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Author Topic: AA-filtering CCD and CMOS  (Read 38548 times)

telyt

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AA-filtering CCD and CMOS
« Reply #100 on: October 14, 2009, 09:25:57 pm »

Quote from: pcunite
If I had spent $30K + on a digital back I can assure you I would prefer it's results as well.

If I were about to spend that much money on a camera I'd be damned sure it provided a tangible real-world benefit before I opened my wallet.

Quote from: pcunite
I think that photographers are too emotional to ever reach any conclusion on which system is better for their needs.

On this we agree completely!  The number of times people have defended their mushy AA-filtered images is staggering!

Quote from: ErikKaffehr
Sorry for the term mush, may be my english. I mean a region without resolved detail.

It might be my technique.  After all 1/125 sec on a monopod & shoulder stock with no mirror pre-release or ST @ full aperture isn't quite optimum.

Quote from: michael
I used to have a lot of respect for Erwin's lens-related work, but his recent digital camera reports are showing cracks in his methodology and understanding. Doing his tests using in-camera JPGs, for example.

My thoughts too.  He also has compared cameras' raw files after processing all samples with the same raw developer.  I don't think he'd have done that when comparing films.  IMHO he's only started on the digital learning curve.
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ErikKaffehr

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« Reply #101 on: October 14, 2009, 09:46:59 pm »

Michael,

When you talk about the A900 and Zeiss lenses are you discussing the zooms or the primes? My take is that the zooms are pretty good but I would guess that both the Zeiss primes (specially the 135/1.8) and the Leica lenses may be a different league.

Going back to the Erwin Puts articles I don't think he uses in camera JPEGS his testing, is based on Capture One on Nikon and I guess Lightroom on the Leica. He certainly does have no bias against Leica. I often have difficulty understanding his writing but still am thankful for information.

Most of us don't really have the option to have access to all equipment and therefore depend on independent reviews and sample pictures. Sites like Imaging Resource have lot of hopefully high quality images, even in RAW. I have unfortunately not seen any MFDB images of the ISO 12233 test charts for instance.

The nearest thing I have seen was actually the MFDB shootout on Luminious Landscape. I have tried to reproduce it partly for an article I have in progress comparing MF Velvia and 24MP DSLR. I actually made prints from small crops and found that the Alpha 900 I have was remarkably good but even a blind man could see that the P45 was better. Stopping the P45 down to f/16 gave significantly worse results, however. Even at f/16 the P45 was better than the Alpha 900.

My guess is that you need to enlarge above A2 to really benefit from MFDBs over DSLRs with 20+ MP. Experienced viewers may see differences easier.



Quote from: michael
Bernard,

I used to have a lot of respect for Erwin's lens-related work, but his recent digital camera reports are showing cracks in his methodology and understanding. Doing his tests using in-camera JPGs, for example.

I have no desire to knock him here, but I have heard from more than a couple of knowledgeable tech journalists recently who are privately musing that everything is not all as it should be with his recent work on cameras and sensors as opposed to lenses.

In other words, I disagree with Erwin's M9 results based on my own tests, and while I haven't done the D3x comparison I have done it with the A900 and the 1Ds MKIII, which others have measured as having comparable resolution to the D3x. The D3x's forte, as you know, is its high ISO capability, and not any particular lead in the resolution department. And I have no need to quibble over Nikon glass vs. Zeiss. The best of both are comparable, and probably differ more in individual samples that in type.

Michael
« Last Edit: October 14, 2009, 11:34:00 pm by ErikKaffehr »
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aaykay

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« Reply #102 on: October 14, 2009, 10:58:32 pm »

Quote from: BernardLanguillier
Since Michael did not test the D3x against the M9 (Michael doesn't own a D3x as far as I know), but based his comment on a generic belief that all DSLRs are basically the same (conclusion being based on a limited amount of D3x usage), I tend to trust Erwin's conclusions more on this particular point, especially knowing that he is known to be very close to Leica.

And Erwin does not own an A900 (as far as I know) and he did not test it head-to-head with the M9, by say putting something like the ultra-fine Zeiss 135mm f/1.8 on the A900 and the 135mm f/3.4 M Leica lens on the M9 for a one-to-one comparison.  He would probably have reached the same conclusion with the A900, that he did with the D3X - maybe even more so, since even the lofty D3X does not get to be coupled with as fine a lens as the Sony's Zeiss, to my knowledge.   The lens obviously has an outsized influence here on the final result, and my personal finding is that the Zeiss primes in the Sony/Alpha system (the 135mm even more than the 85mm) have that extra wallop that even the excellent Zeiss zooms like the 24-70 f/2.8 and the 16-35 f/2.8 does not have.

Clearly, it seems like Michael and Erwin have differing views on what they find to be "better" and you find Erwin's view more convenient and believable.    I personally am pretty neutral on this point.
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ErikKaffehr

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« Reply #103 on: October 14, 2009, 11:43:53 pm »

Hi,

I'm actually a bit confused by Erwin Puts test. For instance he has a picture of a couple of combs. In this case I certainly perceive the M9 image to be sharper than the 3DX image although Erwin says that the D3X is sharper.

Also, the MTF he shows for Nikon has excessive sharpening, I have done a lot of testing with Imatest, although not professionally, and I never had that level of sharpening Erwin shows.

Erwin's stuff is interesting and worth the read, but I don't really feel that the information is complete, especially it is hard to know exactly what he means.

Best regards
Erik


Quote from: aaykay
And Erwin does not own an A900 (as far as I know) and he did not test it head-to-head with the M9, by say putting something like the ultra-fine Zeiss 135mm f/1.8 on the A900 and the 135mm f/3.4 M Leica lens on the M9 for a one-to-one comparison.  He would probably have reached the same conclusion with the A900, that he did with the D3X - maybe even more so, since even the lofty D3X does not get to be coupled with as fine a lens as the Sony's Zeiss, to my knowledge.   The lens obviously has an outsized influence here on the final result, and my personal finding is that the Zeiss primes in the Sony/Alpha system (the 135mm even more than the 85mm) have that extra wallop that even the excellent Zeiss zooms like the 24-70 f/2.8 and the 16-35 f/2.8 does not have.

Clearly, it seems like Michael and Erwin have differing views on what they find to be "better" and you find Erwin's view more convenient and believable.    I personally am pretty neutral on this point.
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BernardLanguillier

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« Reply #104 on: October 14, 2009, 11:50:37 pm »

Quote from: aaykay
And Erwin does not own an A900 (as far as I know) and he did not test it head-to-head with the M9, by say putting something like the ultra-fine Zeiss 135mm f/1.8 on the A900 and the 135mm f/3.4 M Leica lens on the M9 for a one-to-one comparison.  He would probably have reached the same conclusion with the A900, that he did with the D3X - maybe even more so, since even the lofty D3X does not get to be coupled with as fine a lens as the Sony's Zeiss, to my knowledge.   The lens obviously has an outsized influence here on the final result, and my personal finding is that the Zeiss primes in the Sony/Alpha system (the 135mm even more than the 85mm) have that extra wallop that even the excellent Zeiss zooms like the 24-70 f/2.8 and the 16-35 f/2.8 does not have.

Well, the Zeiss 100mm f2.0 I have been using a lot this past year is a totally brilliant performer (said by many to be one of the very best pieces of glass ever). I have not seen a comparison between the 100 and 135, but I would be surprised if they were very far appart.

Quote from: aaykay
Clearly, it seems like Michael and Erwin have differing views on what they find to be "better" and you find Erwin's view more convenient and believable.    I personally am pretty neutral on this point.

What we have here are 2 different views on 2 differents things. The proposition that these views can be compared in absolute terms only stands on the assumption that the A900 and D3x have the same level of performance. That is the point I cannot agree with.

(A>B, C>D) only yields relevant information on the relative value of A and D if the relationship between B and C is known.

I couldn't care less if the M9 were better than the d3x, that doesn't affect me and I have no way to verify this myself. I am only glad to see more valuable photographic options on the market. But it should be clear that Michael's assessement that the M9 is better than the A900 doesn't establish any clear relative ranking between the M9 and the D3x, one way or the other.

Having worked with files from the D3x (an awful lot) and the A900 (a lot less but still enough to form an opinion), I see differences that are as significant as it gets between DSLRs of similar pixel count. Put it otherwise, if the A900 and D3x are the same for Michael, then he doesn't need bother looking at any new DSLR in next 2 or 3 years, they will be the same as well.

I could very well understand that compared to a P65+ that he will use for all his critical work anyway, both are poor resolutionwise. Now for those of us looking at extracting the best possible quality from DSLRs, much cleaner shadows and the ability to apply a lot more low radius sharpening are very relevant and important factors.

Final comment from me on this.  

Cheers,
Bernard

thierrylegros396

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« Reply #105 on: October 15, 2009, 04:00:34 am »

Quote from: ErikKaffehr
Hi,

Sorry for the term mush, may be my english. I mean a region without resolved detail.

I include the region which contains artifacts in my view: [attachment=17192:aliasing.jpg]

Seen as discontinous hairs and brightness variations along strains.

According to imaging theory there should be aliasing artifacts if the lens resolves above the Nyquist limit, so it just may prove that you have a good lens and technique. I won't argue that they are harmful.

Best regards
Erik

Very interresting artifacts image.

But from where comes those artifacts (RAW conversion, filtering, jpeg) ?!

It would be kind to have acces to the RAW file.

Hav a Nice Day.

Thierry
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ErikKaffehr

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« Reply #106 on: October 15, 2009, 08:11:55 am »

Two comments.

Regarding the part of the image beeing "mushy" I don't suggest it's your techique. The aliasing I'm certain to see certainly indicates that your technique works very well. The area just below the eye lacks detail and I don't think it's a DOF issue, more like simply that the detail is smaller than that can be resolved.

Regarding testing I would say that using the same converter for all tested cameras is good science, I may even add that using a known, well documented and basic converter is optimal. After basic testing have been done we can explore different converters, but are you testing converter or camera/lens/sensor in that case?

Imatest that Erwin Puts use does have a built in RAW converter called DC-Raw.

I have some writeup comparing scanned 67 Velvia with my Alpha 900 and see a similar problem. Both the scanned Velvia and the Alpha images need sharpening. So I could tweak sharpening and try to achieve optimal sharpening, but optimal sharpening to one observer may be to much for another observer.

So what I did was to use the normal settings I would start with, Photokit Sharpener with settings for MF film and "Landscape" preset in Lightroom.

My article on MF Velvia vs. Sony Alpha 900 is here: http://83.177.178.241/ekr/index.php/photoa...-sony-alpha-900


Best regards
Erik


Quote from: telyt
It might be my technique.  After all 1/125 sec on a monopod & shoulder stock with no mirror pre-release or ST @ full aperture isn't quite optimum.



My thoughts too.  He also has compared cameras' raw files after processing all samples with the same raw developer.  I don't think he'd have done that when comparing films.  IMHO he's only started on the digital learning curve.
« Last Edit: October 15, 2009, 08:15:52 am by ErikKaffehr »
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bjanes

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« Reply #107 on: October 15, 2009, 08:48:29 am »

Quote from: ErikKaffehr
I'm actually a bit confused by Erwin Puts test. For instance he has a picture of a couple of combs. In this case I certainly perceive the M9 image to be sharper than the 3DX image although Erwin says that the D3X is sharper.

Also, the MTF he shows for Nikon has excessive sharpening, I have done a lot of testing with Imatest, although not professionally, and I never had that level of sharpening Erwin shows.

Erwin's stuff is interesting and worth the read, but I don't really feel that the information is complete, especially it is hard to know exactly what he means.

Best regards
Erik

I'm glad to hear that someone else is confused by Erwin's tests, because I too have done a fair amount of non-professional work with Imatest, and was shocked and perplexed by his MTFs of 250% on many images. His Leica results also are perplexing. At f/2.8 without sharpening (Image L1005878.jpg) shows an MTF of 250%! I was under the impression that MTFs of greater than 100% are caused by sharpening (Norman Koren). In my experience such MTFs result from gross oversharpening and one is likely looking at sharpening artifacts and not true resolution. With Imatest, over-sharpening can result in resolution above Nyquist. Personally, I would not trust such results, but perhaps Erwin knows something that I don't.
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telyt

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« Reply #108 on: October 15, 2009, 09:34:33 am »

Quote from: ErikKaffehr
Regarding testing I would say that using the same converter for all tested cameras is good science, I may even add that using a known, well documented and basic converter is optimal.

Different converters will provide different results with different cameras' raw files and if you want to test the potential of the system then the optimum for that system should be used.  By using the same converter with all raw files all you're testing is a particular set of tools which might not be optimum for any of the tested systems.  In my experience with the DMR for example optimum results are with Imacon Flexcolor, next would be C1, then ACR.
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ejmartin

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« Reply #109 on: October 15, 2009, 10:07:33 am »

Quote from: telyt
Different converters will provide different results with different cameras' raw files and if you want to test the potential of the system then the optimum for that system should be used.  By using the same converter with all raw files all you're testing is a particular set of tools which might not be optimum for any of the tested systems.  In my experience with the DMR for example optimum results are with Imacon Flexcolor, next would be C1, then ACR.

Depends on what you're trying to achieve.  If the goal is to get the most out of a given camera's RAW files then indeed different converters might be appropriate.  If the goal is to discern what of the output can be attributed to the effects of an AA filter and lack or presence of aliasing, then the use of different converters throws an additional set of uncontrolled variables into the testing, that make it hard to know whether what one is seeing is due to say different demosaic algorithms vs the effect of aliasing.
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bjanes

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« Reply #110 on: October 15, 2009, 10:16:28 am »

Quote from: telyt
Different converters will provide different results with different cameras' raw files and if you want to test the potential of the system then the optimum for that system should be used.  By using the same converter with all raw files all you're testing is a particular set of tools which might not be optimum for any of the tested systems.  In my experience with the DMR for example optimum results are with Imacon Flexcolor, next would be C1, then ACR.


What you are saying is true, but one can not necessarily assume that the camera maker's raw converter is the best for their camera. One would think that the camera maker should know how to get the best results from their cameras, but this is not necessarily the case. The maker may use a Sony or Kodak chip and have little expertise in software development. One would then have to test with all available raw converters, and this would greatly complicate the testing, especially when one considers that each converter has multiple parameters. Sharpening is not standardized. Would you omit sharpening (and penalize cameras with a blur filter) or try to determine optimal sharpening?

Since the tester might not want to buy all possible raw converters, many choose to use the camera's JPEG engine or a well regarded raw converter that supports multiple cameras such as C1, DCRaw or ACR, often with default settings. In any case, the results will be subject to criticism by some.
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aaykay

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« Reply #111 on: October 15, 2009, 12:35:33 pm »

Quote from: BernardLanguillier
Having worked with files from the D3x (an awful lot) and the A900 (a lot less but still enough to form an opinion), I see differences that are as significant as it gets between DSLRs of similar pixel count. Put it otherwise, if the A900 and D3x are the same for Michael, then he doesn't need bother looking at any new DSLR in next 2 or 3 years, they will be the same as well.

The default JPEGs that the A900 spits out (even in the "Extra Fine" mode) are pretty lousy, for any kind of comparison with the output of any other camera.  I personally never shoot JPEG with the A900, other than the throwaway lowest resolution JPEG that is shot along with the RAW+JPEG shooting mode.

Also, when you shoot RAW, a common finding with Sony files when processed with any of the Adobe-based products like CS4 or Lightroom is that they just mangle the Sony RAW data, resulting in disgusting results.  Don't have any idea why.  Is there something within the Adobe RAW processing engine that are not optimized for Sony files ? Why is it destroying fine detail that the other RAW processors have no difficulty in revealing ?  No idea at all, but I would not form any judgement on the quality of the A900 files, based on any kind of processing done via Adobe products.

Now, what else ?  I find DXO (especially the latest 5.3.5 release) to be the best RAW processing tool for A900 files.  Some people find Capture One Pro to be good but I found DXO to be better.  Then there are other people who swear by packages like Rawtherapee etc for A900 files and if you use Apple Mac, then RPP (Raw Photo Processor) is supposed to be top-notch.

Bottomline, any opinions formed by processing A900 files via a sub-optimal RAW processor, is not revealing what the product can do, especially when you stick some of the best lenses in dSLR-dom on the camera.  
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BernardLanguillier

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« Reply #112 on: October 15, 2009, 06:32:04 pm »

Quote from: aaykay
Bottomline, any opinions formed by processing A900 files via a sub-optimal RAW processor, is not revealing what the product can do, especially when you stick some of the best lenses in dSLR-dom on the camera.  

My tests were done with C1 Pro 4.8 with the exact same settings I use for my d3x files.

Cheers,
Bernard

telyt

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« Reply #113 on: October 15, 2009, 09:29:02 pm »

Quote from: bjanes
Since the tester might not want to buy all possible raw converters, many choose to use the camera's JPEG engine or a well regarded raw converter that supports multiple cameras such as C1, DCRaw or ACR, often with default settings. In any case, the results will be subject to criticism by some.

And it will be an incomplete test.  However, the internet buzz would turn into "Tester A says Camera C sux".
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telyt

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« Reply #114 on: October 15, 2009, 09:31:14 pm »

Quote from: ejmartin
Depends on what you're trying to achieve.  If the goal is to get the most out of a given camera's RAW files then indeed different converters might be appropriate.  If the goal is to discern what of the output can be attributed to the effects of an AA filter and lack or presence of aliasing, then the use of different converters throws an additional set of uncontrolled variables into the testing, that make it hard to know whether what one is seeing is due to say different demosaic algorithms vs the effect of aliasing.

If you want to see what the effect of the AA filter is take two copies of a camera, verify that their output is identical, then have the AA filter removed from one of them and re-test.  The test would be valid only for that particular camera model, otherwise you have too many uncontrolled variables.
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ErikKaffehr

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« Reply #115 on: October 15, 2009, 09:37:16 pm »

Hi,

I don't want to engage in any Nikon versus Alpha wars. I would just say that:

1) The lens that Bernard uses is of stellar reputation, at least if it's  the 100/2.8 Macro Planar, It's probably one the three or four best lenses ever made for 135 format cameras.

2) Comparing systems with the same converter is what any scientist would consider good science.

3) I have only the 24-70/2.8 ZA lens my self, and I may not consider it my sharpest zoom. The 135/1.8ZA is said to be stellar but the 85/1.4 less so.

4) I have downloaded testshots for the D3X and the Alpha 900 from Imaging Resource and converted myself using Lightroom and also measured using Imatest. There was not a lot of difference.

I'd also add that I made some experiments comparing MFDB Imags dlownloaded from the net with DSLRs. The experiments were based on A2-prints. A verbal description of the outcome is here

http://83.177.178.241/ekr/index.php/photoa...ed#Experiment_1
and
http://83.177.178.241/ekr/index.php/photoa...ed#Experiment_2

Two interesting observations are:

1) It's difficult to tell apart Nikon 3DX and MFDBs at A2 size or smaller (16.5 x 23.4 in)
2) Stopping down the lens to f/22 on MFDB by and significantly reduces the advantage of MFDB over DSLR stopped down to f/8 (this comparison was based on larger print size, around 24x34"). This depends solely on diffraction.

Best regards
Erik

Quote from: BernardLanguillier
My tests were done with C1 Pro 4.8 with the exact same settings I use for my d3x files.

Cheers,
Bernard
« Last Edit: October 16, 2009, 01:46:37 am by ErikKaffehr »
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telyt

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« Reply #116 on: October 15, 2009, 10:55:55 pm »

Quote from: ErikKaffehr
2) Comparing systems with the same converter is what any scientist would consider good science.

pardon my language, but speaking as a scientist that's bullshit.  The only reason to do that is if the one converter you're using is the only one you ever expect to use.  This test would be "how do cameras B and C compare when using only one converter?", not "how do Camera B and Camera C compare?"  The test with only one converter would transmogrify on the internet to "Tester A says Camera C sux" when it's really Camera C doesn't do as well as Camera B when files are converted with Converter D.  Are you only interested in Converter D?  If so then the test you propose is fine.  If you want to see how well each system performs, the test with one converter doesn't tell you the whole story.
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ejmartin

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« Reply #117 on: October 15, 2009, 11:35:23 pm »

Quote from: telyt
If you want to see what the effect of the AA filter is take two copies of a camera, verify that their output is identical, then have the AA filter removed from one of them and re-test.  The test would be valid only for that particular camera model, otherwise you have too many uncontrolled variables.

And this is supposed to be a justification for changing both the camera and the converter, as you originally suggested?  
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« Reply #118 on: October 15, 2009, 11:50:40 pm »

Quote from: telyt
pardon my language, but speaking as a scientist that's bullshit.  The only reason to do that is if the one converter you're using is the only one you ever expect to use.  This test would be "how do cameras B and C compare when using only one converter?", not "how do Camera B and Camera C compare?"  The test with only one converter would transmogrify on the internet to "Tester A says Camera C sux" when it's really Camera C doesn't do as well as Camera B when files are converted with Converter D.  Are you only interested in Converter D?  If so then the test you propose is fine.  If you want to see how well each system performs, the test with one converter doesn't tell you the whole story.

Speaking as a scientist, that's bullshit  

The test Erik proposes would be, "how do cameras B and C compare when their RAW data are subjected to identical manipulations", not "how do cameras B and C compare when treated in uncontrolled different ways?" as you seem to prefer.   If the converter is a potential source of bias, then it is better to use a family of converters on each camera to eliminate that bias, so long as it is known that any converter used applies the same process to any given RAW file.  However, since only dcraw is open source, that's hard to verify for any other converter.  RAW conversion is not a black art, which needs sympathetic vibes between conversion algorithm and camera.
« Last Edit: October 16, 2009, 12:40:52 am by ejmartin »
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telyt

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« Reply #119 on: October 16, 2009, 12:36:31 am »

Quote from: ejmartin
Speaking as a scientist, that's bullshit  

The test Erik proposes would be, "how do cameras B and C compare when their RAW data are subjected to identical manipulations", not "how do cameras B and C compare when treated in uncontrolled different ways?" as you seem to prefer.   If the converter is a potential source of bias, then it is better to use a family of converters, so long as it is known that any converter used applies the same process to any given RAW file.  However, since only dcraw is open source, that's hard to verify for any other converter.  RAW conversion is not a black art, which needs sympathetic vibes between conversion algorithm and camera.

Would you compare an E-6 film and a C-41 film using XTol as a developer, and then conclude anything meaningful about the films' performance?

The problem with the test Eric proposes is that different camera systems require different manipulations to get the most out of the system.  different color profiles, and different capture sharpening for example.  What's the purpose of the test?  It it to compare camera systems?  if so limiting the test to a single converter provides only scanty information, and unfortunately the unscientific voices on the internet (and there are a few of these   ) don't recognize the difference between a test limited to a single converter and a comprehensive test.

An uncontrolled test, BTW, would involve applying random converters to equally random cameras' files.  You have mis-represented my position.  What I'm suggesting is that in order to compare optimum performance of two or more camera systems, optimize each system first then compare, otherwise the test's conclusion will more than likely be erroneous.
« Last Edit: October 16, 2009, 12:45:55 am by telyt »
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