What do you think about MTF lenses? Urgently, what is the lens mTF

Red solid line: f, reduction of 10lp mm black and white line pair on the arc sagittal curve (horizontal resolution), red dashed line: f, reduction of 10lp mm black and white line pair on the meridian curve (vertical resolution), blue solid line:

f, reduction of 30lp mm black and white line pair on the arc vector curve, blue dotted line: f, reduction of 30lp mm black and white line pair on the meridian curve.

Abscissa: Imaged from center to edge. The lens is 24mm, the abscissa is 0-24, on the APS-C machine, the lens has a multiplier conversion rate, that is, 24, as long as the curve before 16 is fine.

Ordinate: represents the contrast restoration of black and white lines on the test board. 1 represents 100% reduction.

10lp mm (red line): The higher the ordinate, the better the contrast of the lens. 30lp mm (blue line):

The higher the ordinate, the better the lens resolution. Solid and dashed lines: The closer the solid line is to the dotted line, the better, and the farther apart it means that there is astigmatism.

For all lines, the higher the ordinate, the better, and the closer to a straight line, the better. Ideally, all the lines coincide in a horizontal line at 1 point (but there is no such lens).

This lens: Red line: Good contrast in the center of the lens, astigmatism at the edges.

Blue line: The resolution of the center is acceptable, and the resolution of the edges is severely reduced. For a wide-angle head, it's still pretty good.

This MTF graph only shows the maximum aperture, not the two-stop stop-down case.

This stuff doesn't have much practical significance. Only in contrast and resolution, some parameters can be provided. See the encyclopedia specifically.

This thing just reflects the resolution and contrast of the wide-angle and telephoto ends at their respective maximum aperture and aperture 8. For example, Nikon's 50 and 50. The MTF you see at 50 is at the aperture but it doesn't, and in fact, it's not as good as the 50 but can you say that the aperture of 50 is worse than the aperture of 50?

Secondly, for example, 85. People originally look at blur, and the edge resolution has little to do with it, after all, it's all blurred. But you have a noticeable drop in the MTF curve.

Secondly, the lens is not just about resolution and contrast, right? Such as distortion, vignetting, anti-chromatic aberration, anti-glare, workmanship, bokeh ability, color reproduction, transparency, focusing speed, and the layering of the picture.

Shows the quantification curve of the image quality of the lens at each aperture. Contrast and resolution are mainly measured.

modulation transfer

Recently, more and more people have found that although it is a standard, some images are not standardized and can be measured, so it is only a reference value and not all.

This method of measuring the frequency of optics is measured by the number of lines that can be displayed within a range of one mm, and its units are expressed in line mm. Therefore, when a lens can achieve the degree of what is in and out, it means that the lens is the so-called perfect lens, but because the design of the lens lens is often affected by many factors, it is impossible to have such an idealized lens.

mtf cut

OFF (MTF cut-off frequency): The OQAS parameter, which indicates that the MTF curve of the human eye will reach the resolution limit when the spatial frequency reaches the frequency value, that is, the MTF value tends to zero.

30c deg for normal people, the higher its value, the better the visual quality.

The full name of MTF is Modulation Transfer Function, commonly known as "modulation transfer function". MTF comprehensively reflects the contrast and resolution characteristics of the lens, which is measured by an instrument, which can completely exclude the influence of objective factors such as film and the subjective factors of manual interpretation, and is a very objective and accurate lens evaluation method.

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1.The abscissa axis represents the distance from the center of the frame, and from left to right represents the imaging from the center to the edge (approx. 22 mm on the horizontal axis of the EF lens and 13 mm on the transverse axis of the EF-S lens)2The ordinate axis represents the MTF value.

3.The black line indicates the maximum aperture, and the blue line represents the f 8 aperture 4The thick line represents 10 lines mm, and the thin line represents 30 lines mm5The solid line represents the radial direction, and the dashed line represents the tangential direction.

Interpretation 1The closer the MTF value is to 1, the better, i.e. the higher the MTF line, the better 2The higher the thick line, the better the contrast performance of the lens.

3.The higher the thin line, the better the resolution of the lens.

4.The flatter the MTF curve, the smaller the imaging gap between the edge and center5The closer the solid line and the dotted line, the better the bokeh image of the lens6

The blue line illustrates the imaging level of the lens at f 8, which approximates the optimal imaging level of the lens 7The black line illustrates the level of imaging at the maximum aperture of the lens, and the value of a wide aperture Supplementary answer: This article is on the Hummingbird Photography Forum.

Through the above two articles, you can roughly understand the MTF curve.

1. MTF (modulation transfer function) is a relatively scientific method for analyzing the resolution ability of lenses;

2. MTF is composed of multiple function coordinate lines, among which: the higher the better, the slower the downward trend, the better; The higher the position of the thick line, the higher the contrast and contrast of the lens; The higher the position of the thin line, the sharper the lens; The higher the black line, the better the lens performs at wide aperture; The higher the blue line, the better the lens performs when the aperture is closed to 8; If the blue line is very close to the black line, it means that the lens performs very well, and only a relatively small number of lenses have this performance; The closer the solid line and the dotted line are, the softer and more natural the bokeh image of this lens, on the contrary, the farther the difference, the worse the bokeh image, 3. As far as the MTF curve coordinates are concerned, the general picture below the ordinate is very bad; The picture is basically qualified; It can be regarded as good, and the above is very good;

4. The MTF curve is not omnipotent, the distortion of the lens, anti-glare performance, close-up shooting ability, focusing speed, etc. can not be seen, in addition, the number does not represent art, and some lenses with lower values sometimes do not look bad in actual imaging (some lenses pay more attention to the imaging quality of the out-of-focus, such as Canon Nikon's 105F2DC, etc.), but relatively speaking, the MTF curve is indeed an objective, accurate and quantitative evaluation of the lens.