steve_dunn2

<p>It's been a few years since I traded in my 17-40 for Canon's 17-55/2.8, but my recollection is that at 24mm, the 17-40 had relatively little curvilinear distortion (barrel or pincushion). If you're finding this sort of distortion (and there's plenty of barrel distortion in this lens at shorter focal lengths), there are many software tools to fix it, including Canon's DPP, the lens aberration correction functions in many other RAW converters (including ACR in the full Photoshop product), and PTLens.</p>

 

<p>If it's that people's heads get stretched in weird ways if they're near the corners of the frame, well, as someone else said, that's par for the course with a wide-angle lens, and the cure is not to put people's heads near the corners of the frame when shooting with a wide-angle lens. Particularly if you're shooting at an angle, which adds perspective distortion as well (but that can also be corrected by a number of tools including some of the same ones mentioned above).</p>

<p>My guess, and it's entirely that, is that it may have something to do with the geometry of the light rays coming out of the back end of the lens, perhaps related to the size of the exit pupil and/or how far it is from the sensor plane. This is related to Philip Wilson's suggestion regarding microlenses. A few years ago, there was some press/hype about how DSLRs worked best with "digitally optimized" lenses because the microlenses on the image sensor needed the light rays to come in within a fairly narrow range of angles for optimal performance, whereas film cares little or not about the angle at which an incoming light ray strikes the film, and so not all of the light coming from some film-era lenses was usable by a digital sensor. Perhaps something similar affects this AF sensor; they've had to put a lot of wizardry into this highly advanced sensor, and maybe that means it's more sensitive to the characteristics of the lens than previous sensors were.</p>

 

<p>There have been issues like this in the past, if I recall correctly, in which <em>some</em> combinations of camera, lens, and teleconverter end up disabling some peripheral AF points even though the lens+TC combo meets the f/5.6 minimum (i.e. an f/5.6 lens will work with all the AF points, yet a lens+TC that's f/5.6 may not). But that affected only certain specific combinations, and I don't believe it happened with just a lens, only with a lens and a TC.</p>

 

<p>As for how it affects third-party lenses, that's a very interesting question, and one I don't expect Canon to answer (other than perhaps to suggest that Canon bodies are designed for optimal performance with Canon lenses and all bets are off if you use third-party lenses). I wonder if the AF system is programmed to react specifically to which lens is connected (the specific lens model appears in the metadata, so clearly the body knows which lens you're using, not just its focal length and aperture) or if it simply checks to see which AF points seem to be receiving adequate light and disables any which aren't.</p>

 

<p>Perhaps we'll be lucky and Bob Atkins will have a crack at this with his knowledge of optics.</p>

<p>I'd agree: if one of those lenses is currently limiting you in some way*, then it will continue to limit you on the 7D, and you should consider replacing it. If the lenses are not currently limiting you, then keep them the same and see how they work on the 7D. Its higher resolution may show you some flaws that you didn't see on the 450D, in which case you'll know which lens(es) you need to replace, but otherwise, if you're happy with the results, then you needn't spend money on new lenses. At least, not right now :-)</p>

 

<p>*: There are lots of ways a lens could limit you, including sharpness, contrast, susceptibility to flare, focusing speed, maximum aperture, and focal length coverage. Before choosing a replacement for an existing lens that's limiting you, it's important to understand how it's limiting you so that you can pick a replacement that fixes that problem. For instance, if you had the 18-200 but not the 10-20 and you found the 18-200 didn't go wide enough, adding the 10-20 would be a good solution, while replacing the 18-200 with a 17-55 would not; no matter how good the 17-55 may be, it really doesn't fix the problem with 18 not being wide enough.</p>

<cite>Has anyone seen whether STM supports full-time-manual focusing? That's one of my favorite features of ring USM.</cite>

 

<p>Somewhere (and I don't recall where, maybe one of Canon's sites, maybe another photography site) I saw mention that at least one of these two lenses uses electronic FT-M, like a few of Canon's other lenses have. This doesn't use a mechanical connection between the focus ring and the actual focusing hardware, but rather detects what you're doing to the focus ring and drives the focus motor accordingly.</p>

<p>I suspect the mirror, too, since that's a significant part of what's commonly thought of as "shutter noise." And Silent Mode is the first culprit that sprang to mind. Check and make sure you don't have that enabled.</p>

<p>Perhaps the most common cause for pop-up flashes not popping up on EOS bodies is that the microswitches under the hotshoe rails are falsely reporting that there's something mounted in the hotshoe (e.g. because they're damaged or because some sort of debris is stuck in them). When there's something already in the hotshoe, the camera will refuse to pop up the flash.</p>

<p>I'm not sure about the 60D so I'll leave that for someone else to comment on. Canon claims the 7D is as well sealed as the mid-1990s professional 1N body was. That's not up to the standards of current pro bodies, but apparently it was good enough for pros back in the day, so it must surely be able to handle more than just light drizzle.</p>

 

<p>I haven't used my 7D in anything more than very light precipitation (and with the sealed 24-105/4L on it, not the unsealed 17-55), so I can't help much from personal experience with this equipment other than to say it handled a little bit of wet snow without problems.</p>

 

<p>Back in the film days, I did use an Elan-family body (either an Elan II/50 or an Elan 7E/30) with an unsealed lens (either 28-105/3.5-4.5 or 28-135/3.5-5.6) in light spray from waterfalls a few times. No problems to report there, either. Unsealed equipment isn't necessarily particularly leaky and it won't stop working at the first sight of moisture, but obviously it's more susceptible than sealed equipment is, and personally, I lean towards not taking a lot of risks of damaging my camera gear.</p>

 

<p>There's always the option of finding a way of protecting unsealed gear, too. If nothing else, a sheet of plastic with a hole just the right size for the end of the lens could work, though one suspects onlookers would not be amused. If it's raining but not windy (i.e. the rain is coming pretty much straight down), a hat or raincoat hood could protect an unsealed body, and a sealed lens (like your 70-200 or my 24-105) could take some rain as long as you wipe off any that threatens to invade the lens mount. Something along those lines might be worth a shot.</p>

 

<p>Hope that helps a bit!</p>

<cite>I'm not sure where the 3 GB figure comes from, but perhaps it is because less than the full 4 GB is usable by apps. There are computer designs that allow a 32-bit processor to access more than 4 GB, but microsoft lists the limit of Windows 7 32-bit as 4 GB.</cite>

 

<p>The full story is quite complex, so here's a <em>very</em> simplified version. First, let's look at the software limits imposed by Windows.</p>

 

<p>By default, a 32-bit Windows app gets a maximum of 2 GB of memory for the app itself, on any version and edition of Windows from the very first version of NT in 1993 right up to the present. Some apps are "large address aware", and that changes things a bit: on 32-bit Windows versions in the last decade or so, if you specify the /3GB switch in your boot configuration (Google will find you the details, including warnings), such an app can see 3 GB. On a 64-bit version of Windows, such an app can see 4 GB with no OS configuration required. Meanwhile, a 64-bit app (running on 64-bit Windows, since 32-bit Windows can't run 64-bit apps) can see vastly in excess of this.</p>

 

<p>On the hardware side, most PC-compatible CPUs since the mid-to-late 1990s have had the ability to access more than 4 GB of RAM, but many motherboards (particularly workstation motherboards) limit this. For instance, the computer I'm using right now has a CPU that can handle more memory, but the chipset in the motherboard cannot, so it's limited to 4 GB. But some peripherals (most notably graphics cards) have to map some of their memory into that 4 GB address space, which leaves less than 4 GB for Windows and programs. This is the mostly commonly-cited "3 GB" limit, although that's not strictly true. Windows can access about 3¼ GB on my computer, which clearly is more than 3 (but less than the 4 I actually have installed). The actual limit will vary depending on your computer hardware, but typically it's in the 3-3.5 GB range.</p>

 

<p>Like I said, that's highly simplified, but hopefully it answers the "where does this 3 GB limit come from" question.</p>

<p>The first lens I had with my Elan II was the 28-105/3.5-4.5. It's a good lens (and while I've never used the 24-85, its reputation is comparable). I eventually upgraded to the 28-135, which I found to be better optically, and of course it adds a bit more reach and the magic of IS. Many years later, I replaced that with the 24-105/4L IS USM, which as the L implies is a pro-quality lens. Each of these replacements was an improvement, but as you'd expect, each one also cost more. Any of them would be a nice upgrade over your 35-80. But maybe an upgrade over the 35-80 isn't what you need. Let me explain.</p>

 

<p>You say you're just starting and you have a 35-80. My suggestion would be to get out there and shoot a whole bunch of stuff with this lens. Find out what you like to shoot, and find out how well this lens suits you. Then you'll have a better idea of what it lacks. Maybe you want to do macro, and the best lens for you to add would be a macro lens. Maybe you need something wider, or perhaps something longer. Maybe you want the shallow depth of field and better background blur that comes from a faster lens. Maybe the 35-80 is a good fit but you want something with higher optical quality. Once you have a feel for how, exactly, the 35-80 is limiting you, you'll be in a better position to decide what to look for.</p>

<p>It could be, but based on a vague recollection, I suspect it could be IS. I believe early production models of this lens (I'm assuming you mean the first generation since you didn't say II) had an IS unit that turned out to have a higher-than-expected incidence of failure. This, like an aperture problem, could conceivably cause a lockup. Mine has date code UT0912, with T being the year (2005) and 09 the month (September), and I recall they'd fixed it by then; if the date code on yours is earlier, perhaps it's one of the wonky ones.</p>

 

<p>So if you haven't already done so, try testing it with IS disabled and see if that makes a difference. And, of course, clean the contacts on the lens and the body, as always when troubleshooting something that could be a communication problem.</p>

 

<p>Not that this makes any difference to the solution (failed aperture, failed IS unit, damaged wiring within the lens, etc., all pretty much mean sending it in for repair), but I agree with previous responses that it's better to be able to provide the technician with more detailed info on what's wrong.</p>

<p>Disclaimer: I have never used a 15-85 or the EW-78E (its official hood) and make no guarantees about the following.</p>

 

<p><a href="http://photography-on-the.net/forum/showthread.php?t=771747" target="_blank">Apparently, it fits</a>. I have no idea if you'll have problems at the wide end of the 15-85, though; that effective 4mm is a pretty significant 4mm at the wide end. Sorry to be able to answer only part of your question; hopefully someone else will be able to answer the rest.</p>

<p>The basic shooting parameters (e.g. ISO, shutter speed, aperture) affect RAW and JPEGs equally, but any of the image settings (e.g. white balance, picture style) do not affect the RAW file. They're <em>noted</em> in the RAW file, and some RAW converters may present them to you as defaults or as a way of matching a JPEG of the same image, but they don't affect the actual image data.</p>

<cite>Why has the branding from the camera been removed?</cite>

 

<p>It's quite common to see brandless items in TV shows, or things such as patterns on T-shirts or commercial logos in the background blurred out. I'm guessing it's some combination of being unwilling to do what amounts to an unpaid product placement and concerns about rights to reproduce things like logos or other distinctive designs belonging to the product's manufacturer. Just a guess, though, from someone with no connection to the industry.</p>

<p>I've triggered both a 420EX and a 580EX II (both individually and both together) from my 7D's pop-up flash and have not had problems. I've never used a 550EX but I don't recall having read any comments suggesting that it is harder to trigger wirelessly than either of the above.</p>

 

<p>As others have pointed out, the remote triggering in this case is done via light, so the slave has to be able to see the light from the master's flash signals well enough to distinguish them from ambient light. Lots of ambient light will reduce range and/or reliability (particularly if there's no direct line of sight from the master to the slave's sensor and you're relying on the signal bouncing off things). If feasible, use the slave's tilt/swivel feature so that its body faces the master.</p>

<p>Even with the slowest card, the camera will shoot at full speed until its buffer fills up. As mentioned in the detailed response above, this is where a faster card helps: the buffer drains more quickly, so you have room for your next burst sooner (or you can keep shooting at a higher rate than you could with a slower card). A faster card also speeds up chimping, and (assuming your card reader is fast enough) makes it quicker to download the images to your computer, which are both nice, but usually if you <em>need</em> speed, it's for shooting, not chimping or downloading.</p>

 

<p>So the main question is how long can you wait for the camera to flush its buffer between bursts? If you need to be able to shoot a burst and then be ready for the next burst almost immediately, you probably need to spend the money to get one of the fastest cards you can find. If you have more time between bursts, on the other hand, you can step down to a card whose speed is decent but not blazing.</p>

 

<p>An example of the latter, from my own personal experience (since I have no dog or horse racing experience to share): shooting planes flying by at an air show. A plane flies by, you shoot a burst, and then it takes a while for the plane to turn around at the end of its run before it comes back for its next run.</p>

<p>And now I see why you have to download your lens profiles. I picked the four lenses I currently own (three zooms and a prime), and it's download <b>90 MB</b> of profiles just for those lenses!</p>

<p>Remember that that "300 dpi" figure assumes continuous tone: each individual dot can take on any shade of any colour. An inkjet printer can't do that; each of those thousand-plus droplets per inch is either a droplet of ink or not*, so you need a lot of those droplets to build up a dither pattern that (to the naked eye) resembles continuous tone. For those who aren't familiar with the concept of dither patterns, have a look at a photograph (a black-and-white one is the simplest example) in a newspaper; from a distance, it looks like it's in shades of grey, but up close you can see it's made of just black and white, with varying patterns being used to make what appears to be grey.</p>

 

<p>*: Many inkjet printers have just one droplet size, but some can vary the amount of ink in a droplet. But even those with variable droplets can only vary it over a limited range of droplet sizes, not enough to make for a true continuous-tone print, and so they also have to use dither patterns.</p>

<p>The 28-105/3.5-4.5 USM was the lens I got when I moved up from an old manual-everything SLR to an EOS 35mm SLR. It was a good lens. I subsequently upgraded it to the 28-135/3.5-5.6 IS USM, and found that in addition to the obvious utility of IS and a bit more reach, it was a better lens. And then, after going digital, I upgraded to the 24-105/4L IS USM, and found that it was a better lens again.</p>

 

<p>Just my personal experience, not backed up by any laboratory measurements.</p>

<p>I haven't used any non-Canon stabilized lenses, so I can't compare Canon's with others, and your model isn't one I've owned. But I've owned five Canon IS lenses over the years (28-135/3.5-5.6, 300/4L, the first generation 70-200/2.8L, 24-105/4L, 17-55/2.8; I still have the last three). What I see in the viewfinder when IS is engaged varies somewhat between lenses; the newer ones have more advanced IS versions, and of course a longer focal length provides more magnification of handheld shakiness. But for all of them, IS takes what would otherwise be somewhat jerky motion and turns it into a smooth "swimming" motion.</p>

<p>I can't directly answer your question, as I have not used the combinations you mention. But I can tell you something about the 17-55. It's been my most used lens for about three years. I've also owned a few L zooms (17-40/4L USM, 24-105/4L IS USM, and 70-200/2.8L IS USM), and the 17-55's optics are comparable to those of the L zooms. I hope that's at least a little bit helpful to you.</p>

<p>Oops - let me correct a mistake in what I wrote. The third paragraph should begin "The purpose of using <em>DNG</em>". Sorry about any confusion that brain fart may have caused!</p>

<p>I can't comment on what things, if any, specific converting or editing programs can do to a DNG file. But as for the purpose of the file? It's supposed to be a RAW file, as in the exact data straight out of the camera's sensor. It's not intended to be a general-purpose image file format like TIFF. Some programs may be able to write some changes directly to a RAW or DNG file, but that's really not the purpose (and a more typical approach is to write a "sidecar" instead: leave the RAW or DNG file as is, and write a small file alongside it that describes what adjustments you made).</p>

 

<p>To use an analogy from the old film days, it's your negative. When you're making prints, you can make them lighter or darker, adjust the colour balance, change the look by using a different paper, etc., but none of these adjustments are written back to the negative. Many minilabs write a series of letters and numbers onto the back of the print denoting what adjustments they made, so that if you like the print and want exactly the same thing done again, you have the information you need; that serves the same purpose as a sidecar.</p>

 

<p>The purpose of using RAW rather than a camera maker's proprietary format is that it's a single, well-document, vendor-neutral format. For instance, a couple of years ago, I upgraded from a Canon EOS 20D to an EOS 7D. The editor I was using didn't support the 7D's RAW files, and while there was a RAW converter update that did, it required a newer version of the editor than what I had, so I couldn't simply download the converter update: I had to buy an upgrade to the entire editor if I wanted to use Canon's RAW format. Alternatively, I could just download the latest free DNG converter and convert my 7D's RAW files to DNGs, and my older editor could then read those without problems. Or, on the other end of things, there's no guarantee that for the rest of time, every RAW converter will support every RAW format back to the very beginnings of RAW files, so at some time in the future, your latest and greatest editing program could leave you unable to open RAW files from whatever your first digital camera was. But if it supports DNG, then it will support any DNG file, whether that's from your first digital camera or your latest.</p>

<p>Not having any fisheye lenses, I've never used PTLens (cited above by another poster) to fix it, so I can't tell you how well it works or how easy it is to use in this regard. But I <em>have</em> been using it for years to fix curvilinear distortion from regular lenses, perspective distortion, lateral chromatic aberration, and even sometimes vignetting. It works (on 16-bit images, too), it's cheap to buy, and it's free to try.</p>

<p>I don't think you should be seeing different behaviours between these two lenses on these two bodies, but as the first response says, standard troubleshooting procedure is to swap then and see whether this is a lens thing or a body thing.</p>

 

<p>You should definitely not expect exactly the same reading on the distance scale every time, particularly at wide angles. Remember that AF is done with the lens wide open, and in most cases* (including this lens on either of these bodies, using any focus point) the specs say that it should get within "depth of focus" (i.e. depth of field with the lens wide open). On a full-frame body with a 24mm lens at f/4, a subject that's 3m away will be within DOF as long as the lens is focused anywhere between about 1.85m and 7.89m. You're seeing a somewhat wider range than this, which doesn't sound good, but you shouldn't expect it to lock on exactly 3m every time. Zoom out to 105 and things should be much better, with a range of approximately ±0.1m, which would hardly be noticeable on this lens' focus distance scale.</p>

 

<p>If you repeat the test and take pictures each time regardless of what distance the AF system found, is the subject adequately sharp in the pictures?</p>

 

<p>*: the central AF point on both of these bodies (along with a couple of the invisible assist points that are not user-selectable and only used when tracking a moving subject) goes into high-precision mode if your lens is f/2.8 or faster, and this mode is supposed to focus within 1/3 of DOF. But with an f/4 lens, this feature is not available.</p>

<p>AF microadjustment gets far more attention than it deserves. Yes, some users' equipment needs it, and if you need it, then you need it. But most users' equipment works just fine without it. People have been using fast lenses with AF bodies for a long time without it.</p>

 

<p>If it turns out you do have repeatable focus errors and your body doesn't have microadjustment, Canon can perform the calibration for you. I have no idea how much this costs, as I've never needed it. I'm just mentioning it so that you know that even if you are among those who run into this problem, you're not stuck without a possible solution.</p>

 

<p>So basically, my message would be: don't obsess over AF microadjustment; get the lens(es) you need and enjoy shooting with them, and worry about this only if it actually happens to you.</p>