[HN Gopher] Photography for geeks ___________________________________________________________________ Photography for geeks Author : excite1997 Score : 245 points Date : 2022-11-27 23:01 UTC (5 hours ago) (HTM) web link (lcamtuf.coredump.cx) (TXT) w3m dump (lcamtuf.coredump.cx) | system2 wrote: | Adding examples makes it better than other sites I've seen. I | will share this with friends. Thanks! | throw0101c wrote: | If anyone wants to move beyond using the "auto" setting on their | camera (or phone), I would recommend the book _Understanding | Exposure_ by Bryan Peterson, the first edition of which was | published in 1990: | | * https://www.goodreads.com/book/show/142239.Understanding_Exp... | | The principles involved haven't changed much in the intervening | decades; the current fourth edition was publish in 2016. | | If all you have is a phone you don't have to get new equipment: | just perhaps a third-party 'camera app' that allows you manual | control of aperture, shutter speed, ISO/sensitivity. | | Once you know how each of these settings alter the resulting | photo you can use them to alter the composition of photos, which | is a whole other craft. | | Edit: seems recent smartphones have little-to-no adjustable | camera settings. | _HMCB_ wrote: | I bought that book months back. Have yet to read it but thanks | for the reminder. | geokon wrote: | I think when you break down all the variables there is really | very little to play with bc no phones have variable apertures. | | ISO is basically a linear gain that's done on the sensor. As | long as you aren't blowing out your photo and loosing | information, it basically makes not difference if you do it in | sensor or later while editing | | So the only variable left is the shutter speed - which is | basically directly dictated by the amount of light you have. | You try to get as much light as you can without blowing | anything out. This is how you get the most information. You can | decrease it to get faster shots with less blur, at the cost of | more noise | | So it all boils down to basically one "slider"/variable between | blur and noise | CWuestefeld wrote: | _ISO is basically a linear gain that 's done on the sensor. | As long as you aren't blowing out your photo and loosing | information, it basically makes not difference if you do it | in sensor or later while editing_ | | This is true for _some_ cameras, but certainly not all. Many | cameras, especially pro or pro-sumer grade, have non-linear | ISO. That is, there are ranges for which it behaves linearly, | but typically there will be some range - say the minimum up | to 1600 or something - where it behaves as a linear range, | and then the next setting up from that (where the settings | are typically 1 /3 stop) will reset to a lower snr. (And yes, | that does imply that in such cases it often yields better | results to go up by one or even two clicks in ISO) | | I'm not sure if there any camera-phones that behave this way, | though. | geokon wrote: | "then the next setting up from that will reset to a lower | snr" | | How does it magically make more photons fit the sensor..? | | And why wouldn't you use that same magic at lower iso gain | factors? | timbeccue wrote: | The base stops are ISO 100, 200, 400, etc. | | Many cameras let you set the ISO in 1/3 stop increments, | but if I recall correctly, many camera manufacturers just | keep the sensitivity at the base stops and adjust the | brightness via software. | | So shooting at ISO 250 really means ISO 200 | (underexposing what you requested) but then adding a | third stop equivalent of brightening to the digital file. | Conversely, using ISO 160 actually means the camera is | using ISO 200 (overexposing) and lowering the brightness | in software. | | What this means, at least 10 years ago when I was more in | tune with the photography world, is that people would | prefer to shoot at the [base ISO stop - 1/3] levels to | because those were the levels with the least noise near | that exposure setting. The cost is you risk saturating | more pixels in the highlights. | | And for the same reasoning, the ISO setting s 1/3 over | the base stops were typically avoided as they were | noisier, albeit with slightly more dynamic range. | spindle wrote: | This is a great resource for finding out which ISO ranges | various cameras are linear over: | | https://photonstophotos.net/Charts/RN_e.htm | lucb1e wrote: | Taking one of the few recent-ish mainstream phones on | this list since the subthread is about smartphone | sensors: Samsung Galaxy S7 has an ISO range of 50-800 and | basically all the noise values (measured in | log2(electrons)) are between 2 and 3. There is a downward | trend from 50 to ~300, above that it's all around 2. | Other phones have similarly shaped graphs with different | absolute values. | | That sounds like the opposite of what GP (CWuestefeld) | described. Am I misinterpreting the graph? | | Lower sounds better to me, so the downward trend on a | scale called "Input-referred read noise" sounds like it | is tuning the Signal to Noise Ratio (SNR) on the sensor | rather than just multiplying the sensor's output value, | and it stops doing that above ~300 ISO. GP described that | it would be a linear multiplier up until (for many | cameras, not specifically smartphones) ~1600 ISO and | _after_ that it would be tuning the SNR. Do smartphones | behave differently for some reason or am I | misunderstanding something? | | (It doesn't seem as though the absolute value says | anything about the quality by the way, as a 10th gen | Apple phone has a much lower value on this "noise" scale | than a 12th gen one. The page does remark "raw values are | not appropriate for comparing camera models because they | are not adjusted for area", so this is probably that.) | throw0101c wrote: | > [...] _bc no phones have variable apertures._ | | :( | rsch wrote: | If you underexpose too severely, the JPEG compression will | eat up all the detail in the shadows. | TreeRingCounter wrote: | > ISO is basically a linear gain that's done on the sensor. | | It's usually not done on the sensor - it's usually done by | the ADC that performs sensor readout. | | Some cameras use a technology like Aptina-DRPix to | dynamically change the capacitance of the sensor FETs, but | (as far as I'm aware) this only exists in a simple binary | form right now. E.g. one of my cameras reduces sensor gate | capacitance when the ISO exceeds 800, but otherwise any ISO | changes only affect off-sensor hardware. | geokon wrote: | Right, sorry. Not on the sensor, but the hardware that's | reads it off the .. which I guess is not technically the | sensor.. haha | | You're still multiplying what is the photo-count or | shotnoise | | Didn't know there is technology built on top of that... | Does changing the capacitance increase the sensitivity | somehow? I guess then the question is.. why isn't that | always enabled. There must be some downside to it | mgraczyk wrote: | This is only true if you take just one capture. On Pixel, | iPhone, and others we take many small captures and merge them | together. There's lots of cleverness there and it allows you | to have less noise without motion blur or blowing out | highlights. | sva_ wrote: | > no phones have variable apertures. | | Even my almost 5 years old Galaxy S9+ has aperture. Surely | something better came out since. | wtallis wrote: | Wikipedia says the S9/S9+ was the first phone since 2009 to | have a variable aperture. The S10 series also had it, but | it was gone again in the S20. So it's definitely not | common, and even in the handful of phones that had it, it | was only one stop of adjustment. | gofreddygo wrote: | Aperture Size, Shutter Speed and ISO. Just understand what they | are. And their units. | | Actually see pictures varying one and keeping others constant | to get a hang of things. | | Then go backwards, check professional pictures and guess the | values. Professional photography forums all photos have these | values published . | | Night/Day photography, moving/still and background focus are | the only 3 skills you need as an amateur photographer. They | rely on the 3 settings above. | | Beyond that lies the rabbit hole that, if you venture, speak | not to any people whom you wish to keep friends. They hate when | you try to tell them. | | Don't spend over 2k on lenses. | | Have printed photos on glossy, matte paper. Touch and feel | them. Worth the time. | Terretta wrote: | This is very well done for a new-to-photography audience. Will be | sharing around to people who say all their things look like | snapshots, what's up with that. | | Great use of examples, except for one: kid on bridge. | | > _At the same time, it must be said that color and tone can be | what separates a mediocre photograph from a memorable one. To | illustrate, let 's look at the potential evolution of this | vacation shot deliberately chosen for its mediocrity..._ | | Then the dynamism is removed by 'correcting' the dutch angle to | horizon, the surprisingly good color balance is skewed off, and | the whole thing gets that circa mid-2000s HDR look from Flickr | and Shutterfly and the like where every photo got tone-mapped. | | Underwhelming of an end result, especially compared to the later | color and tone examples (e.g. kitchen superhero). | SamBam wrote: | I had the exact same thought on that sequence. | | The angle is a personal choice, though I think I agree that the | mirroring angles of the two bridges was more interesting than | having the horizon straightened. But the final "Tone Curve | Corrected" turned a fairly nice image into a typical HDR-ruined | photo, where the eye can't focus anywhere because all the | colors have the same value. | | To add some praise with the criticism, I thought the | explorations of light white the photos of the wife were well | done. Pointing the rear light at the subject's back to create | that subtle halo is nice and I had not considered it. | excite1997 wrote: | In the mid-2000s, HDR was all about jacking up local contrast, | giving you that unique look of gritty skin and halos cropping | up all over the place. I'm talking stuff like this: | | https://digital-photography-school.com/wp-content/uploads/20... | | Less obnoxious tone mapping that compresses shadows and | highlights is a more modern trend, I'd say post-2012. It's | basically done by every cell phone today when shooting a high- | contrast scene. | lxe wrote: | This is helpful for my stable diffusion prompts. | lelandfe wrote: | A lot from the article will not work, because the terms are too | overloaded ("three point"). SD photography and lighting keyword | dump I've tested for 1.5: | | _f1.8, dof, bokeh, soft focus, chiaroscuro, backlit, golden | hour, soft lighting, natural lighting, warm colors [but not | "cool"], Polaroid, lens flare_ | | "85mm", "50mm" etc all make the image realistic, but don't do | anything specific. | | Pro-tip: use "windows" to get many of the outdoor lighting | keywords available indoors. | kyleyeats wrote: | Thanks for these. Can vouch for _golden hour_. I can see why | directors are obsessed with it. | [deleted] | yieldcrv wrote: | I've been using photography and focal length prompts on stable | diffusion since I first installed it, would recommend | muglug wrote: | The main thing about photography is your first 10,000 photos will | likely be bad. Modern technology makes it possible to get through | 10,000 snaps much faster and much cheaper than when using film. | | But taking those photos is not enough -- it's in the editing of | those first 10,000 photos that you will find the hidden | photographer in you. | | Photography is a lot like writing code: you can create something | that does the job, but does not do it beautifully. You can keep | on creating until creating beauty becomes easier. | bradknowles wrote: | I wouldn't say it's your first 10k photos. Because anyone can | just hold down the button and take hundreds of photos. And | those hundreds of photos don't really count as separate | pictures in this regard. | | I would say that it's more like your first 10k different | photographic compositions/subjects. | | From there, I agree that you really learn in the editing. | oogali wrote: | For me, it truly was after my first 10K photos -- speed | shutter and all. | | Once you sit down and go searching through that burst for the | perfect or otherwise usable photo of that burst, you start to | notice the small things: the slight detail changes at the | edges, what may have transpired between captures, how a light | source that changes in milliseconds can affect the overall | feeling. | | It took me about 2.5 years to reach that point. Shooting at | different times of the day, different seasons. Countless | hours tweaking levels and cropping in Photoshop, Capture One, | etc. Lots of changes in gear: UV/haze filters, circular | polarizers, tripods, zoom lenses, prime lenses. Flashes, | reflectors, gray cards. Exploring the different modes on my | camera, Magic Lantern firmware, etc. | | It all counts. But the post processing is the crucial part of | the feedback loop. | spoils19 wrote: | What a great resource! | vanillax wrote: | Love it! | qntty wrote: | See also, Marc Levey (CS professor at Stanford specializing in | computational photography) gave some good lectures at Google a | few years ago on digital photography: | | https://sites.google.com/site/marclevoylectures/home | mgraczyk wrote: | Levoy! | qntty wrote: | Oops, sorry! | lucb1e wrote: | The word "Levoy" does not occur on the page. Perhaps the | site's author should have put their name in the page title | instead of, appropriately, in a header picture! | yieldcrv wrote: | This is good, I would add that "made up composition rules" are | instead "made up composition _guidelines_ ", that people should | learn how to deviate from after constricting themselves with | false constraints | semireg wrote: | The things I'm drawn to in life is where art meets science. In | hindsight, so much of the secret is knowing how to avoid failure. | Baking bread? Build the intuition over time and you'll realize | baking is forgiving so long as you don't do these "5 bad things." | Gardening/farming? Yeah, there's a big list of bad things. | Brewing beer? Another list of things to avoid. The basic rules | (rooted in science) are like guardrails and everything else is | the art. I love this so much. | | In my early 20s I had a week long mind meld knowledge transfer | from a self taught photographer. It made me fall in love with | photography. I'm still using it to this day to photograph new | label printers (black plastic is terrible to photograph) and | labels (oh god they are 2D!). | | I'm doing an OK job. Room for improvement but fine for the | initial launch. You can see them here: | https://mydpi.com/products/professional-synthetic-direct-the... | | In case you're like "why is this guy selling label printers?!" | | I'm a solo software dev that wrote Label LIVE (electron) to | design and print labels. Now I'm vertically integrating with a | printer I've imported from China and labels made in the USA. | | Business and entrepreneurship: just avoid these 9999 things and | you'll be fine! Science and art... | photochemsyn wrote: | An interesting site with lots of information about 35mm | photography and film vs digital techniques is 35mmc.com. Here for | example is a very clear and concise discussion of depth of field | and the factors that control it (such as aperture, focal length): | | https://www.35mmc.com/25/07/2016/basic-optics-photographers/ | skhr0680 wrote: | Pretty awesome overall, one improvement would be to shoot the | model in the focal length shot face on to better illustrate the | big nose, no ears (too wide) and pancake face (too tele) effects ___________________________________________________________________ (page generated 2022-11-28 05:00 UTC)