What is Diffraction in Photography?
ฝัง
- เผยแพร่เมื่อ 3 มิ.ย. 2024
- In this episode Don Komarechka explains everything you need to know about lens diffraction, what causes it, and how diffraction impacts your photos. (Spoiler: it can make them less sharp.)
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I mention diffraction in my lens reviews so often that I get mocked for it by my subscribers ;-) but this is by far the best explanation I've ever heard. Absolutely love DPReview TV. There's always someone who knows more than you do...
Thanks for the kind words! This is obviously distilled down to the core essence of the issue, and people will (and have) picked apart all of it to their own liking or trolling... but I'm glad it's appreciated. :)
I see a lot of landscape photographers take pictures with f/22 or something like that. So many people don’t know what diffraction is or just don’t care about the image quality. But still they buy the ”best cameras” and best lenses for their work. Kind of defeats the purpose. Waste of money.
@@Noksus Really? I never see them using such a high F number unless they want something to achieve and are forced by the amount of light and forgot to bring a ND filter.
@@AngelusHD I think this particular photographer wanted as much depth of field as possible and didn't want to focus stack. The photographer: th-cam.com/video/uMzZRmrqHvw/w-d-xo.html
@@Noksus you completely misunderstand the purpose if using those high f/#’s in landscape photography. There are many cases where focus stacking may not be the way to go with extreme foreground and background elements. Like cityscapes where one might not be in the safest spot. Getting everything in sharp focus from the object 1 foot from the lens and 10 miles from the lens trumps the effects of diffraction. Something you would not likely even notice in an image anyway unless someone pointed it out.
That water example is great! Some really useful information here, thanks for creating!
As a physicist, I approve of this video.
During your experiment with the laser, if you now place a microscopy specimen in the pinhole, the diffraction pattern on the far wall will be modified. If you then move the pinhole around a bit and record the changing pattern while doing so, you can feed these patterns into a computer and obtain an image of the specimen in high resolution. This is lensless coherent imaging, an active research area in which I am working.
That's a fun concept about lensless imaging! I haven't heard of that before, but it makes vague sense the way you describe it. I've often wondered if there was a way to determine the origins of diffracted light and the interference patterns to put things back together. Not the same as you're describing by any means, but there are areas that computational imaging have yet to fully explore.
I'll say it again: Don Komarechka is the Mr. Wizard of photography
That's the best description and example using the water that I've ever seen, well done don, killing it!
Worthy of the lab coat, I'd say.
"All I wanted is sharks with F laser beams attached to their heads"!
The Airy disc illustration is a good example but we have to remember that lasers typically emit a single wavelength, so the interference pattern easier to show. Laser light is also 'coherent' and can make these patterns at great distances.
You can repeat this effect with a fine mesh curtain, like silk and a monochromatic street like a sodium light. It does not work with an LED street light.
With a lens in natural sunlight, you have a much wider range of wavelengths, and virtually no coherence, so the diffraction effects that make your image fuzzy are due to a range of colors.
All these years I've been throwing away sharpness thinking I needed that ultimate depth of field. Shucks. I will change my careless ways. Thanks for explaining it so well.
Thanks for the trip down the rabbit hold, Don.
The bonus tip at the end was worth the trip all by itself.
Keep it up, fella!!
A great demonstration of a complex subject, well done!
Thank you for clarifying this terminology so vividly.
MOAR. The whole family loved this! Kudos 👌
Wonderfully explained and illustrated. Thanks!
Fantastic! The BEST explaination I've ever get!!! Thanks
Ingenious to illustrate diffraction with the water model! :-)
Exceptional explanation, as always from You.
thanks, i knew about Difraction and what it was - eventhough i didnt had it in my physics course - having it visually explained helps a lot.
What a good explanation! It's very useful. Thank you, Don Komarechka
Great video, thank you for your work! We appreciate it!
Much Enjoyed Don!
Wow. Solid video. Definitely looking forward to more.
very nice. and great production value.
Effective aperture, I've been using the same concept in my head when accounting for crop factor or using teleconverters. Thanks for giving me the name for it!
Awesome!!! More of this please.
Clear and to the point, good stuff, thank's.
Amazing educational content!
Thank you for bringing in some education.
Thanks for this. A useful follow up might be to illustrate why stopping down a lens results in more consistent performance across the frame compared to shooting wide open, especially on faster lenses. The fact that the smaller the opening the more the wave curves made me think that the opposite would be the case, since the sensor is flat. Another option would be why the depth of field increases with a smaller aperture opening.
Good stuff, thank you
Great video. We could use more of these
Thanks Don👌👌
As a physicist I really appreciate someone making an effort and educating photographers on this subject. Very nicely done!
Glad the video gets a stamp of approval from a physicist! I tried real hard to shy away from numbers and equations and make this a simple visual exercise for non-technical minds.
@@DonKomarechka Physics graduate here as well. I second Viktor's comments.
Well done
F8 And be there.. Thanks for an easy to understand explanation.
Another great lesson from the Mad Scientist!
Thanks Don this was great. Would love to see a demo of diffraction when doing photos of people or animals and landscapes at some point. And I love the white lab coat.....suits the mad scientist in you....lol
Reminds me of an article I read a few years ago, it said f8 might not be the sharpest aperture value on a high-resolution camera due to diffraction (uses 5DSR and EF11-24 as an example), and f5.6 become the sharpest aperture of that combo.
Nice!
Very good
The diffraction of light in optical devices is actually a special case of Heisenberg's uncertainty principle: The opening of the aperture determines the position x of the photons. Via the formula Delta x X Delta p ~ h (where h Planck constant) this introduces an uncertainty of the momentum - and thus direction of the photons perpendicular to optical axis.
Interesting! I love it when people can make science fun. When I saw that shark I could not stop thinking about Dr. Evil.
So glad that Dr. Evil reference was caught by a few people! :)
Me on entire video:
"Yeah, physics!"
great Video I think. but I didn't understand 😂
should we shoot at smallest F number???
Reminds me of red laser & razor experiment we did in school
This has nothing to do with the video, but your picture of the Assassins Creed Black Flag logo.....best one of the series. Just saying.
Carry on......
Great explanation thanks. What I don’t understand then is why some of my large format lenses go up to 64 in aperture and can even close a little further than that. It must be way beond anything useable. Any clue why this is?
Imagine back in the beginning era of photography that you wanted an 8x10 print. There's a good chance that it would have been taken on an 8x10 sheet of film and then contact printed - no enlarging. Because the film size is so large, the effects of diffraction would not be noticed in the same way. If you shoot large format, you know that you can achieve incredible resolution into the hundreds of megapixels when scanned. This is compromised when you shoot at F/64, but because the image capture area is much larger, you're still going to get a decent image for most classic uses.
Would be nice for more manufacturers to offer in camera focus stacking so there is less need to stop down as much.
the intro music was a throwback sound like dipset
What I would like to understand is how diffraction causes the "stars" look on street lights (for example).
So just out of curiosity, what aperture do you actually shoot this lens at 5:1 magnification to get the best results? This video makes it sound like the maximum aperture of that lens has the least amount of diffraction so it will be the sharpest final image (focus stacked of course). But everything I know about photgraphy makes me think it should be at least a bit stopped down to not only get even sharper results, but also reducing the images needed for a good focus stack. Please correct me, if I'm wrong. I don't know much about macro photography. Does that effective aperture math actually mean you shoot it wide open for maximum shaprness at close focus distance?
A great question! While most lenses are not their sharpest wide open, diffraction isn't as noticeable for "ordinary" lenses when you bring them down a stop or two (or three). When shooting on a high resolution body like the excellent Lumix S1R I was using in this video, I tend to favour the wider apertures of F/2.8 when hitting the highest magnification of 5:1. This translates into just be just over F/16 and on a 47MP body, you would start to see the effects of diffraction come into play. If I stopped down even a little, any gains from avoiding the maximum aperture on a late 90's lens would be obscured from that dastardly diffraction. It's a numbers game and a balance of physics, and the "effective aperture" is really the deciding point here. Long story short: I shoot wide at high magnification.
@@DonKomarechka Thank you for the long answer, I appreciate it :)
So I would suppose that a "modern" macro lens has even more incentive to shoot it wide open (in a situation like this), as the difference in sharpness between the widest and "optimal" aperture setting would not ne as big as with older glass. Again, please correct me if I'm wrong.
I never thought about diffraction having a bigger impact on actual image sharpness than the sharpness falloff between maximum aperture and like 2 stops down. Macro photography sure is a different beast, if not for the technical aspect alone.
@@morimetz You may want to take a look at Don's video about shooting snowflakes - It is a nice, though pretty laboursome, workaround when you need to sacrifice depth of field to avoid diffraction. I include the link below, just in case:
th-cam.com/video/WKA8Boa9hBA/w-d-xo.html
@@morimetz A more modern lens would perform better wide open, yes - and cover the delta in quality a bit better. Even still, because diffraction comes into play so prominently at high magnification, older macro lenses perform still quite well. This is also due to the fact that macro lenses often don't benefit from the latest advances in autofocus or image stabilization compared to other lenses.
One question Don. What was the reason for the shark sticker?
That's a little homage to an Austin Powers movie: th-cam.com/video/J3GKVWcBLNU/w-d-xo.html
Ok - but how much of a real problem is this diffraction going to be in the final analysis? Is it very obviously noticeable in a 5 by 7 print? Or only in an 11 by 14 or bigger print?
I would've believed anything you say, as long as you were in a lab coat.
this guy
.
perfect for
.
Hitchhikers guide to the Galaxy remake
(if someone would be mad enough to even consider that)
The absolute mind blowing fact is. Even if u tear apart the light down to one photon u will get the same banding effect as at the laser.
Yeah, that quantum-level stuff makes my head hurt!
how can i remove or change diffraction
Love these videos and the thorough explanations but I DO NOT love the loud music. Makes it crummy to watch when you’re wearing headphones.
DIPSET ANTHEM 🦅 ☺️☺️☺️
My head hurts, it feels like science, probably with math involved somewhere, and then there is the magnification which makes me think of the hard metal stools in biology lab, the stools that made my ass numb, numb!! Then somehow I drift into thinking of chemistry and exams, and then there was Latin, a language which they would not teach us swear words and the native speakers were dead so there was nobody to ask how to swear. All I learned here was what I already knew: the Panasonic G9 is a nice camera and I can adapt all kinds of lenses to it. I would have learned more but that would require more thought and effort, so, I remain in ignorance, which, nonetheless, depending on the school system, is more than enough for a high school diploma, the only requirement there can be breathing and the ability to make occasional guttural sounds.
The only time I studied physics was in high school , and watching this gave me anxiety
I have a question: Why do some lenses get sharper when stopped down? Is that BS or fact?
They mostly get sharper when stopped down until diffraction softens it more than you're gaining (there are some exceptions designed to be sharp wide open). The bigger the sensor the smaller the aperture you'll still see gains at, with equivalent performing lenses (at the overall image level, pixel-peeping is more complicated). Usually people talk about the f/stop the image will have degraded to a certain degree, but some diffraction is always there.
They get sharper as you avoid using the less-good bits of the lens as much (for the techy it reduces the effect of lens aberrations, which are non-ideal features of the lens, which all have). Diffraction is detailed in the video. There's also a calculator here so you can see how the Airy Disc varies with aperture:
www.cambridgeincolour.com/tutorials/diffraction-photography.htm
(Scroll down for the grid with the blob in the centre.)
Longer version on sensor size: for the same framing (having the same stuff in the image) from the same shooting position, you'll use a shorter focal length lens with a smaller sensor, e.g. on a 1.6x crop body a 50mm lens shows the same Field of View as an 80mm (50*1.6) on a FF body. The f/ratio is lens focal length/aperture (strictly "focal length"/"entrance pupil", which is the aperture as seen through the front of the lens, but don't worry about that, I'm just mentioning it to avoid rude comments). So a 50mm lens at f/4 has a 12.5mm aperture and an 80mm lens at f/4 a 20mm one, so diffraction will be less on the larger sensor at the same f/stop.
Any use?
This guy is like Mike Brady and Bill Nye rolled into one! 😁
It's a day flying moth :-)
I Would love to see a continuation to this series. more of a super in-depth review of the optics of modern lenses. For example Canon RF lenses vs Nikon Z lenses
Novaflex what?
The last time I diffracted they told me to keep 500 yards away from schools.
I like the video super informative but could you try to smack your lips less? It’s quite unbearable with headphones.
The one and only foundation of the real unification CHURCH as we know it. ?👀
Everyone on TH-cam should be required to wear a lab coat if giving a tutorial or lesson of any kind.
When I'm watching nerd porn I keep another tab open with actual porn. Then if I get caught I hit Cmd-W and nobody knows.
First
This kid is deleting comments he doesn’t like. 😂 you are going to kill the subs Chris & Jordan are trying so hard to get for you dude.
Not sure what you're talking about? I don't even have access to the channel to delete comments.
@@DonKomarechka someone at “Amazon” does and they are. Comments about how no one actually notices diffraction in an image unless you compare it to the same image with a wider aperture. People seem to think it’s all about getting the sharpest lens. We all know diffraction exists, but it shouldn’t stop anyone from using those narrow apertures. I could send you images at f/22 with amazing sharpness. And when it comes to film and sunny 16, even more so. It’s okay to embrace those high f/#’s
Since the lens aperture is in the CENTER of the lens and not off to one side, try making your aperture smaller from both sides so the hole/aperture remains in the center. Then make another video.. Let's get it right the 1st time and not over again.
With regards to the example in the ripple tank, I assume? The effect of diffraction here is simply an experiment to illustrate the smaller opening and how light bends around the edges and the center. Regardless of if I centered the smaller opening the resulting bends would be the same. Practically, yes, I don't think you'd want the aperture off center in your lens unless you're doing some very creative light-bending experiments, but the diffraction effect for explanation purposes is fine in this video.
@@DonKomarechka Whether the bends in the lens is not the issue, as I already knew that 60 years ago.. I am only questioning the methods you use to illustrate the effect, as they are not really representative of what happens when the light enters.. The problem is the ability of the lens to gather enough rays in the light spectrum and focus them at an optimum point.. May I suggest a better boob toob explanation by reviewing the same problem with telescopes.. As with everything else in today's half-baked (assed) society, it's "for explanation purposes only and is fine in this video", which makes for boob toobers not being as well informed by the contributors as they should be, who are making these click-bait videos.. OOPS!!! Now I've done it.. LOL! OOOHHH Canadaaaaaa.. LOL!
This is waaay too nerdy for me...I love it! 🙏🏽
Good stuff, thank you