Macro and crop bodies.

[Rob.Marsh]

Hi all,

Just a quick question really.

How is the magnification ratio affected on crop sensor bodies? I understand about applying to to focal length, but when focused at what the lens says is 1:1 on a crop body, is it still 1:1?

I am sure the answer is logical and I am having a funny 5 min, but I can't get my head around it!

Rob

 

[Chaz Photos]

I would guess that if the lens fits a full frame then it will be greater on the Crop body as it is 1 to 1 one a lager space then the sensor but as for a crop lens only I guess its up to the makers to say

 

[puddleduck]

Its still 1:1, just cropped.

 

[Rob.Marsh]

I thought it would be something as simple as that Puddleduck! Cheers!

 

[puddleduck]

I thought it would be something as simple as that Puddleduck! Cheers!

A way to think about this is to imagine a 10 pence piece that is the same size as a full frame sensor. So at 1:1 full frame, the coin exactly fills the frame.

On a crop sensor, you chop off the top of the queens head, and her nose and hair, but the image is still 1:1, just cropped.

 

[HoppyUK]

The effect of magnification with macro on a crop body is just as described (1:1 is still 1:1 etc) but that doesn't give the whole story.

It's no more meaningful than to say a 50mm lens is still 50mm regardless of format, but of course since with a crop camera the image is indeed cropped, then you need a shorter focal length to restore the angle of view and the framing you need. Hence the crop factor.

So, if you want to fill the frame with a close object and a crop camera, you will need a 1.6x (Canon) shorter lens to do it. Put another way, you effectively get more magnification with a crop camera for macro, in the same way as you get more reach with long telephotos.

You also get more depth of field with a crop camera, f/number for f/number, to the tune of one-and-a-quarter stops (Nikon/Canon) which is very handy for macro.