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Howard Sandler | profile | all galleries >> Technical Stuff >> Depth of Field Demonstration tree view | thumbnails | slideshow

Nikon D80 Evaluation | Nikkor 18-200mm f3.5-5.6G IF-ED AF-S DX VR | Nikkor 18-70 DX Evaluation | Depth of Field Demonstration | Nikkor 70-300 mm G Zoom Lens Evaluation | Nikkor 50mm f1.8D AF Lens Evaluation | Nikkor 85mm f1.8 D AF Lens Evaluation | Nikkor 24mm f2.8 AF-D Evaluation | Sigma 105mm f2.8 EX DG Macro Lens Evaluation | Lighting Equipment | Skin Smoothing | Nikkor 35mm f1.8 AF-S DX Evaluation

Depth of Field Demonstration

I wanted to reconcile the standard advice to use a long focal length lens to get a blurry portrait background, with the fact that standing back from the subject increases the depth of field as it's a percentage of the subject to camera distance.

Everything is done on a tripod and with fairly high ISO to keep the shutter speed high. The wall is underexposed, hence the noise.

The experiment shows what's really going on with blurry backgrounds. Standing back and using a longer focal length at the same aperture does not change the depth of field, it just magnifies the blurry background with respect to the size of the subject, so the blur "appears" fuzzier.
70mm focal length
70mm focal length
300mm focal length
300mm focal length
crop of the 70mm shot
crop of the 70mm shot
crop of the 300mm shot
crop of the 300mm shot