Issue 31, Page 78, 'What's APS-C ?

[Forseti]

Towards the bottom of his reply Paul say's - "....for example, a 50mm lens on a 500D or 50D is equivalent to an 80mm Lens on a full-frame D-SLR"

Oh dear, if the so-called experts can't get it right it's little wonder that questions of this nature continue to pop up on the forum. Paul's' reply would, to those that don't know, imply an element of magnification is involved whereas the simple fact is, is that a 50mm lens (or an 80mm lens) will still be a 50mm lens (or 80mm lens) whatever camera it is used on - whether on a crop frame camera or a full-frame camera. In short, the physical characteristics of a lens cannot be changed but the effects are variable depending on the size of sensor.

Might I boldly suggest that the correct answer should have been along the lines of - when setting a focal length of 50mm on a crop frame camera this would give the same field of view (FOV) as if the same lens had been used on a full-frame camera but with a focal length of 80mm having been set. Magnification is not changed - only FOV.

In Paul's reply no mention is made of FOV and this is a glaring omission imho.

[nikonian]

Originally Posted by Forseti

Towards the bottom of his reply Paul say's - "....for example, a 50mm lens on a 500D or 50D is equivalent to an 80mm Lens on a full-frame D-SLR"

Oh dear, if the so-called experts can't get it right it's little wonder that questions of this nature continue to pop up on the forum. Paul's' reply would, to those that don't know, imply an element of magnification is involved whereas the simple fact is, is that a 50mm lens (or an 80mm lens) will still be a 50mm lens (or 80mm lens) whatever camera it is used on - whether on a crop frame camera or a full-frame camera. In short, the physical characteristics of a lens cannot be changed but the effects are variable depending on the size of sensor.

Might I boldly suggest that the correct answer should have been along the lines of - when setting a focal length of 50mm on a crop frame camera this would give the same field of view (FOV) as if the same lens had been used on a full-frame camera but with a focal length of 80mm having been set. Magnification is not changed - only FOV.

In Paul's reply no mention is made of FOV and this is a glaring omission imho.

Reads OK to me. The important words here are EQUIVALENT TO. I think you are nit picking.

[Forseti]

Originally Posted by nikonian

Reads OK to me. The important words here are EQUIVALENT TO. I think you are nit picking.

And that is my point, they are NOT equivalent unless other conditions are met - same camera to subject distance being one. It might appear as 'nit picking' to someone who likes to give the impression of knowing it all but it should be remembered that the people who ask these basic questions of the magazine are most likely beginners and therefore are deserving of an accurate and comprehensive answer.

[nikonian]

just run thru a few AOV. 50mm on a crop camera is 30.32 degrees. 80mm on a FF camera is 30.26 degrees. Now the difference is a gnats ****. These are assuming a Canon 10d and a 5d. What other conditions do you want?

[Forseti]

"To get the same amount of info on a cropped camera one has to increase the distance from camera to subject. Therefore one has to move backwards, run if you like." http://www.photoradar.com/forums/sho...0781#post10781

Um, let me see now - who was it posted these words? And here I will end it because you're being argumentative simply for the sake of it.

[nikonian]

Originally Posted by Forseti

"To get the same amount of info on a cropped camera one has to increase the distance from camera to subject. Therefore one has to move backwards, run if you like." http://www.photoradar.com/forums/sho...0781#post10781

Um, let me see now - who was it posted these words? And here I will end it because you're being argumentative simply for the sake of it.

Glad to see you have admitted defeat. If it was possible to send a diagram on to a thread I could prove it to you. Oh by the way distance always increases DOF. Thats another diagram I could send. Still cheer up you are still on a learning curve.