The role of the visor in the camera

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2023-02-15 14:35

1. Blurred background

In addition to changing the shutter speed, the 　　 visor can also chan<ge the depth of field.

Depth of field: There is a certain length of space in front of the lens σ(before and after the focus adjustment). When the subject is located ✔in this space, the image on the negativ‍e film is exactly between the two circles of confusi•on before and after the focus. The♠ length of the space where the subject is located is calπled the depth of field. In§ other words, the image blu r of the subject in this spac®e is within the limit of the permissiblδe circle of confusion, and the length of this space is the depth  of field.

To put it simply, the shallower t£he depth of field, the more obvious the backg round blur, and the deeper the depth of field, the clearer the background.

Under the same focal length, the larger the ♥shading circle, the smaller the£ F value, the more obvious the blur effect of the backgr®ound and the shallower the depth of field. Therefore, if you↑ want to use the camera to take photos with obvious background blu✘r, you should try to use a large  aperture under the same fo★cal length.

2, change the shutter speed

Generally speaking, the exposur↑e of the camera at the same sensitivity is determined by the size of the viso↕r (aperture F value) and the shutter speed£. In the previous article, we know that the visor F value = the focal €length of the lens / the diameter of the lens apert‍ure, that is to say, the smaller the aperture F value, the larger ↑the aperture, and the greater the amount of light. So we can increase the ap←erture to increase the shutter speed, or reduce th★e aperture to reduce the← shutter speed.

Large aperture lenses usually perfγorm well in low-light environments•. In the field of SLR cameras, a series of lenses called "night glasses", such ÷as Nikon Noct58mm/F1.2 and Leica's NOCTILUX-M50mm÷/F0 The .95ASPH night lens has a lar✘ge aperture.

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