9 ms·

SLR Camera Simulator

176 points by kmfrk 16y ago

kenjackson 16y ago
I don't know much about cameras, so I don't know how accurate it is, but I love the idea. Kudos for this idea and the execution seems good. I like.
- hackermom 16y ago
  Reasonably accurate. add.: it gives a good foundation regarding teaching exposure itself, but, apart from not explaining (nor visualizing) that focal length and perspective are two separate attributes of optics, it also misrepresents the meaning and function of the ƒ value in a very common way often repeated even by seasoned photographers, in that it suggests (and indirectly claims) that ƒ only has to do with the aperture of the lens, and that ƒ is an indicator of what depth of field you will have. In reality, ƒ only tells you how much light is passed to the film plane; it does not tell you the state of the lens' aperture, nor does it say anything about the depth of field. This misleading explanation regarding ƒ is widespread even in literature.
  - kenjackson 16y ago
    Could you expand on the 'f' value thing?
    - hackermom 16y ago
      I hope the above two posts are detailed enough. If not, I'll gladly explain if you have a specific question.
      - kenjackson 16y ago
        It's very good. Thanks alot.
  - sasha61 16y ago
    Actually this is not quite correct. F is ratio of aperture to focal length. As such, it does not tell you the absolute values of either, but it definitely does relate to DOF (although this will be affected by the focal length value - e.g., for the same F, you could have DOF of a few mm at short focal length, and a few dozen metres with long zoom lenses).
    - hackermom 16y ago
      It's entirely correct. ƒ relates to DoF only in that it's relative to the maximum aperture of a specific lens. Without knowing the specifics of the lens, you cannot know from arbitrary ƒ value if the aperture has been contracted (narrowing the flow of light, thus increasing the DoF), if it's just really dark glass in the lens, if someone has a TC mounted that steals 1-2 exposure stops, or if someone has simply used a gray filter or two attached to the end of the lens. I can produce two identical exposures, both of ƒ/8.0, where one has a narrow DoF and the other 4 aperture steps deeper DoF, by simply using a gray filter in one shot, and contracting the aperture in the other. In a third example I can use a very, very dark lens such as f.e. what Leica used to produce in the 60s, still exposing at ƒ/8.0 in wide-open aperture, reaching the same exposure and achieving a narrow DoF (contrary to what anyone would think just knowing it's ƒ/8.0), but without having stopped down a single step and without having used gray filters.
      - ghshephard 16y ago
        I agree with the parent. F-Stop is the ratio of the Focal length to aperture diameter. Increasing that ratio, increase the depth of field. Decreasing that ratio, decrease the depth of field. Instinctively, F23 will put everything in focus (which is why we use it to identify dust spots on our CCDs, whereas F1.4 on anything reasonably close is going to have a DOF measured in inches. Can you come up with a counter example where DOF doesn't change in this direction? Apologies if I'm missing your entire point - I've been starting at it for five minutes, not sure if you are going a different direction.
        hackermom 16y ago
podperson 16y ago
It's kind of a nice idea and a decent start. It doesn't seem to do depth of field very well (f8 should make the background pretty sharp at 43mm; f2.8 at 200mm should have a completely blurred background). It would be nice if it showed non-Canon terminology (Canons say "Tv" while almost all other cameras say "S", for example), at least as an alternative. It should also visually indicate the value being automatically chosen in the different modes. No P (program) mode. This is actually the most useful shooting mode on many DSLRs, especially for novices. It lets you trade off aperture vs. shutter speed. __Advanced Nitpicking__ No auto ISO mode. (Great feature of Pentax cameras -- it's like M but the camera picks the ISO that will work.) No ISO-priority mode. It doesn't allow for things like camera shake and the child's motion (you might pick 1/60 of a second to capture the child sharply, while needing 1/250, say, for the pinwheel). It's not worth allowing ridiculously high (small) apertures (e.g. f29) -- if you're not going to do diffraction, so I'd stop at f22. It would be nice to have faster (bigger) apertures than f2.8 to really show the benefits. It shows autofocus points, but they don't do anything. It would be interesting to allow the user to pick a focus point and assume the metering is weighted on that position, but that's getting pretty advanced.
- sukuriant 16y ago
  Historically, it wasn't "S", it was "T".
- zalew 16y ago
  > No P (program) mode. This is actually the most useful shooting mode on many DSLRs, especially for novices. It lets you trade off aperture vs. shutter speed. oh boy. that's actually the mode that keep novices clueless about what's going on with the settings. > No auto ISO mode, No ISO-priority mode, etc. etc. well, ISO + TIME + APERTURE are ingredients of EXPOSURE, and that should be all you need to know to start shooting. you know this and you can grab the newest high-end dslr or your grandpa's 35mm oldie and know what you're doing. the rest is just geekery.
  - mitjak 16y ago
    >well, ISO + TIME + APERTURE are ingredients of EXPOSURE, and that should be all you need to know to start shooting. you know this and you can grab the newest high-end dslr or your grandpa's 35mm oldie and know what you're doing. the rest is just geekery. Perhaps I misunderstood your point but that doesn't sound right. Iso does not control exposure: in case of film it is the sensitivity of a particular stock, and in case of sensors it's basically analog gain. Since to use a different ISO in a film camera you'd need to use a different roll or sheet of film, you can't vary ISO on a "grandpa's camera" very easily unlike with a digital camera.
sasha61 16y ago
If you have ipod/iphone/ipad, have a look at <http://www.islap101.com/&#62 http://www.islap101.com/> (and review of it at <http://lifehacker.com/5501364/photo-tutor-teaches-basic-camera-exposure-on-the-go-from-your-iphone> http://lifehacker.com/5501364/photo-tutor-teaches-basic-came.... There are actually two apps (one for shutter speed and one for aperture) - and they teach/display those concepts really well - even if I say so myself :-). There are also "recipes" for taking photos in various environments/situations - all prepared by professional photographers.
SonicSoul 16y ago
im a DSLR newb, but i think i just nailed it with: sunny, 55mm, ISO:100, f4, 1/2,000
- mTh 16y ago
  Kudos. But if you are a newbie, then perhaps it would be more useful for you, in order to learn how to use an actual DSLR in the field, to reduce the 'Lighting' to more difficult situations ('Overcast', 'Bright Indoors' etc.) and... 1.) set up the simulator to Tv mode and play with the 'Shutter Speed' and ISO primarily ...and after this: 2.) set up the simulator to Av mode and play with the 'Aperture' and ISO primarily. In this way you will learn how far you can go in real situations and what results you might expect. HTH (EDIT: Ok, you can play with the distance & focal length but I think that for the 1st step it is better to concentrate on the points above).
  - SonicSoul 16y ago
    thanks, so why would Tv mode be more educational than M (which I am guessing stands for Manual) which also allows for playing with shutter speed and ISO ?
    - mTh 16y ago
      Indeed there are cases in which one can use the M (Manual) mode. But usually these cases are rather corner cases, especially for us, the beginners. Basically you ditch the DSLR's photometric engine which does most of the time a very good job, (except some rare situations in which the illumination is very tricky, you want to achieve very special effects etc.). Besides that, it is enough more difficult to play with four variables (Aperture, ISO, Speed AND the exposure indicator (usually a vertical beam in viewfinder)) compared with two variables (ISO & Aperture or ISO & Time respectively) or with just one (Aperture or Time - if you have the ISO set to Auto). The main difficulty here isn't that someone (you) can cope (or not) with four variables in a simulator but to adjust them quickly and exactly in the field given the very short amount of time which you (the photographer) have at your disposition to take "the shoot". That's why the most photojurnalists (from which, more or less, is your truly also) avoid the M mode. OTOH, I have very close "brothers" which are 'studio creatures' which prefer the M mode. And now to respond directly to your question, having the Tv (or Av mode) will give you a much 'closer to real' simulation (especially if you are on-field, on-street, on-sports etc. photographer) and will allow you to concentrate rather on the effect you want to achieve (for ex. how to simulate a good moving effect of the child's rotating toy) in the smallest amount of time (think that in the real world, the children aren't so frozen like the one in our simulator :-) ) and not to concentrate so much in obtaining a correct exposure. Usually the metering system does the job rather well. These systems have enough advanced features today to help you in avoiding the M mode with its quirks: exposure modes, over/underexposing by 1/2, 1/3 EV etc. HTH PS: Disclaimer: No, I'm not against the M mode. But I want to stress its limited usage today. Of course IMHO.
drblast 16y ago
Can anyone explain why the "ISO" setting exists on digital SLR cameras? It seems like this is an unnecessary holdover from film cameras. I ask this as an owner of a Canon Digital Rebel that knows very little about photography. What does changing the ISO setting get you that changing the exposure time or aperture wouldn't?
- sbierwagen 16y ago
  ISO is sensor sensitivity. Higher settings multiply the numbers that come from individual sensor elements by increasingly large amounts. Image sensors are not perfectly noiseless, of course, and the higher the ISO is, the noisier the image, which appears as random speckles of colored dots. You don't notice the difference, though, because you're probably shooting in JPEG mode, not in RAW. In JPEG, the Rebel tries very hard to cover up its sins, and will blur away sensor noise, which is hard to notice unless you grovel over areas of fine detail at 400% magnification. Second time I've linked this in this thread, but http://www.dpreview.com/reviews/nikond5100/page20.asp http://www.dpreview.com/reviews/nikond5100/page20.asp shows some great examples of what sensor noise looks like over a range of ISO values. Edit: Useless editorializing: A SLR isn't a great purchase for someone who knows very little about photography. A point-and-shoot is lighter, cheaper, more durable, easier to use, and in the vast majority of situations, will produce identical results to a SLR. You then graduate to a real camera when get fed up with the various fiddly technical limitations of a point-and-shoot; and bonus, you still have the small camera, which is the one you take with you when climbing mountains, or on vacation, rather than lugging around five kilograms of japanese glass. Tedious polemic: I dearly hope you have more than one lens. The enormous price premium of a SLR is mostly for the privilege of being able to change lenses. If you just stick with the kit lens, then you will have spent rather a lot of money to accomplish nothing a point-and-shoot couldn't do.
  - bradleyland 16y ago
    Just as a counterpoint (not to pick a fight), I'd disagree with a lot of what you said in the latter portion of your post. Entry level SLRs are great, even for people who don't know anything more than point-and-shoot. The advantage of an SLR is that it will focus faster, meter faster, and ultimately take the photo faster. This is a huge advantage for parents, whose children are fast moving targets. What's not necessarily a good idea, is buying the biggest, most expensive SLR you can find. Canon and Nikon both make entry-level SLRs that have modes specifically targeted at novice photographers who will never leave full-auto mode. Buying a more expensive model primarily gets you features. Features that you won't use. The hardware is remarkably similar until you get up in to cameras that cost thousands of dollars. Many people believe that the huge lens is what makes SLR photos clearer in more conditions, but that's not the whole story. The lens is large because of an aspect of the SLR that you'll probably never see: the sensor. The single greatest reason for the increased image quality of an SLR is sensor size. When you shoot with a compact point-and-shoot, you're capturing light with a sensor the size of your pinky fingernail. You could shoehorn the fastest, largest, most expensive SLR lens on to a compact point-and-shoot, and the photos it takes wouldn't compare to an SLR with even a modest lens. The sensor in an SLR camera is closer to the size of a postage stamp, and this makes all the difference. Keep in mind that compacts these days shoot comparable resolution (megapixels) to SLRs. This means that each "pixel" in a compact is microscopically small when compared to the "pixels" in a SLR sensor. This means less area for light to fall, and less light collected. So, even with one lens, and in the hands of a novice, a reasonably priced SLR can result in sharper, more well timed photos in a more diverse range of conditions.
sbierwagen 16y ago
The noise at higher ISO levels isn't terribly realistic for modern SLRs, let alone full-frame pro SLRs. Here's a comparison of several modern entry-level SLRs: http://www.dpreview.com/reviews/nikond5100/page20.asp http://www.dpreview.com/reviews/nikond5100/page20.asp You can go up to ISO 1600 and get (more or less) unnoticeable noise. Note that you have to switch to RAW to show sensor noise-- JPEG mode will blur away noise, trading fine detail for smooth images. Also that lens is really amazingly sharp at both ends of its aperture range. In the real world you wouldn't get anywhere near that level of performance without spending tens on thousands of dollars on a prime (non-zoom) lens.
- ashchristopher 16y ago
  It's a learning tool. Cut them some slack =).
  - sbierwagen 16y ago
    It's a learning tool, and so I would like it to teach that almost all lenses made of mortal glass are less sharp at either end of their aperture range; and that taking a picture of a landscape on a sunny day at f2.8 is a bad idea.
- mortenjorck 16y ago
  It's exaggerated, to be sure, but it's an instructive exaggeration. Showing the noise visible in a 4k still at 8% enlargement isn't going to help a novice understand ISO tradeoffs.
chrishaum 16y ago
This is an awesome tool. Thanks!
angusgr 16y ago
Given this is intended to teach exposure/DoF, it'd be nice to be able to bypass the "SLR" aspect of the camera, ie provide a "continuous snapping" mode where moving a slider instantly updates the "photo" instead of showing the fake autofocus sensor overlay. It's definitely a neat way to interact with it in a browser, though. If you're looking to learn these relationships in a less interactive way, I thoroughly recommend the book "Understanding Exposure" by Brian Peterson.
- ujal 16y ago
  That was also my first thought. The app would be much more informative by providing the results instant.
alok-g 16y ago
Nice idea. A difficult one from implementation standpoint: When I change the distance, it just scales the girl's face as a 2D image -- no perspective. :-) I'm not being picky, just that this is sometimes a consideration for me when clicking... Wish someone can point me to the mathematics behind this stuff. I figure ISO means gain of some amplifier inside so less photons would be needed to get to the same voltage at the expense of more noise. I can see how with the two auto modes, aperture size and shutter speeds relate to each other (basically you need to gather a similar number of photons, given the ISO setting). Yet do not know the mathematics behind why aperture size affects the depth of focus. Likewise, why focal length does the same. What's the mathematical definition of Fstop. And last but not the least, what role the sensor size play into all of this.
- sbierwagen 16y ago
  https://secure.wikimedia.org/wikipedia/en/w/index.php?title=F-number https://secure.wikimedia.org/wikipedia/en/w/index.php?title=... https://secure.wikimedia.org/wikipedia/en/wiki/Focal_length https://secure.wikimedia.org/wikipedia/en/wiki/Focal_length https://secure.wikimedia.org/wikipedia/en/wiki/Depth_of_field https://secure.wikimedia.org/wikipedia/en/wiki/Depth_of_fiel... https://secure.wikimedia.org/wikipedia/en/wiki/Film_speed#Digital_camera_ISO_speed_and_exposure_index https://secure.wikimedia.org/wikipedia/en/wiki/Film_speed#Di...
  - alok-g 16y ago
    This helped: https://secure.wikimedia.org/wikipedia/en/wiki/Depth_of_field#Derivation_of_the_DOF_formulas https://secure.wikimedia.org/wikipedia/en/wiki/Depth_of_fiel... Still do not know how sensor size affects things. Will read more, and hopefully will be able to construct a single mathematical model that couples all of these together.
niels_olson 16y ago
Best review of the basic science I have seen online: http://johnlind.tripod.com/science/ http://johnlind.tripod.com/science/ The the lens calculations are a whole 'nother ball of wax, but here's the quick skinny on the exposure value system: Av + Tv = Ev = Sv + Bv Exposure value: Ev Aperture value: Av = log2 (f^2) Time value: Tv = log2 (1/t) Speed value: Sv = log2 (0.32 * ISO) Brightness value: Bv = subject luminance in foot-Lamberts
bcaulf 16y ago
The beauty of digital photography is that you can take pictures all day at no cost and see your results instantly. So instead of running this program, get your friend with an SLR to go on an outing with you and let you do most of the shooting. Go outside and fill up a memory card while you systematically work through the settings. After you get the hang of exposure you can start in on the different settings for metering, autofocus, manual focus, jpeg processing, black and white, motor drive, use of flash, different lenses, not to mention composition choices, interacting with the subject, use of filters, creative panning or rotating. Real photography is more fun than tweaking sliders on a flash app.

176 points by kmfrk 16y ago

I don't know much about cameras, so I don't know how accurate it is, but I love the idea. Kudos for this idea and the execution seems good. I like.

hackermom 16y ago
Reasonably accurate. add.: it gives a good foundation regarding teaching exposure itself, but, apart from not explaining (nor visualizing) that focal length and perspective are two separate attributes of optics, it also misrepresents the meaning and function of the ƒ value in a very common way often repeated even by seasoned photographers, in that it suggests (and indirectly claims) that ƒ only has to do with the aperture of the lens, and that ƒ is an indicator of what depth of field you will have. In reality, ƒ only tells you how much light is passed to the film plane; it does not tell you the state of the lens' aperture, nor does it say anything about the depth of field. This misleading explanation regarding ƒ is widespread even in literature.
- kenjackson 16y ago
  Could you expand on the 'f' value thing?
  - hackermom 16y ago
    I hope the above two posts are detailed enough. If not, I'll gladly explain if you have a specific question.
    - kenjackson 16y ago
      It's very good. Thanks alot.
- sasha61 16y ago
  Actually this is not quite correct. F is ratio of aperture to focal length. As such, it does not tell you the absolute values of either, but it definitely does relate to DOF (although this will be affected by the focal length value - e.g., for the same F, you could have DOF of a few mm at short focal length, and a few dozen metres with long zoom lenses).
  - hackermom 16y ago
    It's entirely correct. ƒ relates to DoF only in that it's relative to the maximum aperture of a specific lens. Without knowing the specifics of the lens, you cannot know from arbitrary ƒ value if the aperture has been contracted (narrowing the flow of light, thus increasing the DoF), if it's just really dark glass in the lens, if someone has a TC mounted that steals 1-2 exposure stops, or if someone has simply used a gray filter or two attached to the end of the lens. I can produce two identical exposures, both of ƒ/8.0, where one has a narrow DoF and the other 4 aperture steps deeper DoF, by simply using a gray filter in one shot, and contracting the aperture in the other. In a third example I can use a very, very dark lens such as f.e. what Leica used to produce in the 60s, still exposing at ƒ/8.0 in wide-open aperture, reaching the same exposure and achieving a narrow DoF (contrary to what anyone would think just knowing it's ƒ/8.0), but without having stopped down a single step and without having used gray filters.
    - ghshephard 16y ago
      I agree with the parent. F-Stop is the ratio of the Focal length to aperture diameter. Increasing that ratio, increase the depth of field. Decreasing that ratio, decrease the depth of field. Instinctively, F23 will put everything in focus (which is why we use it to identify dust spots on our CCDs, whereas F1.4 on anything reasonably close is going to have a DOF measured in inches. Can you come up with a counter example where DOF doesn't change in this direction? Apologies if I'm missing your entire point - I've been starting at it for five minutes, not sure if you are going a different direction.
      - hackermom 16y ago

podperson 16y ago

It's kind of a nice idea and a decent start. It doesn't seem to do depth of field very well (f8 should make the background pretty sharp at 43mm; f2.8 at 200mm should have a completely blurred background). It would be nice if it showed non-Canon terminology (Canons say "Tv" while almost all other cameras say "S", for example), at least as an alternative. It should also visually indicate the value being automatically chosen in the different modes. No P (program) mode. This is actually the most useful shooting mode on many DSLRs, especially for novices. It lets you trade off aperture vs. shutter speed. __Advanced Nitpicking__ No auto ISO mode. (Great feature of Pentax cameras -- it's like M but the camera picks the ISO that will work.) No ISO-priority mode. It doesn't allow for things like camera shake and the child's motion (you might pick 1/60 of a second to capture the child sharply, while needing 1/250, say, for the pinwheel). It's not worth allowing ridiculously high (small) apertures (e.g. f29) -- if you're not going to do diffraction, so I'd stop at f22. It would be nice to have faster (bigger) apertures than f2.8 to really show the benefits. It shows autofocus points, but they don't do anything. It would be interesting to allow the user to pick a focus point and assume the metering is weighted on that position, but that's getting pretty advanced.

sukuriant 16y ago
Historically, it wasn't "S", it was "T".
zalew 16y ago
> No P (program) mode. This is actually the most useful shooting mode on many DSLRs, especially for novices. It lets you trade off aperture vs. shutter speed. oh boy. that's actually the mode that keep novices clueless about what's going on with the settings. > No auto ISO mode, No ISO-priority mode, etc. etc. well, ISO + TIME + APERTURE are ingredients of EXPOSURE, and that should be all you need to know to start shooting. you know this and you can grab the newest high-end dslr or your grandpa's 35mm oldie and know what you're doing. the rest is just geekery.
- mitjak 16y ago
  >well, ISO + TIME + APERTURE are ingredients of EXPOSURE, and that should be all you need to know to start shooting. you know this and you can grab the newest high-end dslr or your grandpa's 35mm oldie and know what you're doing. the rest is just geekery. Perhaps I misunderstood your point but that doesn't sound right. Iso does not control exposure: in case of film it is the sensitivity of a particular stock, and in case of sensors it's basically analog gain. Since to use a different ISO in a film camera you'd need to use a different roll or sheet of film, you can't vary ISO on a "grandpa's camera" very easily unlike with a digital camera.

sasha61 16y ago

If you have ipod/iphone/ipad, have a look at <http://www.islap101.com/&#62 http://www.islap101.com/> (and review of it at <http://lifehacker.com/5501364/photo-tutor-teaches-basic-camera-exposure-on-the-go-from-your-iphone> http://lifehacker.com/5501364/photo-tutor-teaches-basic-came.... There are actually two apps (one for shutter speed and one for aperture) - and they teach/display those concepts really well - even if I say so myself :-). There are also "recipes" for taking photos in various environments/situations - all prepared by professional photographers.

SonicSoul 16y ago

im a DSLR newb, but i think i just nailed it with: sunny, 55mm, ISO:100, f4, 1/2,000

mTh 16y ago
Kudos. But if you are a newbie, then perhaps it would be more useful for you, in order to learn how to use an actual DSLR in the field, to reduce the 'Lighting' to more difficult situations ('Overcast', 'Bright Indoors' etc.) and... 1.) set up the simulator to Tv mode and play with the 'Shutter Speed' and ISO primarily ...and after this: 2.) set up the simulator to Av mode and play with the 'Aperture' and ISO primarily. In this way you will learn how far you can go in real situations and what results you might expect. HTH (EDIT: Ok, you can play with the distance & focal length but I think that for the 1st step it is better to concentrate on the points above).
- SonicSoul 16y ago
  thanks, so why would Tv mode be more educational than M (which I am guessing stands for Manual) which also allows for playing with shutter speed and ISO ?
  - mTh 16y ago
    Indeed there are cases in which one can use the M (Manual) mode. But usually these cases are rather corner cases, especially for us, the beginners. Basically you ditch the DSLR's photometric engine which does most of the time a very good job, (except some rare situations in which the illumination is very tricky, you want to achieve very special effects etc.). Besides that, it is enough more difficult to play with four variables (Aperture, ISO, Speed AND the exposure indicator (usually a vertical beam in viewfinder)) compared with two variables (ISO & Aperture or ISO & Time respectively) or with just one (Aperture or Time - if you have the ISO set to Auto). The main difficulty here isn't that someone (you) can cope (or not) with four variables in a simulator but to adjust them quickly and exactly in the field given the very short amount of time which you (the photographer) have at your disposition to take "the shoot". That's why the most photojurnalists (from which, more or less, is your truly also) avoid the M mode. OTOH, I have very close "brothers" which are 'studio creatures' which prefer the M mode. And now to respond directly to your question, having the Tv (or Av mode) will give you a much 'closer to real' simulation (especially if you are on-field, on-street, on-sports etc. photographer) and will allow you to concentrate rather on the effect you want to achieve (for ex. how to simulate a good moving effect of the child's rotating toy) in the smallest amount of time (think that in the real world, the children aren't so frozen like the one in our simulator :-) ) and not to concentrate so much in obtaining a correct exposure. Usually the metering system does the job rather well. These systems have enough advanced features today to help you in avoiding the M mode with its quirks: exposure modes, over/underexposing by 1/2, 1/3 EV etc. HTH PS: Disclaimer: No, I'm not against the M mode. But I want to stress its limited usage today. Of course IMHO.

drblast 16y ago

Can anyone explain why the "ISO" setting exists on digital SLR cameras? It seems like this is an unnecessary holdover from film cameras. I ask this as an owner of a Canon Digital Rebel that knows very little about photography. What does changing the ISO setting get you that changing the exposure time or aperture wouldn't?

sbierwagen 16y ago
ISO is sensor sensitivity. Higher settings multiply the numbers that come from individual sensor elements by increasingly large amounts. Image sensors are not perfectly noiseless, of course, and the higher the ISO is, the noisier the image, which appears as random speckles of colored dots. You don't notice the difference, though, because you're probably shooting in JPEG mode, not in RAW. In JPEG, the Rebel tries very hard to cover up its sins, and will blur away sensor noise, which is hard to notice unless you grovel over areas of fine detail at 400% magnification. Second time I've linked this in this thread, but http://www.dpreview.com/reviews/nikond5100/page20.asp http://www.dpreview.com/reviews/nikond5100/page20.asp shows some great examples of what sensor noise looks like over a range of ISO values. Edit: Useless editorializing: A SLR isn't a great purchase for someone who knows very little about photography. A point-and-shoot is lighter, cheaper, more durable, easier to use, and in the vast majority of situations, will produce identical results to a SLR. You then graduate to a real camera when get fed up with the various fiddly technical limitations of a point-and-shoot; and bonus, you still have the small camera, which is the one you take with you when climbing mountains, or on vacation, rather than lugging around five kilograms of japanese glass. Tedious polemic: I dearly hope you have more than one lens. The enormous price premium of a SLR is mostly for the privilege of being able to change lenses. If you just stick with the kit lens, then you will have spent rather a lot of money to accomplish nothing a point-and-shoot couldn't do.
- bradleyland 16y ago
  Just as a counterpoint (not to pick a fight), I'd disagree with a lot of what you said in the latter portion of your post. Entry level SLRs are great, even for people who don't know anything more than point-and-shoot. The advantage of an SLR is that it will focus faster, meter faster, and ultimately take the photo faster. This is a huge advantage for parents, whose children are fast moving targets. What's not necessarily a good idea, is buying the biggest, most expensive SLR you can find. Canon and Nikon both make entry-level SLRs that have modes specifically targeted at novice photographers who will never leave full-auto mode. Buying a more expensive model primarily gets you features. Features that you won't use. The hardware is remarkably similar until you get up in to cameras that cost thousands of dollars. Many people believe that the huge lens is what makes SLR photos clearer in more conditions, but that's not the whole story. The lens is large because of an aspect of the SLR that you'll probably never see: the sensor. The single greatest reason for the increased image quality of an SLR is sensor size. When you shoot with a compact point-and-shoot, you're capturing light with a sensor the size of your pinky fingernail. You could shoehorn the fastest, largest, most expensive SLR lens on to a compact point-and-shoot, and the photos it takes wouldn't compare to an SLR with even a modest lens. The sensor in an SLR camera is closer to the size of a postage stamp, and this makes all the difference. Keep in mind that compacts these days shoot comparable resolution (megapixels) to SLRs. This means that each "pixel" in a compact is microscopically small when compared to the "pixels" in a SLR sensor. This means less area for light to fall, and less light collected. So, even with one lens, and in the hands of a novice, a reasonably priced SLR can result in sharper, more well timed photos in a more diverse range of conditions.

sbierwagen 16y ago

The noise at higher ISO levels isn't terribly realistic for modern SLRs, let alone full-frame pro SLRs. Here's a comparison of several modern entry-level SLRs: http://www.dpreview.com/reviews/nikond5100/page20.asp http://www.dpreview.com/reviews/nikond5100/page20.asp You can go up to ISO 1600 and get (more or less) unnoticeable noise. Note that you have to switch to RAW to show sensor noise-- JPEG mode will blur away noise, trading fine detail for smooth images. Also that lens is really amazingly sharp at both ends of its aperture range. In the real world you wouldn't get anywhere near that level of performance without spending tens on thousands of dollars on a prime (non-zoom) lens.

ashchristopher 16y ago
It's a learning tool. Cut them some slack =).
- sbierwagen 16y ago
  It's a learning tool, and so I would like it to teach that almost all lenses made of mortal glass are less sharp at either end of their aperture range; and that taking a picture of a landscape on a sunny day at f2.8 is a bad idea.
mortenjorck 16y ago
It's exaggerated, to be sure, but it's an instructive exaggeration. Showing the noise visible in a 4k still at 8% enlargement isn't going to help a novice understand ISO tradeoffs.

chrishaum 16y ago

This is an awesome tool. Thanks!

angusgr 16y ago

Given this is intended to teach exposure/DoF, it'd be nice to be able to bypass the "SLR" aspect of the camera, ie provide a "continuous snapping" mode where moving a slider instantly updates the "photo" instead of showing the fake autofocus sensor overlay. It's definitely a neat way to interact with it in a browser, though. If you're looking to learn these relationships in a less interactive way, I thoroughly recommend the book "Understanding Exposure" by Brian Peterson.

ujal 16y ago
That was also my first thought. The app would be much more informative by providing the results instant.

alok-g 16y ago

Nice idea. A difficult one from implementation standpoint: When I change the distance, it just scales the girl's face as a 2D image -- no perspective. :-) I'm not being picky, just that this is sometimes a consideration for me when clicking... Wish someone can point me to the mathematics behind this stuff. I figure ISO means gain of some amplifier inside so less photons would be needed to get to the same voltage at the expense of more noise. I can see how with the two auto modes, aperture size and shutter speeds relate to each other (basically you need to gather a similar number of photons, given the ISO setting). Yet do not know the mathematics behind why aperture size affects the depth of focus. Likewise, why focal length does the same. What's the mathematical definition of Fstop. And last but not the least, what role the sensor size play into all of this.

sbierwagen 16y ago
https://secure.wikimedia.org/wikipedia/en/w/index.php?title=F-number https://secure.wikimedia.org/wikipedia/en/w/index.php?title=... https://secure.wikimedia.org/wikipedia/en/wiki/Focal_length https://secure.wikimedia.org/wikipedia/en/wiki/Focal_length https://secure.wikimedia.org/wikipedia/en/wiki/Depth_of_field https://secure.wikimedia.org/wikipedia/en/wiki/Depth_of_fiel... https://secure.wikimedia.org/wikipedia/en/wiki/Film_speed#Digital_camera_ISO_speed_and_exposure_index https://secure.wikimedia.org/wikipedia/en/wiki/Film_speed#Di...
- alok-g 16y ago
  This helped: https://secure.wikimedia.org/wikipedia/en/wiki/Depth_of_field#Derivation_of_the_DOF_formulas https://secure.wikimedia.org/wikipedia/en/wiki/Depth_of_fiel... Still do not know how sensor size affects things. Will read more, and hopefully will be able to construct a single mathematical model that couples all of these together.

niels_olson 16y ago

Best review of the basic science I have seen online: http://johnlind.tripod.com/science/ http://johnlind.tripod.com/science/ The the lens calculations are a whole 'nother ball of wax, but here's the quick skinny on the exposure value system: Av + Tv = Ev = Sv + Bv Exposure value: Ev Aperture value: Av = log2 (f^2) Time value: Tv = log2 (1/t) Speed value: Sv = log2 (0.32 * ISO) Brightness value: Bv = subject luminance in foot-Lamberts

bcaulf 16y ago

The beauty of digital photography is that you can take pictures all day at no cost and see your results instantly. So instead of running this program, get your friend with an SLR to go on an outing with you and let you do most of the shooting. Go outside and fill up a memory card while you systematically work through the settings. After you get the hang of exposure you can start in on the different settings for metering, autofocus, manual focus, jpeg processing, black and white, motor drive, use of flash, different lenses, not to mention composition choices, interacting with the subject, use of filters, creative panning or rotating. Real photography is more fun than tweaking sliders on a flash app.