The spec sheets on today’s flagship digital cameras are impressive to say the least. Nikon offers 36, Sony 42, and Canon’s 5DS a staggering 51 megapixels. And that’s just right now, and that’s not touching the likes of Hasselblad and Phase One 100MP offerings. Ever since digital cameras began to supplant film as the industry standard, resolution has been the headline feature of every camera along the way.
The trend of packing more and more pixels onto our image sensors doesn’t seem to be slowing down, as every year we marvel at the newest staggering megapixel number, only to see that number surpassed mere months later. However, in this relentless contest for king of the resolution mountain, it seems rare that we stop and ask the question: how much resolution do we actually NEED?
Naturally, the answer to this question will be a personal one and dependent on a number of factors, but there are a few constants that can help you as a photographer, to answer it for yourself. For example, we have standards in place to describe the abilities of the human eye, and unless your intended audience is a nest of bald eagles, these guidelines can suggest the point of diminishing returns, resolution-wise.
What is Camera Resolution?
First, it’s important to understand what we’re talking about when we describe the resolution of a photo. Resolution is essentially the ability of the human eye, camera sensor, printer, or screen to differentiate between two points. To calculate this ability, you need two key pieces of information: the distance between the two points, and the relative viewing distance from those points. Imagine that you’ve lit two candles, placed them 1 foot apart, and drove a mile away from them. At this distance, you would most likely be unable to tell if you were looking at one candle or two. In order to see that there are, in fact, two candles, you would need to move them further apart, or get closer to them.
This relationship between size and distance can be described as an angle, in degrees or arcminutes, where 1 degree = 60 arcminutes. For reference, the size of the full moon when viewed from earth is about 1/2 degree or 30 arcminutes. This is a necessary basis element to understand.
Resolution of The Human Eye
I hear you asking, nay, begging the question: what is the resolution of the human eye?
20/20 vision is described as being 1 arcminute. This equates to a factor of 1/3438. Using the candle example again, this means that someone with 20/20 vision would be able to begin to differentiate the candles, 1 foot apart, from 3,438 feet away, or 0.65 mile. Of course, most adults have worse than 20/20 vision, and some have better than 20/20, but as this is the standard for fighter pilots, let’s use it as a basis for our measure of what we “need” in a photo.
However, we don’t generally look at photos from over half a mile away, so this number still doesn’t get to the heart of the matter. Let’s convert this to a more applicable scale. To determine the resolution of the human eye at a distance of 12 inches, we would divide 12 by 3438, and we get about 0.0035 inch. 1/0.0035 = approx. 286 ppi (points/pixels per inch). Finally we’ve gotten back to a measurement that photographers are used to. So, if we slightly exceed this number, 286, up to a nice round 300 ppi, people with 20/20 vision will no longer be able to see individual pixels, and your photo will look smooth and sharp, from a distance of 12 inches.
Best Resolution for Print Size
This benchmark of 300 ppi still doesn’t quite bring us to the resolution we need, as ppi only describes pixel density, and is therefore only part of the equation. In order to determine the ideal resolution of an image at 300 ppi, you still need the finished size of the image. Or, to work backwards, using the resolution of your camera, you can determine the maximum print size at this magical pixel density.
|Actual Pixel Dimensions
|Print size at 300 ppi
|4608 x 2592
|15.36” x 8.64”
|6000 x 4000
|20” x 13.3”
|7360 x 4912
|24.5” x 16.37”
|7952 x 5304
|25.5” x 17.68”
|8688 x 5792
|28.96” x 19.3”
If you’re shooting any of these high-megapixel cameras and printing your photos at smaller sizes than those listed above, you’re theoretically wasting resolution, as the camera is capturing more detail than the human eye can see. Of course, it’s often useful to be able to crop into these large files and retain detail and image quality, and it’s always better to have too much resolution than not enough. If you already know the final size at which a particular image will be printed, you can easily determine the minimum resolution you’ll need by multiplying the dimensions (in inches) by 300.
Viewing Distance Matters with Resolution
We’re almost there, but this still only tells part of the story. As we remember from everyone’s favorite candle allegory, we still need to factor in the distance from which your print will be viewed. The magical 300 ppi pixel density is calculated based on a viewing distance of 12 inches. If you hold your hand 12 inches from your face, you’ll see that this feels incredibly close, and holding it any closer begins to feel downright uncomfortable.
This brings up another aspect of human eyesight, that our eyes can only actually resolve fine details to their full ability in the central area of our field of vision, an area of our eyeballs known as the fovea, which contains the greatest concentration of cone cells. This area takes up only 1% of the retina, or roughly 2 degrees. Take a moment to look at the keyboard of your computer, and then try to read the words on the screen with your peripheral vision. You can’t do it, right? This means that even if we’re looking at a small printed picture, say 4” x 6”, 12 inches from our face, we can’t actually resolve all of the detail at the same time. So, trying to look at a 24” x 16” print from 12 inches away is illogical.
If, instead of the 1 foot viewing distance, we stand 3 feet away, suddenly we only need a 100 ppi pixel density to meet the standards of 20/20 vision, and the 36mp file from your D810 can be printed at about 73” x 49”. You may have begun to see where I’m going with this. As print sizes increase, you need more pixels, but you’ll also most likely be viewing these larger prints from a further distance, so you don’t need as much pixel density, so you actually don’t need as many pixels. Essentially, we end up back at the measure of resolution as an angle. If a photo takes up 10 degrees of our field of view, whether it’s a 4” x 6” at 1 foot or a 20” x 30” at 5 feet, our eyes will be able to resolve the same amount of detail.
Often, when speaking about high megapixel cameras, I hear the comment that you would only need ‘so much’ resolution if you were blowing your photos up to billboard size. In reality, billboards are viewed from so far away that the pixel density can be greatly reduced without anyone noticing. If the closest you’ll be able to get to a billboard is 30 feet, the image could be printed at 10 ppi, and your eyes wouldn’t be able to tell the difference. At 10 ppi, you could blow a 12mp iPhone image up to 38 ft. x 21 ft. without the image appearing pixelated. Or, to think about it in another way, the next time you see a billboard, from a reasonable distance, hold your phone in front of it, about a foot from your face, and you’ll see that your phone screen will probably hide the entire billboard from your view. That tells us that your eyes are able to resolve the same amount of detail in your phone screen as in that massive billboard.
Resolution for On-Screen Displays
If you don’t intend to print your work, and online publication is the final destination of your image, then your resolution needs are even less demanding. HD and UHD displays look incredibly smooth from recommended viewing distances, but the actual resolution in megapixels isn’t actually particularly high.
|Actual Pixel Dimensions
|1080 x 720
|1920 x 1080
|3840 × 2160
|27″ iMac 5k
|5120 x 2880
Without zooming, these are the resolution limits of these various displays. When viewing an image at full size with pixel dimensions exceeding those of your display, your graphics card will simply discard the superfluous information. Again, much of the resolution of your image will be wasted, and your 51 megapixel image will only serve to impress the pixel-peepers.
Resolution of Camera Lenses
But wait, there’s more. Your camera sensor will only be able to capture as much detail as your lens can resolve. The resolution capabilities of a lens are more difficult to quantify, as this step of the image-making process is still analogue. DxoMark has developed a measurement of this ability called “perceptual megapixels” which measures the effective resolution of a camera/lens combination. This P-Mpix score is listed as a single number, but we also know that most lenses have an optical sweet spot in the middle, and lose some sharpness towards the edges of the frame, so it’s still difficult to determine how those perceptual megapixels are distributed across an image. Still, this score is helpful when comparing lenses, and once we know the final print size and pixel dimensions we need, we can use these scores to determine whether a given camera and lens combination will deliver the detail we need.
A bad lens can easily turn a high megapixel camera into a low megapixel camera. For example, according to DxoMark, the mighty, 36mp Nikon D810 can resolve only 10mp when fitted with a $300 Nikkor 28-200 f/3.5-5.6G. So, while the full potential of your camera’s sensor may be overkill for your final prints, it’s difficult to deliver that level of detail to your camera’s sensor, and a low quality lens can quickly handcuff it’s performance.
I could have saved myself a lot of work by titling this article “It’s better to have too much resolution than not enough” and leaving it at that. The truth is that the digital cameras being produced today are incredibly good, and the effective difference between 24 and 51 megapixels is usually, in practice, imperceivable, unless of course you crop or zoom in to where you can only see a small fraction of the full picture.
The bottom line is this: unless you’re making large prints from your photos, and displaying those prints somewhere that they will be carefully examined, such as an art gallery, much of the resolution of your camera will most likely be wasted most of the time. Does this mean that you should sell your DSLR kit and shoot everything with your 12mp iPhone camera? Of course not, because, first of all, it’s better to have too much resolution than not enough, and also, image quality is dependent on more than just the ability to render fine details. It’s also important to take into account a camera’s dynamic range, bit depth, high ISO capabilities, and other characteristics that may be more difficult to quantify than resolution.
Buying a camera is a personal choice, dependent on a variety of factors, preferences and needs. Resolution is often the highlight feature pushed by camera manufacturers, but should clearly not be the sole consideration of photographers. When comparing cameras, consider how your photos will be displayed, decide on the minimum number of megapixels you’ll need, and move on to other features and abilities.
Karatasi za vipimo kwenye kamera za dijiti za kisasa ni zenye kuvutia kusema kidogo. Nikon ina Sony 4G na Canon 5DS ina Nikon 4G na Sony 4G. Na hiyo ni tu sasa hivi, na hiyo si kugusa kama Hasselblad na Awamu ya Kwanza 100MP matoleo. Tangu kamera za dijiti zilipoanza kuchukua nafasi ya filamu kama kiwango cha tasnia, azimio limekuwa kipengele kikuu cha kila kamera njiani. Mwelekeo wa kufunga pikseli zaidi na zaidi kwenye sensorer zetu za picha haionekani kupunguza kasi, kama kila mwaka tunashangaa na idadi mpya ya megapixel ya kushangaza, tu kuona idadi hiyo ilizidi miezi michache baadaye. Hata hivyo, katika mashindano haya ya kukata tamaa kwa mfalme wa mlima wa azimio, inaonekana ni nadra kwamba sisi kuacha na kuuliza swali: kiasi gani cha azimio sisi kweli haja? Jibu la swali hili ni la kibinafsi na linategemea mambo kadhaa, lakini kuna mambo machache ambayo yanaweza kukusaidia kama mpiga picha kujibu swali hilo. Kwa mfano, tuna viwango vya kuelezea uwezo wa jicho la binadamu, na isipokuwa wasikilizaji wako wa lengo ni kiota cha vipepeo wa bald, miongozo hii inaweza kupendekeza hatua ya kupungua kwa mapato, kwa ufumbuzi. Uamuzi wa Kamera ni Nini? Kwanza, ni muhimu kuelewa nini sisi ni kuzungumza juu wakati sisi kuelezea azimio la picha. Uwezo wa kuona ni uwezo wa jicho la binadamu, sensorer ya kamera, printer, au screen kutofautisha kati ya pointi mbili. Ili kuweza kuamua uwezo huo, unahitaji habari mbili muhimu: umbali kati ya sehemu hizo mbili, na umbali wa kutazama kutoka sehemu hizo. Fikiria kwamba umewasha mishumaa miwili, ukiweka umbali wa meta moja kati yao, na kuendesha gari umbali wa maili moja kutoka kwao. Kwa umbali huu, huenda usingeweza kujua kama ulikuwa ukitazama mshumaa mmoja au mawili. Ili kuona kwamba kuna mishumaa miwili, unahitaji kuisogeza mbali zaidi, au kuikaribia. Ukubwa wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili wa mhimili. Kwa mfano, ukubwa wa mwezi kamili unapoonekana kutoka duniani ni karibu digrii 1 au dakika 30 za arc. Hii ni msingi muhimu ya kuelewa. "Kutokana na ""resolution"" ya jicho la binadamu, tunaweza kuuliza swali hili: ""resolution"" ya jicho la binadamu ni nini?" Maono ya 20-20 ni sawa na 1 arcminute. Hii ni sawa na sababu ya 1 3438. Kwa mfano, mtu mwenye uwezo wa kuona 20 20 anaweza kuona tofauti kati ya mishumaa iliyo umbali wa mita moja na ile iliyo umbali wa mita 3,438. "Watu wazima wengi wana uwezo wa kuona wa chini ya 20%, na wengine wana uwezo wa kuona wa juu kuliko 20%, lakini kwa kuwa hii ni kiwango cha marubani wa kivita, hebu tuitumie kama msingi wa kipimo chetu cha kile tunachohitaji kwenye picha.""" Hata hivyo, kwa kawaida hatutazami picha kutoka umbali wa zaidi ya nusu maili, kwa hiyo idadi hii bado haifiki kiini cha jambo hilo. Hebu kubadilisha hii kwa kiwango zaidi husika. Kwa mfano, kwa kuona umbali wa macho ya binadamu, tunaweza kugawanya 12 na 3438 na kupata 0.0035 inchi. 1 = 0.0035 = karibu P2P (Points kwa Pikseli kwa Inchi) Hatimaye tumerudi kwa kipimo ambacho wapiga picha wamezoea. Ikiwa unaona picha ya juu ya 286 na ppi ya juu ya 300, watu wenye uwezo wa kuona wa 20 20 hawatakuwa na uwezo wa kuona pixel moja kwa moja, na picha yako itaonekana laini na kali kutoka umbali wa inchi 12. Utaratibu bora kwa ukubwa wa uchapishaji Kiwango hiki cha 300 ppi bado hakituleti kabisa kwa azimio tunalohitaji, kwani ppi inaelezea tu wiani wa pikseli, na kwa hivyo ni sehemu tu ya equation. Ili kuamua azimio bora la picha ya 300 ppi, bado unahitaji ukubwa wa picha ya kumaliza. Kwa mfano, unaweza kutumia picha ya kamera yako kuamua ukubwa wa kuchapisha kwa kiwango cha pixel. Picha za picha za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel za pixel. Bila shaka, ni mara nyingi muhimu kuwa na uwezo wa kupanda katika faili hizi kubwa na kuhifadhi maelezo na ubora wa picha, na ni daima bora kuwa na azimio sana kuliko si kutosha. Kama tayari kujua ukubwa wa mwisho ambayo picha fulani itakuwa kuchapishwa, unaweza kwa urahisi kuamua azimio chini unahitaji kwa kuzidisha vipimo (katika inchi) kwa 300. Kuangalia umbali ni muhimu na azimio Sisi ni karibu huko, lakini hii bado inaelezea sehemu tu ya hadithi. Kama tunavyokumbuka kutoka kwa hadithi ya mshumaa inayopendwa na kila mtu, bado tunahitaji kuzingatia umbali ambao uchapishaji wako utaonekana. Uwezo wa pixel ya 300 ppi ni sawa na urefu wa kutazama wa 12 inches. Ukishika mkono wako inchi 12 kutoka uso wako, utaona kwamba hii inahisi karibu sana, na kuushika karibu zaidi huanza kuhisi kutokuwa na furaha. "Hii inazalisha kipengele kingine cha maono ya binadamu, kwamba macho yetu yanaweza tu kutatua maelezo madogo kwa uwezo wao kamili katika eneo la kati la uwanja wetu wa maono, eneo la jicho letu linalojulikana kama ""fovea,"" ambalo lina mkusanyiko mkubwa wa seli za koni." Sehemu hii inachukua asilimia 1 tu ya retina, au karibu digrii mbili. Chukua muda kuangalia keyboard ya kompyuta yako, na kisha kujaribu kusoma maneno kwenye skrini na maono yako ya pembeni. Huwezi kufanya hivyo, sawa? Hii inamaanisha kwamba hata ikiwa tunaangalia picha ndogo iliyochapishwa, sema 4 × 6 inches kutoka kwa uso wetu, hatuwezi kutatua maelezo yote kwa wakati mmoja. Kwa hiyo, kujaribu kuangalia 24 × 16 prints kutoka inchi 12 mbali ni isiyo ya busara. Ikiwa, badala ya umbali wa kutazama wa futi moja, tunasimama futi tatu mbali, kwa ghafla tunahitaji tu wiani wa pixel ya ppi 100 ili kukidhi viwango vya maono ya 20 na faili ya 36mp kutoka kwa D810 yako inaweza kuchapishwa kwa karibu 73x49px. Huenda umeanza kuona ninakwenda wapi na hili. Kwa sababu ya ukubwa wa uchapishaji, unahitaji pixel nyingi, lakini kwa kweli unahitaji picha kubwa zaidi, na kwa hivyo unahitaji pixel ndogo. Kimsingi, sisi kuishia nyuma katika kipimo cha azimio kama pembe. Ikiwa picha inachukua digrii 10 ya uwanja wetu wa kuona, iwe ni 4 × 6 × 1 au 20 × 30 × 5 miguu, macho yetu yataweza kutatua kiasi sawa cha maelezo. Mara nyingi, wakati wa kuzungumza juu ya kamera za megapixel, nasikia maoni kwamba unahitaji tu 'hata hivyo' azimio ikiwa ulikuwa ukiongeza picha zako hadi ukubwa wa ubao wa matangazo. Kwa kweli, mabango ya matangazo huonekana kutoka mbali sana hivi kwamba unene wa pikseli unaweza kupunguzwa sana bila mtu yeyote kugundua. Ikiwa karibu zaidi utaweza kupata ubao wa matangazo ni futi 30, picha inaweza kuchapishwa kwa ppi 10, na macho yako hayataweza kusema tofauti. Kwa mfano, kwa ppi 10, unaweza kupanua picha ya iPhone ya 12mp hadi 38 ft x 21 ft bila picha kuonekana pixelated. Au, kufikiria juu yake kwa njia nyingine, mara ya pili unaona billboard, kutoka umbali wa busara, kushikilia simu yako mbele yake, kuhusu mguu kutoka uso wako, na utaona kwamba screen simu yako pengine kuficha billboard nzima kutoka mtazamo wako. Kwa hivyo, macho yako yanaweza kuona maelezo mengi kwenye skrini ya simu yako kama kwenye ubao mkubwa. Uamuzi kwa ajili ya On-Screen Inaonyesha Kama huna nia ya kuchapisha kazi yako, na kuchapishwa mtandaoni ni marudio ya mwisho ya picha yako, basi mahitaji yako ya azimio ni hata chini ya kudai. HD na UHD inaonyesha kuangalia incredibly laini kutoka mapumziko kupendekeza kuangalia, lakini azimio halisi katika megapixels si kweli hasa juu. Picha za Pixel: 1080p, 720p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p, 1080p Wakati kuangalia picha katika ukubwa kamili na vipimo pixel kuzidi wale wa kuonyesha yako, kadi yako ya graphics itakuwa tu kutupa habari ya ziada. Kwa mfano, picha ya picha ya pixel ya 51 ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel ya Pixel. Uamuzi wa Lens za Kamera Lakini subiri, kuna zaidi. Sensor ya kamera yako itaweza tu kukamata maelezo mengi kama lensi yako inaweza kutatua. Uwezo wa azimio la lensi ni vigumu zaidi kupima, kama hatua hii ya mchakato wa kufanya picha bado ni analog. DxoMark imebuni kipimo cha uwezo huu kinachoitwa "megapixels ya utambuzi" ambayo hupima azimio la ufanisi wa mchanganyiko wa kamera / lensi. P-Mpix score ni alama ya kipekee, lakini lensi nyingi zina sehemu ya macho katikati na hupoteza usawa kuelekea kingo za sura, kwa hivyo bado ni ngumu kuamua jinsi megapixels hizo za utambuzi zinagawanywa kwenye picha. Hata hivyo, alama hii ni muhimu wakati wa kulinganisha lenses, na mara tu tunapojua ukubwa wa mwisho wa uchapishaji na vipimo vya pixel tunahitaji, tunaweza kutumia alama hizi kuamua kama mchanganyiko wa kamera na lensi utatoa maelezo tunayoyahitaji. Lens mbaya inaweza kwa urahisi kugeuka kamera ya megapixel ya juu katika kamera ya megapixel ya chini. Kwa mfano, kulingana na DxOMark, Nikon D810 ya 36mp inaweza kutatua 10mp tu wakati imewekwa na Nikkor 28-200 f3.5-5.6G. Kwa hiyo, wakati uwezo kamili wa sensor ya kamera yako inaweza kuwa overkill kwa ajili ya prints yako ya mwisho, ni vigumu kutoa kwamba ngazi ya maelezo kwa sensor ya kamera yako, na lensi ya ubora wa chini inaweza haraka handcuff utendaji wake. Ningeweza kujiokoa kazi nyingi kwa kutaja makala hii <unk>Ni bora kuwa na azimio nyingi kuliko kutokuwa na kutosha<unk> na kuiacha hapo. Kwa kweli, kamera za dijiti zinazozalishwa leo ni nzuri sana, na tofauti ya ufanisi kati ya 24 na 51 megapixels ni kawaida, katika mazoezi, haijulikani, isipokuwa ikiwa utapanda au kupanua hadi unaweza kuona sehemu ndogo tu ya picha kamili. Kwa kweli, isipokuwa wewe ni kufanya prints kubwa kutoka picha yako, na kuonyesha prints mahali ambapo wao itakuwa makini kuchunguzwa, kama vile nyumba ya sanaa, mengi ya azimio la kamera yako pengine itakuwa kupoteza muda mwingi. Je, unajua kwamba ni lazima ufanye kazi na kamera yako ya 12MP ya iPhone? Bila shaka si, kwa sababu, kwanza kabisa, ni bora kuwa na azimio kubwa sana kuliko kutokuwa na kutosha, na pia, ubora wa picha unategemea zaidi ya uwezo tu wa kutoa maelezo mazuri. Pia ni muhimu kuzingatia kamera ya mbalimbali dynamic, kina kidogo, uwezo wa juu ISO, na sifa nyingine ambayo inaweza kuwa vigumu zaidi ya kuhesabu kuliko azimio. Ununuzi wa kamera ni chaguo la kibinafsi, linalotegemea mambo mbalimbali, mapendezi na mahitaji. Uamuzi ni mara nyingi kipengele highlighted kusukumwa na wazalishaji kamera, lakini ni wazi haipaswi kuwa kuzingatia pekee ya wapiga picha. Wakati kulinganisha kamera, kuzingatia jinsi picha yako itaonyeshwa, kuamua juu ya idadi ya chini ya megapixels unahitaji, na kwenda juu ya vipengele vingine na uwezo.