Yes, the color rendition sucks. But I use Olympus Viewer (nee Studio), which gives the same color rendition that the camera's JPEG engine does. And I know the settings I want (noise filter off, contrast medium, etc.), and just use the raw images because of better demosaicing/sharpening and no luminance NR. (My camera's "NR = Off" setting is not really off.)
What is considered CPU-intensive? I'm sure people could say the same about netbooks, but I develop 10MP raw images on mine. Works just fine, but a little slow.
I should have added more qualifications to my statement. This whole "format equivalence" thing is only valid within certain parameters; in particular, I should have said that I'm assuming that you have the appropriate lenses available, that the lenses are diffraction-limited in the appropriate regime, and that you are also noise-limited at the sensor end. Film resolution is of course an issue; I was thinking in digital-land, where pixel count can (and often is) relatively independent of format size.
Your statements about the reality of lens design are good ones. Yes, a 25mm f/0.7 shot on Four Thirds can produce the same image as a 50mm f/1.4 shot on 35mm at four times the ISO, but the difference is that the former just plain doesn't exist, and would be quite soft if it did.
But, again, if you're talking about depth-of-field limited photography, you're going to be at higher f/numbers anyway. Many good Four Thirds lenses are essentially in the diffraction-limited regime as early as f/5.6 or even lower. (I'm not quite sure exactly where it is, since they outresolve the hell out of the sensor.)
And you're right about low ISO: if you want the absolute best signal-to-noise ratio (which is what I think in terms of, since I shoot digital), you need larger formats, simply because there is no ISO 25 on Four Thirds.
Ah, yes. I forgot that large-format lenses usually use leaf shutters anyway. From what I know about them, their maximum shutter speed is somewhat limited; as I recall the Leica S2 lenses have shutters limited to 1/500 or so.
The problem with large format -> smaller apertures -> greater DOF is that large formats inherently have smaller DOF. For instance, my camera has a sensor which is half as large (roughly) in each linear dimension as fullframe. So my f/4 gives the same depth of field as f/8 on fullframe. To maintain the same shutter speed, the fullframe camera has to use four times the ISO. But, in general, its larger sensor can give the same image quality at four times the ISO, so everything cancels out in the end.
When you're depth-of-field limited, it turns out any format size can produce about the same image. On this beastie you'll have to use f/100 to get the same depth of field that I get at f/8.
I know how a focal plane shutter works. You're still limited in how narrow you can make the slit and have its width well-controlled; my camera's frame is about 13mm tall, and at minimum shutter speed the slit is about 600 microns tall and travels across the frame at 6 meters/second. Not trivial engineering at all!
Also, I believe that the very long lenses used for this sort of thing are pretty much a wash. But I do know that a lot of bird photographers have been moving from Canon to Nikon for the Nikon superteles (500 f/4 and such), so they can't be that bad.
Things *have* changed in recent times. Nikon introduced a 35mm-frame DSLR about two years ago, the D3, and now has four fullframe models that are just astounding in low-light performance. The D3S is the best of them: see dpreview's review at http://www.dpreview.com/reviews/nikond3s/page33.asp .
Yes, but this is less important than the amount of time that each piece of the sensor is exposed for certain sorts of highspeed photography. I shoot hummingbirds, for instance, and what I care about is that each piece of the bird is exposed for a very short time -- I'm not terribly concerned about whether it's the *same* very short time. (The travel time on my sensor, which has 1/2 the linear size of fullframe, is about 1/180.)
Some sorts of high speed photography are very concerned about this, I imagine, and they're unlikely to be able to use a focal plane shutter at all.
You can shoot in light that's so low that you can barely see in it with a few thousand bucks of equipment now. (Thinking a Nikon D700 and 50/1.4 lens or something.)
At the moment highspeed photography is limited by how fast the shutters will go. The larger focal-plane shutters used for this larger format are likely to be even slower than the ones used on today's DSLR's.
My camera, a bog-standard Olympus DSLR, can do up to 1/4000. Nicer cameras can do 1/8000, but I don't know of any off-the-shelf DSLR that can do faster.
I can shoot 1/4000 at ISO 800 f/5.6 in sunlight. With a f/2.8 lens (you'd use at least f/2.8 for highspeed work, f/2 if you can get it) you can get up to 1/8000 in outdoor light at a reasonable ISO. (Four Thirds cameras can do ISO 800 with reasonable quality; the best APS-C, like the Nikon D300, can do ISO 1600; fullframe can do ISO 3200.)
This thing might be able to get up to 1/8000 in worse light, but only if you can find a f/2.8 or f/2 lens for it. Large-format lenses tend to be slow.
If an individual taxpayer's beliefs can decide what that tax money gets to be used for, then this should apply to any belief and any sort of expenditure.
That decision is a difficult one, and has lots of grey areas. But there are black and white on either side of the grey area.
A ten-year-old girl is quite clearly a person. A two-day-old embryo is quite clearly not. This debate is fundamentally different than the one over third-trimester abortion.
Religious people are just as entitled as anyone else to participate in ethical debate. But in any sane society they must do so via secular, valid arguments, starting with something other than their own particular supernatural beliefs as a postulate.
If a person wants to say "My religion tells me that it is not just for black people to live as second-class citizens, and here is a series of ethical, constitutional, and rational reasons why blacks deserve fundamental rights", as many of the civil rights leaders did, then that is perfectly acceptable.
But many people pushing for embryos to be protected have no argument other than "My religion tells me that flushing an embryo is murder, thus you shouldn't do it", and that sort of argument has no place in a rational society. If your religious beliefs serve as a personal guide for you to make ethical decisions, fine, but if your ethical conclusions rely on your religious dogma alone then you can't expect anyone else to share them.
The question of eugenics is completely unrelated. We are not comparing a "gay embryo" to a "straight embryo"; we are comparing an embryo, of whatever sexuality, to an adult of whatever sexuality.
It was far easier for me to learn to drive once I understood what the parts of the car do. Once I understood what a clutch is and why there is a gearbox, it was easier to learn how to use the stickshift.
He's already using center spot-focus. (That's what I leave my Olympus on too -- why should I let it pick what to focus on? I want to do that!)
Actually, most Canon lenses (and, for that matter, most Olympus ones too) have full-time manual autofocus -- you don't have to switch anything, just grab the ring and turn it. That's what he's resorted to doing, but it's harder without a split-prism. I dunno why they stopped putting those on viewfinders; you can get a third-party one for $100 for Olympus at least.
The funny thing is, we've called Canon, and they say nothing is wrong. The 100-400L, at least, was bought new from B the 500D was also bought from B&H. I've checked the AF calibration using one of those calibration charts and it seems fine.
I'm a little befuddled too, since my ancient E-510 with a cheap lens will lock right in on some subject that he can't focus on, with any amount of monkeying with the AF.
Thanks for the advice. I do have a nice telephoto for Olympus, but I bought it used, and can't afford a top-end body. My dad can however, and I'll advise him to check out the 7D. Good to know that its focus points are just plain smaller than the 500D's. Still, that's not the only issue with the 500D (and 350D) autofocus -- sometimes they will just plain refuse to lock/shoot when there's no reason for it (isolated bird on twig seems to prompt this behavior).
The E-510 I have (old consumer Olympus body) has a fairly large center point, BUT if there is sufficient contrast at the very center it will focus on whatever's right under the dot. It seems to be the best of both worlds; the single-shot AF seems absolutely rock-solid. The one time I had trouble with it it turns out a bit of grass had gotten stuck right over the AF sensor -- remove it and it's great again.
Random question: My father shoots Canon, and has gotten sort of frustrated with the ADHD problem of the autofocus. Using two different lenses (70-200/2.8, 100-400) and two different bodies (350D, 500D), he's noticed that the AF is easily distracted by foreground clutter, and will also inexplicably refuse to confirm an AF lock (and thus shoot) in some situations you'd think are easy, like a bird on the end of a twig with a background distant enough to be a blur. Have you experienced anything like this? (This is in single-shot center-point AF mode.)
I have an old Olympus SLR, and if you can see even a tiny piece of a bird visible through the foreground brush, it'll lock right in and shoot, perfectly in focus.
Olympus doesn't make the lens I want (a 300 f/4), so I've thought about switching to Canon. But the AF scares me a bit.
Slashdot Mirror
I already do this, you insensitive clod! //choral singer
Yes, the color rendition sucks. But I use Olympus Viewer (nee Studio), which gives the same color rendition that the camera's JPEG engine does. And I know the settings I want (noise filter off, contrast medium, etc.), and just use the raw images because of better demosaicing/sharpening and no luminance NR. (My camera's "NR = Off" setting is not really off.)
What is considered CPU-intensive? I'm sure people could say the same about netbooks, but I develop 10MP raw images on mine. Works just fine, but a little slow.
It already has in some fields. See arxiv.org.
I should have added more qualifications to my statement. This whole "format equivalence" thing is only valid within certain parameters; in particular, I should have said that I'm assuming that you have the appropriate lenses available, that the lenses are diffraction-limited in the appropriate regime, and that you are also noise-limited at the sensor end. Film resolution is of course an issue; I was thinking in digital-land, where pixel count can (and often is) relatively independent of format size.
Your statements about the reality of lens design are good ones. Yes, a 25mm f/0.7 shot on Four Thirds can produce the same image as a 50mm f/1.4 shot on 35mm at four times the ISO, but the difference is that the former just plain doesn't exist, and would be quite soft if it did.
But, again, if you're talking about depth-of-field limited photography, you're going to be at higher f/numbers anyway. Many good Four Thirds lenses are essentially in the diffraction-limited regime as early as f/5.6 or even lower. (I'm not quite sure exactly where it is, since they outresolve the hell out of the sensor.)
And you're right about low ISO: if you want the absolute best signal-to-noise ratio (which is what I think in terms of, since I shoot digital), you need larger formats, simply because there is no ISO 25 on Four Thirds.
Yes, in dim pre-dawn light the high sensitivity will be a huge, huge advantage. Of course, f/8 on this thing will have dof of a few millimeters.
Ah, yes. I forgot that large-format lenses usually use leaf shutters anyway. From what I know about them, their maximum shutter speed is somewhat limited; as I recall the Leica S2 lenses have shutters limited to 1/500 or so.
The problem with large format -> smaller apertures -> greater DOF is that large formats inherently have smaller DOF. For instance, my camera has a sensor which is half as large (roughly) in each linear dimension as fullframe. So my f/4 gives the same depth of field as f/8 on fullframe. To maintain the same shutter speed, the fullframe camera has to use four times the ISO. But, in general, its larger sensor can give the same image quality at four times the ISO, so everything cancels out in the end.
When you're depth-of-field limited, it turns out any format size can produce about the same image. On this beastie you'll have to use f/100 to get the same depth of field that I get at f/8.
I know how a focal plane shutter works. You're still limited in how narrow you can make the slit and have its width well-controlled; my camera's frame is about 13mm tall, and at minimum shutter speed the slit is about 600 microns tall and travels across the frame at 6 meters/second. Not trivial engineering at all!
Also, I believe that the very long lenses used for this sort of thing are pretty much a wash. But I do know that a lot of bird photographers have been moving from Canon to Nikon for the Nikon superteles (500 f/4 and such), so they can't be that bad.
Things *have* changed in recent times. Nikon introduced a 35mm-frame DSLR about two years ago, the D3, and now has four fullframe models that are just astounding in low-light performance. The D3S is the best of them: see dpreview's review at http://www.dpreview.com/reviews/nikond3s/page33.asp .
The D700 I mentioned above is their affordable fullframe model: http://www.dpreview.com/reviews/nikond700/page32.asp
Yes, but this is less important than the amount of time that each piece of the sensor is exposed for certain sorts of highspeed photography. I shoot hummingbirds, for instance, and what I care about is that each piece of the bird is exposed for a very short time -- I'm not terribly concerned about whether it's the *same* very short time. (The travel time on my sensor, which has 1/2 the linear size of fullframe, is about 1/180.)
Some sorts of high speed photography are very concerned about this, I imagine, and they're unlikely to be able to use a focal plane shutter at all.
You can shoot in light that's so low that you can barely see in it with a few thousand bucks of equipment now. (Thinking a Nikon D700 and 50/1.4 lens or something.)
At the moment highspeed photography is limited by how fast the shutters will go. The larger focal-plane shutters used for this larger format are likely to be even slower than the ones used on today's DSLR's.
My camera, a bog-standard Olympus DSLR, can do up to 1/4000. Nicer cameras can do 1/8000, but I don't know of any off-the-shelf DSLR that can do faster.
I can shoot 1/4000 at ISO 800 f/5.6 in sunlight. With a f/2.8 lens (you'd use at least f/2.8 for highspeed work, f/2 if you can get it) you can get up to 1/8000 in outdoor light at a reasonable ISO. (Four Thirds cameras can do ISO 800 with reasonable quality; the best APS-C, like the Nikon D300, can do ISO 1600; fullframe can do ISO 3200.)
This thing might be able to get up to 1/8000 in worse light, but only if you can find a f/2.8 or f/2 lens for it. Large-format lenses tend to be slow.
Can a pacifist say the same about arms research?
If an individual taxpayer's beliefs can decide what that tax money gets to be used for, then this should apply to any belief and any sort of expenditure.
That decision is a difficult one, and has lots of grey areas. But there are black and white on either side of the grey area.
A ten-year-old girl is quite clearly a person. A two-day-old embryo is quite clearly not. This debate is fundamentally different than the one over third-trimester abortion.
Religious people are just as entitled as anyone else to participate in ethical debate. But in any sane society they must do so via secular, valid arguments, starting with something other than their own particular supernatural beliefs as a postulate.
If a person wants to say "My religion tells me that it is not just for black people to live as second-class citizens, and here is a series of ethical, constitutional, and rational reasons why blacks deserve fundamental rights", as many of the civil rights leaders did, then that is perfectly acceptable.
But many people pushing for embryos to be protected have no argument other than "My religion tells me that flushing an embryo is murder, thus you shouldn't do it", and that sort of argument has no place in a rational society. If your religious beliefs serve as a personal guide for you to make ethical decisions, fine, but if your ethical conclusions rely on your religious dogma alone then you can't expect anyone else to share them.
The question of eugenics is completely unrelated. We are not comparing a "gay embryo" to a "straight embryo"; we are comparing an embryo, of whatever sexuality, to an adult of whatever sexuality.
The Democrats didn't filibuster all that much when Bush was in charge...
It was far easier for me to learn to drive once I understood what the parts of the car do. Once I understood what a clutch is and why there is a gearbox, it was easier to learn how to use the stickshift.
He's already using center spot-focus. (That's what I leave my Olympus on too -- why should I let it pick what to focus on? I want to do that!)
Actually, most Canon lenses (and, for that matter, most Olympus ones too) have full-time manual autofocus -- you don't have to switch anything, just grab the ring and turn it. That's what he's resorted to doing, but it's harder without a split-prism. I dunno why they stopped putting those on viewfinders; you can get a third-party one for $100 for Olympus at least.
The funny thing is, we've called Canon, and they say nothing is wrong. The 100-400L, at least, was bought new from B the 500D was also bought from B&H. I've checked the AF calibration using one of those calibration charts and it seems fine.
I'm a little befuddled too, since my ancient E-510 with a cheap lens will lock right in on some subject that he can't focus on, with any amount of monkeying with the AF.
Thanks for the advice. I do have a nice telephoto for Olympus, but I bought it used, and can't afford a top-end body. My dad can however, and I'll advise him to check out the 7D. Good to know that its focus points are just plain smaller than the 500D's. Still, that's not the only issue with the 500D (and 350D) autofocus -- sometimes they will just plain refuse to lock/shoot when there's no reason for it (isolated bird on twig seems to prompt this behavior).
The E-510 I have (old consumer Olympus body) has a fairly large center point, BUT if there is sufficient contrast at the very center it will focus on whatever's right under the dot. It seems to be the best of both worlds; the single-shot AF seems absolutely rock-solid. The one time I had trouble with it it turns out a bit of grass had gotten stuck right over the AF sensor -- remove it and it's great again.
It's actually something that came up in DPReview's tests: see http://www.dpreview.com/lensreviews/canon_70-200_2p8_is_usm_c16/page4.asp . (Note that this is the IS version of the lens; the non-IS version has a less-sophisticated optical formula, I believe).
The loss of detail in those photos is because of optical defects, camera shake, and focus errors, not a limitation of the recording medium.
Random question: My father shoots Canon, and has gotten sort of frustrated with the ADHD problem of the autofocus. Using two different lenses (70-200/2.8, 100-400) and two different bodies (350D, 500D), he's noticed that the AF is easily distracted by foreground clutter, and will also inexplicably refuse to confirm an AF lock (and thus shoot) in some situations you'd think are easy, like a bird on the end of a twig with a background distant enough to be a blur. Have you experienced anything like this? (This is in single-shot center-point AF mode.)
I have an old Olympus SLR, and if you can see even a tiny piece of a bird visible through the foreground brush, it'll lock right in and shoot, perfectly in focus.
Olympus doesn't make the lens I want (a 300 f/4), so I've thought about switching to Canon. But the AF scares me a bit.