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Photo Forum / Digital Photography / DSLR Cameras / August 2005Canon 20D - ISO 100 performance?
Hey all, In RPD, I noticed the following comment (specific attribution not necessary): "...[Poster was] irritated with Canon for sacrificing ISO 100 performance in the 20D/350D..." Sorry to say that I've not been following 20D discussions closely enough to understand what was 'sacrificed'. Could someone please post a susinct summary of what the basis of this complaint is? Thanks, -hh || Hey all, || [quoted text clipped - 8 lines] || someone please post a susinct summary of what the basis of || this complaint is? Its not a Nikon?  Signature-- "Nobody can make you feel inferior without your permission." -- Eleanor Roosevelt > Hey all, > [quoted text clipped - 7 lines] > enough to understand what was 'sacrificed'. Could someone please post > a susinct summary of what the basis of this complaint is? Succinctness is not a characteristic of such "discussions". Try reloading your newsreader with more posts and read the existing threads. SignatureJohn McWilliams > Hey all, > [quoted text clipped - 11 lines] > > -hh Basically the ISO 100 noise is slightly higher than the ISO 100 noise of the 300D/10D. This is due to the smaller pixel pitch on the 20D and 350D. The difference in noise is smaller, and Canon users should be thankful for having a ISO 100 in the first place. Most of the cameras using Sony's 6 megapixel CCD start at ISO 200. Signaturehttp://www.pbase.com/bcbaird >> Hey all, >> [quoted text clipped - 19 lines] > for having a ISO 100 in the first place. Most of the cameras using > Sony's 6 megapixel CCD start at ISO 200. The noise is even higher between iso100 and 200 than on a D60. Indeed, shooting RAW, the D60 keeps up with the 20D in most respects image-wise up to iso800 and even surpasses it on colour (I like the D60 colours). Added to which the 20D jpeg images are softer (to reduce noise) than the D60 and less saturated. Exposure on the D60 is much more forgiving. For flowers etc I prefer the D60. Overall speed is another issue with the 20D streets ahead. I also find that the D60 is often more accurate in focus (albeit slower) for lenses greater than f2.8. Canon 3 years ago really did do rather well with the D60 - that it still stands up against today's offerings. > The noise is even higher between iso100 and 200 than on a D60. Indeed, > shooting RAW, the D60 keeps up with the 20D in most respects image-wise up [quoted text clipped - 6 lines] > rather well with the D60 - that it still stands up against today's > offerings. I agree that Canon did very well with the D60 several years ago, I still use mine quite regularly. Also, the saturation and general image impact of the D60 is often more pleasing to me. However, one or two other comments you made I do not agree with. The 20D is behind the D60 (in how clean the image is) at ISO 100, but by 200 they are essentially even, and at 400 the 20D has a slight lead. At 800 the 20D simply shines, often showing images that are very close to the D60 at 200. I use ISO 1600 on the 20D far more often than I dared use 400 on the D60. As far as exposure goes I have found the 20D to exceed the accuracy of the D60. Also, for focus accuracy, it is basically a tie for me, unless using an f2.8 or faster lens. And the 20D just blows the D60 away in focus speed and low light focus ability. C! >The 20D is behind the D60 (in how clean the image is) at ISO 100, but >by 200 they are essentially even, and at 400 the 20D has a slight lead. >At 800 the 20D simply shines, often showing images that are very close >to the D60 at 200. I use ISO 1600 on the 20D far more often than I >dared use 400 on the D60. If this is true, it might be because of the 20D's faster readout, and the root cause may be the same issue that causes banding; poor digitization to make faster burst speeds possible. This would affect the lowest ISO the most, as the limit for shadows tends to more related to digitization than noise. Of course, it is also possible that the shadow blackpoint is treated differently, and noise is clipped away, but also detail (blackened), in the D60 shadows. I know the 10D and 20D are totally different in the way the converters tend to treat the deepest shadows. Anyway, comments like yours and the person you responded to leave a lot of questions, as you don't specify whether you are talking about JPEGs, RAW renders in a specific program, or the RAW data itself. Signature<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS@no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>>< > Basically the ISO 100 noise is slightly higher than the ISO 100 noise of > the 300D/10D. This is due to the smaller pixel pitch on the 20D and [quoted text clipped - 3 lines] > for having a ISO 100 in the first place. Most of the cameras using > Sony's 6 megapixel CCD start at ISO 200. Thanks for the susinct respose, Brian. Now to verify that I understand this correctly from a "big picture" perspective, what this suggests is that the traditional paradigm of film that "lower ISO always results in finer grain" is functionally not equivalently true for digital...correct? If I've indeed gotten this correct, I have to admit to having missed this one until now. Thanks. -hh >Now to verify that I understand this correctly from a "big picture" >perspective, what this suggests is that the traditional paradigm of >film that "lower ISO always results in finer grain" is functionally not >equivalently true for digital...correct? The grain size is immutable in a digital sensor; all that can vary is its intensity, and characteristics. Signature<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS@no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>>< > Now to verify that I understand this correctly from a "big picture" > perspective, what this suggests is that the traditional paradigm of > film that "lower ISO always results in finer grain" is functionally not > equivalently true for digital...correct? One key advantage of digital is that the grain is constant size regardless of ISO. The dynamic is noisier with higher ISO, esp. above 800 or so. The "lowest" iso of a camera is slightly noisier in some cameras than at one stop faster ISO. In the end (make a print) it's hardly perceptible. Cheers, Alan Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. > The difference in noise is smaller, and Canon users should be thankful > for having a ISO 100 in the first place. Most of the cameras using > Sony's 6 megapixel CCD start at ISO 200. I wonder why the Sony-CCD cameras don't at least give you the option of going to 100 ISO if you really want to. Would the results be too horrible to bear, or are they worried about comparisons against other cameras that do provide this capability, or what? > > The difference in noise is smaller, and Canon users should be thankful > > for having a ISO 100 in the first place. Most of the cameras using [quoted text clipped - 4 lines] > horrible to bear, or are they worried about comparisons against other > cameras that do provide this capability, or what? Well, what I don't get is why Nikon will start at 200, yet the Minolta 7D (using the same Sony sensor, IIRC) can start at 100, with excellent noise characteristics. Signaturehttp://www.pbase.com/bcbaird >> The difference in noise is smaller, and Canon users should be thankful >> for having a ISO 100 in the first place. Most of the cameras using [quoted text clipped - 4 lines] > horrible to bear, or are they worried about comparisons against other > cameras that do provide this capability, or what? Maxxum 7D uses the same sensor line and goes 100 to 3200. 3200 is, not surprisingly, quite noisy. I'm not convinced that there is anything at all wrong with the sensor at 100 that Nikon and Pentax could not have included it. OTOH, many kit/consumer lenses go with the likes of D70's and *ist's, so that extra stop of speed at the slow end is a benefit of sorts. per http://www.dpreview.com/reviews/konicaminolta7d/Samples/ISO/lumi-graph.gif you can see that the 7D is slightly noisier at 100 than 200. For faster glass, it is germane to note, that having the ISO 100 does allow shallower depth of field for a brighly lit situation. Cheers, Alan. Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. >Maxxum 7D uses the same sensor line and goes 100 to 3200. These numbers are fairly arbitrary. I would not be concerned about a camera only going down to "ISO 200", if you can set the camera to "ISO 200" and shoot just like it was ISO 100, without blowing reasonable highlights, or if you could do it at ISO 125. Different camera metering system have different ways of utilizing the 12 bits of RAW data. I have 2 DSLRs, the Canon 10D and 20D, and they are from the same series, and do things quite differently. If I use the same f-stop and shutter speed, on a tripod-mounted lens, and switch cameras set to the same ISO, the 10D registers darker in the RAW data. If I let each camera meter on its own, the 10D gives a higher absolute exposure by 2/3 stop, nearly closing the gap in the RAW data, but the default JPEG render of the in-camera converter, combined with the metering, will blow out highlights much quicker on the 10D. The native ISO of the sensor (as windowed by the digitizer) is clearly lower for the 10D; the 10D, however, meters so as to push it about 2/3 stop. IOW, if we can say that native ISO of the 20D is 100, then the native ISO of the 10D is 64, relatively speaking; if we consider the native ISO of the 10D to be 100, then the native ISo of the 20D is 160. IOW, the 20D has moved to a higher native ISO than the 10D. >3200 is, not >surprisingly, quite noisy. Of course, this could be due to the defaults leaving a lot of RAW headroom. Unless you take a shot with manual exposure with a known light intensity, you don't know what is really going on. >I'm not convinced that there is anything at all wrong with the sensor at >100 that Nikon and Pentax could not have included it. Maybe not, but you could lose up to a stop of the highlight headroom present at ISO 200. Signature<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS@no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>>< >>Maxxum 7D uses the same sensor line and goes 100 to 3200. > [quoted text clipped - 3 lines] > highlights, or if you could do it at ISO 125. Different camera metering > system have different ways of utilizing the 12 bits of RAW data. In D/SLR's the metering system does not use the sensor data. > I have 2 DSLRs, the Canon 10D and 20D, and they are from the same > series, and do things quite differently. If I use the same f-stop and [quoted text clipped - 23 lines] > Maybe not, but you could lose up to a stop of the highlight headroom > present at ISO 200. Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. >>>Maxxum 7D uses the same sensor line and goes 100 to 3200. >> These numbers are fairly arbitrary. I would not be concerned about a >> camera only going down to "ISO 200", if you can set the camera to "ISO >> 200" and shoot just like it was ISO 100, without blowing reasonable >> highlights, or if you could do it at ISO 125. Different camera metering >> system have different ways of utilizing the 12 bits of RAW data. >In D/SLR's the metering system does not use the sensor data. Your definition of "utilizing" is a bit narrow, don't you think? "Utilizing" does not mean "deriving directly from". The design of the camera acknowledges the absolute sensitivity of the camera, and how sensor exposure maps to the RAW data at a given ISO. Signature<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS@no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>>< >>>>Maxxum 7D uses the same sensor line and goes 100 to 3200. > [quoted text clipped - 9 lines] > > Your definition of "utilizing" is a bit narrow, don't you think? No. > "Utilizing" does not mean "deriving directly from". Your phrasing, not mine. The meter just measures the light presented to it to set exposure for a given (notional/nominal) sensitivity. From your own experience with various Canon's it is hardly consistent. > The design of the camera acknowledges the absolute sensitivity of the > camera, and how sensor exposure maps to the RAW data at a given ISO. From your own explanations it would appear that Canon have not settled on a common mapping of what that should be... Cheers, Alan Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. >>Maxxum 7D uses the same sensor line and goes 100 to 3200. > [quoted text clipped - 3 lines] > highlights, or if you could do it at ISO 125. Different camera metering > system have different ways of utilizing the 12 bits of RAW data. What do you mean? The metering systems in D/SLR's is not based on the imaging sensor ... it's based on the sensor in the optical/prism path before exposure. > I have 2 DSLRs, the Canon 10D and 20D, and they are from the same > series, and do things quite differently. If I use the same f-stop and [quoted text clipped - 10 lines] > then the native ISo of the 20D is 160. IOW, the 20D has moved to a > higher native ISO than the 10D. No standard? I think what really hurts 10D/20D shooters is the lack of a spot meter in the camera. That would allow critical setting for highlight exposure. >>3200 is, not >>surprisingly, quite noisy. > > Of course, this could be due to the defaults leaving a lot of RAW > headroom. Unless you take a shot with manual exposure with a known > light intensity, you don't know what is really going on. Even when I do, there is so much pre and post A/D amplification going on that the image can't help but be noisy. >>I'm not convinced that there is anything at all wrong with the sensor at >>100 that Nikon and Pentax could not have included it. > > Maybe not, but you could lose up to a stop of the highlight headroom > present at ISO 200. Not if I meter to place the highlight at the top for that sensitivity. And if I need a faster speed or smaller aperture, then it's no big deal to go to 200. On the other hand, if I need less speed or larger aperture I at least have the 100. Slower than 100 would be a benefit in some instances as well. Cheers, Alan Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. >>>Maxxum 7D uses the same sensor line and goes 100 to 3200. >> [quoted text clipped - 7 lines] >imaging sensor ... it's based on the sensor in the optical/prism path >before exposure. Is the response of the sensor and the digitization of the voltages unknown, and not utilized? >> I have 2 DSLRs, the Canon 10D and 20D, and they are from the same >> series, and do things quite differently. If I use the same f-stop and [quoted text clipped - 10 lines] >> then the native ISo of the 20D is 160. IOW, the 20D has moved to a >> higher native ISO than the 10D. >No standard? I think what really hurts 10D/20D shooters is the lack of >a spot meter in the camera. That would allow critical setting for >highlight exposure. I wouldn't mind having one, but I'd probably use it very rarely. I don't really have a lot of experiences where I wish I had a spotmeter, and unless the camera had a +3 EC setting, it is pretty useless for automation. Point the spotmeter at the brightest highlight and +2 EC, and you've wasted about half of the RAW values in the green channel; more in the others. +3 EC on the dial is essential for maximal use of a spotmeter. Spot for the subject, and you may blow out the background, so what good is it? Film paradigms do not work optimally with digital. >>>3200 is, not >>>surprisingly, quite noisy. >> Of course, this could be due to the defaults leaving a lot of RAW >> headroom. Unless you take a shot with manual exposure with a known >> light intensity, you don't know what is really going on. >Even when I do, there is so much pre and post A/D amplification going on >that the image can't help but be noisy. What about the other end; ISO 200. If you expose a grey-card based on an external meter, where do the RAW values fall? >>>I'm not convinced that there is anything at all wrong with the sensor at >>>100 that Nikon and Pentax could not have included it. >> Maybe not, but you could lose up to a stop of the highlight headroom >> present at ISO 200. >Not if I meter to place the highlight at the top for that sensitivity. I really have a hard time understanding you. Which sensitivity? If you expose so that the highlights are just short of clipping the RAW data when the camera is set to ISO 200, you may actually have an exposure index of ISO 100, or even less, of the subject is low-contrast. The limit of pull-ability is the contrast of the scene. If you can't pull a typical-contrast scene one stop with the camera set to ISO 200, then you can't use an exposure index of ISO 100 without clipping. I would say that you need about 2.5 stops of headroom above middle grey before you can adequately claim an exposure index. >And if I need a faster speed or smaller aperture, then it's no big deal >to go to 200. On the other hand, if I need less speed or larger >aperture I at least have the 100. Slower than 100 would be a benefit in >some instances as well. If the sensor doesn't collect enough measurable photons, though, you can only achieve the lower exposure index through neutral density filters (actually, a magenta filter would be better on many DSLRs; I do most of my strong-light, low-ISO shooting with a magenta filter over the lens, for better blue and red shadows). Signature<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS@no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>>< > No standard? I think what really hurts 10D/20D shooters is the lack of > a spot meter in the camera. That would allow critical setting for > highlight exposure. I don't need/want a spot meter in my camera. It's probably the primary reason I never bought Canon stuff way back when. An averaging meter combined with many years of experience works just fine. > Hey all, > [quoted text clipped - 3 lines] > "...[Poster was] irritated with Canon for sacrificing ISO 100 > performance in the 20D/350D..." Whatever the right answer, it would appear that the "natural" neutral gain ISO of various sensors is not at ISO 100, and for most "consumer" sensors it would appear to be somewhere between 100 and 400. So it's not surprising at all if some cameras are noisier at 100 than at 200. And frankly it is totally meaningless in most (a very heavy most) cases. Just make a large print (8x12) of a well exposed image and this will bear out from ISO 100 to 400 (even 800) for most DSLR's. Cheers, Alan. Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. |
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