This article is written in photographic slang and, moments, filled with my subjective opinions. This article describes the nuances of using crooked cameras and lenses that few people pay due attention to.
‘Crop’, ‘Crop’, ‘kropnuty camera’, роп kropnuty camera ’,‘ kropnuty matrix ’,‘ kropny sensor ’are synonymous with a camera with a reduced photosensitive element (matrix, film). These concepts are strongly intertwined with the concept of the crop factor and you can read the basic information about crop in the ‘Crop Factor‘ section.
Full-frame, full-format cameras, Full Frame, FF, FF, Full sensor size – these are synonyms of cameras that have the original, not reduced photosensitive element. Nowadays, many photo enthusiasts believe that FF cameras are a panacea and the peak of the evolutionary development of modern digital cameras. Due to the fact that the price of amateur sprinkled cameras is several times lower than that of full-frame cameras, a lot of amateur photographers use exactly sprinkled cameras and dream of switching to full frame. The size of the matrix of full-format cameras is equal to the size of a standard 35mm film (film type 135). But the full frame is not the limit.
There are medium and large format cameras, where the size of the photosensitive element is several times larger than the size of the photosensitive elements in full-frame cameras. Strangely enough it sounds, but modern full-frame digital cameras belong to a narrow format. It turns out a certain deception – on the one hand, the full frame is something transcendental, on the other hand – the full frame is just a narrow format.
Photographers who have shot their whole life on medium or large format often look down on modern prohibitively expensive ‘Full-frame Cameras’ Nikon D4s, Canon 1DX, etc. I am writing this to the fact that there should be a clear understanding that full-frame cameras are only one of the steps in the evolution of camera design.
Since I use the Nikon system the most, I will give examples based on Nikon’s photo equipment.
Basically, everyone knows that it is easier to control the depth of sharply depicted space with the help of the FF camera. With the help of a full-format camera, it is easier to achieve a thin depth of field, blurring the far and near plan.
But there is a second side of the coin in which the crop exceeds the full frame. To get the same viewing angle from a full-length Nikon AF-S Nikkor 24-70mm 1: 2.8G ED N lens used on a full-size camera, you need to use an analog on the crop — Nikon AF-S Nikkor 17-55mm 1: 2.8G ED IF SWM DX . We assume that the 17mm cropping and 24mm of the full frame give approximately the same viewing angle and omit the difference of 1.5mm EGF (Equivalent Focal Distance, 17mm * 1.5-24mm = 1.5mm). But because of the different real focal length, the lenses have different depth of field and different hyperfocal distance. In practice, this affects the fact that using 17mm is easier to make a wide depth of field than with 24mm in full frame. By example, this is expressed by the fact that when I photograph a group of people in poor light (for example, in the temple), a thin GRIP of 24mm@F/2.8 lens in the full frame is felt very strongly and some of the people who “fall out” from the sharpness zone are blurred. I do not need anyone to be blurred in the picture. At the same time, if you shoot the same scene with a 17mm@F/2.8 lens on a crop, the sharpness zone will be larger, this will allow all people to be captured into the sharpness zone, and when printing such a picture, all the participants in the survey will admire their sharp image. In this case, the lenses use the same luminosity, and photographing takes place at the same exposure.
Often you can find the conversion of the f-number for the cropped lenses. For example, F / 2.8 for Nikon AF-S Nikkor 17-55mm 1: 2.8G ED IF SWM DX on Nikon DX cameras will have the equivalent of F / 4.2. You can look at the example of Nikon 14-24 2.8 on photozone.de. This does not mean that such a lens has a real darker aperture (lower real aperture ratio in terms of T-stops) when used on sprinkled cameras – it only means that the depth of field for such a lens will be equal to F / 4.2 equivalent for full-format cameras. Attention: this recalculation does not affect the exposure, it only affects the recalculation of the depth of field.
Thus, using Nikon AF-S Nikkor 17-55mm 1: 2.8G ED IF SWM DX at 17mm and F / 2.8 we get the equivalent of 25.5mm and F / 4.2. That is, to get the same large depth of field with the Nikon AF-S Nikkor 17-55mm 1: 2.8G ED IF SWM DX lens when using the Nikon AF-S Nikkor 24-70mm 1: 2.8G ED AF-S N we have to close the aperture before f / 4.2. But in the case of a full-length lens, this will entail not only an increase in the depth of field, but also a lowering of the exposure. Exposure will have to compensate for a longer shutter speed, or a higher ISO sensitivity, or a higher flash output.