.com/equivalence/
It brings attention to the fact that it is misleading to specify equivalent focal length along with non-equivalent relative apertures (thus breaking simple proportion: ApertureDiameter = FocalLength / FNumber). It is great that you specify both.
In recent Nikon 18-55vr review:
[indent]Equiv. focal length: 27-82.5 mm (full format equivalent)
Equiv. max. f-stops: f/5.0-8.0 (full format equivalent, in terms of depth-of-field - not speed)
[/indent]
Only slight detail: values should be f/5.3-8.5 since crop factor for Nikon DX cameras is 1.52, not 1.4.
It could be also improved by linking to this excellent article (or write some shorter explanation on your site): http://www.josephjamesphotography.com/equivalence/