Macro Photography Diffraction - Explained Simply!
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- Опубликовано: 28 сен 2022
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Here's another way to understand bellows factor. I like to think about it in terms of focal length and aperture. Since F stops are fractions - F2.8 can be written F 1/2.8 - if we have a lens effectively 100mm from the focal plane (at infinity, say), at F4, the aperture will be 25mm in diameter. (1/4 x 100 = 4) If we double the lens extension, that F4 literally becomes F8. (200 / 25 = 8) It's not LIKE F8, it actually IS F8, F-stop being the ratio of aperture to focal length. To get F4 for exposure purposes at 200mm extension, we would need an aperture of 50mm (200mm / 4 = 50mm. That would be marked F2 on our lens.) This seems very "physical" to me, and that's kind of how my brain works. Thus, we get double the extension = 2 stops, half again the extension is one stop(ish) for a rule of thumb. Of course, if your camera has an actual bellows, it will seem obvious this way. With a helicoid-focusing lens maybe not so much. Many bellows units come/came with a ruler of some sort, sometimes actually marked with bellows factor for a given lens. With through-the-lens metering available, we don't think so much about bellows factor for exposure any more at all, unless we're using a manual flash. For diffusion purposes, it seems more comfortable to me to know that the aperture (which is a ratio after all) actually IS reduced as we focus closer. Of course, your "projecting light on a bigger area" analogy works fine too. I'll think of that one in terms of an enlarger because that's physical and real to me.
Wow this is a great way of thinking about it - thank you Carl!
Just what I needed! 👏
Finally someone that explained it in way I could understand. Greatly appreciated.
Great information to have. Basically every full level of magnification reduces the fstop by a factor of one original fstop...4 to 8 to 12 to 16. What an easy way to remember how to control light! Thanks for the simple explanation.
Thank you for keeping the examples very simple. Nice visual representations, too!
Excellent! Thanks a lot.
Your explanations are very good
I remember going over this subject in high school physics but I don't remember it too well and I can't explain it too well because I was taught it in French and the vocabulary is half forgotten. I remember we did experiment where we had pieces of glass painted black and we would put one straight scratch and run light through the scratch. Light came out the other side not too surprisingly. Then we would do the same thing but the scratch was done with two razor blades very close to together and run light through the pair of scratches and we compared that to two openings in a wall and waves in water hitting the wall and the results were very similar: two arcs of intersections of two sets of waves coming from two point sources of waves close to each other. In that way we demonstrated that light was a wave. What we did in class was duplicate something what was discovered in about the 1700s
definitly learned something and liked it, thank you!
Best explanation of diffraction I've heard. Thanks!
Very helpful, thank you.
Learned something new today 😲. I was not "concious" about this effect, I just realized that it is sometimes blurrier, sometimes sharper. Now I know another possible reason. I usually simply leave the apperture on 11, but from now on when shooting on 2x, I will decrease to 8. Many thanks for this tip! 😉
This was a great video and I really enjoyed it. Thank you, Micael!
As always Michael excellent info. Through your instruction I have finally broken my bonds with AUTO and have a much better understanding of manual settings. I’m also a Patreon and love supporting your efforts! Thank you!
Thank you for the support Teresa!
Outstanding video with a simple explanation. Great job Micael! 👍
Fantastic explanation thank you
Admittedly, this hurts my art-centric brain 😆 Not your fault whatsoever, the highlights / summaries here are still very helpful and clearly explained. Especially the 1x / 2x guidelines. Diffraction was something I never really paid attention to years ago. Looking back at some old images, it definitely shows. Thanks for your vids!
Excellent!
Thank you for explaining something very complicated. Made sense, thanks 🙏
Thank you! It's rare to face accessible information like this. Im subscribing.
Very helpful!
Thanks Michael very informative 👍📸
👍 That enlightened me a lot ! Thanks.
thanks for tackling such a complex subject 👍
Thanks for that explanation. I work in camera retail and it is always great to find understandable ways to explain things, and I learned here myself.
Bra förklarat! :)
Ha en fin vecka!
Great explanation, thank you sooooooooo much......
Thank you for this video. I appreciate it very much.
One of the best information videos on macro photography diffraction issues. Thanks.
In my experiance, diffraction responds well to software sharpening. Focus stacking is another solution.
Useful video 🌿
Great Video..
Very nicely explained, great video for us visual learners!
Fantastic video, and explains a complicated subject in an understandable way. I learnt several things in this video alone. Thank you!
Thank you. Very interesting and informative
Thank you very much for the explanation. I loved the relative exposure graph and I went ahead and made my own since my rf 100m macro lense has 1.4x magnification at its closest. Now I know what to set it to depending on the distance I take the shot!!!!!!!
simple and easy to grasp explanation of aperture induced diffraction and of effective aperture in high magnification- which must be accounted for in macro photography. The next video to watch is how to diffuse your light source. Well done!
Thanks!
Thanks Micael - learned a bit 🙏
Thank you so much for this video, now I understand how it works and what aperture I need to set. I recently added a macro ring to my macro lens (to get more magnification) and noticed that there was a lot more diffraction with f16 and thought the ring was bad. But your video helped me understand that the larger the magnification, the smaller the aperture should be set. Good luck!👍👍👍
I had a similar problem a couple weeks back when I forgot to take off my diffusion filter. Going from regular photography into macro, the super subtle diffusion suddenly becomes incredibly in your face, and not very pretty at all. =D
Thank you for this tutorial. I‘m new in macro photographie and this is surley a good tip.
While I like what you said, the fact remains that the depth of field on a practical subject like the head of a bee is so small that your f/8 limit is simply not going to get all of one eye in acceptable focus, That is why we see so many dead insect focus stacked photos. I do believe that the disadvantage of the small pixel sensors (I have a Canon R7) that certainly does show up when pixel peeping on a monitor goes away when making reasonable sized prints viewed from a reasonable distance. Diffraction blurs the whole image more evenly which looks better to me than having a band of sharpness in the middle of a sea of blur. Sometimes I believe we do better shooting at 1:1 and cropping compared to being too close and too small aperture to get the frame filled. Does diffraction make a super sharp lens (Laowa) no better than a normal one or at too small aperture do they even out? My best 3x shots were taken with a normal 50mm f/1.8 on tubes but I attribute that to the greater ease of focus placement offered by an auto-diaphragm. That makes my preference about a stop smaller aperture in many cases and makes me want to chase insects on cold mornings when they are slow enough to allow focus stacking. We can't win them all. Good video.
This was the best explanation for the diffraction for "idiots", not how gurus, masters, experts and geniuses try to explain it. Thanks.
Very nice information
Hi Micael !
Definitely the best video on this subject, congratulations!
Glad you liked it!
Very interesting thanks a lot
Good cleared my doubt about difraction and macro effect on aperture.
Light is diffracting when it hits an edge, the physical barrier causes some of the photons to be scattered. So some light is always diffracting, its just that as your aperture gets smaller, more and more of the light is destined to hit an edge. Even wide open some light is diffracted, from the edge of the lens itself to even the glass (nothing, not even air, is perfectly transparent...some light is already diffracted before it even reaches you) but the ratio of diffracted light to non-diffracted light is so small you don't notice.
Wow is it really that simple? Thanks I’ll look deeper into this.
Very enlightening! I wondered why my new A7R4 was not as sharp in macro shooting! I'll revert to my older camera body for those shots! Thanks!
Thanks, and good on you for this video for I just got a Nikon 105 Z Macro for this Winther in the woodland around Me, All the best Robert G, in Scotland UK.
Super informative video which has explained a lot to me. Thanks for making sense of a problem of lack of sharpness.
Nice video and thank you for helping to clarify this topic. This makes an excellent argument for focus stacking. As you know, you can shoot wide open and your desired depth of field is only limited by the size of the stack. Of course the caveat is that you need a subject that will stay still during the stack. However, focus stacking can produce super-sharp shots minimizing diffraction. I just that it was worth pointing this out as an option.
Great Video! so good you described that 👌🏻 i now use the fuji 80mm f2.8 macro with 2x teleconverter. There i can see that very practical, and the camera show me the effective fstop so its pretty shocking what numbers i get on the display when i turn up to f22 on the objective :D
I subscribed after watching this video. Thank you!
Thanks for watching :)
With such talent and skills in drawing you deffinitely do not need any marco pics )
Thanks alot! Very usefull.
Cheers
Thanks 😄
Aperture at Infinity is something new to me, New Learnings from you
As a rule of thumb i use f11 for full frame and f8 or f9 for APSC to keep diffraction minimal.
Maybe not quite what one would hear in a physics 101 lecture but you get the message across well Micael. I was rather surprised when Nikon released their new 105 macro - which displays effective aperture as you focus closer - to read criticism that it was not constant aperture. You have hopefully educated some of these critics.
I liked your way explaining things 👏 good work
You got a +1 subscriber 😁
Thank you 😊
Hi Michael, diffraction always happens at any f stop. Water waves or light waves always get bent around the edges. Your water diagrams were nearly right. The second one with the small aperture was fine, but the first one was right in as much as there were straight waves through the middle, but it was missing the curved ones at the edges. Diffraction is always there, but it gets worse as the aperture gets smaller. At smaller apertures a bigger *proportion* of the light is passing through close to the edges and will be bent.
plus, the diagram assumes that the waves travel in same directions, which in most cases it is not true.
In there any lens example that exploits this phenomena, and uses different material in the aperture blades to give some artistic effect?
Yes of course. Just trying to simplify to make this easier to understand. If I would have made a 100% accurate video mentioning every detail it would be 2 hours long and nobody would learn anything because they would be bored to death :)
@@MicaelWidell I know, I know. Well, I would be interested. This video got me thinking: do you think it would be possible to demonstrate the diffraction by using a prism? I mean, splitting light into a "rainbow" and align it to the camera lens, and then take pictures at different fs? this idea might be refine though. what do you say?
@@nelzackleo The effect of a prism is refraction, not diffraction.
@@AndrewRock refracted light can't be defracted?
I often shoot macro even with f22 or f32 and sure, diffration kicks in, but i got more dept of field and i can get the sharpness back by using Sharpen AI by Topaz.
Can't get my head around it, will watch again, and again. I've used my moms old Nikon Micro 55mm AF (without D) to digitize her slides, and I think the sweet spot is f/8 - usually around 1:1.8 to 1:1.2 magnification depending on setup. So I've used the same when trying to capture insects, but since I haven't trained them as well as you have, I rarely can do manual focus stacking. Also had a winter now of focus stacking my 80s Legos, and me and focus stacking aren't friends, especially with points of light in the background. Retro space Lego requires points of light in the background. Had to buy a 60mm Nikon Micro AF (without D) because the old one is falling apart. And I'm considering doing f/22 this summer to get more of the bug in focus without stacking. After watching this video a few more times
This video is awesome!!! It's not fair that there are only about a thousand likes!
Thank you for the kind words 😃
Very cool video, even if I haven't finished it yet
Great video! I recently finally bought Laowa 90mm and been shooting at f11. Looks sharp but could be sharper. Bonus…..I see all the dirt on my R6 sensor now that I never knew existed….keep cleaning it but can’t seem to get it all….😢😊
In the video you were unsure about the explanation for diffraction. Hopefully, this will help.
A wavefront can be modelled by an infinite number of point sources with each one producing a spherical wave front in which the waves in any direction are modelled by sinusoidal waves. Summing all of these waves will produce a plane moving in the direction of the wave. Simplifying the model as a wave as in your diagram we can introduce a slit of length d that is parallel to the original wavefront. We can assume that the light is monochromatic with wavelength lambda. The waves can interfere with each other, so if one wave meets another wave that has a phase difference of half the wavelength (lambda/2), the two waves will cancel each other out. The wavefront can be modelled by a linear wavefront orientated at an angle theta to the direction of the original wavefront, so if theta is 0, the wavefront after the slit will continue in the same direction as before. This angle theta also denotes the angle where the waves cancel each other out, so for an angle from 0 to just less than theta there will be a wave but there will not be a wave at angle theta.
Let us assume that a wave at the right hand end of the slit interferes with a wave from the middle of the slit (d/2) such that it will cancel out. Using trigonometry, we have:
(d/2) sin(theta/2) = lamda/2
sin(theta) = lambda/d
theta = arcsin(lambda/d)
If we consider the next point source just to the left of the right hand and middle points, the same relationship still holds. Continuing this for all similarly spaced points along the slit, we find that the wave will cancel out for all of these pairs of points in the slit.
Using the above equation, the angle theta will increase as the width of the slit (d) decreases and this fits in with you saying that the diffraction increases with increasing f-number. In addition, the equation also shows that the diffraction depends on wavelength. So, red will diffract more than blue.
For more information look at "Diffraction" on Wikipedia or:
ruclips.net/video/JqSm-gI6opo/видео.html
The video is quite good as long as you can put up with the tutor being a bit silly.
Great explanation. What app do you use on your iPad to draw and capture your drawings for RUclips video? My audience would benefit from me teaching like you drawing on the iPad. Thanks!
I actually just used the Notes app from Apple that comes preinstalled. If you don't have a pen you can enable finger drawing as well.
This was extremely useful. Now I know why on Canon RF 100mm 2.8 I should use f8 and not f22. Thank you!
The explanation of diffraction comes the restriction on the position of the photon as is passes through the aperture. As you close the aperture the position becomes more certain - it went through the hole and the smaller the hole the better you know where it was. However, there is a trade off in that as the position of the photon becomes more certain its momentum becomes less certain. Momentum is the mass times the velocity in a cerain direction. The mass and velocity (speed of light) cannot change (are certain), and so it is only the direction that becomes uncertain. The effect is extermely tiny, but over the focal length of a lens (say 50 mm) the photo may divert enough after passing through the aperture to hit a neighbouring pixed (say 5 micron off) rather than the one that was originally srtaight ahead (i.e. divert by about 6 one thousandths of a degree). It can be calculated from the 'Heisenberg uncertainty principle' [(uncertainty in position times uncertainty in momentum ) is greater-than-or-equal-to (Planck's constant divided by 4 pi)]. In photography terms, roughly you start to get diifraction degradation when the pixel pitch (in micron) is smaller than 1.33 times the f-stop.
Here some concepts:
Diffraction is constant. It's always there. However with wider apertures, the image signal is stronger so the diffraction becomes less strong in the relevant case.
F number is dependant on the lens focal length, however for diffraction the physical exit pupil matters. So wider lenses (shorter focal lengths) will show diffraction much sooner. And a really telephoto lens will be fine at f/64. Which also helps to understand why large format film is fine to shoot at f/128. Because it's using lenses that are something like 600mm.
A good resource for understanding the physical concepts of light(and optics) is Huygens Optics on RUclips. Especially their video on the single spit experiment
Instead of rays, think of it as particles. That's how light is. It is both a wave, like in the ocean, and a particle (which would behave the way you described rays)
So on my 24MP aps-c camera I find 2x f11 and 1x f16 to be about the most softness I find acceptable. I'm pretty new to macro still, but the video does a really good job explaining the phenomenon in simple terms. Thanks
The problem kicks in sooner on small sensors, thats another advantage of full frame. If its just for posting online, like many of us do now, its not so critical.
Great job explaining how diffraction works. So if I'm using Tokina macro lens which has 1x magnification number and add raynox RDX250 filter, am I counting it as 3x manification or still just one? Raynox doesn't have aperture.
This is why focus stacking is a thing 😊
Great info. So would it be beneficial to use a 2X apsc macro lens on a full frame camera, to get less pixel density, and therefore less diffraction? I know from my own experience that I get great results, with a Laowa 2X apsc 58mm macro ,on my sony A7IV camera. What do you think?
Hi Micael. Your theory is well-explained and I have no disagreement with principles laid out in the video. But I strongly disagree with the results for example on the starting image we see comparing f/22 to the larger aperture. There is absolutely no need for anything like this level of blur at f/22. With my D850 and Tamron 90mm x1 Macro lens I have done experiments with much smaller apertures up to f/64 and even these have virtually no bluriness due to diffraction. For example a 4cm diameter nectarine blown up to fill a large desktop screen showed no discernible softness. And another factor is that we often want a whole insect or other creature to be in focus (though not always) and the supposed softness has to be balanced against the majority of the creature being out of focus anyway, the effect of which makes diffraction softness as I have witnessed it on my gear pale into insignificance. I did a more detailed analysis of this here, with illustrations of the same picture using different f stops up to f/64. I am thinking that this effect may possibly vary a lot depending on camera or lens used, although I don't know: photonomy.co.uk/discussion
Yeah sorry the thumbnail image is not real, I just applied gaussian blur to the right side to get a clear illustration - yes the diffraction is not as severe in reality.
mmm, there is a bit of missunderstanding here, I was very confused too when I learned this.
Diffraction doesn't exists because of the small aperture, it exists because the light hits the edges.
In the waves example, even with a large opening, in the center it goes straight, but on the sides, the waves do spread.
There is diffraction no matter what aperture you have, what gives the impression that you have more or less is because... stacking of light.
The common mistake is to think that a single line goes from the target point, through the lens, to the pixel.
No, the light goes from the target point, to the full lens, fully redirected to the pixel, unless blocked in the edges by the iris.
You stack the whole light from the lens to a single pixel, for all pixels, this is why reducing the aperture doesn't cut the photo's sides.
So a pixel will be the light from the right target point and a bit of diffracted light from other target points.
By reducing the aperture, you get less light that doesn't hit edges, but roughly the same amount of diffracted light.
So the pixel has overall more light coming from wrong targets, making the blur effect.
You see more blur, with the same amount of diffraction.
I'm Glad I found this channel. I'm new to Macro and almost made an expensive mistake if i'm understanding correctly. I have T7 Rebel 24.1 MP and was looking at moving to a much high MP count to get a sharper image. What sensor resolution would be versatile for landscape and Macro, Would 30 MP be acceptable?
30 mp is perfect. I have that on my Sony camera. But honestly anything above 20mp will be enough for most people.
Question. Why does the "real apeture" change the closer the subject is from the lens? At the same time as the Bokeh get enhanced/ shorter depth of field.
I've always accepted that macro needs more light, but never understood why. I love learning things like this. Thank you
Your eye looks normal, was this before or after? Hope it's better.
Thank you Mr. deGrasse Tyson. This was a great explanation!
Micael deGrasse Tyson... Mike Tyson?
Micael. I have a problem.I bought a used meike 320 flash. I think I have the same diffuser as you (similar to a dooor). The problem is that no matter what flash power on manual mode I set, almost all the light passes through the diffuser. I don't know what to do anymore, I just bought a 65mm laowa and this flash but I can't diffuse the light.Regards
It’s because of the edge of the aperture. My non-scientific way of thinking of it is it’s kind of like a discontinuity and the waves interact with it and spread out.
Smaller apertures have a higher ratio of “edge” to area so the contribution of the blur from the edge is more. Larger aperture have a smaller ratio of edge to area so the contribution of blur is less.
The blur is always there though. But at say, f/2.8, the brightness from the large area dominates the brightness of the blur so it is less perceptible. But it’s still there. It might just be 10 stops dimmer so it’s invisible.
Of course, at larger apertures, other lens defects become more obvious.
That's an interesting and intuitive way to think about it
I took high resolution RAW photos last week - Both Flickr and IG preferred another slightly blurry image I took on my old phone - Not sure where I go from there - ICM perhaps?
A lot of photographers get confused or do not care about fstops a f/2.8 is a larger openings then f/22. The f is function is the mm size of your lens or the sensor to the lens distance. So a fstop of f/2.0 on a 50mm lens is 50/2.0 or 25. So what your saying when you magnify by 1x the lens is in affect at 100mm or 100/2.0 or 25
This is the explanation I am looking for , but maybe it would be better to include more sample photos taken with the same working distance and same focal length but different Sensor resolution. Pixel peep to see what’s the difference. Thanks
Thanks for this! I think I already knew what defraction is in a schematic way, as you also showed it on one of your drawings. But I still wonder what it means in reality for especially my camera. 48 megapixel, canon R5, RF 100 millimeter 2.8L, very good sensor. And what is the effect of extra light added? A good flash? Artificial LED light? There is also a factor of blurriness that you can minimize by adding light. Is that also connected to the phenomenon of diffraction? It seems to me, without me knowing anything about that, that the amount of light is a factor here, that you should and you (micael) do use, when you make your macro shots. Could this be put in your scheme? Right now, at least, I am a bit confused about how much of this and how much of that I should add, to get sharper pictures at high f-stop values.
But thanks! Very interesting!
Hi thanks very much for this. I will try to find the effective aperture table for my lens, but I have a question regarding that. In the table you refer to there are columns for magnifications of 1X 2X 3X etc magnification, please can you tell me how these magnifications are possible with a prime lens... does this refer to how close the lens is to the subject?
He said he got the chart from the Canon MP-E 65mm which does 1x-5x magnification. There's also the Laowa 25mm that does 2.5x-5s. As far as I know, those are the only ones that go past 2x.
Another great video, very informative, thanks. It's ironic how you're iritis showed the difference between F2 and F22.
😄
Better to get the shot than miss it because you’re worried about a lens error that makes little difference. I shoot macro a lot, using an old Micro-Nikkor 105 f/2.8 (not comparable to a Samyang 135mm f/2) and I regularly shoot at f/22. The only time I don’t is if I’m using a rail and focus stacking. _Then_ I shoot at f/8.
thats crazy you notice only
a little difference
@@justinwilliamson5834 Macro shooters use f/22 all the time. Shallow depth of field is your enemy in macro and macro lenses are designed with this in mind. People have to get over this diffraction phobia. You would have to enlarge to a ridiculous degree to even see it and even then, not at a normal viewing distance.
And I reiterate that it’s always better to get the shot on settings you might not normally use than to _miss the shot altogether._
question for you Micael - not sure if is diffraction in this case but my 50mm f/1.4 is blurry at it's widest aperture and it gets sharper at smallest apertures. I never tested the sharpness at f/11 or smaller. Why does that happen at f/1.4? If not diffraction in this case, what is it?
It is pretty common for 50mm f/1.4 lenses to be unsharp at f/1.4. Most likely not related to diffraction. It simply is hard to create a perfectly sharp f/1.4 lens. Lenses are in general sharpest around f/5.6.
When all the light is forced through a single small aperture, this causes the waves to overlap, interfere and cancel each other.
Hello, the Sony Alpha A7 IV camera does not have Focus bracketing - is software modification expected?
Thank you
If you want to do focus bracketing you need to do it in your computer yes. I have videos about this. Search my name and "focus stacking".
I am pretty sure the magnefication/diffraction works somehow else. Maybe that is the answer for zoom lenses though. If I shoot a landscape at f/22 I will not be able to see say the branches because of diffraction but as I get closer (you are getting closer to go from 1 to 2 magnification, this is NOT a zoom lens) and take a photo of a branch it will look much more detailed.
What lens is you recommend lawoa lens for canonr6 ?
Please use my lens guide
definitely, bigger pixel - less diffraction. as well as higher sensitivity of course.
Hello, what do you photograph during the winter - I'm from the Czech Republic and the insects are starting to hide ? Thank you.
Watch my videos from winter months and you'll get an idea :) A lot of water drops, ice, leaves etc.
@@MicaelWidell Thank you.
Great topic, But for me your BW example with blur vs magnification shows only why eg. apsc starts to get earlier suffering from diffraction than FF. It does not explain so well why magnification or actually distance and focal length should matter. In my opinion it is the angle of the light waves that matters in magnification. The angles are different for infinity focus compared to typical macro distances. Then your picture makes a lot of sense.