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08-12-2008, 08:46 AM   #1
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CCD Vs CMOS

I have only shot with a K10D and some P&S cameras. However, my neighbor has a Canon Digital Rebel and shot some pictures of her daughters wedding ...and was disappointed with her shots. I offered to try and fix them up in PS if she wanted to select some of her favorites (I wasn't going to work on all 450 of them!).

Anyway, first time I have really pixel peeked at a CMOS image and noticed a lot of noise in the shadow area, surprising as it was and an out-of-doors wedding and she shot the whole show at ISO 200. Now I get far superior results from my K10D and was wondering if that noise in the shadows is an issue with the CMOS sensors in general and particularly in the K20D. I had alway thought CMOS did better in low light situations! ...Anyone like to comment?

Thanks, Mike.

08-12-2008, 08:49 AM   #2
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was she shooting jpeg

was she exposing properly

i can get lots of shadow noise on my K20D if i underexpose, or i can get almost none if expose correctly
08-12-2008, 09:21 AM   #3
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Mike,
All three of the cameras mention use CMOS(complementary metal oxcide technology) The future of sensors is CMOS, because the CCD( charged coupled device technology is over fifty years and can't meet the density requirements of newer DSLRS. It seems that the upper limit for CCD is six megapixels in our current APS_C sensors. We could go higher, but noise would be much higher. Camera such as the K100D and Nilon D40 have 6mp sensors along with earlier Pentax DSLR's. It is amazing how much the packing density increased since I retired from Sony Electronics just seven years ago. I think that her results may well be just a camera setup issue, as Gooshin stated already.

Dave


QuoteOriginally posted by MikePerham Quote
Now I get far superior results from my K10D and was wondering if that noise in the shadows is an issue with the CMOS sensors in general and particularly in the K20D. I had alway thought CMOS did better in low light situations! ...Anyone like to comment?

Thanks, Mike.
08-12-2008, 10:21 AM   #4
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QuoteOriginally posted by MikePerham Quote
I have only shot with a K10D and some P&S cameras. However, my neighbor has a Canon Digital Rebel and shot some pictures of her daughters wedding ...and was disappointed with her shots. I offered to try and fix them up in PS if she wanted to select some of her favorites (I wasn't going to work on all 450 of them!).

Anyway, first time I have really pixel peeked at a CMOS image and noticed a lot of noise in the shadow area, surprising as it was and an out-of-doors wedding and she shot the whole show at ISO 200. Now I get far superior results from my K10D and was wondering if that noise in the shadows is an issue with the CMOS sensors in general and particularly in the K20D. I had alway thought CMOS did better in low light situations! ...Anyone like to comment?

Thanks, Mike.
Low light and underexposure are not the same thing. I'm finding the K20 to be about equal to perhaps a little less noisy than the K10. I can't speak directly to the Canon, as I have very little hands on experience with their fles, but a friend of mine is churning out lovely work with his CMOS chipped Rebel. No noise, and very good colour.
The difference is the photographer, my friend has been shooting all his life, and knows photography, knows his equipment, and knows how to get good quality from it.

08-12-2008, 10:25 AM   #5
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QuoteOriginally posted by Big Dave Quote
All three of the cameras mention use CMOS(complementary metal oxcide technology)

Dave, I am under the impression the K10D is based on the CCD design... can someone confirm?


Later


BB
08-12-2008, 10:30 AM   #6
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the K10D is in fact CCD, as is the K200D

made by sony..

present in alot of sony's, and nikons...

Canons CMOS is made by their own little elves.

Our CMOS is made by Samsung (altho it would be interesting to know how much the pentax engineers had to do with its development and at what stages)
08-12-2008, 11:04 AM   #7
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There's a lot of falsehood going on in this thread. Sorry to use the word "false" which some people will find offensive, but there it is.

I believe, given my background, that I can shed some light here.

CCDs are an older technology than CMOS, true. But not outdated by far. The main differences are:

1-CCD : larger photosites (other things being equal), deeper energy wells to capture more light (larger dynamic range, in theory), more expensive to manufacture. All things being equal, the best CCD is a better imaging tool than the best CMOS.

2-CMOS : manufactured in the same plants that are used for semiconductors, thus cheaper to make (for a given price, a CMOs will probably be better than a CCD), smaller photosites meaning less light gathering power (somewhat mitigated by using microlenses, though that's not a magical solution), analog processing can be done on-chip before reading the data, more heat generation (not always), theoretical faster readout time.

Which is best? None. I'm using in my lab a CCD that can count single photons and read them out at 500 000 frames per second. At 1 MP. Some sensors are faster than that. But that does not make CCD better. Any imaging device is a SYSTEM, of which the sensor is just one part.

The choice of CCD v. CMOS is done at the design level, and often balanced between cost and performances. Processing has a lot of impact too.

End of class. For today
08-12-2008, 11:13 AM   #8
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When I was looking at web cams I found that to get low light you used CCD. CMOS was not as good but was cheaper.

Samsung appaently found a way to get decent results from the cheaper CMOS sensor.

08-12-2008, 02:01 PM   #9
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Nice tute bdery.
Is it known whether the K10D CCD sensor was more expensive/'as good' as the K20D CMOS sensor?
08-12-2008, 02:08 PM   #10
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QuoteOriginally posted by bdery Quote
None. I'm using in my lab a CCD that can count single photons and read them out at 500 000 frames per second.
500,000 FPS
08-12-2008, 05:35 PM   #11
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BB,
You are absolutely right on that one. I misspoke there, but I beleive that the basic idea is correct. So naybe 10mgp is the magic number instead of 6mgp. It looks like Nikon,Canon and Pentax have gone to CMOS with their more expensive models.

Dave

QuoteOriginally posted by BBear Quote
Dave, I am under the impression the K10D is based on the CCD design... can someone confirm?


Later


BB
08-12-2008, 05:37 PM   #12
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QuoteOriginally posted by BBear Quote
Dave, I am under the impression the K10D is based on the CCD design... can someone confirm?


Later


BB
K10D is CCD ...the K20D is Pentax's first CMOS sensor.

Mike.
08-12-2008, 05:44 PM   #13
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No, images were not underexposed, at least in terms of the overall image - obviously shadows received less exposure ...and yes she shot JPEG. Regardless, I thought the noise in the shadow area's was way beyond what I would have expected to see based on my own experiece. Even using P&S camera's with their small sensors I have obtained results as good as or better than what I found with the Rebel shots.

Anyway, I expect my next DSLR (whatever Pentax introduce above the K20D) will be CMOS.

...Thanks for the responses. Mike.
08-12-2008, 06:13 PM   #14
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QuoteOriginally posted by MikePerham Quote
No, images were not underexposed, at least in terms of the overall image - obviously shadows received less exposure ...and yes she shot JPEG. Regardless, I thought the noise in the shadow area's was way beyond what I would have expected to see based on my own experiece. Even using P&S camera's with their small sensors I have obtained results as good as or better than what I found with the Rebel shots.

Anyway, I expect my next DSLR (whatever Pentax introduce above the K20D) will be CMOS.

...Thanks for the responses. Mike.
i didn't catch which rebel she was using. i can add that the first thing i noticed on the K20D compared to the 30D i had before (shares the sensor with the rebel xt.) was that i had to deal with much less noise at the same ISO.
so there are differences within cmos cams. xt owners seem to have been disappointed when they got their XTi. astro shooters stuck to XT with 8MP over the 10MP of the XTi due to more noise than they bargained for. not every canon is as great as the next, even if all canon dslr from the 6MP rebel to today's flagship use cmos.
08-12-2008, 07:18 PM   #15
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QuoteOriginally posted by MikePerham Quote
No, images were not underexposed, at least in terms of the overall image - obviously shadows received less exposure ...and yes she shot JPEG. Regardless, I thought the noise in the shadow area's was way beyond what I would have expected to see based on my own experiece. Even using P&S camera's with their small sensors I have obtained results as good as or better than what I found with the Rebel shots.

Anyway, I expect my next DSLR (whatever Pentax introduce above the K20D) will be CMOS.

...Thanks for the responses. Mike.
Mike

If it was JPEG you need to be aware that canon has been reported to oversharpens their JPEGs vs Pentax. It may not be a fair comparison of CMOS vs CCD but more a comparison of Pentax Engineers vs Canon Engineers, in terms of their interpretation of what makes a good image. You should really compare RAW images.

Also you should look at the camera itself, and do a couple of tests to determine how much contrast each camera is using with the JPEG settings. With the K10D, at minimum contrast, there is a change in grey scale of 40 for each stop, starting from 25 and going to about 230. This leaves about 5 stops where grey scale value is roughly linear, With max contrast each stop in this range is a grey scale of 50, leaving only 4 stops. High contrast can make for noisy shadows at times.

You might suggest your friend look at the contrast settings. When I am out in bright light shoting JPEGs with harsh shadows, I put contrast to minimum. On cloudy dats where lighting is flat, I put it to maximum.
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