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  1. #11
    Join Date
    Feb 2006
    Location
    Des Plaines, IL
    Posts
    9,560

    Lightbulb Getting by on one lens

    There are those who simply cannot accept the fact that having a good variety of optical capability is one way to go, if you can. So for argument’s sake (of course, what other reason could there possibly be?), let’s adopt the one camera, one lens (light-sniper approach).

    Let’s start off with something everyone can identify with, the lowly 50mm lens.

    Doing the math, the α850/α900 Full Frame sensor has i dimensions of 36mm horizontal by 24mm vertical and 43.3mm diagonal. Thus, the horizontal field of view using a 50mm lens would be d i / f = d 36 / 50 = d 0.72 and the vertical field of view using a 50mm lens would be d i / f = d 24 / 50 = d 0.48.

    At a working distance of 10 meters, the horizontal field of view is therefore 7.2 metres and vertical field of view is therefore 4.8 metres; at a distance of 100 feet, the horizontal field of view is 72 feet and the vertical field of view is 48 feet, etc. (The horizontal AOV is about 39.6 at any distance).

    Architectural shot

    The subject house is 60-feet across the front, 40-feet from front to back. 20-feet tall to the top of the roof.

    At the very least, how far back do we have to stand to get the entire front of the home in one shot with the 50mm lens?


    60-ft/0.72 = 83.3-ft

    Okay, how about a Full-body pose, using a vertical shot?

    The person is 6-feet tall.

    How far back do we have to stand to get the entire height with a 50mm lens?

    6-ft/0.72 = 8.33-ft

    Obviously, you don’t frame that tight, so you need to move back about another foot or so, to have some top and bottom room in the shot, but you get the idea.

    Okay, the 50mm (normal lens) was fun ... but what about a wide-angle lens?

    The advantage of a 28mm lens:

    Thus, the horizontal field of view using a 28mm lens would be d i / f = d 36 / 28 = d 1.3 and the vertical field of view using a 28mm lens would be d i / f = d 24 / 28 = d 0.86.
    At a working distance of 10 meters, the horizontal field of view is therefore 13 metres and vertical field of view is therefore 8.6 metres; at a distance of 100 feet, the horizontal field of view is 130-feet and the vertical field of view is 86-feet, etc.

    Architectural recalc


    At the very least, how far back do we have to stand to get the entire front of the home in one shot with the 28mm lens?


    60-ft/1.3 = 46.2-ft

    Full-body pose recalc?

    The person is still 6-feet tall.

    How far back do we have to stand to get the entire height with a 28mm lens?

    6-ft/1.3 = 4.62-ft

    Okay, doing it with a telephoto lens ... what about that SONY CZ 135mm f/1.8? How well would that work out as a single lens for this?

    Thus, the horizontal field of view using a 135mm lens would be d i / f = d 36 / 135 = d 0.27 and the vertical field of view using a 135mm lens would be d i / f = d 24 / 135 = d 0.18.
    At a working distance of 10 meters, the horizontal field of view is therefore 2.7 metres and vertical field of view is therefore 1.8 metres; at a distance of 100 feet, the horizontal field of view is 27 feet and the vertical field of view is 18 feet, etc.

    Architectural recalc

    At the very least, how far back do we have to stand to get the entire front of the home in one shot with the 135mm lens?

    60-ft/0.27 = 222.2-ft (could be a couple of houses away.)

    Full-body pose recalc?

    The person is still 6-feet tall.

    How far back do we have to stand to get the entire height with a 135mm lens?

    6-ft/0.27 = 22.2-ft … or somewhere across the house, in another room. Remember, another foot or two, to allow for some proper framing.

    EDIT: The bottom line to this exercise, which I initially failed to point out, is that you can get your shot ... but you have to deal with the distance between you and your subject, depending on your lens choice. Having just ONE fixed focal length lens is foolhardy, unless you live on the Bonneville Salt Flats, with nothing between you and you subject. Even there, the rising heat will distort the air as you move further away.

    Obviously, the development of the nimble 'zoom' lens allows the photographer to reduce or mitigate the impact of this distance problem. As a beginning photographer, the 18-250mm f/3.5-6.3 is a tremendous idea, although it is kind of dark indoors. You can often mitigate that lighting issue, w/o a flash, with using a 28mm f/2.8 or 50mm f/1.8 lens (or BOTH, as they can be had (new) for under $200 each) and reclaim your available light.

    But, experience has shown that the 18-250 lens is, probably ...



    the MOST versatile "one lens solution" available.
    Last edited by DonSchap; 11-15-2009 at 05:56 AM.
    Don Schap - BFA, Digital Photography
    A Photographer Is Forever
    Look, I did not create the optical laws of the Universe ... I simply learned to deal with them.
    Remember: It is usually the GLASS, not the camera (except for moving to Full Frame), that gives you the most improvement in your photography.

    flickr & Sdi

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