Thursday, April 29, 2010

Behaviors of SLR Lenses on Canon APS-C

Field of View
Comparison of the field of view you get at various focal lengths and lenses. It's easier to visualize with pictures. The camera is a Canon Rebel T2i (aka 550D) which has an APS-C sensor (1.6 crop factor). Camera is tripod mounted while lenses are changed. Sorry, I forgot to take "normal" range photos with the zoom. I'll do a second set of tests for that. These still images are at 4:3 Aspect Ratio. Video mode will crop the top and bottom to form a 16:9 image.

11mm (17.6mm effective)
Tokina 11-16 AT-X Pro 2.8 (Zoom)
16mm (25.6mm effective)
Tokina 11-16 AT-X Pro 2.8 (Zoom)
18mm (28.8mm effective)
Sigma 18-50 EX DC Macro 2.8 (Zoom)
50mm (80mm effective)
Sigma 18-50 EX DC Macro 2.8 (Zoom) 
50mm (80mm effective)
Nikkor SC 50mm 1.4 (Prime), adapted from F-mount to EF
Note how the view is narrower than the Sigma above.  Infinity focus is slightly before the infinity marker on the lens.
70mm (112mm effective)
Canon EF 70-200 F2.8/L IS (Zoom)
85mm (136mm effective)
Canon EF 85mm 1.8 (Prime)
200mm (320mm effective)
Canon EF 70-200 F2.8/L IS (Zoom)








Focus Breathing
A slight change of FOV may be observed when changing focus.  All the SLR lenses from the previous test exhibit this to some degree.

Focused to Foreground
Note the trees on either side of the picture.  Focus to foreground which is about 9 feet away shows less of trees on either side.  Lens is a Canon EF 70-200 F2.8/L IS at 70mm.

Focused to Background
Focus to background shows more of the trees on either side.  Lens is a Canon EF 70-200 F2.8/L IS at 70mm.







Lenses Tested
Tokina 11-16MM F/2.8 ATX 116 Lens for Canon EOS AF Digital - Tokina ATX116PRODXC (paid link)
Sigma 18-50mm f/2.8 EX DC SLD ELD Aspherical Macro Lens for Canon Digital SLR Cameras (paid link) 
Canon EF 85mm f/1.8 USM Medium Telephoto Lens for Canon SLR Cameras (paid link) 
Canon EF 70-200mm f/2.8L IS USM Telephoto Zoom Lens for Canon SLR Cameras (paid link) 


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