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January 11, 2007



Been a long time, Abiola, but your Nikon-related posting finally brought me out of the woodwork. Given the digital sensor's effect of multiplying every focal length by 1.5, in which situations do you make use of what is effectively a 128mm lens? For portraiture and general low-light situations I will often use the standard old 50mm f/1.4 -- but at an effective 75mm, I sometimes find that is too long as well. I enjoy your blog.



Thanks for commenting. The 85mm may have the equivalent field of view to what a lens 1.5x as long would have on 35mm film, but the optical properties of the lens itself aren't altered in any way by the reduced size of the sensor which actually records the light it gathers, and said optical properties were my primary concern in acquiring it. There were three issues involved for me:

1 - To reduce the amount of distortion which facial features undergo. I find that the enlargement of, say, noses, or - if the subject is leaning forward, foreheads - is *very* noticeable at 50mm, even on an APS-C sensor.

2 - To provide more distance between myself and subjects, making things more comfortable for both of us than things would be with the 50mm. This is the chief factor in my considering the purchase of a 105mm prime: it makes taking candids easier, and the fact that both Nikon and Sigma's 105mm offerings are macros with supposedly near-ideal working distances guarantees that they'll have more than niche usefulness. But that's a story for another day ...

3 - To be better able to utilize shallow depth of field effects in my photos. If you go to the following site,

you'll see that on APS-C, at 6 feet and an aperture of f/2.2, a 50mm lens gives you an acceptable DOF of 0.48 feet, while an 85mm lens at the exact same aperture slashes that to 0.16 feet. Even a 50mm lens with an aperture of f/1.4 will give you roughly twice as much DOF when shot wide open, but when you take into account that most lenses aren't at their best wide open ... The bottom line is that at a given aperture the 85mm enables one to better blur distracting backgrounds while enjoying near peak sharpness where one wants it. The applicability of this clearly goes beyond just headshots.

Of course, all this theory is very nice, but what really sealed the deal for me on this focal length was seeing what Ryan Brenizer (aka Flickr's Carpe-icthus) has been able to do with the 85mm f/1.4D.

Having seen his shots, there was no question in my mind that a lens of this focal range can be a viable option both outdoors and indoors in a surprisingly wide range of situations. For those occasions when it won't do, I can simply pull out the 50mm, or (more usually nowadays) the Tamron 28-75mm f/2.8, both of which I now routinely pack along in my camera bag.

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