“Experience Sharing“ Don“t try to replace zoom with fixed focus + crop

2020-08-12 08:07:46 0 Comment 2518 views
abstract

A few days ago, I saw a very interesting question in Zhihu, asking whether 24mm fixed focus and 85mm fixed focus can be cut to cover the focal length

A few days ago, I saw a very interesting question in Zhihu, asking whether we can use 24mm fixed focus and 85mm fixed focus to cover the focal length of 24-105.

The questioner's idea is also very good. Both 24 and 85 are large aperture lenses. Even the equivalent aperture is larger than the standard 24-105 through cropping, and the blur is better. Although cropping will bring about a lot of pixel reduction, it is enough to have 8-12 million pixels in our daily photos. This year, the resolution of computers is 4K (8 million pixels), and mobile phones are also 1080P (2 million pixels). ) Resolution.

This idea is good, but it doesn’t make much sense. Today’s article talks about it from two perspectives. One is the parameter angle, and the other is the actual use angle.

First of all, the parameter angle, we assume that the camera is the highest Sony A7R4 in the current full frame, this 61 millionIf the 24mm of the pixel sensor is cut to 48mm, the pixel will become 15.25 million pixels, which means that if it is cut to a focal length of 50mm, the pixel will be very small. If it is cut to about 85mm, the pixel will be reduced to a very small Degree (approximately five or six megapixels), it is likely that there is not much use value.

Of course, this is not the main problem. After all, we have to talk about taking pictures from the perspective of practical use. I think the disadvantage of fixed focus cropping instead of zooming is the viewfinder.

Here is a digression. Why is the viewfinder of Leica's rangefinder camera highly regarded by many people?


“Experience Sharing“ Don“t try to replace zoom with fixed focus + crop

If you take a photo with a Leica rangefinder camera, the picture you see in the viewfinder is different from the picture you took. The part enclosed by the white frame is the picture you took.

This What’s the advantage? When you take a photo, you can know that someone or something will enter your photo in 0.5 seconds.

But at the same time there will be another question, which is the answer to me. Troublesome thing to say: What you see in the viewfinderIt's not the picture you took. It will make you confused between these two pictures. It will take a long time for people who have just played Leica to understand it.

Similarly, if you use a SLR camera or a micro single camera to take pictures, the viewfinder or LCD The picture you see on the screen is different from the picture you took. You want to take a 50mm picture, but the picture you see before pressing the shutter is 24mm. The difference between these two focal lengths is not small. Are you sure that the 50mm you cut into after the post is the 50mm picture you want?

Why do I think this is a problem, because I have encountered this kind of thing this year. There was only one prime lens in my hand, Sigma 20 1.4.

This lens is suitable for shooting the Milky WayStarry sky, but I had an appointment with a girl to take pictures, can I take pictures in 20mm? It is difficult to shoot girls with ultra-wide angle, and the focal length of commonly used girls will not exceed 24mm.

But I only have a 20mm fixed focus, what should I do? I thought of a solution. My D850 has 1.5X and 1.2X crop modes, respectively, so that the images captured are 30mm and 24mm focal lengths. Even with the 1.5X crop mode, the photo still has 19.5 million pixels, which is basically enough.

In the beginning, I used the no-cut mode when taking pictures. I thought that post-cutting would be fine anyway, but the 20mm shot girl is too wide, although I consciously hinted that I could cut Cut, but what I see with my naked eye is 20mm focal length, I can't take pictures at 30mm.

Later I turned on the 1.5X crop mode in the camera settings, so that I can see it on the LCD screenThe picture is a 30mm picture. Okay, these photos are much more comfortable.

“Experience Sharing“ Don“t try to replace zoom with fixed focus + crop

“Experience Sharing“ Don“t try to replace zoom with fixed focus + crop

This 1.5X crop I used, 30mm is also displayed in the parameter For the focal length, if I shoot directly at 20mm without cropping, the four corners will have to be a circle larger, which is too difficult for me to compose the picture.

“Experience Sharing“ Don“t try to replace zoom with fixed focus + crop

I used the 1.2X crop mode, which is equivalent to a focal length of 24mm. If I shoot directly with 20mm, The effect is definitely not good.

In theory, we can indeed achieve the zoom effect by cropping, but in actual use, our eyes cannot see the cropped image, which will affect our composition and shooting ideas.

“Experience Sharing“ Don“t try to replace zoom with fixed focus + crop

The same is true when shooting landscapes. This is a 400mm focal length shot. In fact, I was also holding a 70-200 lens while shooting this photo. But I didn't get a similar picture with 70-200.

So do you know the photos I took with 70-200 on the same camera? This is the picture below. Compared to 400mm, I used 70-200 to shoot more heavilyFor large scenes, because the focal length of 200mm is not enough to capture the details like 400mm.


“Experience Sharing“ Don“t try to replace zoom with fixed focus + crop

“Experience Sharing“ Don“t try to replace zoom with fixed focus + crop

Actually, I have also photographed similar scenes with the 200mm end. This time it may Some people say: Ah, isn’t it the same as the one taken at 400mm above?

“Experience Sharing“ Don“t try to replace zoom with fixed focus + crop

The problem is that when I used 200mm to take this picture, I didn’t even consider cutting this picture when I selected and retouched the picture later, because when I took the picture, I didn’t take a small part of it. +The idea of ​​cooking smoke, the focal length of 200mm can only support me to shoot such larger scenes.

Don’t think this is incredible. The pictures we see when taking pictures are very important. This is also what I mentioned at the beginning that taking pictures with Leica rangefinders will have a long adaptation period. When you are in the camera When the picture you see is different from the picture you took at the end, it will be difficult for you to adapt.

Today’s article is to tell you: Don’t use 2 fixed focus to replace the zoom effect, if you find it troublesome, just buy a 24-105 zoom, don’t expect 24+85 fixedsetOr 24+50 fixed focus can simulate 24-105 zoom.

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