Light Transmission Comparisons

Theoretically, all lenses, when set to the same f/stop, should deliver the same amount of light to the film/sensor. In practice, there are differences in effective light transmission, due to different optical designs, and different materials and coatings.

Below find a table of observations of differences between lenses. Since most of us don't really have the equipment to do these tests scientifically, we'll do them in terms of comparisons between lenses.


  • Shoot under the same conditions
  • At the same subject
  • At the same or similar focal length
  • With the same settings. (Meaning, bracket shots with each lens covering the same range of settings, adjusting ISO or shutter consistently.)
Lens 1 Lens 2 Results Observer Sample Set/Thread
35mm f/2 O 35mm f/1.4 AIS 35mm f/1.4 AIS 2/3 stop faster at f/2 Kukkurovaca Link
50mm f/1.4 S 35mm f/1.4 AIS 35mm f/1.4 AIS slightly faster at f/1.4 Kukkurovaca Link
105mm f/2.5 K 55-200 VR 55-200 VR roughly 1/3 faster at f/5.6 Kukkurovaca Link
50mm f/1.8 AF-D 18-55 18-55 faster at f/5.6 Eddie Barksdale Link
180mm f/2.8 P 55-200 VR At f/5.6, minimal difference. At f/11, 55-200 somewhat (1/2-stop?) faster. Kukkurovaca Link
35mm f/2.8 S 50mm f/1.8D 50mm f/1.8D roughly 1/2 stop faster at f/2.8 David Chu No Pictures
50mm f/1.4 S 50mm f/1.8D f/1.8D very slightly (less than 1/3 stop) faster at f/2. Kukkurovaca Images pending
35mm f/1.4 AIS 50mm f/1.8D 35mm f/1.4 as fast at f/2 as the 50mm f/1.8 AF-D at f/1.8. Kukkurovaca Images pending
300mm f/4.5 Late non-AI 400mm f/5.6 ED AIS Very little, if any, difference in transmission Kukkurovaca Images pending
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