Is there really a big difference between 18 55 and 17 40?

The difference is just too big!

The poor imaging quality is very large. The correction of distortion, the restoration of color, the sharpness of imaging, the resolution of the lens, etc., are much worse!

Taking lenses as an example, the transmittance of coated lenses is more than 99%, while the transmittance of non-coated lenses is about 95%, and how much is the difference between coated and non-coated lenses for a lens with more than 10 lenses? Where can the light from the uncoated lens be reflected when it is dismantled? -- The loss of light has a very negative effect on the sharpness of the image!!

At the same time, its maximum aperture is much worse!

The size of the maximum aperture is the main basis for measuring the grade of a lens from the surface. When the light is relatively low, the advantage of a wide aperture can be used even more, and the poor quality of the image is even more obvious.

For example, in an outdoor area with very strong light, the difference between the two lenses is not too big. But if you go indoors and the light is dimmed, the difference is too obvious.

At the same time, in terms of clarity, it is impossible to solve the problem by post-production software adjustment! If you increase the sharpness, you will increase the granularity!

This friend upstairs, speak with evidence! Reasoning!

18-55 and 17-40 Aside from ** and imaging results that are difficult for novices to judge.

The biggest difference is that 18-55 can't be used on the full-frame fuselage, and in these years, 99% of the "masters" who say that so-and-so lens is good and so-and-so can't do it are all ignorant of pretending to understand and two beeps to beep. Don't take the master's word for it.

Generally, photographers just shoot a small jpg or something, not specifically engaged in the art of publishing, and the actual difference between these two heads is not as big as the red circle on the appearance.

The first 18-55 18-135 18-200 is the focal length, that is, the size of the optical zoom (simply put, the larger the focal length, the farther the shot).

Second, as far as the lenses are concerned, these three lenses are all set lenses, and if you don't have a box, you can only buy and disassemble the head.

Third, the comparison between lenses shows that 18-55 is the worst (the focal length is too small, the height is not too low, and the combination inside the lens has weaknesses).

18-200 moderate (that is, a more comprehensive lens, generally better for travel, from the wide angle can be extended to the telephoto end, but there is an obvious weakness, the focal length is too large, the lens combination can not be used to the best effect).

18-135 is the best (the first focal length is appropriate, the second is the inner focus lens, the third is put to the telephoto end lens does not need to be locked, it is more convenient, and the fourth is a new lens, used for 7D as a sleeve, that is, the full-frame camera can be a lens to have).

The above three lenses are relatively cheap lenses for non-high-end products 18-135 18-200 can enter the middle ranks.

1. Focal length. The focal length of 18-135 is 80 (128mm) longer than that of 18-55, 2. Bokeh result.

18-135 can be shot a little farther away, and the void effect is okay; The 18-55 does not have a telephoto, so you can't shoot a little farther, and the bokeh effect is poor (the background is slightly closer, and it basically can't be bokehed).

3. Lens aperture.

The 18-135 caliber (67) is larger than the 18-55 (58), and the larger the lens aperture under the same process, the better the quality of the film.

4、**。18-135 is much more expensive than 18-55 (18-55 is about 700 without IS, while 18-135 is around 2200, more than 1,000 more expensive).

18-55 lens is good.

1. Quality. The 18-55 lens has two kinds of sleeves, and the image quality is very good, while the 17-85 lens only has one sleeve for the EF-S17-85mm, and the image quality is poor.

2. Do pure ** aspects. The ** pin of the 18-55 lens is usually within 3,000 yuan, while the ** of the 17-85 lens is more than 3,200 yuan.

45 14-18 and 45-(14+18) are actually the same example: 45 pears are divided between two children, 14 and 18, and the rest is 45-14-18

In fact, it is equivalent to adding up the number of points first, and then subtracting the total number, and finding the remaining quantity is 45-(14+18).

45-(14+18) If the symbol outside the parenthesis is a minus sign, then the symbol inside the parentheses will be changed, and the plus sign will become a minus sign, then it will be 45-14-18

So there is no difference between the two.

The writing is different, but the result is the same.

The zoom factor of the zoom lens is the largest number divided by the smallest number 18-55 and the wide-angle end of 18-105 is the same as 18mm, which can take pictures with a wider field of view, that is, the imaging range is the same, the large telephoto end 55 is different from 105, that is, the scene can be magnified more with 105, and it can be pushed up. For example, 18105 has a large zoom range, which is more convenient for non-professionals to use, and can go all over the world with one shot, but there will inevitably be distortion at both ends of the zoom factor if there are too many zoom magnifications, so the zoom range of the general zoom lens is not more than 3 times, such as 24-70, 70-200 and so on.

In short, 105-55=50. That is, the 18-105 has a 50 mm longer focal length than the 18-55, and the latter can achieve a larger rubber formation when the distance between the camera and the subject is the same and the same constant. If 50 mm is used as a standard lens similar to the human eye (angle of view, magnification is 0), then 105 mm is equivalent to a small telephoto lens with a magnification of about 10 magnification.

Solution: 5 18 and 40 48 are divided into points:

Re-score: So:

Calculate separately to know who is bigger and who is small:As can be seen from the above results, 48 18 47 24 .