Zoom and Magnification

[Ubergeek]

I have tried to provide an explanation on Zoom and Magnification on my blog for newbies as its something i am always being asked by mates who confuse zoom and magnification:

Tim Naylor's Photography

If you could take a look and let me know i havent missed something or that my interpretation of the two isnt wrong

Regards.

[daft_biker]

Magnification is usually only used in macro photography and does not vary with the size of the sensor - 1:1 (or 1x) is 1:1 on all formats just the larger the sensor the more of the subject you can fit in. (at 1:1 1mm of the subject takes up 1mm of the sensor)

Your article discusses the crop factor in working out the 35mm equivilant focal length of a lens. A 300mm isn't going to give you 9.6x magnification on APS-C, it gives you the same angle of view as a 480mm lens would on 35mm.

You may be better trying to explain angle of view and why different focal length lenses give different angles of views on different sensor sizes.

A 3x zoom simply means the longest focal length is 3x bigger than the shortest focal length, it doesn't tell you anything about angle of view or what the actual focal lengths are.

[Ubergeek]

Hmmm seems I am still confused myself lol

I think my idea of zoom is correct the ration between the longest and shortest focal length, however isn’t angle of view another way of describing the “magnification”? You change the angle of view depending on how much of the image you want to record on the sensor?

I have deleted my blog post until I am confident I know what I am talking about lol

Thanks for helping me understand.

[OsmosisStudios]

Originally Posted by Ubergeek

Hmmm seems I am still confused myself lol

No offense, but you probably shouldnt be writing authoritatively about it then.

[vandergus]

Well, using a longer focal length while maintaining the same distance to the subject does increase magnification, but the formula you used wasn't right. And it isn't dependent on the size of the format, as daft_biker pointed out. This link may help to spell things out a little more clearly.

[Ubergeek]

Cheers thats makes sense.