The problem of asking for help in large format photography

The 1 lens with a focal length of 300mm is a telephoto lens.

This question is multiple choice, you should choose X, wrong! Under normal circumstances, the 300mm lens gives us the feeling that it is already a telephoto lens and can be used as a telescope head. In fact, these are all based on the habit of our commonly used 35mm camera frame. For example, in the 4/3 system, 25mm lens is the standard lens, APS-C format camera, 35mm lens is the standard lens, Quan Huafu (35mm film) is 50mm, medium format (6X6) is 80mm, 4X5 large format camera is 180mm, and 8X 10 large format camera is the standard lens.

2. The main parameters for selecting a large-format lens are: (lens focal length), (lens image field size (that is, the diameter of the imaging circle under the minimum aperture), and (applicable frame).

This is a fill-in-the-blank question. No matter what format the camera is, the focal length of the lens is what we care about. It has something to do with the perspective and perspective of the lens. The image field of the lens, that is, the size of the lens imaging circle, is directly related to the adjustment of the lens during a week of shooting. Therefore, if it takes a week to shoot, the greater the redundancy of the image field, the greater the space for later axis shifting operation. The last item is the application of the framework, which is not difficult to understand. If you use 8X 10 pan/tilt, you can use it as a telephoto on 4X5. Of course, you can also use the 4X5 pan/tilt with a large image field as a wide-angle camera on 8X 10, but this is not the mainstream after all, so it is best to choose the frame.

The diagonal of the 3.4X5 camera frame is (160mm), and the conversion coefficient with Quan Huafu digital camera lens is (0.28).

In fact, the actual size of the so-called 4X5-inch format cameras is 99.6mmX 125.4mm, so the diagonal of their frames is about160 mm. Since the diagonal length of Quan Huafu is about 45 mm, 45/ 160 is about 0.28.

4. The last question is that you can't see the photo clearly, which probably means taking an ideal architectural photo based on the vertical line of the only building in the building.

Shooting buildings with a large format camera is mainly to correct the exaggerated angle of view when shooting at close range (it is seriously affected by obstacles when shooting at long distance). At this time, the camera should be as stable and horizontal as possible. At this time, we only need to adjust the pitch angle and axis movement of the lens plate until we are satisfied with the perspective.