![]() This second calculation tells us that if you take a picture at the same distance with the 25mm at f/1.4 on the m4/3 camera, that aperture corresponds to f/2 on the 35mm and f/2.8 on the 50mm as far as depth of field is concerned. What if I do the math a second time to match the same virtual aperture of the m4/3 lens? The virtual aperture depends on the focal length, and the focal length for the 36×24 format is longer than the other two lenses because it has to cover the same angle of view on a larger sensor. The 50mm lens has a larger aperture for the same f-stop number and that makes sense. So for the three lenses mentioned above, it would work this way: The virtual aperture is what interests us here because it is used to calibrate the opening and closing of the diaphragm aperture. We can calculate the virtual aperture with the following formula: Focal length/f stop = virtual aperture. What you are seeing here is the optical image of the physical aperture (called Virtual Aperture) seen through the front lens element. The Relative aperture (f-ratio or f-stop): the quotient of the focal length and the virtual aperture.The Virtual aperture (also called entrance pupil): the optical image of the physical aperture seen through the front element of the lens.To be more precise, aperture refers to three distinctive terms: In the introduction, I referred to it as a hole inside of our lens. We have three lenses with different focal lengths but almost identical angles of view on their respective formats:įirst let’s look at the aperture. Let’s get out of the way what has already been explained many times. The question is: is it correct to compare lens apertures between camera systems by considering just the depth of field? Let’s look into this a little more. The easiest way to do this is to compare equivalent f-numbers. They are also interested in the overall look and shallow depth of field a fast lens can deliver. Therefore it has become common practice to compare depth of field between lenses designed for different sensor sizes to get a clearer picture of how your image will look when taken with a smaller sensor. Photographers are interested in knowing how sharp a lens is wide open, how beautiful the bokeh (quality of the out-of-focus area) can be and how capable the lens is at isolating a subject. Shallow depth of field is popular for portraits, among other things. It’s not just a technical aspect but also an artistic/creative element. A smaller aperture like f/11 will produce a deeper depth of field so the distance will be longer and more areas will be in focus.ĭepth of field matters because it can play an important role in the look/style you want to achieve. A fast aperture like f/1.4 will produce a shallow depth of field so that distance will be shorter and your image will have more out-of-focus areas. In other words, it is the area that appears sharp (in focus) in the photograph. Aperture and Depth of Fieldĭepth of field refers to the distance between the nearest and farthest points from the focal plane that appear in focus. Why? Because this is usually what matters to people when it comes to comparing camera systems. Take note of the first point (the amount of light) and save it somewhere because I want to talk about depth of field first. This aperture affects two things: the amount of light that hits the sensor when you take the picture and the depth of field of your image. Smaller aperture (also referred as “slow”) ![]()
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