Why is the electronic shutter subject to diffraction?

No, it's the opposite, the edges of the mechanical shutter diffract the light, while the electronic shutter is not affected as it does not exist; there is no physical element that could cause diffraction.

Chulster's answer here shows that the effect is only noticeable in situations of very high contrast, such as bright light sources (similarly to the well-known star diffraction of the iris of the objective).

aperture – How to calculate the effective loss of megapixels due to diffraction?

How to calculate an image effective number of megapixels at each aperture setting, especially with regard to diffraction loss?

Suppose we already know the size of the sensor, its true number of megapixels, and assume that the camera is associated with a perfect lens.

python – improved speed of this diffraction calculator based on numpy

I will simulate diffraction patterns of a normal incident Gaussian profile beam from a 2D network of point diffusers with a height distribution.

The 2D table of diffuser positions X, Y and Z each has a size N x N and these are summarized in each call to E_ab(a, b, positions, w_beam). It's done M x M times to build the diffraction model.

If I estimate ten floating point operations per dispersion site per pixel and one nanosecond per flop (which my laptop does for numpy small matrices), I would expect time to be 10 M^2 N^2 1E-09 seconds. For the small N, this runs a factor of 50 or 100 slower than that, and for the large N (bigger than say 2000), it slows down even more. I guess it has something to do with the pagination of the large paintings in memory.

What can i do to increase the speed of fat N?

Note: Right now, the height variation Z is random, in the future I plan to also include an additional systematic pitch variation term, so even if the purely Gaussian variation might have an analytical solution, I have to do it numerically.


Since I randomly distribute the height of pZ here, the plots will be a little different each time. My output (run on a laptop) is this, and I can't even begin to understand why it takes longer (~ 16 seconds) when w_beam is small only when it is large (~ 6 seconds).

My estimator 10 M^2 N^2 1E-09 suggests 0.25 seconds, these are about 50 times slower, so there can be substantial room for improvement.

1 16.460583925247192
2 14.861294031143188
4 8.405776023864746
8 6.4988932609558105

Python script:

import numpy as np
import matplotlib.pyplot as plt
import time

def E_ab(a, b, positions, w_beam):
    X, Y, Z = positions
    Rsq = X**2 + Y**2
    phases = k0 * (a*X + b*Y + (1 + np.sqrt(1 - a**2 - b**2))*Z)
    E = np.exp(-Rsq/w_beam**2)  * np.exp(-j*phases)
    return E.sum() / w_beam**2 # rough normalization

twopi, j = 2*np.pi, np.complex(0, 1)

wavelength = 0.08
k0  = twopi/wavelength

z_noise = 0.05 * wavelength

N, M = 100, 50
x = np.arange(-N, N+1)
X, Y = np.meshgrid(x, x)
Z = z_noise * np.random.normal(size=X.shape) # use random Z noise for now
positions = (X, Y, Z)

A = np.linspace(0, 0.2, M)

answers = ()
for w_beam in (1, 2, 4, 8):
    E = ()
    tstart = time.time()
    for i, a in enumerate(A):
        EE = ()
        for b in A:
            e = E_ab(a, b, positions, w_beam)
            EE.append(e)
        E.append(EE)
    print(w_beam, time.time() - tstart)
    answers.append(np.array(E))

if True:
    plt.figure()
    for i, E in enumerate(answers):
        plt.subplot(2, 2, i+1)
        plt.imshow(np.log10(np.abs(E)), vmin=0.0001)
        plt.colorbar()
    plt.show()

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What is the difference between diffraction spikes and stray light?

When looking for glare on Google, we often find images that also include stars (rays / diffraction spikes), like this:

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What is the difference between diffraction spikes and stray light and are both terms interchangeable?

sensor – Is it best to shoot with a diffraction limited aperture or sharpest lens aperture?

In older cameras like Nikon D80 with a pixel count of 10 megapixels. The diffraction limited aperture is F / 13 but it is known that the lenses are usually the sharpest at F / 8, so it is obvious to shoot at F / 8 for the clearest images.

But when I look at new cameras, they have 24 megapixel sensors with DLA of F / 5.6 or higher.

So, when shooting on new cameras, which aperture should be taken for the clearest photos, especially for archive quality photos? The DLA or the goal opening the sharper? Is the focal distance and the distance between the camera and the subject also coming into play?

Things get even more complicated when you realize that goal technology has also evolved.

Is limited opening diffraction independent of the lens?

I've always understood that diffraction-limited aperture was a property of the camera and its sensor, and not the lens. The camera has a certain sensor size and a number of megapixels, which together determine the diffraction limited aperture.

However, according to DxOmark, it seems that the Canon 70-200 f / 2.8L IS II USM lens defies the diffraction-limited aperture. On the basis of these measurements (Sharpness tab), the sharpness is green even at f / 32.

On the other hand, the Canon 24-70 f / 2.8L II USM lens has a clear diffraction visible even at f / 22 based on these measurements (Sharpness tab).

Based on this analysis, 5DS R has a diffraction limited aperture of f / 6.7, although the resolution is so high that DxOmark would likely rank light diffraction in the "green" category. Still, I'm still surprised that 70-200 is green in f / 32 and that 24-70 is reddish orange in f / 22.

So is limited-opening diffraction an absolute property of the camera / sensor? Can lens design affect diffraction?

Web site design – UX suitable for diffraction of data from two different tables

I have the obligation to create a web-based report fusion application. Users will be able to download two identical reports. They should be able to see the differences and select the data from which they will use the report to generate a final integrated document.

I plan to store the data from both reports in database tables (each with its own table) before displaying them on the user interface.

I am looking for a UX / UI solution / idea to display the differences and an option allowing the user to select the data from the report. It is also possible that the user can change the value.

Technical batteries we will use: spring boot, Thymeleaf + JS + jQuery, Bootstrap, Hibernate

Please advice ..

Regards,
Hendry

openness – Is there a diffraction chart and maximum sharpness online?

Diffraction

For the Canon EOS 1300D, you can see the calculated DLA of f / 6.8 when reviewing this camera by The-Digital-Picture. Bryan also published a short article on what is DLA and its impact on images.

All Canon cameras reviewed at The-Digital-Picture since about 2004 have the calculated DLA list. It is included in the "Specifications" list of each camera. There is also a chart in the main body of the journal that shows DLA as well as other sensor specifications and compares them to other similar cameras. The list of Rebel T6 / 1300D is quite brief. If you look at the list included in the analysis for, say, the EOS 5D Mark III, there are many more sensors with different pixel sizes in the comparative list.

Since DLA for a digital sensor is strictly a function of the size of its photosites (a / k / a pixel well), any other camera with the same pixel pitch should have the same DLA. Even if you are interested in the DLA of a non-Canon sensor, as long as the camera in question has a Bayer mask in front of the sensor, it will have the same DLA as a Canon camera with the same pixel pitch.

Regarding the specific objectives: The objectives do not have DLA. But if a lens is sufficiently "flexible", even at its maximum sharpness, it can still project aerated discs larger than the DLA of the camera to which it is connected. In this case, the DLA of the sensor would not be the most restrictive obstacle to obtain the clearest images possible. It would be rather the limits of resolution of the goal.

Especially for the EF 75-300mm f / 4-5.6 III (or one of its predecessors), it is quite possible that the lens will not be able to resolve points as small as the size in pixels of many cameras. The EF 70-300mm f / 4-5.6 IS STM or EF-S 55-250mm f / 4-5.56 STM lenses are significantly sharper than EF 75-300mm f / 4-5 lenses, 6 III.

Acuity

What we call "sharpness" is actually a combination of many variables. Among these are the contrast, the resolution (in terms of lines per millimeter or lines per height of the image that the lens can project), diffraction, chromatic aberration, the astigmatism, etc. This is before we even go to manufacturing tolerances and the variation of a copy from one lens or camera to the other.

Ultimately, each specific lens and specific camera used together can have optical performance slightly, sometimes even greater than slightly, better or worse, contributing to what we call "sharpness". Tests performed by review sites are often done on a single copy of a goal or with a single combination of lens and case. Roger Cicala's blog on lensrentals.com is a good source of goal data, usually with at least ten copies.

At the very least, you should review the goal tests done with the same device or devices similar to those that you intend to use with a forward looking goal.

Do the smaller apertures have more depth of field beyond the diffraction limit, even if the sharpness of the peak suffers?

First of all, he was a number on the film. If Bryan Peterson was not aware at that time, it would only show what he did not know, do not that it was not really a problem.

There were differences though. First of all, we did not have EXIF ​​data, and most people did not have enough notes to really know why X was more accurate than Y. Even for those who kept notes, were doing real tests, like taking 100 photos of the same subject by varying the camera settings to see what worked well and what did not work was enough for that very few people all really tried.

Second, for most people, the standards were much lower. Watching images on a computer screen, in particular, makes a lot It's easier to zoom in narrow, to the point of seeing really minor flaws that you'd never see in a reasonably sized print or projecting a slide even really great.

Third, there is something of a psychological effect involved. When shooting at f / 22, all is a little fuzzy, so you have a tendency (for example) not to look at it as closely. Most people will never notice it much because they tend to stop looking closer when they realize (subconsciously) that there is more detail to see. On the other hand, if you photograph, f / 5.6 for example, the parts of the image that have exactly the same size of CoF as the f / 22. look fuzzy because you can (at least usually) see much sharper areas.

Fourth, a lot depends on the quality of the lens used. If you look / play with goals from 50 or 60 years ago (for example), you can trust that, by today's standards, they are rather horrible when they are wide open. An f / 2 lens can easily need to be stopped until f / 8 or before fairly good by modern standards. The aberrations when it was wide open were serious enough that the quality improved again to f / 11 or even f / 16 in many cases. A big goal and a very bad goal are about equal to f / 22 – but at f / 8, the big goal will be a lot better.

To get closer to your direct question: yes, the size of the sensor has a considerable effect. With a larger sensor, you need to get closer to the subject to get the same framing with the same focal length as the lens. This means that a larger sensor will normally reduce the apparent impact strength so that you will gain more by stopping. Secondly, if you use a larger sensor, you enlarge less to get the same print size. This prevents the loss of sharpness of a small aperture from being almost as apparent.

To give an extreme example, many of the most famous "classic" photographers like Adams and Weston belonged to what they called the f / 64 club. Turning an 8×10 camera (or even bigger), they necessary a tiny aperture to get any DoF, and (quite obviously after the name) considered that the f / 64 aperture was ideal. The loss of sharpness mattered little, for the simple reason that they rarely grew larger. From an 8×10 negative, even a 24×30 print is only a 3: 1 enlargement – slightly less the enlargement only to produce a 3×5 print from a full-frame digital camera.

Edit: First of all, f / 22 is only rarely necessary from the point of view of DoF. Consider hyperfocal distances for a 50mm lens at different apertures:

f / 8: 41 feet
f / 11: 29 feet
f / 16: 21 feet
f / 22: 15 feet

The closest point that is the focus of the focus is half of that number in each case. Therefore, going from f / 16 to f / 22 saves you about 3 feet of foreground that is net. There are probably times when winning only 3 feet is worth no matter what. Let's be honest though: it's not very common – and probably in 95% of the cases where you can use f / 22 to do the job, you can use the focus stack (for example) to accomplish the same thing. and get a much higher sharpness.

For a typical landscape, it is rarely necessary. For example, consider an FF camera with a 50mm lens held at eye level (for example, 60 "above ground), with the nearby ground level and level. For simplicity, suppose that they keep the camera roughly level. .

In this case, the nearest first plan at the beginning very The edge of the photo is about 250 inches (just under 21 feet). This means that f / 8 is small enough for the all image to fall into the DoF. Someone looks really closely to very The edge of the photo might notice that it's just a little sweeter than the center – but what they see is always a little sharper at the edge and a lot sharper in the center than if you took the picture at f / 22.

I feel compelled to add, however, that DoF is not the only reason to use a small aperture. I sometimes use a small aperture specifically to give a rather soft and low contrast image. Setting f / 22 (or f / 32, if necessary) can be a very economical alternative to a soft-focus lens, and when you want to get a soft and dreamy look as one would expect. from a pinhole camera, f / 32 can be an easy task. replace.

Conclusion: It is quite possible to produce very beautiful images by taking pictures at f / 22 or f / 32 – but when / if you use it, you have to do it based on at least one idea what to expect and knowing that want the kind of photo you will have. Make do not do it because Bryan Peterson (or whoever else) has assured you that it was the right thing to do, and that you should not do it hoping that an image at f / 22 appears as sharp as f / 11.

Let me conclude with a short series of photos. These were all taken from a tripod with the predefined mirror, all at a few seconds apart so that the light changed very little, and so on. First, an overview:

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Then 100% of the crops at f / 11, f / 16, f / 22 and / f32:
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Now, it is true that we are here at least to a certain extent, but it is also true that the loss of quality at f / 22 and (especially) f / 32 is quite obvious. Frankly, although most tests show a loss at f / 16 when shooting high-contrast flat targets, here on an actual photo, f / 16 does not look as if it's different from f / 11.

OTOH, at f / 22, the loss of quality is rather noticeable, and at f / 32, the result is frankly awful.

Oh, and these are all taken at 200mm. If you believe that a long lens will spare you the effects of diffraction, get ready for some disappointment …

Optics – What types of lenses with "slightly different diffraction behavior" were used in "large-format photography in the 1980s"?

Apodization filters in large format lenses were very popular in the 1980s. Baffles in such lenses can significantly affect the diffraction characteristics of such lenses.

Targets such as the Rodenstock Imagon had been around since the late 1920s, but they resurfaced when several 35mm camera makers introduced lenses for 135 format cameras using baffles or similar screens for soften the bokeh between the mid to late 1970s and 1980s.

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Rodenstock Imagon "sink strainers"

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Fujinon 85mm f / 4 SF (soft focus)

This Soft Focus "fashion" culminated in the 1980s and lasted long enough to allow Canon to introduce the EF 135mm f / 2.8 SF ("Soft Focus") in 1987 as one of their primary goals. EF for the new EOS system.

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Canon EF 135mm f / 2.8 Soft Focus

There are also several DIY "tips" to get the look of a blurry lens.

Although the only person who can say with certainty what they had in mind is the person who wrote this statement, I guess.