All peo­ple who shoot, from ama­teurs to those who make mon­ey on it, are faced with the recal­cu­la­tion of the lens by crop. Only the lat­ter per­fect­ly under­stand what it is about, and they oper­ate with this, for the rest this text is intend­ed. It’s time to go back to basics and break down every­thing you need to know about the crop fac­tor. Let’s fill the gap!

Pho­to: canon.com.au

What is crop factor

Before talk­ing about crop, it is imper­a­tive to start with the cam­era matrix, which is inex­tri­ca­bly linked with it. It is locat­ed inside the car­cass and is a light-sen­si­tive sen­sor. For any cam­era, this is the most impor­tant ele­ment. From the smart­phone cam­era, to the lat­est mod­els of major brands. The cam­era obscu­ra is the only option where a matrix is ​​not need­ed.

In sim­ple terms, a matrix is ​​\u200b\u200ban ana­logue of pho­to­graph­ic film. In ana­log cam­eras, the image passed through the lens and fell on the pho­to­sen­si­tive lay­er of the film. In mod­ern, dig­i­tal, every­thing is the same, only it gets on a pho­to­sen­si­tive matrix. It is formed there, and then saved to a mem­o­ry card.

Pho­to: dpreview.com

The so-called full-frame (FF, Full Frame, full-frame) matrix has a size approx­i­mate­ly equal to the size of a 35-mm film frame. Of course, this adds to the size of the cam­era, and the price of zeros. To reduce all these indi­ca­tors (includ­ing for smart­phone cam­eras. It is impos­si­ble to imag­ine a full matrix there), man­u­fac­tur­ers have reduced this sen­sor.

There is an estab­lished set of such short­ened matri­ces on the mar­ket. For exam­ple, 1.5, 1.6, 2, 4. All this is the crop fac­tor. The num­ber indi­cates how many times this matrix is ​​​​small­er com­pared to full-frame. So, if you mul­ti­ply the dimen­sions of the matrix with a crop of 1.5 by one and a half, then you will get the dimen­sions of the FF.

In every­day life, this indi­ca­tor is used main­ly to deter­mine the focal length of the lens and install it on var­i­ous cam­eras.

Chronol­o­gy of the appear­ance of crop matri­ces

In ana­log pho­tog­ra­phy, there was no such thing as crop fac­tor. Although there was a wide range of frame win­dow sizes on the mar­ket, each of them cor­re­spond­ed to a cer­tain focal length of the lens, which was con­sid­ered to be nor­mal. For exam­ple, for large cam­eras with a frame size of 9x12 cm, a lens with a focal length of 135mm was stan­dard, for a medi­um for­mat 6x6 — 80mm, and for a stan­dard one — 50mm. And on each of them, such a com­bi­na­tion of frame size and stan­dard lens pro­duced more or less sim­i­lar results.

Lens­es with the same focal length on cam­eras with dif­fer­ent frame sizes will behave com­plete­ly dif­fer­ent­ly. We tend to think of the 50mm as more of a por­trait lens. How­ev­er, on medi­um for­mat it would be wide-angle. And on a large one — ultra-wide-angle. Despite such dis­crep­an­cies, there was no crop in the days of ana­log pho­to­graph­ic equip­ment: it was not nec­es­sary to recal­cu­late the val­ues ​​​​of lens­es and trans­late — an appro­pri­ate set of lens­es was pro­duced for each type of equip­ment.

There are a lot of lens adapters and cropped sen­sors out there now, and you have to do some cal­cu­la­tions to fig­ure out how a par­tic­u­lar lens will per­form on your cam­era.

Image: setafi.com

How crop factor works

The lens projects a round (yes, round) image straight into the body of the cam­era. The frame frames crop this cir­cle to a famil­iar rec­tan­gle. Thus, only part of the entire image is cap­tured. The small­er the matrix, the small­er this rec­tan­gle. Accord­ing­ly, a small­er piece of the pass­ing image will be obtained at the out­put. When shoot­ing with a cropped matrix, the cam­era, as it were, cuts out a rec­tan­gle 1.5 / 1.6 / 2 times small­er from a full-size frame.

Hav­ing pho­tographed on the FF cam­era and cut out a rec­tan­gle 1.5/1.6/2 times small­er from the pho­to in the cen­ter on the com­put­er, you will get exact­ly the same frame as you would get on the crop matrix.

The crop fac­tor is how many times the sen­sor is reduced com­pared to the full frame. To under­stand how a lens designed for a full matrix will behave in a crop, you need to mul­ti­ply the focal length by this val­ue.

For exam­ple, in a cam­era with a 1.5 cropped sen­sor, a 50mm lens will pro­duce an image of 50 x 1.5 = 75mm. If you screw a 75mm lens onto a film cam­era, you will get an image with a sim­i­lar angle of view. Despite the fact that the lens on the crop is 50mm, and on ff — 75mm.

Image: picturecorrect.com
Image: picturecorrect.com
Image: picturecorrect.com

Crop vs full frame

The most pop­u­lar crop fac­tor in afford­able cam­eras is 1.5 and 1.6. On the one hand, the larg­er the sen­sor, the high­er the qual­i­ty of the result­ing pho­tos. This is also affect­ed by the qual­i­ty of the lens and the lev­el of light­ing. But the fact remains, the matrix decides.

There are even medi­um for­mat dig­i­tal cam­eras, where the sen­sor size exceeds the stan­dard full frame. For exam­ple, Has­sel­bald or the Fuji­film GFX line, where the matrix size can reach 40mm. They cost like a good car, but the images tak­en on them can be print­ed on a bill­board.

The qual­i­ty of a full frame is the res­o­lu­tion of the image, the lev­el of detail, clar­i­ty, lack of noise in low light. If you send pic­tures tak­en under the same con­di­tions to crop and FF for print­ing, then the first one will lose in all respects. In addi­tion, a full frame is eas­i­er to crop: if dur­ing pro­cess­ing you often crop the frame to the required piece, then FF will not lose qual­i­ty from this. Crop, on the oth­er hand, will go strong­ly in pix­els with a detailed approx­i­ma­tion.

The oth­er side of the coin is that the full frame is pri­mar­i­ly impor­tant for those who work with the image, and the cam­era is a work­ing tool for him. If you shoot for your­self and do not spend a lot of time pro­cess­ing, and also appre­ci­ate com­pact cam­eras, then crop is your choice. He, too, can pro­duce a good pic­ture that will suit your needs and request.