Comparing lens angles Cropped v Full Frame

K

Kennett

Suspended / Banned
Messages
142
Name
Barry
Edit My Images
No
If EXIF details shows an image has been taken at a 20mm lens angle on a cropped sensor body, would the equivalent 20mm angle still be the same on a full frame camera? If not, is there a way of working out what it would be?
 
If you have Nikon it is a crop factor of x1.5, Canon is x1.6.

So, for Nikon 20mm on crop = 20*1.5 = 30mm field of view on full frame.

Or if you work it the other way, 20mm on FF is 20/1.5 = 14mm field of view on crop.
 
Last edited:
Thanks for the help Ned, much appreciated.

I'm just pleased to see someone knew what I was talking about, wasn't even sure I understood myself after reading what I had posted.
 
The angle of view is exactly the same whether cropped or full frame, since it is set by the focal length of the lens.

It's simply the cropped version will show a smaller amount (the centre) of the scene than the full frame.
 
Brian G said:
The angle of view is exactly the same whether cropped or full frame, since it is set by the focal length of the lens.

It's simply the cropped version will show a smaller amount (the centre) of the scene than the full frame.
Click to expand...

That is precisely wrong.

The angle of view changes due to the sensor size, the focal length stays the same.
 
Nawty said:
That is precisely wrong.

The angle of view changes due to the sensor size, the focal length stays the same.
Click to expand...
No, I'm afraid it's you that is wrong.
The area of view changes, not the angle, which is solely controlled by the focal length of the lens.
The lens still "sees" the same angle of view, the cropped sensor just sees less of the overall image.
juggler said:
The field of view changes; the angles don't.

The compression effect of a 135mm lens on FF is just the same as the compression effect of an (actual) 135mm lens on a crop sensor. You can just see less of the scene.
Click to expand...
Thank you.
At least someone understands the physics.
 
You must log in or register to reply here.
Back
Top