Serene Life

by garik

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0

The best way to focus at infinity is by using a so-called Bahtinov mask or a Hartmann Mask. A problem you will have to deal with is tripod motion during the long exposure. Also, if you photograph the sky, the rotation of the Earth will cause the stars to become small trails. It is almost impossible to take perfectly sharp pictures without using remote ...


2

There are basically two ways to do this: Autofocus works properly with an IR-pass filter in place, as does auto-assisted manual focus (you turn the focus ring, the camera tells you if things are in focus). You are effectively focusing in a low-light situation, however, as the autofocus sensor has an IR-blocking filter just like the image sensor does. Many ...


1

Magic Lantern has a focus stacking feature. if you have a Canon DSLR, see there if your camera is supported.


1

Just capture all the focus planes at the same time... https://www.lytro.com/ http://en.wikipedia.org/wiki/Light-field_camera


0

As others have wrote - it is difficult to make lenses that can focus at very different distances. Designer of the lenses have to choose possible distances because it may affect size, weight, complexity and finally cost of the lenses. In fact there are also lenses than can focus at very close distances but CAN'T at far distances. The example is this: Canon ...


1

Going on the assumption you are asking about using point focus vs area focus, there isn't a perfect answer and it depends entirely on what your skill with the focus system is, the capability of the focus system and what you are shooting. The strength of area auto focus is that it allows the camera to quickly find something to focus on without thinking ...


1

Combining and restating Toph's answer and Matt Grum's comment: learn when to best use the (many! different!) autofocus modes of your camera, and practice with them extensively. There are many combinations of AF modes and some of them will be absolutely horrible for certain situations, while others will be horrible for other situations. You've already ...


2

I have a few things I try when timing doesn't allow pre-selecting a focus point: Focus and recompose Using the center focus point I'll half-press the shutter and recompose to my desired composition. Use a smaller aperture You can use a depth of field calculator (such as this one) to ensure the subject you're photographing is in focus within the near and ...


1

This is most easily achieved by using the change of density between air and water and a domed enclosure. When light passes from water to air through a piece of glass or plastic, it is bent by the transition. This effect can be used to form a lens that only applies when submerged. When above water, the air-air interface allows light to pass through ...


3

You can make lenses that are designed for a glass air interface too. Most famous of these is probably that of the Nikonos: Many Nikonos lenses, the "UW" series, were specifically designed for underwater photography only. It is said that, even to this day, no underwater lens matches the Nikonos "UW" lenses for sharpness and color saturation underwater. A ...


-4

The Camera Lenses does not know focus, it is just gears you can turn. Therefore air has nothing to do with focus. The camera uses a complex algorithm to determine when a picture is in focus or oof. And it will turn the gears via internal focus motor, or in lens motor to adjust focus. I think this may answer you question how camera determine focus: ...


0

The apparent distance of an object in a water viewed from air ,d_prime, equals true distance* 1/1.3333 (index of refraction of air/ index of water). So an object d feet away will appear to be 25% closer in water. So you can just find the focus distance on land and then make the adjustment.


1

That is simple. Your lens does loose focus on zooming because it is not panfocal. Depth of field: While zooming out you will shorten the focal length which results in a much deeper depth of field. The gain in depth of field sort of compensates for the inaccuracy of focal pane itself. The other way around the focal pane moves in the other direction and ...


7

The lens is not parfocal in either direction. What you have discovered is the difference between narrow Depth of Field (DoF) at longer focal lengths and deeper Depth of Field at wider focal lengths. The focusing error you introduce when you focus at 18mm and then zoom to 105mm is greater than the shallow DoF at 105mm even at f/8, so you notice how out of ...



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