Bill Pierce
Well-known
Here is an interesting piece which, among other things, points out the advantage and necessity with wide angle lenses of the CCD sensor in digital M Leicas as compared to the CMOS sensor in many DSLR's.
http://www.luminous-landscape.com/essays/an_open_letter_to_the_major_camera_manufacturers.shtml
http://www.luminous-landscape.com/essays/an_open_letter_to_the_major_camera_manufacturers.shtml
johnnygulliver
Established
a very interesting and thought provoking article Bill, many thanks for posting the link.
antiquark
Derek Ross
I'm not quite sure what the writer is saying, but it sounds like he doesn't understand how ISO works. Is he saying that a D700 should produce brighter pictures than a D40 (at the same ISO) because the sensor is better?
semilog
curmudgeonly optimist
That is a fascinating and thoughtful article.
Moreover, it is extremely funny if you think about all the baying for "fast, wide primes" for various digital systems (especially micro 4/3). Apparently, super-fast lenses not only aren't that much brighter, but in some cases they won't even buy you shallower DOF!
Now, that said, the "CCD advantage" in the M8/9 has almost nothing to do with CCD structure (as implied but NOT demonstrated with data in the linked article). Rather, the advantage of the M8/9 comes from the use of an eccentric microlens array. In fact, the requirement for that specialized array is specifically because the CCD sensor prefers to see light entering normal (perpendicular) to the sensor plane.
Note that an eccentric microlens array is also being used by Fuji on the APS-C, CMOS sensor for the X-100 — which is fitted with a fast (f/2) wide angle lens.
Fuji knows what they're doing.
For BOTH CCD and CMOS sensors, the best approach will eventually be to use backside-illuminated sensors (back-illuminated CCDs have been common in scientific imaging for well over a decade, and back-illuminated CMOS sensors are increasingly prevalent in consumer devices with small sensors). A good article that shows how beneficial backside illumination can be is here (scroll down to Figure 3).
By putting the photosites closer to the sensor surface, the "tunnel effect" is minimised and quantum efficiency can be nearly perfect (approaching 100%).
Unfortunately, making large back-illuminated sensors is still very expensive. Too expensive, at present, for 4/3, APS-C, and larger sensors. And these sensors, because they are very very thin, are (mechanically) fragile — and the bigger they get, the more fragile they are. Not rugged enough to put in a Nikon D4, yet. But maybe by the time the D5 is out...
Moreover, it is extremely funny if you think about all the baying for "fast, wide primes" for various digital systems (especially micro 4/3). Apparently, super-fast lenses not only aren't that much brighter, but in some cases they won't even buy you shallower DOF!
Now, that said, the "CCD advantage" in the M8/9 has almost nothing to do with CCD structure (as implied but NOT demonstrated with data in the linked article). Rather, the advantage of the M8/9 comes from the use of an eccentric microlens array. In fact, the requirement for that specialized array is specifically because the CCD sensor prefers to see light entering normal (perpendicular) to the sensor plane.
Note that an eccentric microlens array is also being used by Fuji on the APS-C, CMOS sensor for the X-100 — which is fitted with a fast (f/2) wide angle lens.
Fuji knows what they're doing.
For BOTH CCD and CMOS sensors, the best approach will eventually be to use backside-illuminated sensors (back-illuminated CCDs have been common in scientific imaging for well over a decade, and back-illuminated CMOS sensors are increasingly prevalent in consumer devices with small sensors). A good article that shows how beneficial backside illumination can be is here (scroll down to Figure 3).
By putting the photosites closer to the sensor surface, the "tunnel effect" is minimised and quantum efficiency can be nearly perfect (approaching 100%).
Unfortunately, making large back-illuminated sensors is still very expensive. Too expensive, at present, for 4/3, APS-C, and larger sensors. And these sensors, because they are very very thin, are (mechanically) fragile — and the bigger they get, the more fragile they are. Not rugged enough to put in a Nikon D4, yet. But maybe by the time the D5 is out...
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semilog
curmudgeonly optimist
He clearly understands how ISO works, and that is not what he's saying.
antiquark
Derek Ross
I re-read it... he's saying that the ISO is cranked up for wider apertures. That means that the camera would have to query the lens about the aperture, then adjust the amplifier gain accordingly.
A simple test of this theory would be to use a lens that doesn't communicate its aperture to the camera, and check if wide aperture images are darker than expected.
However, it would be a huge flaw if camera makers didn't normalize the ISO for wide apertures. Basically, every wide aperture photo would be underexposed. I can't see how people would perceive this as a "feature."
A simple test of this theory would be to use a lens that doesn't communicate its aperture to the camera, and check if wide aperture images are darker than expected.
However, it would be a huge flaw if camera makers didn't normalize the ISO for wide apertures. Basically, every wide aperture photo would be underexposed. I can't see how people would perceive this as a "feature."
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semilog
curmudgeonly optimist
Of course that's right. People will complain, regardless. They want to have their f/1.2 cake and eat it, too.
But this also provides a rather vivid demonstration of the fact that RAW files and EXIF data don't always tell the "raw truth."
eddie1960
Established
On Pentax cameras there are some metering exposure issues with k and m series lenses ( i have 4 i frequently use) and typically they are out about a third to a half stop
Soothsayerman
Established
Here's an interesting article on CCD tech vs CMOS tech...
http://www.dalsa.com/corp/markets/ccd_vs_cmos.aspx
http://www.dalsa.com/corp/markets/ccd_vs_cmos.aspx
semilog
curmudgeonly optimist
^---- solid summary.
antiquark
Derek Ross
In the article he says: "One might be better off purchasing smaller aperture lenses and increasing the ISO."
However, if my calculations are correct (big if), you're still benefiting from fast lenses. The worst EV adjustment for f1.4 is 0.5, which means that the ISO will have to go from, say, 100 to 140. If you choose an f2.0 lens, you'll have to increase the ISO to 200, which will be noisier than ISO 140. Thus, the 1.4 lens isn't exactly a waste of money.
However, if my calculations are correct (big if), you're still benefiting from fast lenses. The worst EV adjustment for f1.4 is 0.5, which means that the ISO will have to go from, say, 100 to 140. If you choose an f2.0 lens, you'll have to increase the ISO to 200, which will be noisier than ISO 140. Thus, the 1.4 lens isn't exactly a waste of money.
semilog
curmudgeonly optimist
Assuming, of course, that the T stops of both lenses (lens T-stops, not sensor T stops) are actually proportional to their marked f/ numbers. That's not always a valid assumption, especially when you're comparing a 5 or 6 element f/2 lens to a 10 or 12 element f/1.2 lens.
Note that when people working in filmmaking buy a lens for $10, 20, 30k they expect that the aperture ring will show T-stops!
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semilog
curmudgeonly optimist
JPSuisse
Well-known
This is really a very technical issue here. Although I'm an engineer and can even follow part of these very interesting articles (luminous landscapes and dalsa.com), I'm disappointed that we are stooping so low here. Or, that we have to go to such lengths to understand what big corporations are doing to us....
"The morality of art consists of the perfect use of an imperfect medium." The problem with all these in camera modifications is that the character of your lenses is probably being hidden. In such a way, you'll never master your imperfect medium.
For me, it's another reason not to replace my failing D100 with a new DSLR. I hate deception.
Kind regards,
JP
"The morality of art consists of the perfect use of an imperfect medium." The problem with all these in camera modifications is that the character of your lenses is probably being hidden. In such a way, you'll never master your imperfect medium.
For me, it's another reason not to replace my failing D100 with a new DSLR. I hate deception.
Kind regards,
JP
In the end, you pick a digital camera that gives you the image that you want. With a film camera, you can just load it with the film that gives the look you want. Digital camera- stuck with the sensor. Comparing images from my M8 with the EP2, shooting both at Low ISO, 160 and 200 respectively, the biggest difference that I see is more noise in the shadow areas on the EP2 images. The M8 images are smoother, less noisy. CCD vs CMOS? Olympus boosting gain because of sensor vignetting? More signal processing on the M8- I know that is not true! They are fairly minimalist on the in-camera processing. I don't care- the M8 images look better.
The EP2 is fun, makes a good image, uses lots of different lenses, and I can use it for making movies. But the M8 images are "cleaner".
The EP2 is fun, makes a good image, uses lots of different lenses, and I can use it for making movies. But the M8 images are "cleaner".
JPSuisse
Well-known
PKR,
don't call me a hypocrite now...
Good thing I don't have to pay my bills with the equipment I've got. I can view it as pure art. The bills get paid by making semiconductor components for you guys buying this stuff!))
Now where's that NEOPAN 1600...
JP
don't call me a hypocrite now...
Good thing I don't have to pay my bills with the equipment I've got. I can view it as pure art. The bills get paid by making semiconductor components for you guys buying this stuff!
))Now where's that NEOPAN 1600...
JP
j j
Well-known
Can someone explain why any of this is a problem at all in any way? Even if true is it not just a camera correcting exposure?
semilog
curmudgeonly optimist
jrv
Member
If the author in the first article is upset to learn the camera applies a gain (ISO change) to normalize for different aperture settings, I wonder what they think of what the in-camera imagine processing is doing when a high-ISO setting is used? They might think "colorization" tame by comparison.
I would be very surprised if any camera CCD sensor has only a single readout channel. There are simply too many pixels, read too quickly, for ~ 14 bits of A/D. Uniformity is an issue for camera CCDs, but there are fewer places "drift" is introduced and calibration/correction should be easier than with CMOS.
I would be very surprised if any camera CCD sensor has only a single readout channel. There are simply too many pixels, read too quickly, for ~ 14 bits of A/D. Uniformity is an issue for camera CCDs, but there are fewer places "drift" is introduced and calibration/correction should be easier than with CMOS.