[HN Gopher] Silly Camera Numbers
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Silly Camera Numbers
Author : mkchoi212
Score : 45 points
Date : 2022-07-31 11:09 UTC (1 days ago)
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(TXT) w3m dump (web.mit.edu)
| buildbot wrote:
| One little nit is the acceptable shutter speed for a given lens
| focal length depends _heavily_ on the camera and shutter type
| being used!
|
| In the past, 1/focal length was perfect advice. You can adjust
| this down very quite far if you have a lens or body with image
| stabilization, typically down to as far as 1/30 or even lower.
|
| Also bodies get higher resolution, the amount of blur you can see
| goes up as well as you start sampling higher frequency movements
| of the camera body. You probably need 1/2 x focal length above
| 24MP, unless you have stabilization.
|
| There are also different types of shutters, for example a leaf
| shutter in the lens vs. a focal plane shutter. Focal plane
| shutters can inject some shutter shock at lower speeds, where as
| leaf shutters don't have this effect and can be handheld to much
| lower speeds, I have gotten very sharp shots as low as 1/8th.
|
| Finally, if your camera has a mirror or not also effects this, as
| the mirror swing imparts vibration as well.
|
| Knowing exactly how the camera reacts at different speeds will
| let you tweak this rule a lot!
| joshe wrote:
| I miss this old school straightforward writing style.
|
| I'd love to have a search engine that just searches writing like
| this.
| [deleted]
| mgdlbp wrote:
| Technical minutia, but I found that I felt a lot more confident
| once I understood this: The reason f-number is written like so is
| because it's not a measure of actual aperture diameter but is
| instead the ratio of aperture diameter to focal length.
| Specifically, (f-number) = (focal length)/(aperture diameter),
| or: N = f/A
|
| equivalent to, A = f/N
|
| Hence the format _f_ /N, since you (theoretically) use f-number
| to calculate actual aperture diameter when given a specific focal
| length. That aperture is in the denominator also explains why
| smaller f-numbers are brighter.
|
| _Why those weird numbers in particular?_ As in the article, a
| 'stop' is a doubling or halving of the brightness (technically,
| 'illuminance') of the image produced by the lens. Since the
| amount of light that passes through an aperture is proportional
| to its area, which is in turn proportional to the square of its
| diameter, one stop corresponds to a sqrt(2) ~ 1.4 ratio between
| two aperture diameters. Hence, the standard scale of full f-stops
| is the powers of two and their geometric means:
| f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32,
| f/45, f/64
|
| The full stop scale in the article has some errors: f/1.8 instead
| of f/1.4, a typo for f/4/0, and a lack of f/45 (though f/1.8 is
| the stop below f/2 in the finer 1/3- and 1/4-stop scales):
| f/1.8, f/2.8, f/4/0, f/5.6, f/8.0, f/11, f/16, f/22, f/32, f/64
|
| _But why measure image brightness using f-number instead of
| aperture diameter directly?_ Because brightness also depends on
| focal length: Doubling the focal length of a lens doubles the
| size of the image of an object seen through it. Since the light
| from the object is spread out over four times the area, the image
| brightness is quartered. This means lenses with equal aperture
| diameters and different focal lengths will not have the same
| exposure. (below edited, I confused myself at first!) But
| photographers would rather not have to consider focal length when
| choosing an aperture for proper exposure. Designing lenses such
| that their aperture controls are labelled with f-number enables
| this, since actual aperture diameter then scales automatically
| with focal length to cancel out its effects on exposure.
| xdennis wrote:
| Some lenses are clearer on this and write the aperture as
| "1:2.8" instead of "f/2.8". It makes it clearer why 1/2.8 is a
| larger aperture than 1/4.
| starky wrote:
| I don't find the explanation here to be clear. This suffers from
| the classic issue where they explain the basics and then proceed
| to give practically no details on how to start applying the
| knowledge.
|
| For anyone wanting to learn this more in detail I highly
| recommend the book "Understanding Exposure" by: Bryan Peterson.
|
| My personal approach to taking handheld photos in manual mode
| using natural light is as follows:
|
| 1. Look at the scene and determine what the most important factor
| is. For example: * Do I need to freeze motion? Then I need to set
| a short shutter speed. * Is the image being taken in low light?
| Then I probably want to open the aperture and set my shutter
| speed as long as is suitable for what I can hold. * Do I need a
| large depth of field or to maximize sharpness? Then I need to set
| the aperture to a suitable value to achieve that.
|
| 2. After I consider the most important factor and set either
| shutter speed or aperture to a starting value, set the second
| most important factor using the same thought process.
|
| 3. Adjust the ISO so the image is exposed properly. Knowing your
| camera, is the ISO going to result in an acceptable image? If
| not, then go back to the first step and adjust your shutter speed
| and aperture to bring the ISO down to an acceptable value.
|
| 4. Take the photo and review.
|
| Of course, this doesn't apply to every scenario but it generally
| is a good approach for the types of photos where the exposure
| settings are critical. If I'm shooting a landscape outdoors, then
| I'm probably starting off by setting ISO to 100 first and then
| the aperture to the sharpest value for the particular lens I'm
| using as I'm sure that the shutter speed will be acceptable
| regardless of what it ends up having to be or will be what drives
| me to use a smaller aperture.
| McNutty wrote:
| As someone who has never thought much about photography, I
| found the OP to be a good explanation and I found the E.T.
| exercise to be enlightening.
| Animats wrote:
| For film cameras.
|
| For film cameras, holding exposure time times f-stop constant
| does not produce the same image density. Exposure time for film
| is not straight photon integration, like it is for a CCD array.
| You can only trigger each film grain once, but new photons can
| repeatedly add electrons to a single CCD pixel. So there's what's
| called "reciprocity failure".[1]
|
| [1] https://en.wikipedia.org/wiki/Reciprocity_(photography)
| dekhn wrote:
| After one attempt at photography in high school, with a SLR and
| a darkroom, I decided to wait until I felt that the tech had
| matured enough so that I never, ever had to deal with physical
| film media. Reciprocity is a perfect example; when I'm in art
| mode (or scientific data collection), I never want to think
| about the nonlinearity of my sensor.
| stas2k wrote:
| What tripped me when shooting and developing film is that it
| usually works in negative. With digital you are always looking
| for overexposure, while negative film is OK with overexposure.
| Light builds silver density, while lack of it leaves a clear
| base with no information.
|
| Then you get an analogue NOT operation when printing the
| negative on the enlarger. Two negative processes make a
| positive.
|
| Film photography is very interesting as it combines art with
| optics and chemistry. Just pure magic seeing the image fade
| into the paper when developing.
| aimor wrote:
| This really got me too when I went from film to digital. I
| still really miss having so much range in the highlights.
| xdennis wrote:
| Anecdotally, I heard that this is the reason why, as
| recently as 10 years ago, a majority of movies were shot on
| film: it handles highlights so well. It took a while for
| digital to catch up.
| frizkie wrote:
| I've always been interested in photography but really got into
| the weeds over the pandemic. Learning the exposure triangle (how
| aperture, shutter speed, and ISO are related/not related) has
| completely transformed how I think about cameras and taking
| photos. There is definitely some inherent mathematical/practical
| beauty in the meaning and relationships between these different
| camera settings.
|
| I wouldn't want this comment to be interpreted as "shooting in
| manual is superior", in fact I would suggest against it in almost
| all cases - the deeper understanding will help you use nearly any
| camera in existence.
| staindk wrote:
| My dad's a hobbyist photographer and through him I've learned
| to generally shoot in aperture priority mode. For my intents it
| generally feels 'manual enough'.
|
| Then you leave ISO on auto if it makes sense for the lighting
| conditions, or manually set it if needed.
| zokier wrote:
| > Then you leave ISO on auto if it makes sense for the
| lighting conditions, or manually set it if needed
|
| Fun thing with modern cameras is that "iso" doesn't actually
| matter much at all. Typically you can just use one or two
| fixed iso settings for everything and adjust the exposure in
| post as needed. Keyword for reading more about this is "iso
| invariance".
| staindk wrote:
| Thanks for the term! That's a rabbit hole we'll venture
| down next time I see my dad.
|
| I initially had a paragraph half written out in the comment
| you replied to detailing how my dad's new cameras perform
| extremely well at absurd (12800???) ISOs, which "iso
| invariance" would definitely explain.
|
| My camera is an older Canon 5D MK1 which shoots mostly fine
| at 200 ISO and lower, and gets grainy quite fast at 400 ISO
| and above. If and when the photography bug bites me harder
| I'll probably upgrade to a slightly newer body aha.
| sanitycheck wrote:
| Bear in mind you need to shoot raw, not jpg, in order to
| benefit from this.
|
| In a tricky exposure situation, dial exposure
| compensation way down (-3 to -5 EV) and take the shot.
| You probably want a low-ish ISO selected too. Then in
| lightroom/whatever just crank the exposure slider up and
| fiddle with the levels & curves - easy way to not blow
| out your highlights.
| staindk wrote:
| Yep good point. RAW is amazing in that regard.
| hef19898 wrote:
| Lately I'm close to apperture priority. With Nikon you can
| over ride the apperture setting in Programm / Automatic mode.
| Most of the time automatic is just fine. In case I want
| something "special", longer exposure for stuff like
| waterfalls or shorter exposure for movement, I just change
| the apperture until I'm happy with the shutter speed.
| Preferring low ISO values, that makes you appreciate fast
| lenses.
| apgwoz wrote:
| Even better advice can (probably) be attributed to Weegee:
| "F8 and be there."
|
| https://en.wikipedia.org/wiki/%C6%91/8_and_be_there
| dm319 wrote:
| Funny, I was just comparing two photos from some holiday snaps I
| have taken. One on a Google pixel phone and another on an old
| 100mm lens produced in the late 70s paired with a DSLR. The
| differences are stark, and remind me that focal length, dynamic
| range, shutter/aperture settings all have big impacts on how the
| final image turns out. Particularly important is how dynamic
| range and tones of the scene are translated to the recorded
| medium, as decisions always need to be made with a focus on
| specific tones. HDR goes some way to help with this these days,
| but artistic decision-making is still a thing.
|
| [1] https://photos.app.goo.gl/aeCJPnp5BSZ9aBxT6
| ChuckMcM wrote:
| This is a good basic discussion, and it works well for digital
| cameras as well as film cameras. The difference is that you can
| take 100 digital photos, see the differences, and it didn't cost
| you anything to develop them :-).
|
| I encourage new people to photography to try to be disciplined
| about learning how their camera changes as different settings.
| Get out of the tyranny of "auto" mode and try all the things. You
| may find it quite fun.
| samatman wrote:
| I've had trouble getting out of the local optimum with my
| mirrorless. For shots that rely on the glass, so to speak, it
| can't be compared with a phone at all: the shots aren't better,
| they don't exist on the phone to begin with.
|
| But for the kind of picture my phone _can_ take, it frequently
| does a better job. I can tell going through my collection when
| I used the mirrorless immediately, because the result is
| subjectively different, but we 're comparing quality equipment
| with good defaults with very small (nonetheless excellent)
| equipment with metric boatloads of machine learning applied.
|
| Getting past this involves an immediate and very steep learning
| curve which I've only intellectually engaged with; the practice
| of adjusting the basic parameters consistently gives me worse
| results, and I haven't put in the time to get past that.
| neogodless wrote:
| > you can take 100 digital photos
|
| ... for practice, learning, or stationary, long-lasting
| subjects.
|
| Of course you want to get a good _feel_ for the aperture,
| shutter speed and sensitivity so that when you see a beautiful
| bird about to take off for flight, or a butterfly touch down
| ever so momentarily, you aren 't fumbling with settings, and
| you've already got a good _sense_ of what settings will work.
|
| Definitely agree though - many cameras have "priority" modes
| where you're really only changing the shutter speed or
| aperture, and it's still doing the rest automatically for you,
| so you can _focus_ on whatever that one setting does, while
| also seeing what the smart camera tells you the other settings
| should be in those situations.
| ghaff wrote:
| Though for moving objects, the ability to just fire off a
| rapid sequence on a digital camera can net you a shot which
| is at least incrementally better--or even the difference
| between a great shot and a dud. There were motor drives in
| film days of course but they weren't as fast as modern
| digital cameras and unless you were a pro, using them much
| got expensive in a hurry.
|
| Early on, digital did have a problem with shutter lag--Sony
| even had a series of ads touting the fact that their camera
| was faster than others--but it's not a problem now especially
| with better cameras.
| jillesvangurp wrote:
| Turning auto off and making your own, deliberate, choices is
| indeed the way to build up some intuition on how to capture the
| same scene in different ways. Shooting digital is easier. But
| often reviewing what you shot is hard on tiny screens in full
| sunlight.
|
| Depth of field is one of the more obvious things you control
| with the aperture. But another thing it impacts is sharpness.
| Depending on your lens, it likely is a little fuzzier wide open
| than it is stopped down a little. Basically, you are covering
| part of the lens and controlling the way it distorts the light
| a little. Wide open it diffuses the light a bit. And it will do
| so differently in different parts of the photo. Knowing how
| your lens performs under different conditions is something you
| need to explore through trial and error. Another thing it
| impacts is color and contract. Just how, depends on the lens.
| Some lenses have a clear optimum, others are better across a
| wider range of apertures. People spend a lot of money on glass
| to get these effects.
|
| In the same way, the shutter speed is not just about
| controlling the amount of light it is also about motion and
| motion blur that can both mess up your photo or be something
| you use creatively. The best tip you can give a beginning
| photographer to not too slow. Your camera might be able to
| handle it and you might have steady hands. But stuff still
| moves in your scene and it will introduce blur.
|
| Some types of photography you want to have fast shutter speeds
| to capture really crisp moving subjects (e.g. sports
| photography, moving kids). Even on a bright day you might want
| to shoot at higher ISOs just so you can shoot a little faster.
| A zoom lens stopped down focused on a fast moving subject will
| do a lot better if you can shoot at 1/2000s of a second rather
| than getting a blurry thing at 1/30th. But sometimes that kind
| of effect is what you want when shooting e.g. a static subject
| against a waterfall.
|
| The ISO dial basically allows you to compensate for loss of
| light by pretty much multiplying the signal. This is something
| you can easily do in post as well if you are shooting raw. It
| just gives you more wiggle room with aperture and exposure. Of
| course the issue is that you end up boosting the noise along
| with that as well. More sensitive sensors can be pushed a
| little further for this. But mostly, lower is better in terms
| of noise. Basically, you pick the aperture and exposure that
| produce the effect you want and the iso control allows you to
| get away with it when that is pushing the limits a bit too far.
| With some cheaper cameras, you end up trading off noise against
| creative control. Easier to shoot at night with the lens wide
| open at a low shutter speed that still works hand held. But
| less chance of blurry photos if you shoot a bit faster at a
| higher iso.
|
| Then there are different focal lengths that not only "zoom" in
| the subject but also change the perspective. Using a very wide
| or zoomed in perspective and compensating with your feet can
| produce very different photos even if your subject ends up
| being roughly the same in the picture.
| SAI_Peregrinus wrote:
| > But often reviewing what you shot is hard on tiny screens
| in full sunlight.
|
| If you have a mirrorless camera, you can use the viewfiender
| to review.
|
| I tend to leave the rear screen on my camera turned off. It
| just wastes battery life, it's not usually useful for
| anything.
| Ma8ee wrote:
| > it didn't cost you anything
|
| Except the time to sort through 300 photos after just an
| afternoon with your kids at the beach...
| scrumbledober wrote:
| i was hoping for cameras with silly numbers i.e. very very long
| focal lengths (x000mm) or incredibly small apertures (f/9001)
| Hackbraten wrote:
| > f/9001
|
| I see what you did here.
| mgdlbp wrote:
| Would you be interested in a true 3248 mm f/8?
|
| https://www.telescope.com/Astrophotography/Astrophotography-...
|
| Telescopes do tend to prefer specifying girth rather than
| length, though.
| dekhn wrote:
| I've used a refractor (4" lens, f7, 714mm focal length) as a
| telephoto. It's great. I ended up buying a crazy-ass lens and
| building a solar telescope (look at the sun) which was fun
| until the focal point melted the enclosure.
| roywiggins wrote:
| The Nikon COOLPIX P1000 has a very silly 3000mm equivalent
| superzoom.
|
| https://www.dpreview.com/reviews/nikon-coolpix-p1000
|
| For silly apertures, you want the Pinhole Pro Max.
|
| https://www.pcmag.com/news/hands-on-thingyfys-pinhole-pro-ma...
| staindk wrote:
| I loved this[1] recent video by DIY Perks and think you would
| enjoy it too. He essentially builds a housing for a lens with a
| massive aperture.
|
| [1] https://www.youtube.com/watch?v=9cT0jXI7l4E
| Lammy wrote:
| Realtalk: focal distance is the only number a beginner needs to
| learn about. Just set your camera to "Auto" and it will take
| great photos. This is why we invented computers lol
| thekid314 wrote:
| Letting the camera take control will result in good photos. But
| great photos are more likely when you take technical control
| and put thought behind each photo.
| Lammy wrote:
| Yes, and it's fine to learn that stuff as an intermediate
| photographer! I just think framing shots is by far the most
| important thing for beginners because that provides the
| motivation for them to keep going out and taking more photos.
| dwringer wrote:
| Art is often characterized by the specific objectives set by
| the artist. An automatic computer algorithm to handle the
| exposure will only typically have one (or a few) preprogrammed
| set(s) of objectives, thus it adds a constraint to the artist.
| Great art can be made either way though.
|
| For a beginner I agree learning the intricacies of exposure may
| not be one of the most pressing concerns, or particularly
| relevant in many cases, but if someone wants to get more into
| the hobby for whatever reason (artistic or otherwise) it isn't
| a bad idea to start experimenting with exposure settings even
| if the results aren't initially good.
| kibibyte wrote:
| Something worth adding here for those who want to complicate
| their lives even more, these equivalences get complicated when
| you need to compare across different sensor formats (full-frame
| vs crop vs micro-4/3rds). Something I learned recently is that
| f/5.6 on a 300mm lens on a crop sensor is more similar to
| something like an f/8 or f/11 on a 450mm on a full frame.
| Including ISO into this makes that comparison more complicated as
| well.
|
| More on that subject https://photographylife.com/equivalence-
| also-includes-apertu...
| themadturk wrote:
| There's an old exposure rule that is probably next to useless
| now, but worked pretty well for film cameras when you didn't have
| a light meter: exposure of a subject in sunny bright conditions
| is an aperture of f/16 and shutter speed set to the film's ISO.
| So a starting place for a bright, sunny day when using Kodachrome
| 64 film would be f/16 at 1/60th of a second (or an equivalent
| aperture/shutter speed combination). From there an experienced
| photographer could estimate exposure for other lighting
| conditions. Of course, negative film (either color or black and
| white) is more forgiving of exposure errors than slide film.
| These days if your exposure meter isn't working, it means your
| whole camera isn't working...
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