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Author Topic: Phase One IQ250  (Read 5757 times)
jerome_m
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« on: January 24, 2014, 12:39:55 PM »
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The article about the new IQ250 says that the back is very good at ISO6400. That may be the case, but it also says " In the past, with CCD digital backs it was just about impossible to use any ISO over 400 and expect decent image quality." Well, "decent image quality" is open to interpretation, but my old H3D-31 gives these results at ISO1600 when open in Phocus with default noise reduction:




Below a crop and comparison with the D800 (on top):




The complaint about poor iso performance comes from backs without micro-lenses (which can be used on technical cameras but have lower base sensitivity), but manufacturers have been selling backs with micro-lenses and a smaller sensor (the same size as the IQ250's sensor) for some time.

The phase IQ250 should improve noise level about one stop over CCD backs with micro-lenses, not much more.
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NancyP
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« Reply #1 on: January 24, 2014, 04:29:09 PM »
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I really shouldn't look at posts about MF. The drool is not good for the keyboard.
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michael
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« Reply #2 on: January 24, 2014, 06:01:11 PM »
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Only one stop. Likely wishful thinking.

But, let's wait for some real-world comparisons. There will be several people with Hasselblad, Phase and Leica S systems on our Antarctic expedition this week, so we'll know soon enough.

M
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Nemo
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« Reply #3 on: January 25, 2014, 05:02:14 AM »
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An obvious practical difference between CMOS and CCD sensors is high ISO image quality. This is due to the way these sensors handle different sources of noise.

But there is another practical difference: image quality at base ISO.

Full frame transfer CCD cells and much wider, and the base ISO is lower, so the gain applied to the high quality signal also is lower. Then, you have 16 bit AD converters (not 16 "output", but 16 bits converters). This allows for wider tonal range in the shadows. And this richer tonality gamut in the shadows at base ISO is the key of the higher perceived image quality in medium format backs.

The base ISO from CMOS sensors is higher, applied to a weaker signal (smaller cells) and due to this reason usually 14 bits converters are used. The tonal gamut in the shadows is not as rich as that of CCD/16 bit systems.

If all this is correct, the high ISO comparative should be complemented with low ISO comparative (looking at tonal gamut in the shadows). This does not mean comparing at the same ISO value, but comparing at the different base ISO values (for instance, ISO 50 for the CCD and ISO 100 for the CMOS), because those systems' base ISOs are adapted to the different conditions and characteristics of each system.

So, "CMOS versus CCD" is not all the story. The idea should be "CCD/16bits/50ISO versus CMOS/14bits/100ISO" systems.

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ErikKaffehr
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« Reply #4 on: January 25, 2014, 05:24:11 AM »
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Hi,

I don't think you analysis is correct. Dark areas are actually a weakness of CCDs.

Best regards
Erik


An obvious practical difference between CMOS and CCD sensors is high ISO image quality. This is due to the way these sensors handle different sources of noise.

But there is another practical difference: image quality at base ISO.

Full frame transfer CCD cells and much wider, and the base ISO is lower, so the gain applied to the high quality signal also is lower. Then, you have 16 bit AD converters (not 16 "output", but 16 bits converters). This allows for wider tonal range in the shadows. And this richer tonality gamut in the shadows at base ISO is the key of the higher perceived image quality in medium format backs.

The base ISO from CMOS sensors is higher, applied to a weaker signal (smaller cells) and due to this reason usually 14 bits converters are used. The tonal gamut in the shadows is not as rich as that of CCD/16 bit systems.

If all this is correct, the high ISO comparative should be complemented with low ISO comparative (looking at tonal gamut in the shadows). This does not mean comparing at the same ISO value, but comparing at the different base ISO values (for instance, ISO 50 for the CCD and ISO 100 for the CMOS), because those systems' base ISOs are adapted to the different conditions and characteristics of each system.

So, "CMOS versus CCD" is not all the story. The idea should be "CCD/16bits/50ISO versus CMOS/14bits/100ISO" systems.


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Christoph C. Feldhaim
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« Reply #5 on: January 25, 2014, 05:38:20 AM »
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You got it all wrong !

In the end it will all come down to the weight of the system including the sensor.

The heavier the better.

  • If the system is heavy enough to keep the photographer at home,
    if he/she is not really in the mood to take images that's good.
    Great system!
  • If the system is heavy enough to force the photographer to really look at the scene,
    feel and explore it and deeply think about composition, viewpoint, depth of field, color and light  and
    not to forget the message and care about each single image as much as possible that's good.
    Great system!
  • If the system is heavy enough to keep the photographer from taking a crappy scene because its not worth the hassle that's good.
    Great system!

In the end the advantage of one system above another should not be measured in f-stops but pounds and inches.
Maybe some gifted specialist could calculate a "bulkiness factor" for each system to get a real comparison.

So what is bulkier?
CCD or CMOS?

Have a nice weekend
Cheers
~Chris

P.S. Going out now and pointing my photocopier along with a diesel aggregate at some random crap for sheer fun.
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OldRoy
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« Reply #6 on: January 25, 2014, 06:51:22 AM »
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There will be several people with Hasselblad, Phase and Leica S systems on our Antarctic expedition this week....
M
Why does this fail to surprise me?
 Cheesy
Roy
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ErikKaffehr
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« Reply #7 on: January 25, 2014, 06:59:26 AM »
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Hi,

On the other hand, carrying is a Hasselblad 555 with a P45+ back with five lenses and a Sony Alpha 99 plus two "professional" zoom lenses, an Arca D4 and an RRS TVC 33S makes for some good exercise needed by elderly overweight gentlemen like me.

Best regards
Erik


You got it all wrong !

In the end it will all come down to the weight of the system including the sensor.

The heavier the better.

  • If the system is heavy enough to keep the photographer at home,
    if he/she is not really in the mood to take images that's good.
    Great system!
  • If the system is heavy enough to force the photographer to really look at the scene,
    feel and explore it and deeply think about composition, viewpoint, depth of field, color and light  and
    not to forget the message and care about each single image as much as possible that's good.
    Great system!
  • If the system is heavy enough to keep the photographer from taking a crappy scene because its not worth the hassle that's good.
    Great system!

In the end the advantage of one system above another should not be measured in f-stops but pounds and inches.
Maybe some gifted specialist could calculate a "bulkiness factor" for each system to get a real comparison.

So what is bulkier?
CCD or CMOS?

Have a nice weekend
Cheers
~Chris

P.S. Going out now and pointing my photocopier along with a diesel aggregate at some random crap for sheer fun.
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bjanes
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« Reply #8 on: January 25, 2014, 07:20:06 AM »
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So, "CMOS versus CCD" is not all the story. The idea should be "CCD/16bits/50ISO versus CMOS/14bits/100ISO" systems.

Almost everything Nemo states is inaccurate and I would advise readers to ignore the post.

Does he think PhaseOne people are crazy. Why else would they offer a new camera with a smaller and inferior sensor at a US$10,000 premium over prior models?

Bill
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ErikKaffehr
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« Reply #9 on: January 25, 2014, 07:43:40 AM »
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Hi Bill,

Who is crazy? Phase One, cudstomers, Nemo, You, me and Bobby McGee? Countless permutations ;-)

:-) Sorry for the bad joke :-)

Erik



Almost everything Nemo states is inaccurate and I would advise readers to ignore the post.

Does he think PhaseOne people are crazy. Why else would they offer a new camera with a smaller and inferior sensor at a US$10,000 premium over prior models?

Bill
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jerome_m
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« Reply #10 on: January 25, 2014, 08:53:21 AM »
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The "about one stop better" comes from an educated comparison of CCDs and CMOS cameras having similar pixel size. For example, the Pentax 645D and the Nikon D600 have about the same pixel size and noise at the pixel level is about one stop better on the D600. The IQ250 uses pixels of 5.3 Ám, a size intermediate between the D800 and the D600. These cameras exhibit noise reduction artefacts from about iso 800 when examined at the pixel level, I don't see why the IQ250 would be any different.

In any case, the only way to know is indeed to try. I posted a test design here: http://www.luminous-landscape.com/forum/index.php?topic=86523.0. If someone could point an IQ250 at the same colour chart and banknotes, the results would be interesting.
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michael
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« Reply #11 on: January 25, 2014, 09:46:06 AM »
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Using pixel size as a metric really makes no sense, especially when comparing different generations of sensor, different technologies, different manufacturers, and different generations.

Michael
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jerome_m
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« Reply #12 on: January 25, 2014, 10:03:42 AM »
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I am talking about comparing pictures at 1:1 on screen here. I don't see why 5.3 Ám pixels in a Sony MF sensor would be less noisy than 5.3 Ám pixels in a different Sony sensor.

Or do you believe we should be comparing cameras of the same sensor size between generations on the final print? That is fine with me. What is the difference between the noise of the IQ250 and the IQ140 at iso 800?
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Nemo
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« Reply #13 on: January 25, 2014, 12:15:04 PM »
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Using pixel size as a metric really makes no sense, especially when comparing different generations of sensor, different technologies, different manufacturers, and different generations.

Michael

That is right, mostly because CMOS sensors' active surface is smaller than CCD's active surface.

I would compare two systems at their base ISOs, even if those values are different.

Noise is not the thing to look at, when we compare at the lowest ISO value, but tonal gamut in shadows.
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BJL
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« Reply #14 on: January 25, 2014, 04:01:52 PM »
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That is right, mostly because CMOS sensors' active surface is smaller than CCD's active surface.
With the pixel sizes of "SLR" and "MF" sized sensors and good modern gapless micro-lenses, sensors both gather light falling over almost the entire photo site area, whether CCD or CMOS.  Also, with recent designs, well capacities are about the same for either CCDs or CMOS sensors at the same pixel pitch. The differences you talk of were relevant for older CMOS designs, and perhaps still are for the far smaller photosites in compact cameras and phones, but are probably not relevant to these big, modern sensors.

But let us not sweat the theory: I am fairly sure that tests will soon enough show that Phase One is not lying when it says that the CMOS sensor of the IQ250 has about one stop more dynamic range than even the CCD of the IQ260 with its larger 6 micron pixel pitch (14 stops vs 13.): http://www.phaseone.com/en/Camera-Systems/IQ2-Series/IQ2-Specifications.aspx
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Nemo
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« Reply #15 on: January 25, 2014, 06:37:05 PM »
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With the pixel sizes of "SLR" and "MF" sized sensors and good modern gapless micro-lenses, sensors both gather light falling over almost the entire photo site area, whether CCD or CMOS.  Also, with recent designs, well capacities are about the same for either CCDs or CMOS sensors at the same pixel pitch. The differences you talk of were relevant for older CMOS designs, and perhaps still are for the far smaller photosites in compact cameras and phones, but are probably not relevant to these big, modern sensors.

But let us not sweat the theory: I am fairly sure that tests will soon enough show that Phase One is not lying when it says that the CMOS sensor of the IQ250 has about one stop more dynamic range than even the CCD of the IQ260 with its larger 6 micron pixel pitch (14 stops vs 13.): http://www.phaseone.com/en/Camera-Systems/IQ2-Series/IQ2-Specifications.aspx

There is a substantial difference in photos gathering. It is not a question gapless microlenses.
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Vladimirovich
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« Reply #16 on: January 25, 2014, 07:42:18 PM »
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and perhaps still are for the far smaller photosites in compact cameras and phones, but are probably not relevant to these big, modern sensors.
you forgot that innovations in terms of getting every single photon in the bucket are exactly in smaller sensors and then trickle to big ones Wink
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ErikKaffehr
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« Reply #17 on: January 26, 2014, 12:34:11 AM »
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What substantial difference?

Best regards
Erik

There is a substantial difference in photos gathering. It is not a question gapless microlenses.
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Lorenzo Pierucci
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Work hard & be nice to people


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« Reply #18 on: January 26, 2014, 12:51:52 AM »
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The heavier the better.

  • If the system is heavy enough to keep the photographer at home,
    if he/she is not really in the mood to take images that's good.
    Great system!
  • If the system is heavy enough to force the photographer to really look at the scene,
    feel and explore it and deeply think about composition, viewpoint, depth of field, color and light  and
    not to forget the message and care about each single image as much as possible that's good.
    Great system!
  • If the system is heavy enough to keep the photographer from taking a crappy scene because its not worth the hassle that's good.
    Great system!


P.S. Going out now and pointing my photocopier along with a diesel aggregate at some random crap for sheer fun.

This is so damn right: my best photos so far come from my Mamiya RZ67 system whit no prism finder.

Said so:

I will now make a statement and question, I'm newbie on image quality, and a photographer professionally for just 5 years. But i really don't understand why everybody use the D800 as comparison meter. I own a d800 with a nice park of prime lens, i calibrate it with color passport and do my work on C1. I also own a Leaf Valeo 22.

The Valeo is 10 ( ! ) years older technology, super low to sensibility to light ( is best is iso 25, is 50 is just ok ) and incredibly slow. Also it work only with Leafcapture ( which looks designed from north korea military ).

Even so, if i shoot in my studio the image quality ( color and contrast ) is way superior to the D800. The D800 always end up with resolve complex areas in a muggy way, even when i shoot with the nikon 14-24, on a tripod, with mirror up. I mean is a great sensor, and is way more useful as portable, cheap, and usable with capture1. But if it come to Quality, real image quality, what i feel i can get from my Valeo is just superior ( and client feels the same to ).

How can the d800 chip be compared, i presume, with the IQ250?

humble opinion.
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Nemo
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« Reply #19 on: January 26, 2014, 04:01:15 AM »
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What substantial difference?

Best regards
Erik


The full-well capacity of the CCD of the Leica M9 is 60.000 photons per pixel. The CMOS of the M (type 240), with slightly smaller "pixels", 40.000. This means a difference of 0,6EV.

The dynamic range is a combination of signal and noise though.

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