Zoom Nonsense

<p>Seems to me that the only thing sillier than the megapixel race is the practice of manufacturers to report focal lengths in 35mm equivalents then shrink the sensor size and brag about the increased telephoto reach of a camera. By the this logic every lens on every camera has, literally, an infinite telephoto reach, so long as you're willing to crop down close enough to the central point of the sensor (or film). In fact, in theory, every camera can have the magnification of an electron microscope. Nonsense on stilts. We consumers have been trained to ignore digital zoom for just this reason, but shrinking the sensor is no different (or worse if manufacturers are shrinking the sensor <em>because</em> they want to advertise the higher telephoto reach).</p>

<p>Anyone have any suggestion about how to educate the public on this misleading practice? Maybe request a standard form that lists not only focal length in 35mm equivalents but always, right next to it, a "crop factor" indicating the sensor size as a ratio of 35mm full-frame. When people got used to this number, comparisons would become more informative, as in: "Well this camera has maximum telephoto of only 140mm in 35mm equivalents, but it's crop factor is only .2, which makes it better than the other one with a maximum telephoto of 150mm but a crop factor of .1." </p>

<p>Yes, I know megapixels matter here too, becasue a smaller sensor can achieve higher resolution by increasing megapixels, but this comes at a price in image quality, so it makes sense, at least to me, to report crop factor separately. After all crop factor matters to lens purchasers; should matter, though for a different reason, to digicam buyers as well. What does anyone think?</p>

<p>dpreview always has a table for every new camera that includes sensor size. They also list the min/max aperture range. A 300mm f7 lens isn't that useful to me.</p>

<p>Many photographers are familiar with 35mm film and particularly what focal length to use for a particular situation. If I tell you the focal length on my video camera is 5.4 - 108 mm, what do you know? Would it help to know it has a 1/3 sensor (three, actually)?</p>

<p>Propose an alternative. I could get used to angle-of-view comparisons. I already consider sensor size, and dpreview.com publishes sensor pixels per square millimeter.</p>

<p>actually, I wish they would adopt an angle of view listing. With all the different crop factors it would be much more meaningful than focal lengths these days.</p>

<p>Caveat emptor. (It's your responsibiity to understand what you're buying.)</p>

<p>What Brian said. </p>

<p>What happened to the buyer's responsibility for doing the research to find out how something works before he hands over his money? Why is it necessary to dumb down the universe to the lowest common denominator? Why do we have to "educate the public" about how to spend money on non-essentials? When will the "public" be made to accept the consequences of its own ignorance?</p>

<p>um...shouldn't this thread be in 'Casual Photo Conversations'?</p>

<p>I learnt long ago that when working in sub-standard media, ie not 35mm motion picture but 8mm and 16mm, that your choice of framing can make up for the lack of resolution. So shoot tight.<br>

If you agree that you do not really need the number of pixels that most modern cameras come with, depending on the display medium, then it is quite acceptable to 'crop' the sensor to get a narrower angle of view. This way I get a 2300mm AoV with a x12 zoom and x2,2 adaptor in a 10Mp camera. Normally I qualify my remarks by saying '430mm angle of view' rather than simply say 'a 430mm lens'. When I 'stepped up' from 3Mp to 5Mp I realised that I could be a little looser in my framing to achieve an A3 print, though of course better to use the whole frame. Using 35mm terms is not nonsense but cropping the sensor could be nonsensical.<br>

But for all that I think I agree with some of what you are saying Lolalobo. </p>

<p>Thanks to all for the responses, though I don't get the bit about "buyer beware" as I can't see how that's relevant. The point I'm making is that it might be helpful to the consumer who is trying to understand a product to have information in a standard form that addresses the issue I raise. And although I don't recommend doing away with 35mm equiv. listing, I think it would be better to include an additional bit of information. I suggested sensor-area ratio (sensor area divided by area of a 35mm frame); I like angle of view suggested here too.</p>

<p>I'm really curious, how much time have you spent with the average consumer in shopping for a digital camera? I mean, in a store, at a counter, talking to them.</p>

<p>I ask this in all seriousness, because in my experience, "sensor-area ratio" would go over about as well as a discussion on dark-current noise in sensor design. </p>

 

<p>And Rob's point is the reason for the buyer beware idea. Most consumers are not capable of understanding much more about cameras than megapixels, and they obviously don't really understand that, or it wouldn't be so important to them, and wouldn't be used so heavily as a selling pitch.</p>

<p>Consumers are, on the whole, pretty ignorant about what they buy. Just take a look at the DSLR type forums and the questions being asked by people who bought a DSLR and have no idea what the manual is telling them, or actually haven't even read it. That ignorance needs to be fixed, not by making the information more complex and esoteric, but simply by having people learn more about what they are buying before they purchase. Caveat emptor.</p>

<p>The only reasonably common point of reference in discussing lens "angle of view" is still the 35mm film (full frame) lens focal lengths. More advanced users are familar with the way the focal lengths work in their sensor/film sizes, the casual users who have no film reference still may have some idea what's being discussed. They can certainly compare different cameras with that common reference.</p>

<p>Place an "angle" and most won't really be able to address it meaningfully quickly and I'd expect that manyof the folks who "know" 35mm references won't understand or be able to tell you what the angle is on their favorite lenses of the top of their heads. Go to actual focal lengths and sensor sizes (whether in real measurements or the various , uh, descriptive terms used) and most users let alone non-fanatic consumers will be stymied without looking it up.</p>

<p>All of these points are well taken, and I agree that anyone fooled into thinking that megapixels are by themselves a measure of quality, but I think there is room for someone of medium sophistication ot benefit by an additional bit of data. For example, I was pleased when DPReview started listing pixel density because, to my eye, and from my experience, that's the single factor that most determines whether I will like the images created--it doesn't tell you everything, of course, but it's a good initial guide, at least for me. So I wish pixel density were a standard bit of reported info, not just on DPReview. It is in this light that I think a crop-factor ratio would be valuable. If I were browsing super zooms, e.g., and I saw that two cameras had roughly equal telephoto reaches, it would be convenient to see if this might just be the result of a small sensor. To be fair, DP Review does give sensor size also, but not as a ratio (which is more convenient for those of us who don't keep in mind the area of a 35mm sensor) and not everyone uses DPReview.</p>

<p>It's nonsensical to get worked up over this. The equivalent focal lengths offers a useful comparison tool for one feature - "view." </p>

<p>Parsing pixel geometry isn't particularly useful in isolation. Generational changes over time have overcome prior state of the art and will likely continue to do so. Plenty of other factors come into the choices, especially but not only with digicams. One can't say that all cameras with the same sensor or pixel density perform the same. The Nikon D3 and D700 use the same sensor, the Sony A900 and D3x are probably the same pixel density.</p>

<p> </p>

<p>Angle of view would cover it all in the simplest possible way.<br>

But I'm grateful for the so called 'ignorance' of consumers mentioned here. If DSLRs were bought only by us 'not ignorant' folk think how much they'd cost.</p>

 

<p>I remember when the Nikon 5000 cameras came out that a good many were returned to the shop as non-functioning becuase people couldn't work the on-off switch. :-)</p>