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Optical vs. Digital Zoom

Implying Motion While Zooming

Zoom on a camera can add to the pleasure of digital photography. However, many consumers are confused between optical and digital zoom. An understanding of the difference between the two zooms will help you choose the digital camera that is right for you.

Most people who have used a 35mm camera or an APS camera are aware of only optical zoom. Optical zoom uses the optics (lens) of the camera to bring the subject closer. Digital zoom is an invention of digital video cameras. It is not uncommon to see digital videocams with 300x digital zoom.

For our purpose, digital zoom is not really zoom, in the strictest definition of the term. What digital zoom does is take a central portion of the image and enlarging it, thus ‘simulating’ optical zoom. In other words, the camera crops a portion of the image and then enlarges it back to size. In so doing, you lose image quality. If you’ve been regularly using digital zoom and wondered why your pictures did not look that great, now you know.

Is digital zoom therefore all bad? No, not at all. It’s a feature that you might want in your digital camera (in fact, all digital cameras include some digital zoom, so you can’t really avoid it), especially if you don’t care about using (or don’t know how to use) an image editing software. So, as far as digital zoom is concerned, you can do it in camera or you can do it afterwards in an image editing software. Any cropping and enlarging can be done in an image editing software, such as Photoshop.

So, when a digital camera is advertised with 3x digital zoom, no big deal. You can achieve the same 3x (and in fact as much as you want) digital zoom effect in an image editing software. The advantage of doing it later is that you can then decide exactly which portion to crop and how much to enlarge (3x, 4x, …). If you do it in camera, image quality is irreversibly lost.

Someone in a digital camera forum once mentioned that he uses digital zoom because it might mean the difference between capturing a great shot or not at all. Umm, let’s think about this a bit. True, if by zooming digitally in camera you get to see what your subject is doing and thus can capture the shot at the right moment. Not quite true, if it’s something like a landscape shot, and the mountains are not going to move, because you can achieve the same cropping and enlarging effect after the fact in your image editing software. So, it’s really up to you, if you know what you’re doing.

What, therefore is the rule of thumb, when it comes to using zoom? Here it is: Always use optical zoom. When buying a camera, choose one that warns you that you are about to use digital zoom or that allows you to disable digital zoom (most do). If you do use digital zoom, use it only if it does not appreciably impact your image quality. If you rarely print past 4×6 in. photos, the destructive effect of digital zoom may not be apparent at that small size.

When comparing cameras, you should always use optical zoom. There is no point in comparing digital zoom with digital zoom or optical zoom with total zoom (some camera manufacturers will add their digital zoom to optical zoom for a ‘total zoom’ value). Always — and only — compare optical zoom with optical zoom.

Optical Zoom vs. Resolution
What about optical zoom vs. resolution? Sigh! Now you all know that we cannot and should not be comparing apples and oranges, but we still try. The megapixels resolution of a digital camera can be thought of as the number of pixels available to capture an image.

Do not compare optical zoom with megapixel resolution because optical zoom is not megapixel resolution-dependent. That is, the resolution of your final image does not change no matter how much you zoom in. If your digital camera is 15MP and has a 12x optical zoom lens with focal length of, say, 30-360mm, then at 30mm, your image is 15MP and at 360mm, it is still 15MP. With digital zoom/enlargement, the megapixel resolution decreases as you “zoom” in digitally. If you now bring the cropped image back to the same 15MP size, then there are pixels interpolation and the resulting image suffers in quality.

We always disable digital zoom in camera, choosing to do our own cropping and enlarging in an image editing software.

Optical vs. digital zoom? There is no contest. Only optical zoom matters when selecting a digital camera.

What we are really trying to say is this: do not compare. You’ve got to decide what is more important to you: resolution or optical zoom? If the answer is both, then find a digital camera that has both. It’s that simple. If it’s outside your pocketbook range, then choose a digital camera for what is more important to you.

One important consideration with regards to resolution is important to make here: don’t be fooled by the high megapixel resolution advertised for a camera. A compact digital cameras with around 6-8 MP produces perfectly beautiful images for most point-and-shooters. Go higher and overall image quality seems to get worse instead of better. It has to do with pixel density: cram too many ever tinier pixels close together onto a tiny image sensor and all kind of image quality issues come up, including the all important noise. I am here talking about compact digicams with tiny sensors (usually sized at 1/2.3-in. to 2/3-in.). The micro Four Thirds and APS-C digital cameras have much bigger sensors and the megapixel resolution can safely go as high as 24+ MP.

Smart, Safe and Intelligent Zoom
Realizing that digital zoom is not really a good thing because it negatively affects image quality, camera manufacturers have introduced a new type of digital zoom variously called “Smart Zoom” (Sony), “Safe Zoom” (Canon) and “Intelligent Zoom” (Panasonic and others). Smart/Safe/Intelligent Zoom (let’s collectively called them Intelligent Zoom, or iZoom for short) can be viewed as an “ethical” digital zoom which avoids interpolating the image and so avoid degrading image quality. iZoom works only if you select an image size smaller than the full available image size. So, for example, if your digital camera is capable of producing a 12MP image, Smart Zoom is available only if you select to save your images as 7MP or less. In other words, with this particular type of digital zoom, the MP resolution decreases as you ‘zoom’ — in other words you are just cropping the center of the image (without enlarging and interpolating back to the original resolution).

Say, your digital camera is 12MP and you select to save your images as 10MP. So, in effect, you are forfeiting 2MP of image data (extracted from all over the image area) that the digital camera’s sensor has captured and now has to throw away [you hope the camera makes the right decision and does not throw away important image data]. Enter iZoom that says, “Hey, instead of throwing away 2MP of good data from all over the image area, why don’t I crop out all the pixels starting from the outside perimeter? When I’ve cropped out 2MP of image data all around, I have 10MP left over and that’s what you want, right?” Notice, the 10MP image does not have to be interpolated and enlarged back to 12MP as traditional digital zoom does (because you elected to save it as 10MP, remember?). So, in effect, you’ve basically more or less retained the same image quality but you have to save your resulting simulated zoomed image in a smaller image size. Of course, if now you turn around and enlarge it in post-processing, you will be limited to what a 10MP image can be enlarged up to without image degradation.

I call iZoom “ethical digital zoom” because it is not made available at full image size — this would cause image degradation. The smaller you elect to save your image, the more iZoom power you have available (folks, you’re basically just cropping the image without re-enlarging, which you can also do at any time in post-processing).

So, our recommendation still holds. If you want zoom power, only optical zoom matters! iZoom is the better form of digital zoom, but what you gain in simulated zoom power (again, you’re just cropping), you lose in image size. There’s no free lunch.

Again, don’t buy a digital camera based on digital (traditional or inteligent) zoom. Always compare optical zoom with optical zoom. If you are comparing 2 digital cameras with the same optical zoom, but one has intelligent digital zoom and the other has traditional digital zoom, then the intelligent zoom has a slight advantage. But personally, I wouldn’t even look at that because there are a lot more important features to differentiate the cameras.

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144 Comments

  • At last an explanation and technical data will provide much needed guidance in the purchase of a new camera. Thank you so much.

  • I appreciated the information because I am buying a camera for my daughter and wanted to get one that she would get the one that had beneficial features.
    Thanks.

  • ha, it was an awesome review i had here, i didnt know much about these stuffs, but now i could write an essay, thanx for the writer. it was superb

  • Simple summary:

    Classical digital zoom means:
    1. cropping away the edges of the image
    2. resizing the resulting image to the original size

    Smart Zoom means:
    1. cropping away the edges of the image

    But for each of these there is an additional reason for the function, which is not mentioned in the article. There are more things happening when you use these functions, and some of the things that are happening are very useful!

    Firstly, the viewfinder image is being magnified showing the area you really want to keep – this allows you to watch the action inside your intended frame more comfortably. Second, and most importantly, the matrix exposure and white balance calculations/decisions are being made using only the area of interest. Lastly, a smaller image is being processed, which usually allows a higher frame rate.

    In summary, digital zoom, which you call Smart Zoom, and digital zoom with resizing, are both useful functions and are not to be dismissed. Likewise, optical zoom is not all its cracked up to be. Some lenses become so dim at the long end and so distorted at the wide end, that you might as well reasonably knock off a couple of “x” to be safe.

    Five years ago, only the full image was of reasonable resolution for prints, but that is no longer the case. It’s time we started evaluating cameras based on the end result, and that means evaluating them based on real experience. Thankfully, there are a host of people on the Internet just jumping at the chance to put cameras through their paces and show you the results.

  • Michael,

    Agreed and good summary.

    As you point out, the article was originally written way back and we update it as necessary. Plus, comments from readers like yourself also add to the understanding of the subject. As the article points out, nothing wrong with using digital zoom (even the destructive kind) if it helps you see the scene better and gets you the picture. Personally, we still prefer to do the “digital zooming” in post-processing. After all, all photographers crop their pictures to fit the composition desired.

    We always evaluate cameras based on the end results and actual in-the-field use. If you use a feature purported to be good (like the camera is advertised to have a very high ISO and a new intelligent processor to allow you to take beautiful, noise-free pictures in low light), but the end result shows differently, then we call that out. Back then digital zoom was the big subject everyone wanted to understand. Today, it’s noise.

    However, what used to be “gimmicks” on cameras are now becoming useful and practical features. Smart zoom, in-camera panorama, creative filters, HDR, noise reduction — all are progressively becoming better, even to the point that they do not negatively affect the final image. Certainly, for point-and-shoot photography, I use them all the time in-camera. For more serious photography, I still prefer to apply them in post-processing.

    Truth is, when the time comes when the camera can intelligently apply in-camera all the processing that we do today in post-processing [such as level adjustment, noise reduction, sharpening] without negatively affecting the image quality, who cares how the final result is obtained? I have no doubt this time is coming. And, as reviewers, we can then all retire, job done.

  • So you say decide what’s more important to you megapixels or optical zoom. But then you say that megapixels above 8 are not any better. So wouldn’t it make sense to get 8 mp with the highest optical zoom possible??

  • Like we wrote one paragraph earlier in the article, this is pretty much a moot point today with resolution reaching above 14MP and optical zoom going way beyond 10x. In other words, you can have both megapixels and zoom galore. In fact, we don’t have much control over megapixels resolution today, so determine the amount of zoom you want, realizing that, as in everything, there are tradeoffs with higher zoom levels.

  • I was unsure about the difference until this article very informative and good thing not biased told good and better about both info needed looking at buying new camcorder. Thanks

  • Hi, I have found your article really helpful. The last camera i had was a 35mm other than a compact digital that pictures went blurry esp when zooming in when in video mode. The still picture were good though but the battery housing door got damaged. I am wanting to start taking photos again and I need one that can do good landscapes and also zoom in to cover nature shots plus be able to have photos of our sheep when we are showing etc. I have looked at the Samsung WB100 and the Fujifilm FinePix S4300 which i think I prefer. I have also looked at the Sony SLT_A37 with detachable lenses. I’m now a little confused when some say 26x optical zoom and the other says 18-55mm iS lens. Help please to clarify this and any cameras you would recommend please as I would like to get into photography and maybe sell a few now and then. Thanks and sorry if i’m being a numpty.

  • To calculate optical zoom power, simply divide the end focal length by the start focal length.

    So, the Sony SLT-A37 is a DSLR and comes with a 18-55mm kit lens which has 55 / 18 = 3x optical zoom. [55 divide by 18 = 3]

    The Samsung WB100 has a 4 – 104mm lens and therefore 104 / 4 = 26x optical zoom.

    The Fujifilm S4300 has 4.3 – 103.2mm lens and therefore 103.2 / 4.3 = 24x optical zoom (the specs online on some sites claiming 26x optical zoom are in error).

    There are a number of reasons why your pictures are blurry and a new camera may not change that at all.

    1. One of the reasons why your picture gets blurry when zooming in video mode is because, as you change the focal length, the camera needs to refocus. Some of the newer superzoom cameras claim that if you set focus mode to Continuous Focus, then the camera will refocus as you zoom. In practice, most cameras fail at this, refocusing only when you stop zooming.
    2. A second reason may be that, as you zoom, the minimum required distance between the camera and subject increases. So, if you are too close to your subject, when you zoom, the camera may not be able to lock focus because you are simply too close.
    3. As you zoom, especially to the long focal lengths, it becomes more difficult to handhold the camera and a sturdy tripod is necessary (or somewhere flat to rest the camera). Otherwise, camera shake will result in blurred photos.

    If you already have a 35mm DSLR, then you probably have a more than good enough camera. There are just so many good cameras out there that answer your needs that is is difficult to recommend one.

  • Hi Thanks for your reply. Unfortunately I no longer have my 35mm camera and the digital cameras battery housing has broken hence the search. I think I read from you that the greater the zoom the better sensor you require to kep the picture crisp. Ive been looking at the fujifilm finepix selection and they say the sensor is 1/2.3″ is that a good enough sensor to cope twith the 24 or 26x zooms or will it leave them a bit blurry? Sorry for bothering you again. From your article you say that only the micro four thirds and APS-C cameras have big enough sensors and i’m not sure what you mean by this or which cameras they are. I’m trying not to just buy a camera and regret it later as it doesn’t do as I wanted or as I learn more and want to do more with it I find it can’t and have to purchase another one. Thanks again for any help.

  • I want to buy a camera. which one should i buy Nikon P510 or Nikon P7700?

  • I have an online jewelry shop and it is so important to get great quality close up shots in order for consumers to get a good, detailed look at what they may want to purchase. I also love taking pictures of birds, lanscape,sunrise/sunset and after dark photos.
    Could you recommend a camera with a price tag around 400.00?

  • Amazingly accurate and appropriate description of the facts in a very very user friendly language with examples.

  • sir i need a camera or handy cam that has super zooming without effecting the image or video quality . i m dabble minded to select between Samsung wb100 16mp with 26 optical zoom and handy cam HMX F80 5 mp with 52 optical zoom, plz sir help me which is the best between wb100( 16mp +26 optical zoom) and HMX handy cam ( 5mp + 52 optical zoom) to make images and video from long distance without effecting the quality,

  • As the saying goes, “There’s no free lunch.” It all depends on what is more important to you: still image quality, optical zoom reach, videos mostly.

    The 16mp of the WB100 is better than the 5MP of the handy cam and so the WB100 should be better for still images, especially if you intend to print them big. If you mostly shoot videos for posting on Youtube or family viewing on TV then the 5MP of the handy cam may be adequate.

    You also need to decide whether you need the 52x optical zoom (35.3 – 1836mm equiv.) reach of the handy cam or if the 26x optical zoom (22.3 – 580 mm equiv.) of the WB100 is sufficient for your needs. The WB100 has a wide angle lens (22.3mm equiv.), great for wide vista landscapes shots. The handy cam allows you to bring far away subjects real close (1836mm equiv.) but image quality will probably be less than the WB100. So, do you prefer landscapes or super telephoto shots?

    Thw WB100 is primarily for still pictures with family video thrown in; the handy cam is primarily for family videos.

    As you can see, there’s no easy answer and that is why there are so many models to choose from.

  • Which is the best camera ?
    Sony cyber-shot dsc-h200 or panasonic lumix lz30
    In subject of mega pixel, optical zoom, and digital zoom.

  • Another advantage of digital zoom:

    I take pictures of birds and I have found that autofocus fails in a lot of situations especially when the subject is small in the frame. (I use autofocus because I often only have 2 or 3 seconds to get the shot before the bird flies away.) But if I increase the zoom into the digital range, so that the subject fills more of the frame, the autofocus works better. The net result is that I now almost always zoom out to the max optical + digital and end up with better pictures of birds, because a grainy in-focus shot is better than an out-of-focus hi-res shot.

    So if your subject is small in the frame, I would strongly recommend using max digital zoom to increase your chances of getting an in-focus shot.

    Perhaps the focusing technology will someday improve where I can select a pinpoint and it will get lock on to it. But for right now its not there.

  • Try and see if you can decrease the size of the AF frame to fine tune where the camera focuses on.

  • I agree that photos should be taken with optical zoom in most cases. However, I find that my Canon SX50 with 4X digital gives me th ability to find photos to take that I would not even see if I did not have 200X, like the pilot of a blimp over the beach, a barn window on the side of a mountain, or a ship on the horizon. I also can use it as a telescope for distant islands and moon and planet viewing and photography, etc. It enables me to see what the final composition would look like, even if I choose to shoot at optical zoom levels and enlarge it more at home. For many photographers, the idea of composing and shooting faraway images never comes up, because of the quality loss. This makes long zoom unimportant. For an amateur like me, it is an important aspect of getting shots nobody else gets. I have a favorite shot of the Tower of Pisa taken from a bus moving at 100 km/hr from a mile away. A real photographer would ask why I didn’t visit the tower.

  • I like how you “think outside of the box.” The two “zooms” are both tools at the photographer’s disposal, so yeah, by all means feel free to creatively use them as you think best. It’s quite ingenious using it as a scope to find interesting subjects far away. The more I age, the more I celebrate people’s creative and unorthodox use of technology.

  • I’m really trying to compare because I’ve got nothing to go on. I’m new at the MILC game, having used a handycam with 150x digital zoom previously. Now I have the option of buying a zoom lens that goes up to 210mm. But… How far IS that?? I only know of my 150x. Is it farther than that? Am I going to get the same distance out if it? I need some way to compare before I spend 350 dollars on it.

  • Amy,

    I doubt any camera zoom lens can match up with a handycam digital zoom. But, as the article indicates, you cannot compare optical zoom with digital zoom because the latter is not “real.” Also, if you look at any one frame of a handycam, you will notice the image is not really in sharp focus. Because it is a movie, the frames go by fast and our eyes do not stop to look at each frame. A still picture is different and any hint of blurriness is very apparent.

    When you compare optical zoom to optical zoom, you need to find the focal length equivalent. These are usually listed on their technical specifications page online.

    So, a 3x optical zoom 70mm-210mm has further reach than a 10x optical zoom 12mm-120mm, since 210mm is greater than 120mm. On the other hand, the 10mm is a wider angle than the 70mm.

  • Time-tested. After 5 years, the value of the article still holds as good. Very informative indeed. Can you explain a bit 30x, 40x zoom while focal length spectrum is already defined for the particular lens.

    If you already have covered this in another article just post the link.

  • Greaaaaaaaaaaattttttt aricle. I knew nothing about the cameras but now I know something 🙂

  • it really very important information. Now i came to know the difference between Optical and Digital Zoom. When i have gone through the above it is information before purchasing a camera and what to look at

  • So what would the best optical zoom be to do portrait pictures and will the same amount work for landscapes and actions

  • Landscape generally requires a very wide angle coverage (14-24mm) while it is most useful to use a mid telephoto (70-200mm) for portraits. Of course, nothing stops you from creatively using a wide-angle for portraits and mid tele for landscape.

  • i was wondering what photo editing software you’d recommend or that you were talking about with being able to ZOOM and save quality. every software i’ve used, from Adobe on have pixelated with even a little bit of zoom no matter what i did in settings including telling it to retain compatible ratios

  • The point of the article is that you cannot digital zoom and save quality, whether you do it in camera or in post processing. It’s therefore better to keep the original image quality by not digital zooming in camera, otherwise the image quality will be irreversibly lost.

    In Adobe Photoshop, I use Bicubic Smoother (under Resample Image) when I need to resize an image just a tad larger, but image quality does suffer.

  • We are looking for a reasonalby good camera with a relatively long zoom. It seems to me the sensor size and the number of pixals come into play. For instance, a 12mp,1/ 1.7 sensor with a 300mm lens (Olympus Stylus 1) vs a 18mp, 1/1 sensor with a 200mm lens (Sony RX10).

    To me it seems the Sony gives more total zoom because when you crop you still have more pixals that contain more data.

    Your comment?

  • We are here choosing between two very good (and expensive) long zoom cameras, but we should make our choice based on image quality, not that we believe that we can supplement the RX10’s optical zoom with cropping (i.e. digital zoom) because of its larger sensor. It’s never a clean cut mathematical comparison. But, if we find that the image quality of the Stylus 1 is good enough for our needs at its 200-300mm range, then it’s cheap compared to the RX10. If it’s image quality is not good enough (at the 200-300mm range), then the RX10 may be our choice (assuming, that is, if we can afford it).

    I like the review comparison here and here.

    Of course, there are other factors to take into consideration besides optical zoom power, sensor size and MP resolution. What about size, weight, handling, availability of accessories, etc. etc.? If we were shopping for a long zoom and had to choose between those two, we would handle them both at a friendly camera store and test shoot with our memory card before dropping that much dough on the table.

    Good luck on your choice!

  • When I digital-zoomed under the sun into a distant dark object (say, a cave), should I expect my camera doing better exposure control?

    I tried that with my cheap cameras and seems they don’t work that way–the object remains underexposure. I tried also digital zoom bright characters on the stage in a dark concert hall; The characters came out overexposure. Perhaps better cameras will do them right, hence making digital zoom somewhat useful?

  • Digital zoom is not “real” zoom; it’s a misnomer and should really be called “enlarge a portion of the image after it has been taken by the camera.”

    That’s it. That’s really what the standard digital zoom is doing: the camera takes the picture (a really dark cave, in your example), then enlarges it. Nothing, as far as exposure is concerned, changes because the picture has “already been taken” (on the image sensor, though not actually written to memory card).

    Can you tie exposure compensation to zoom? It already is as far as “optical” (i.e. real) zoom is concerned.

    Just ignore whatever digital zoom specs you see on a camera. Don’t use it as your criteria to select and purchase a camera. If zoom power is important to you, always look at the optical zoom specs (and, of course, sensor size and low noise performance are also important).

  • Hi,
    I’m one of those who use digital zoom a lot.
    I have a Canon SX50 that has a 50x optical zoom, along with a 4x digital zoom, giving at max a 200x zoom.
    I try to shoot everything at or under the 50x optical zoom setting, for better image quality. But I shoot a lot of wildlife shoots, that are beyond the reach of the 50x optical zoom.
    Especially birds in flight, like Tundra Swans or Bald Eagles, that are really far away. I find there is just more image detail separation for such long shots at 100x zoom, 50x optical plus 50x digital zoom, than when just shooting with optical zoom, and cropping later. Especially if your exposure compensation value isn’t just right when shooting a white Tundra Swan or a Bald Eagle, against a bright sky.
    The other area digital zoom really helps is when framing a shot at far distances.
    I can watch a swan on a far shore flap its wings, and take that special shot, which would be completely unseen under optical zoom only.
    My struggles are more with image quality and camera slowness when shooting between JPEG, Superfine JPEG, and RAW.
    The Canon SX50 is a great little camera.
    It puts so much within your reach.
    When you just can’t get closer to your subject, digital zoom can still make that shot happen.

  • “digital zoom really helps is when framing a shot at far distances.”

    Original author circa Nov2009 makes the same point:

    “True, if by zooming digitally in camera you get to see what your subject is doing and thus can capture the shot at the right moment.”

    I would add that digital zoom while taking video, can give a worthwhile increase in video quality: digitally zooming onto a dark area can cause the processor to add video gain. Compared with doing this in post production, this gives higher quality (less noise) images, even though it does not increase resolution, as optical zoom would. I’ve used this to advantage for shooting video of bands in clubs, with my iPhone 6.

  • I absolutely agree since video is a whole new ballgame as far as digital zoom is concerned. Since we are not viewing each single image by itself but a series of moving images (which, individually, may or may not be sharp, detailed or noisy), digital zoom can — and is — used a lot in shooting videos. In fact, the advertised zoom in most consumer video cameras is digital zoom (that is why they can advertise 200x zoom).