The advantages and disadvantages of square and round light-reducing mirrors

1. Select round for ND and square for GND.

1. Advantages of the circle

1. The manufacturing difficulty is reduced. The quality of the circle is not enough to be polished, and the square is basically flat. Therefore, in the 3rd gear, even something as round as Kengo can pass, but in the 6th gear and above, it is impossible to do it.

2. Square ones have the risk of light leakage, especially long exposures of more than 1/10 second.

3. The round ones are, for example, durable and maintenance-resistant. And the round ones are usually made of glass, and the square ones are usually made of resin. The resin is not hard enough and is prone to flowering and aging.

Disadvantages of the circle

1. Filter size problem, many need to be one size larger and may not be compatible.

2. It is not possible to stack 2-3 pieces, otherwise the frame will be too thick and there will be dark corners or even occlusion. Of course, the 2-3 square pieces will definitely change color.

-----------------------

2 Contemporary camera metering is still reliable. Except for red light, flash, and sunrise and sunset moments, the camera's automatic metering is completely reliable. Also, pay attention to white plus black minus. In addition, a more advanced point is that if a certain lens has a large vignetting angle, then positive exposure compensation is also required. For example, the Zeiss 21 2.8 uses at least +1 compensation at 2.8 aperture. When this lens reaches aperture 4.5, there is no vignetting, so the exposure does not need to be compensated. And with digital cameras, expose to the right as much as possible, and then pull it back later.

As for the camera parameters, if you want fog, the shutter speed is basically fixed. But ISO is not absolute. As far as the current full-frame cameras like D800 and D610 are concerned, ISO800 is no problem at all. Today's cameras and latitude are trustworthy.

As for the use of filters, I can only tell you roughly, on a sunny day, use an ND8 and a CPL+GND0.6. Set the aperture to 8-16, APC to 11, and leave the rest to the shutter. Adjust the ISO settings.

Today's full-frame SLRs are very tolerant. Unlike before, there is no problem with plus or minus 2 stops. The difference between the sky and the sea in your article is 3 levels. It can be restored in the later stage without using GND. Furthermore, Thanks to HDR, you can shoot bracketed exposures with three stops of -1.0.1 and then synthesize them in post.