Gear Talk > Canon General
Crop factor for macros
squarebox:
I was just reading a review(http://www.the-digital-picture.com/Reviews/Canon-EF-100mm-f-2.8-USM-Macro-Lens-Review.aspx) where it should a difference between 3 focal lengths of macro and how it affects bokeh.
I'm familiar with a focal length crop factor of 1.6x for APS-C sensors, but my question is does this affect MFD or maximum magnifcation as well?
I'm specifically curious as i have a non-usm 100mm Macro lens with a 550D but am planning to upgrade to a 5dmk3 and 100L in the near future and am curious how the magnification may change and bokeh.
wickidwombat:
--- Quote from: squarebox on May 11, 2012, 12:53:30 AM ---I was just reading a review(http://www.the-digital-picture.com/Reviews/Canon-EF-100mm-f-2.8-USM-Macro-Lens-Review.aspx) where it should a difference between 3 focal lengths of macro and how it affects bokeh.
I'm familiar with a focal length crop factor of 1.6x for APS-C sensors, but my question is does this affect MFD or maximum magnifcation as well?
I'm specifically curious as i have a non-usm 100mm Macro lens with a 550D but am planning to upgrade to a 5dmk3 and 100L in the near future and am curious how the magnification may change and bokeh.
--- End quote ---
you are going to notice 2 thing right off the bat
1) it no longer seems to get as close because you lose your 1.6 (note a kenko 1.4 TC will nearly fix this nicely you can also stack it with the extension tubes to get closer still) kenko TC will work with any EF lens unlike the canon ones.
2) the Dof will seem unbelievably shallow so you are going to want to stop down anyway therefore adding a TC into the mix wont hurt
neuroanatomist:
--- Quote from: squarebox on May 11, 2012, 12:53:30 AM ---I'm familiar with a focal length crop factor of 1.6x for APS-C sensors, but my question is does this affect MFD or maximum magnifcation as well?
--- End quote ---
Tehcnically, it affects neither - the MFD is a property of the lens, so it will be unchanged. The maximum magnification will remain 1:1.
But, what will change are the field of view and the apparent magnification. A macro lens delivering 1:1 magnification at the MFD is projecting a life-sized image onto the sensor. Because of the smaller sensor, your 550D can capture an opject up to ~22x15mm, whereas the 5DIII will capture a a larger object, up to 36x24mm. But...that's only 4 more MP spread over a larger area, so the pixel density is lower. That means if you shoot the same size object at the same distance (assuming the object is small enough to fit within the APS-C sensor area), when you view both shots at 100% on your monitor, the shot taken with the 550D will appear to have more magnification, resulting from the higher pixel density.
squarebox:
as always helpful responses from everyone :D
Marsu42:
--- Quote from: wickidwombat on May 11, 2012, 01:33:58 AM ---1) it no longer seems to get as close because you lose your 1.6 (note a kenko 1.4 TC will nearly fix this nicely you can also stack it with the extension tubes to get closer still) kenko TC will work with any EF lens unlike the canon ones.
2) the Dof will seem unbelievably shallow so you are going to want to stop down anyway therefore adding a TC into the mix wont hurt
--- End quote ---
I had the 100mm non-L and now upgraded to the L, but I'd advise anyone to get the Kenko 1.4x in any case, even on crop it's a great addition. The only problem with the non-L and the tc is that the af fails when the aperture drop is too large at very close macro distances, this didn't happen to me with the L.
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