[HN Gopher] Exposure Simulator
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Exposure Simulator
Author : sneela
Score : 117 points
Date : 2026-02-11 11:16 UTC (11 hours ago)
(HTM) web link (www.andersenimages.com)
(TXT) w3m dump (www.andersenimages.com)
| ChrisMarshallNY wrote:
| That does a fairly good job.
|
| I'm sure that image nerds would poke holes in it, but it seems to
| work pretty much exactly the way it does IRL.
|
| The noise at high ISO is where it can get specific. Some
| manufacturers make cameras that actually do really well, at high
| ISO, and high shutter speed. This seems to reproduce a consumer
| DSLR.
| arghwhat wrote:
| With the disclaimer that I am comparing to the memory of some
| entry-level cameras, I would still say that it's way too noisy.
|
| Even on old, entry-level APS-C cameras, ISO1600 is normally
| very usable. What is rendered here at ISO1600 feels more like
| the "get the picture at any cost" levels of ISO, which on those
| limited cameras would be something like ISO6400+.
|
| Heck, the original pictures (there is one for each aperture
| setting) are taken at ISO640 (Canon EOS 5D MarkII at 67mm)!
|
| (Granted, many are too allergic to noise and end up missing a
| picture instead of just taking the noisy one which is a shame,
| but that's another story entirely.)
| einr wrote:
| Noise depends a lot on the actual amount of light hitting the
| sensor per unit of time, which is not really a part of the
| simulation here. ISO 1600 has been quite usable in daylight
| for a very long time; at night it's a somewhat different
| story.
|
| The amount and appearance of noise also heavily depends on
| whether you're looking at a RAW image before noise processing
| or a cooked JPEG. Noise reduction is really good these days
| but you might be surprised by what files from even a modern
| camera look like before any processing.
|
| That said, I do think the simulation here exaggerates the
| effect of noise for clarity. (It also appears to be about six
| years old.)
| kqr wrote:
| The kind of noise also makes a huge difference. Chroma
| noise looks like ugly splotches of colour, whereas luma
| noise can add positively to the character of the image.
| Fortunately humans are less sensitive to chroma resolution
| so denoising can be done more aggressively in the ab
| channels of Lab space.
|
| Yes, this simulation exaggerates a lot. Either that, or
| contains a tiny crop of a larger image.
| ChrisMarshallNY wrote:
| Yeah, I don't think that it's easy to reproduce noise (if it
| was, noise reduction would be even better). Also, bokeh/depth
| of field. That's not so easy to reproduce (although AI may
| change that).
| 1e1a wrote:
| Video showcasing ISO noise behavior of a few different cameras:
| https://youtu.be/iiMfAmWbWSg?t=94s
| ChrisMarshallNY wrote:
| That's a pretty good demo!
|
| Very limited camera choices, though.
| 1e1a wrote:
| Yeah, it would be interesting and useful to see this across
| many more cameras.
| ChrisMarshallNY wrote:
| Some of the new Nikon cameras have excellent high-ISO
| performance. Also, they now own RED, so we should see
| some interesting stuff, down the road.
| asdff wrote:
| dpreview is good for that. They shoot a test image of
| every camera on the market, and you can compare specific
| iso values on the same subject side by side.
| sneela wrote:
| I recently bought a film camera (Minolta X-700) and I wasted a
| whole roll because I inverted the aperture (i.e, 2 = sharp, 32
| = blur)...
|
| I'm interested to see how the roll turns out - gave it for
| development the other day, had a good laugh with the employees
| though.
|
| I now have a mnemonic for it: Blor - a (somewhat) portmanteau
| of Blur and low. So low aperture = blur.
|
| Edit for clarification: I mean low number (2 vs 32) = blur
| 4gotunameagain wrote:
| The larger the entrance pupil is, the narrower the depth of
| field is.
|
| The smaller, i.e. the closest to an ideal pinhole camera, the
| wider the depth of field is. A an ideal pinhole camera has
| infinite depth of field.
|
| Unfortunately the aperture f numbers are the wrong way round;
| larger numbers correspond to smaller diameters.
| tiagod wrote:
| High aperture = Blur
|
| Unfortunately the lower number actually means bigger
| aperture.
| sneela wrote:
| And that's what exactly confused me :)
|
| With my mnemonic, I say low *number = blur
|
| I should have been more specific
| Filligree wrote:
| The aperture size is usually described as e.g. f/32,
| where f is a camera-specific constant.
|
| Denominator, not numerator. That's why larger number =
| smaller aperture.
| armadsen wrote:
| To be a little more precise, f is not a camera-specific
| constant. It's the focal length of the lens. It's a
| formula that tells you the diameter of the entrance
| pupil. So at a focal length of 50mm, an aperture value of
| f/2 means an entrance pupil diameter of 25mm.
|
| But photographers generally just say "f2", meaning an
| aperture value of two set on the dial of the camera/lens.
| It's one stop faster (twice as much light) as f/2.8.
| It'll give you a relatively shallow depth of field, but
| not as shallow as e.g. f/1.4.
| Toutouxc wrote:
| Note that both very high or very low aperture settings also
| bring their own optical issues. At very low values (big hole)
| you're getting hurt by different aberrations (essentially too
| many paths the same rays can take to the sensor) and at very
| high values you're getting hurt by diffraction. At the low
| end, it's good to go a little higher than the lens
| advertises, and at the high end anything over F13-F18
| (depending on the gear) is usually quite bad.
| JKCalhoun wrote:
| I think it is excellent as well--that it also demonstrates
| aperture and shutter priority is a bonus.
|
| I do feel (image nerding now) that its shutter/ISO visual for
| showing the image over/under-exposed is not quite correct. It
| appears they show incorrect exposure by taking the "correct"
| image and blend (multiply) with either white or blend with
| black (on the other end of the exposure spectrum) to produce
| the resulting image.
|
| I suppose I am expecting something more like "levels" that
| pushes all the pixels to white (or black) until they are forced
| to clip. (But maybe I am too trained in photo-editing tools and
| expect the film to behave in the same way.)
| kqr wrote:
| No, you're correct. I would have expected the highlights to
| blow out much sooner (for digital) and the shadows to block
| up much sooner (for analogue). The simulation doesn't portray
| this accurately, but it gives the general idea!
| turnsout wrote:
| It needs to be updated to do its calculations in linear light,
| but it's probably useful for getting an intuitive sense of what
| the different levers of photography do to an image.
| zokier wrote:
| Camera ISO and noise can be really complicated and even
| contentious topic. One complication is that some cameras are
| "ISO invariant" and on those cameras afaik it is beneficial to
| stick to the one or two native ISO values. There is also the
| whole discussion around ETTR etc
| 1e1a wrote:
| Changing the ISO appears to scale the noise differently from the
| rest of the image.
| dahart wrote:
| Yep, just like a real camera.
| ggambetta wrote:
| Nice, but I'm going to need some ND filters :)
| pimlottc wrote:
| It seems to be impossible to grab the sliders on mobile Safari
| dahart wrote:
| Try tapping on the target value
| trimaster wrote:
| Not sure why value on the exposure compensation scale changes in
| manual mode when ISO is fixed. Shouldn't it be static in that
| case, unless ISO was in auto?
| czpl wrote:
| That's a light meter, not exposure compensation.
| cratermoon wrote:
| This is missing a setting for the kind of light falling on the
| subject. Is it full open sunlight? Open shade? Overcast?
| Sidelight? Backlight?
|
| It all matters.
| PetitPrince wrote:
| For me it's missing something to illustrate the relationship
| between shutter speed and motion blur. If the subject was a
| running fan instead of of lightbulb that would have been ideal.
| moon2 wrote:
| From the website:
|
| If I ever find a good moving prop like a small fan, maybe I'll
| also re-shoot new previews to demonstrate how shutter speed
| affects moving objects.
|
| Now, I'm just not sure how would one simulate a running fan
| with a picture. While for a static image you can have separated
| foreground and background and then apply effects for simulation
| (I know iPhone HEIC images have this property), for moving
| images you have to simulate the blur and the stillness, which
| is probably more difficult in terms of coding.
| andyfilms1 wrote:
| I love the idea that this guy was easily able to scrounge up
| a florescent bulb in a beer coozie, but a desk fan is somehow
| unobtainable.
| erghjunk wrote:
| that's an insane amount of noise at 200 ISO.
| 10729287 wrote:
| Probably Foveon sensor.
| semiquaver wrote:
| I know that modern systems like aperture priority or full auto
| make things easier, but I maintain that the many photos I took
| with a fully manual film camera (Canon AE-1) were simply better
| than those taken with any subsequent DSLR. The simple act of
| calibrating the shutter speed, aperture size, and manual focus
| before and during shooting helps you slow down and think about
| composition and framing, making the end result more valuable.
| Same goes for the limited number of shots on a roll of film.
|
| Nowadays it's easier to just take lots of shots and fiddle with
| the setting and do bracketing and such. But I maintain something
| important was lost by the move to automatic cameras.
| mmh0000 wrote:
| Don't worry! We're moving away from automatic cameras, too.
| Soon, you'll just use ChatGPT to generate your vacation images
| on demand.
|
| I'm being a little hyperbolic, but it really seems like, for a
| non-insignificant portion of the population, that will be true.
| blacklion wrote:
| Friend of mine suggested "vacation camera" concept when
| Panoramio was established (around 2006): box with compass,
| GPS and Internet connection. You point it to the sight, press
| button, it downloads photos of this sight. If you have
| premium subscription, it downloads professional photos with
| professional post-processing.
|
| Inserting user's mates was a problem in 2006.
| sixothree wrote:
| The rate at which people are currently posting AI enhanced or
| modified images of themselves is a bit surprising to me.
| Apparently people very much like wearing different outfits or
| travelling to new places without actually having to put them
| on or actually leave the house.
| moon2 wrote:
| That's why I love fiddling with analog cameras for a bit, or
| even experimenting with old lens on newer DSLRs. I have a Canon
| Rebel from 2011 and sometimes love to use my soviet Zenit
| Helios 44M lens in it. I do have the Zenit which came with this
| lens, but I have yet to develop its film.
| RankingMember wrote:
| I've started fiddling with an old Canon 30D again just
| because it's completely devoid of all the automatic post-
| processing I've become so used to with my phone camera. It's
| nice to just see the image as it is.
| asdff wrote:
| Well, to be fair, you see the image how the proprietary jpg
| engine chooses to automatically post process the raw file.
| Even this age canon cameras there was some controversy in
| that regard. And even if you view the raw file you are
| looking at how your raw file viewer chooses to post process
| a minimal preview for you to view for that raw file.
|
| You want full control you fall into the rabbit hole of
| dcraw where you can option out how that raw processing
| engine actually works, what algorithms are used and what
| parameters for those algorithms. Even lightroom you are
| just using the algorithm they decided for you already with
| parameters they decided are fine.
| asdff wrote:
| I used to have an old rebel xti, how do you actually confirm
| focus shooting like this? as far as I remember there were no
| aids for manual focus like film slr ground glass or modern
| mirrorless live view focus peaking.
| caseyohara wrote:
| > Same goes for the limited number of shots on a roll of film.
|
| You can approximate the same limitation on digital cameras by
| simply using a very small SD card.
| kqr wrote:
| Or put a large file on a regular size SD card.
| caseyohara wrote:
| I guess it depends on what "large file" and "regular size
| SD card" mean to you.
|
| The best selling SD card on B&H is 128 GB. Let's consider
| that "regular size".
|
| Fujifilm's GFX100 II is a popular medium-format mirrorless
| camera. Its sensor is 102MP. So each 14-bit RAW image is
| about 170 MB.
|
| 102M pixels x 14 bits = 1.428B bits = ~178M bytes = ~170 MB
|
| So a 128 GB SD card can hold ~771 images that are 170 MB.
| That's a lot more images than a standard roll of film.
| Toutouxc wrote:
| I think they meant that you can pad your regular SD card
| with random data and leave just enough space for a few
| photos.
| jacobgkau wrote:
| Approximate, sure, although you can still go back and delete
| photos from a small SD card, whereas film's more of a
| consumable resource.
| asdff wrote:
| Even today you are better off shooting manually once you have
| metered the scene.
|
| Otherwise your meter will pick up on color differences in a
| given framing and meter slightly differently. Shots will be
| 1/30th of a second, 1/25th of a second, then thanks to the
| freedom of aperture priority you might get little weird 1/32ths
| of a second you don't have discretely on a dial. How about iso.
| same thing, one shot iso 200, another iso 250, 275 this other
| one. Oh this one went up to iso 800 and the meter cut the
| shutter speed. Aperture too. This one f2 this one f4 this other
| one f2.5. This wasn't such a big deal even in the full auto
| film era since 35mm film has such latitude where you can't
| really tell a couple stops over or underexposed.
|
| All these shots, ever so slightly different from one another
| even if the lighting of the scene didn't really change.
|
| Why does this matter? Batch processing. If I shot them all at
| same iso, same shutter speed, same aperture, and I know the
| lighting didn't really change over that series of shots, I can
| just edit one image if needed and carry the settings over to
| batch process the entire set of shots.
|
| If they were all slightly different that strategy would not
| work so well. Shots would have to be edited individually or
| "gasp" full auto button which might deviate from what I had in
| mind. Plus there are qualitative trade offs too when one
| balances exposure via shutter speed, vs via aperture, vs via
| iso.
| omoikane wrote:
| I agree with slowing down and taking my time if I am shooting
| something static, but if I am outdoors taking pictures of
| anything that moves (e.g. birds), I am going to shoot in full
| auto burst mode until the buffer/SD card is full.
|
| I understand I am relying more on luck and not being as
| deliberate with composition when I do that, and I have high
| respect for people who are able to get great wildlife photos
| with film. But for amateurs like me, it's far easier to get
| better pictures simply by taking more pictures.
| gyomu wrote:
| Yeah, digital is just a game changer for wildlife
| photography, especially when considering the extremely fast
| smart autofocus / high shooting frame rates / top tier
| stabilization modern systems have.
|
| _"It was night and day. Six minutes instead of six years
| tells the story," McFadyen says. "Instead of 12 frames per
| second, I can now shoot at 30 frames per second, so when a
| bird dives at 30 miles per hour, it makes it so much more
| likely you'll capture it at the right moment.
|
| McFadyen says that the focusing system is also "incredibly
| fast" on mirrorless cameras. "It can lock on the kingfisher's
| tiny eye at these super-fast speeds," he adds."_
|
| https://petapixel.com/2025/11/27/photographer-recreates-
| king...
|
| This is a bit of a marketing puff piece, but the core
| insights are correct - the kind of shots the photographer is
| talking about here were insanely hard to pull off on film,
| still very tricky to achieve with digital bodies in the 2010s
| - but modern tech makes them almost trivial.
| moon2 wrote:
| This is honestly the best and most simple way to learn
| photography, at least something basic that is still very hard to
| grasp sometimes. I know photography is not just about the
| photometer, and about depth of field, but this simple simulator
| helps to learn about these relationships between aperture size,
| shutter speed and ISO which always bugged me (sometimes my shots
| were bad and sometimes great).
| agos wrote:
| this is a cool idea, but not very well executed. it appears it
| just overlays white on top of anything? exposure does not work
| this way
| Toutouxc wrote:
| > image "noise" or "grain" that is introduced into a picture as
| you increase the ISO
|
| Not this absolute shit again. This is not how photography works
| or how physics actually work. Image noise does NOT come from high
| ISO, it comes from low exposure (not enough light hitting the
| sensor). ISO is just a multiplier between a number of photons and
| the brigthness of a pixel in your photo. The implementation of
| the multiplier is (usually) half-analog and half-digital, but
| it's still just a multiplier. If you keep the exposure the same,
| then changing the ISO on a digital camera will NOT introduce any
| more noise (except for at the extremes of the range, where, for
| example, analog readout noise may play a role).
|
| This "simulator" artificially adds noise based on the ISO value,
| as you can easily discover: Set your shutter to 1/500 and your
| aperture to F8, then switch between ISO 50 and ISO 1600 and look
| at the letters on the bulb. ISO 50, dark but perfectly readable.
| ISO 1600, garbled mess. Since the amount of light hitting the
| simulated sensor stays the same, you should be seeing slightly
| LESS noise at ISO 1600 (better signal to noise ratio than at low
| ISO), not more.
|
| edit: To add something genuinely useful: Use whatever mode suits
| you (manual, Av, Tv) and just use Auto ISO. Expose for the
| artistic intent and get as much light in as possible (i.e. use a
| slower shutter speed unless you need to go faster, use a wider
| aperture unless you need a narrower one). That's the light that
| you have, period. Let the camera choose a multiplier (ISO) that
| will result in a sane brightness range in your JPEG or RAW
| (you'll tweak that anyway in post). If the photo ends up too
| noisy, sorry but there was not enough light.
|
| ISO is an almost useless concept carried over from film cameras
| where you had to choose, buy and load your brightness multiplier
| into the camera. Digital cameras can do that on the fly and
| there's usually no reason not to let them. (If you can come up
| with a reason, you probably don't need this explanation)
| shakow wrote:
| > If you keep the exposure the same, then changing the ISO on a
| digital camera will NOT introduce any more noise
|
| So does this mean that changin the ISO directly on my camera,
| or in DarkTable/whatever at post-proc time is virtually the
| same?
| gruez wrote:
| > Image noise does NOT come from high ISO, it comes from low
| exposure [...] changing the ISO on a digital camera will NOT
| introduce any more noise (except for at the extremes of the
| range, where, for example, analog readout noise may play a
| role).
|
| Sounds like you're saying that setting higher ISO does cause
| noise, but as long as you don't go too high you won't really
| notice the difference?
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