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Author Topic: RAW files: 1Ds3 and Phase P30+  (Read 74687 times)
Frank Doorhof
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« Reply #60 on: June 21, 2008, 01:03:30 PM »
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I always like these two:

.
Same goes for the 645, some lenses enhance the feel, some are less.

So the whole story is probarbly:
80% the whole setup, independed on camera.
20% the used capture device, where I suspect that the contrast and rendition of black (and those two are very close connected) are key elements for the 3D look.
The lack of an AA filter could be just as important because there is no interpixel infection (hope that's a correct translation).

Some say that due to the bellows focussing of the RZ you get more contrast out of the lenses which in basis looked strange for me, although when thinking about it could make alot of sense. The lens stays EXACTLY the same throughout the whole focus range, meaning the optical system does not change and can not pick up stray light or scatterlight, meaning it could indeed render more contrast and better black rendition.
However I never dove into that subject so it could be BS (it's something that was told to me and it's not something I will discard without testing), fact is that it seems that the RZ gets even more "real" looking pictures than the 645 with the SAME digital back, problem is..... what do I see.
Do I see the difference in lenses, the bellow focus, or the construction of the RZ.
And that will probarbly never be answered.

For me it also doesn't really matter, I keep in mind which lens gives me what I want and that's the one I will use if possible.
« Last Edit: June 21, 2008, 01:05:11 PM by Frank Doorhof » Logged
reissme
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« Reply #61 on: June 21, 2008, 01:39:20 PM »
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@reissme,
I never said you need $30,000 to get the 3D effect.
On the conturary I say it's debit to MANY other factors, however......

What I do know for 100% is that if you photograph the same scene with a DSLR and with a MFDB the MFDB will have MORE of that 3D effect.

I think that most is debit in the higher dynamic range and cleaner pixels.
Interpixel contrast is very important for 3D looks in hometheater, as is blacklevel (although those two are related).

You can do the test quite easily.
Take your best 3D looking shot and make a curve adjustment where you lift the center part, you will see that the 3D effect slowly goes away.
Same happens when you pull up your blacks (no real black anymore).

This is one of the reasons why in projectors I waited a LONG time to switch from a CRT projector to now a D-Ila.
The D-Ila is the first digital projector with a native CR of 35.000:1 (measured it myself, so no brochure talk) without the use of an Iris of dynamic settings, the 3D look of that projector is STUNNING.

In digital capture the same rules should apply.
In other words, to have that 3D effect all the elements should already be in place and the last factor is the capture device.
Capture the same scene with a DSLR and it's 3D looking, capture the same scene with a MFDB and it's even more so.
But it's not so that a DSLR can't capture a 3D looking image

That's why it's ridicilous to just say this is done with MF and this is done by DSLRs.

HOWEVER, the scene you see here with the stones and lizard is a clear example, again look at the stones and the lizard, both look much less flat on the MFDB sample.
[a href=\"index.php?act=findpost&pid=202714\"][{POST_SNAPBACK}][/a]
Hey Frank
As 203 points out, you can't see the real quality in Canon file that was upsized to proportions of the Phase file. I will  trust  only new tests with both cameras shooting same objects, in the same light, same perspective, with different lenses, differnt f numbers to get same Dof and to compensate for different CMOS/CCD size.
Menachem Reiss www.reiss.co.il
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reissme
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« Reply #62 on: June 21, 2008, 02:04:43 PM »
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I always like these two:

.
Same goes for the 645, some lenses enhance the feel, some are less.

So the whole story is probarbly:
80% the whole setup, independed on camera.
20% the used capture device, where I suspect that the contrast and rendition of black (and those two are very close connected) are key elements for the 3D look.
The lack of an AA filter could be just as important because there is no interpixel infection (hope that's a correct translation).

Some say that due to the bellows focussing of the RZ you get more contrast out of the lenses which in basis looked strange for me, although when thinking about it could make alot of sense. The lens stays EXACTLY the same throughout the whole focus range, meaning the optical system does not change and can not pick up stray light or scatterlight, meaning it could indeed render more contrast and better black rendition.
However I never dove into that subject so it could be BS (it's something that was told to me and it's not something I will discard without testing), fact is that it seems that the RZ gets even more "real" looking pictures than the 645 with the SAME digital back, problem is..... what do I see.
Do I see the difference in lenses, the bellow focus, or the construction of the RZ.
And that will probarbly never be answered.

For me it also doesn't really matter, I keep in mind which lens gives me what I want and that's the one I will use if possible.
[a href=\"index.php?act=findpost&pid=202721\"][{POST_SNAPBACK}][/a]
Hey Frank
I like your work
The 3-D look you say is only due to shallow DOF that can be done easily with the Canon 1DSMIII by using 85 mm F:1.2L or 50 mm F:1.2L
Menachem Reiss www.reiss.co.il
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203
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« Reply #63 on: June 21, 2008, 02:07:08 PM »
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If you can not look at images and see the 3D or no 3D (as I invited people to do with the images I posted above) then does it matter?

If you have to conduct scientific tests and look at 100% pixelpeep side by side with some other image, then what does it matter?

Again, with that dragon thing, I think all you are seeing is more vs. less pixels.

By the way, does one of these pictures of the guy working on the car look more 3D than the other?

http://luminous-landscape.com/forum/index....ndpost&p=201600

And on that note, I am off the 3D topic...
« Last Edit: June 21, 2008, 02:31:58 PM by 203 » Logged
Frank Doorhof
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« Reply #64 on: June 21, 2008, 04:21:13 PM »
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@203,
Totally correct, it's sometimes like people are telling me what I see cannot be true, again if that was the case I would have NEVER invested in the system to start with.

If other people don't see it I won't try to confince them it is true, I always say that it's quite possible that they don't see it
For me it has to be obvious other wise I won't invest.
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Ray
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« Reply #65 on: June 21, 2008, 07:18:12 PM »
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What's with the zipper artifacts on the 1Ds3 image on the blue-yellow border below "Ready-Mop"?   Kind of nasty, but more likely an issue with the raw converter than the raw file itself.

The P30 looks to have indeed regarding sharpness, but also has significant jaggies; both it would seem can be attributed to the lack of AA filter.
[a href=\"index.php?act=findpost&pid=202705\"][{POST_SNAPBACK}][/a]

Emil,
You are looking at crops of 200% enlargements. In addition, the 1Ds3 file was upressed, using bicubic, to the same size as the P30 file (after cropping the P30 file to approximately the 3:2 aspect ratio) and then sharpened.

The 200% crops show jaggies because the monitor resolution is fairly low at 96 or 120 ppi. If one were to print the full size image, that is, make a print about 7ftx10ft, which one would need to do to inspect the amount of detail you see in these 200% crops from the same distance, then it would be normal practice to interpolate the file to 240ppi for best results and sharpen accordingly. You should then not see any jaggies.
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Ray
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« Reply #66 on: June 21, 2008, 08:17:58 PM »
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@203,
Totally correct, it's sometimes like people are telling me what I see cannot be true, again if that was the case I would have NEVER invested in the system to start with.

If other people don't see it I won't try to confince them it is true, I always say that it's quite possible that they don't see it
For me it has to be obvious other wise I won't invest.
[a href=\"index.php?act=findpost&pid=202745\"][{POST_SNAPBACK}][/a]

The 3D effect is surely only apparent in relation to other images which lack that subtle effect. Most of us who process images in Photoshop are able to discern a whole range of subtle effects, slight changes in hue and contrast, differences in the 'solidity' of color, subtle changes in DoF and sharpness etc.

A difference in the processing of the same file, whether it be 35mm or MFDB, can have a far greater effect on the final appearance of the result than any generic 3D difference between 35mm and MFDB.

For example, I used to prefer the RAW converter Raw Shooter Premium to Adobe's Camera Raw, for many images, but not all. I found I could often get a more vibrant result and shapes that seemed to have a more solid color, like the P30 red apple in #203's shot.

Since Adobe bought out RSP, they seem to have adopted some of the same type of controls that were a feature of RSP, such as detail enhancement, vibrancy and saturation sliders as well as generally more control such as variable pixel width for sharpening. However, it's still difficult to emulate the precise effect that I used to get with RSP, but it's not impossible to at least to get close to it. But I need to have a copy of the RSP conversion open at the same time so I have something to work towards.

What I would question is:

(1) Is the 3D effect of MFDB just a combination of lighting, quality of lens, choice of F stop and the particular way the RAW converter handles the files.

(2) There seems to be general confusion about the need to change f stop when comparing images from different size sensors. Subtle differences in DoF can contribute to a sense of a different degree of 3D effect. Even in the comparisons of same scenes in this thread from #203, who seems to be a fairly competent photographer, the same f stop (F8) has been used with both cameras. Why?

(3) If an MFDB system simply produces better results because of a whole range of factors which are part of the system, including bigger pixels, more pixels, better lenses, better tethering, faster flash sync etc, then no argument. That's presumably what you pay for.
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Dale Allyn
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« Reply #67 on: June 21, 2008, 08:26:56 PM »
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Having now had some time to examine #203's P30/1Ds3 images, I see no significant differences in over all quality between the two files, that matter to me.

At 200% magnification on my monitor, the P30 has the edge regarding clarity of text at the point of focus. The fact that the red apple in the P30 shot has a more solid red (should we describe that as a 'fat' red?) is an effect which one could no doubt achieve in the 1Ds3 image after a bit of selective manipulation in PS.

[attachment=7136:attachment]

After grey-balancing the two images, the magenta cast in the P30 shadows has been dispelled, only to be replaced by a strong cyan cast in the very deepest shadows. That's not a problem in this image because it's only apparent after the shadows have been lightened to an extreme and unnatural degree, but it's a curious effect and might be entirely due to the way ACR handles P30 files.

[attachment=7138:attachment]

The fact that the same f stop has been used in both these images is a flaw in the methodology. In these two shots from #203, an attempt has been made to match horizontal FoVs rather than vertical FoVs. The sensor dimensions along the horizontal axis differ by a factor of 1.33 and so should the f stops used. In other words, in this comparison, F6.3 should have been used with the 1Ds3. It does make a difference. Parts of the image which are nearest to the camera are noticeably sharper in the 1Ds3 image, as you can see from the following 100% crop showing roughly equal shadow noise but superior 1Ds3 resolution.

[attachment=7137:attachment]

The sameness of f stops used also raises a doubt about the slightly greater resolution of the P30 at the point of focus. Would the difference have been even narrower if the 1Ds3 had been used at F6.3 instead of F8? Most 'good' 35mm lenses tend to be sharpest somewhere between F5.6 and F8.
[a href=\"index.php?act=findpost&pid=202670\"][{POST_SNAPBACK}][/a]

Ray,

As one who prefers ACR for my image conversion and workflow, and as a new owner of Phase One P25+, I can say that ACR is not the best tool for processing RAW P1 files. (And some suggest that it's not best for Canon files either, though it's my tool of choice there.) I'm not proficient in the use of Capture One, and I do alright with CS3/ACR, but I get much better results using C-1 when working with the Phase files. And there is a visible difference between using C-1 v3.7.8 and C-1 v4.1.1, of which I prefer the results from v4.1.1.

My Phase One file experience is limited and I'm new to MFDB, but I am comfortable with processing digital files. My approach (for now) is to process the RAWs in C-1 v4.1.1 and do final processing for output in PS (CS3).
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Ray
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« Reply #68 on: June 21, 2008, 08:49:01 PM »
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Ray,

As one who prefers ACR for my image conversion and workflow, and as a new owner of Phase One P25+, I can say that ACR is not the best tool for processing RAW P1 files. (And some suggest that it's not best for Canon files either, though it's my tool of choice there.) I'm not proficient in the use of Capture One, and I do alright with CS3/ACR, but I get much better results using C-1 when working with the Phase files. And there is a visible difference between using C-1 v3.7.8 and C-1 v4.1.1, of which I prefer the results from v4.1.1.

My Phase One file experience is limited and I'm new to MFDB, but I am comfortable with processing digital files. My approach (for now) is to process the RAWs in C-1 v4.1.1 and do final processing for output in PS (CS3).
[a href=\"index.php?act=findpost&pid=202763\"][{POST_SNAPBACK}][/a]

I understand that. Nikon owners believe that Nikon Capture produces better results with Nikon RAW images. Some Canon owners prefer Canon's DPP to ACR and I used to prefer RSP. It would be no surprise if Capture One produces better results with Phase One files than ACR.

The question might be, is it just difficult to emulate the Capture One result in ACR or actually impossible?

Which apple do you prefer below? The red apple on the right is a 1Ds3 apple, ehanced in PS after conversion in ACR. The apple on the left is the P30 apple.

Does the P30 apple look more enticing? Does it have a greater 3D effect? Is it more solid or healthier-looking, or fresher?

[attachment=7152:attachment]
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Dale Allyn
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« Reply #69 on: June 21, 2008, 08:59:12 PM »
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Which apple do you prefer below? The red apple on the right is a 1Ds3 apple, ehanced in PS after conversion in ACR. The apple on the left is the P30 apple.

Does the P30 apple look more enticing? Does it have a greater 3D effect? Is it more solid or healthier-looking, or fresher?

[attachment=7152:attachment]
[a href=\"index.php?act=findpost&pid=202766\"][{POST_SNAPBACK}][/a]

I could go for a nice pear.

Actually, the image on the left looks poorly processed (no offense intended). There's a magenta cast to the apple and to the letters on the Coke can. Other elements are off as well. I'm not suggesting "sides", just wanted to mention my experience with the different conversion software (which is widely understood as it relates to other cameras and SW  as well). I own Canon gear and intend to keep it.  I like it. I almost bought a 1Ds3. And now I have a P25+ with Mamiya glass (which has some advantages over some Canon glass IMO). It's all good.

Happy shooting.

edit: typo
« Last Edit: June 21, 2008, 09:00:05 PM by DFAllyn » Logged

Panopeeper
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« Reply #70 on: June 21, 2008, 09:20:19 PM »
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As one who prefers ACR for my image conversion and workflow, and as a new owner of Phase One P25+, I can say that ACR is not the best tool for processing RAW P1 files

The color reproduction needs to be adjusted. This can be done with more or less success using one of the calibration scripts. However, I expect that custom pofiles will be accepted in the near future; that should solve the problem, which is allegedly non-existent (if one listens to Adobe)

I can imagine, that the noise processing of C1 is better, as they have more information regarding the raw data. Plus, this market segment is too tiny for Adobe to move even a finger (this is strictly my opinion).

There is another issue: the ISO handling.

I am pretty sure, that you don't know, that your back does not have different ISOs; the ISO setting is imaginary. Don't be upset, this is very good so, I would be happy to have my camera that way.

However, the handling of such raw files should be different from the "customary" ones. ACR's handling is, that ISO 200 is regarded as basis, and images with other ISOs get a default intensity adjustment (misnomer in ACR: "Exposure"): ISO 100 becomes darkened by 1 EV, ISO 400 gets +1 EV and ISO 800 gets +2 EV. (You don't see these adjustments on the slider!)

Now, this may work well in some circumstances, but in other cases it may be disastrous. It may show you a dark image despite good exposure, or it may indicate horrendeous overexposure of a perfectly ETTR shot image.

I can imagine, that C1 makes it better.
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« Reply #71 on: June 21, 2008, 09:26:52 PM »
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There is another issue: the ISO handling.

I am pretty sure, that you don't know, that your back does not have different ISOs; the ISO setting is imaginary. Don't be upset, this is very good so, I would be happy to have my camera that way.

However, the handling of such raw files should be different from the "customary" ones. ACR's handling is, that ISO 200 is regarded as basis, and images with other ISOs get a default intensity adjustment (misnomer in ACR: "Exposure"): ISO 100 becomes darkened by 1 EV, ISO 400 gets +1 EV and ISO 800 gets +2 EV. (You don't see these adjustments on the slider!)

Now, this may work well in some circumstances, but in other cases it may be disastrous. It may show you a dark image despite good exposure, or it may indicate horrendeous overexposure of a perfectly ETTR shot image.

I can imagine, that C1 makes it better.
[a href=\"index.php?act=findpost&pid=202769\"][{POST_SNAPBACK}][/a]

Actually, Gabor, I do understand this, thanks to your posts at GetDPI and elsewhere. I'm still not completely clear as to which is the very best ISO to shoot this back on, but tend to shoot on ISO 50 or 100 and process in C-1. I have not profiled my back for ACR and I do see markedly better results using C-1 for my conversion.

Cheers.
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Panopeeper
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« Reply #72 on: June 21, 2008, 09:54:38 PM »
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Actually, Gabor, I do understand this, thanks to your posts at GetDPI and elsewhere
I'm sorry, I did not recognize your tag from other forums.

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I'm still not completely clear as to which is the very best ISO to shoot this back on

The ISO setting has to roles:

1. evaluation of the necessary exposure,

2. instruction of the raw processing.

You should figure out, which setting yields the most accurate metering. Try to achieve ETTR using the in-camera histogram. If the P25+ displays a raw histogram, that's great. Using a neutral WB (Uni-WB) is not an option, if your customers are standing behind your back and want to see the result on the LCD.

So, shoot the same scnery, same illumination with metering based on different ISOs, and verify the actual, i.e. raw exposure. You can use Rawnalyze, but you have to convert the raw file in DNG (Adobe's DNG converted does this very fast).

If you know, which ISO setting reflects the raw data state the closest, stick to that. Meter and shoot with that setting, as long as you can. If the light is not enough, the shutter would have to be too long, reduce the exposure with bias, and be aware, that you are now working with "ISO 400" or "ISO 800".

The ISO 800 image of Buy's bathroom with the P45+ was almost three stops lower exposed than the very right. When you process that in ACR, it becomes increased by 2 EV. That is quite noisy already (though the noise is nice). Two stops from the right edge is quite good.

If C1 treats your images as clipped, even though they are not, and you can't help with exposure/brightness correction (I don't know, how C1 is acting in such circumstances), then go with a lower ISO; that makes C1 believe, that higher pixel values are "acceptable".

Finally, pls post a raw file of whatever with whatever setting, except a black frame, only as technical reference for me. I am hunting for the error, which I noticed in the raw file of the P30+ posted above by 203.
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Gabor
Dale Allyn
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« Reply #73 on: June 21, 2008, 10:29:34 PM »
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I'm sorry, I did not recognize your tag from other forums.
No problem at all. For some reason I used a slightly different screen name. And besides, no one expects people to keep track of everyone on the web.
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The ISO setting has to roles:

1. evaluation of the necessary exposure,

2. instruction of the raw processing.

You should figure out, which setting yields the most accurate metering. Try to achieve ETTR using the in-camera histogram. If the P25+ displays a raw histogram, that's great. Using a neutral WB (Uni-WB) is not an option, if your customers are standing behind your back and want to see the result on the LCD.

So, shoot the same scnery, same illumination with metering based on different ISOs, and verify the actual, i.e. raw exposure. You can use Rawnalyze, but you have to convert the raw file in DNG (Adobe's DNG converted does this very fast).

If you know, which ISO setting reflects the raw data state the closest, stick to that. Meter and shoot with that setting, as long as you can. If the light is not enough, the shutter would have to be too long, reduce the exposure with bias, and be aware, that you are now working with "ISO 400" or "ISO 800".

The ISO 800 image of Buy's bathroom with the P45+ was almost three stops lower exposed than the very right. When you process that in ACR, it becomes increased by 2 EV. That is quite noisy already (though the noise is nice). Two stops from the right edge is quite good.

If C1 treats your images as clipped, even though they are not, and you can't help with exposure/brightness correction (I don't know, how C1 is acting in such circumstances), then go with a lower ISO; that makes C1 believe, that higher pixel values are "acceptable".

Finally, pls post a raw file of whatever with whatever setting, except a black frame, only as technical reference for me. I am hunting for the error, which I noticed in the raw file of the P30+ posted above by 203.
[a href=\"index.php?act=findpost&pid=202773\"][{POST_SNAPBACK}][/a]

Thanks for these details. I was under the impression that the P25+ uses a base or native ISO of 50, but I could be wrong. I will do some testing.

I'm not using ACR for any Phase files at this point. They're simply better looking when processed with C-1 (IMO). I can get them close with ACR, but it requires a bit more effort.

Re. Rawnalyze: I'm a Mac user, so I don't believe that option is available to me.

And to clarify: Guy's ISO 800 shots in his bathroom were captured with the P25+ back, not the P45+ (just to keep the details in line).

Regarding a raw file to be posted: do you want it with no clipping; histogram mostly right; histogram centered; doesn't matter as long as it's not black?

Dale
« Last Edit: June 21, 2008, 10:38:09 PM by DFAllyn » Logged

Panopeeper
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« Reply #74 on: June 21, 2008, 10:56:36 PM »
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Re. Rawnalyze: I'm a Mac user, so I don't believe that option is available to me.
Someone will test it with Crossover in the coming days. (But Crossover is not for free.)

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Guy's ISO 800 shots in his bathroom were captured with the P25+ back, not the P45+
The P45 was a typo. I saw that you too have the P25+.

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Regarding a raw file to be posted: do you want it with no clipping; histogram mostly right; histogram centered; doesn't matter as long as it's not black?
If you have one with something in the very shadow, that's the best (like the softbox or the bag in the above shot).
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Gabor
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« Reply #75 on: June 22, 2008, 12:44:59 AM »
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I am pretty sure, that you don't know, that your back does not have different ISOs; the ISO setting is imaginary. Don't be upset, this is very good so, I would be happy to have my camera that way.

[a href=\"index.php?act=findpost&pid=202769\"][{POST_SNAPBACK}][/a]

It is not necessarily very good, unless Phase One have managed to eliminate the noise from amplification and ADC.  Amplification in software after the fact also amplifies all sources of noise in the file.  The earlier the ISO amplification is in the signal processing chain, the fewer additional noise sources are amplified along with the image data.
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« Reply #76 on: June 22, 2008, 12:51:12 AM »
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Re. Rawnalyze: I'm a Mac user, so I don't believe that option is available to me.

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Someone will test it with Crossover in the coming days. (But Crossover is not for free.)

[a href=\"index.php?act=findpost&pid=202781\"][{POST_SNAPBACK}][/a]

I was able to get Rawanalyze to work under Crossover Mac, at least its basic features were in place.  But what made the purchase of Crossover a no-brainer for me was that it runs IRIS
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Ray
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« Reply #77 on: June 22, 2008, 01:04:06 AM »
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I am pretty sure, that you don't know, that your back does not have different ISOs; the ISO setting is imaginary. Don't be upset, this is very good so, I would be happy to have my camera that way.
[a href=\"index.php?act=findpost&pid=202769\"][{POST_SNAPBACK}][/a]

Gabor,
Have I misunderstood the basic process that Canon employs to achieve low noise at high ISO, a process which many digital cameras, I believe, do not employ and as a result do not achieve such low noise at high ISO?

As I understand it, the Canon CMOS sensor includes a miniature analog pre-amplifier at every photosite, which responds to the ISO setting and applies a set amount of gain to the analog signal before it's converted to digital.

The consequence of this analog preamplification is that subsequent 'system' noise from that point on, is less in proportion to the original amplified signal and S/N is improved as a result.

A similar (but not precise) audio analogy would be Dr Dolby's brilliant noise reduction system for miniature tape recorders, wherein the audio signal before it's recorded on the tape, is amplified at the frequencies which are similar to the tape recorder's system noise (tape hiss), then on playback the signal is reduced back to normal at the precise frequencies it was previously boosted, together with the tape hiss.

I see no advantage in post A/D ISO creation in place of pre-A/D analog boost.
« Last Edit: June 22, 2008, 01:07:12 AM by Ray » Logged
Ray
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« Reply #78 on: June 22, 2008, 01:26:12 AM »
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Actually, the image on the left looks poorly processed (no offense intended). There's a magenta cast to the apple and to the letters on the Coke can. [a href=\"index.php?act=findpost&pid=202767\"][{POST_SNAPBACK}][/a]

Both images were initially processed the same way in ACR with the eyedropper used on the grey card to create a more accurate WB, and shadows and contrast sliders set to zero.

In the initial comparisons I posted, the 1Ds3 apple displays weaker reds but more detail on the apple skin. I hear the comment of weaker reds quite frequently when MFDB images are compared with 35mm images. I just increased the strength of the red apple in PS. If weak reds are a problem, then a specific calibration for the camera, in ACR, should be carried out. I haven't bothered to do that for my own cameras, but I do wonder if people who find ACR unsatisfactory might change their mind if they did a calibration.
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« Reply #79 on: June 22, 2008, 02:05:11 AM »
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Gabor,
Have I misunderstood the basic process that Canon employs to achieve low noise at high ISO, a process which many digital cameras, I believe, do not employ and as a result do not achieve such low noise at high ISO?

As I understand it, the Canon CMOS sensor includes a miniature analog pre-amplifier at every photosite, which responds to the ISO setting and applies a set amount of gain to the analog signal before it's converted to digital.

The consequence of this analog preamplification is that subsequent 'system' noise from that point on, is less in proportion to the original amplified signal and S/N is improved as a result.

A similar (but not precise) audio analogy would be Dr Dolby's brilliant noise reduction system for miniature tape recorders, wherein the audio signal before it's recorded on the tape, is amplified at the frequencies which are similar to the tape recorder's system noise (tape hiss), then on playback the signal is reduced back to normal at the precise frequencies it was previously boosted, together with the tape hiss.

I see no advantage in post A/D ISO creation in place of pre-A/D analog boost.
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My understanding is different.  There is fairly good evidence that Canon employs a standard variable gain amplifier (VGA) off the sensor to implement ISO; two in fact, one for the "main" ISO's 100-200-400-800-1600 etc, and a second one to implement "in-between" ISO's; see

[a href=\"http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/noise-p2.html#read_vs_iso]http://theory.uchicago.edu/~ejm/pix/20d/te...tml#read_vs_iso[/url]

Low noise at high ISO is a result of low noise in the circuitry involved in reading out the sensor to the VGA, it seems to me.  It also seems to me that they would do better using a single VGA for all ISO; this would eliminate the anomalously large read noise that makes in-between ISO's not much better than underexposing at the next lowest "main" ISO.
« Last Edit: June 22, 2008, 02:07:10 AM by ejmartin » Logged

emil
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