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Author Topic: Ten Years after….  (Read 10001 times)

Theodoros

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Re: Ten Years after….
« Reply #80 on: February 19, 2014, 06:10:45 PM »

My apologies for the tangent in the conversation; back you your original topic:I have seen no visual evidence of this claim that those older (and noisier) 22MP CCD sensors give better shadows or less noise than modern high resolution CCDs (let alone the coming wave of medium format CMOS sensors) in any relevant comparison of "end products", meaning viewing prints or on-screen images from various cameras at the same size. Because printing (or otherwise displaying) an image with more pixels at the same size and thus at higher PPI increases the SNR of the signal received by the viewers' eyes and improves the fineness of perceived tonal range, cleanness of shadows and such; this is due to "dithering", roughly speaking. This benefit of "more pixel per image" has to be offset against the engineer's measure of the DR of the individual pixels.

A familiar illustration is seen in comparisons between prints of the same size made using the same film emulsion in different formats: the emulsion in each case has the same "DR", but the larger prints with a lower degree of enlargement show improved tonality and cleaner shadows.

P. S. Traditional silver halide negatives have a "per pixel DR" of about 1: if you look close enough, the pixels are all either pure black (silver from an exposed silver halide crystal) or white. All tonal gradations seen are due to "dithering" of that information, due to the size scale of the "pixels" being far below what the eye can resolve.
A usual mistake we do, is to compare "memories" we have with modern equipment… The older backs have improved a lot from modern software… actually all backs have improved - but the older the back, the more evident the improvement. Please check this for DR… there was no other reason I shot it, but to test imacon 528c for DR in single shot.
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BernardLanguillier

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Re: one more time: these are not differences in _sensor_exposure_ at all
« Reply #81 on: February 19, 2014, 07:24:03 PM »

I agree that there is noting wrong with the approach but let me try to get this across one more time:
there is no difference in the exposure received by the sensor, so describing it as under-exposure is flatly wrong, and misleading.
Thus there is no deviation from "supposed ideal ETTR exposure."
The differences are just in the subsequent positioning of the numeric raw levels, so are essentially just different ways of using discrete numerical levels to encode the signal from the sensor.

Let's compare two situations, leaving DSLRs aside:
1. Camera A where an exposure of 1/60 sec at f8 and ISO 100 results in highlights using the highest possible values in the raw file, just short of clipping, the so called ETTR. Let's assume, by chance, that the level of illumination used in this test is the one defined by the ISO standard,
2. Camera B, say an IQ280, with the exact same exposure results in the raw values being 2 stops short of the brightest possible values in the raw file.

I could be wrong, but according to my understanding of the definition of ISO in digital defined in ISO Standard 12232, sensor sensitivity, rated by its ISO number, is related to the exposure necessary to saturate the camera. Which means to reach the highest possible raw values.

According to this definition, the actual digital ISO of Camera B is lower than 100 when ISO100 is dialed in camera.

For all practical matters, this is similar to what film companies used to do when they rated Velvia at 50 while it was actually an ISO40 film. The purpose was to expose the film less than the camera thought in order to avoid blowing highlights and saturating colors more, in other words under-expose the film.

I fail to see how the approach used by Phaseone is not about under-exposing the sensor per the ISO definition of what ISO rating is.

Now, I believe that the approach used with camera B:
1. Results in more ability to brighten highlights in post processing without running into clipping, which is seen by most photographers as a great thing,
2. Results in shadows having less raw values available per shadow stop, which is not that great for advanced users who would probably want to tap better in the DR potential of their camera, but is still not a disaster.

Now, what part are you not in agreement with?  :)

Cheers,
Bernard
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BJL

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Re: Ten Years after….
« Reply #82 on: February 19, 2014, 10:38:44 PM »

Bernard,
There are so many errors in your post, and we are so far off the topic of his thread that I propose to respond by starting another thread on the whole subject of misunderstanding of the multiple ISO 12232 defined measures of (1) exposure index, (2) recommended MINMUM usable exposure index based on highlight handling and (3) recommended MAXIMUM exposure index based on shadow handling ... Along with your persistent failure to see he difference between how much exposure the SENSOR gets and how much that signal I s subsequently AMPLIFIED in order to produce the raw levels. Meanwhile, I suggest reading a bit about ISO 12232: there is a decent Wikipedia page.
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Theodoros

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Re: Ten Years after….
« Reply #83 on: February 20, 2014, 03:03:37 AM »

If I may, isn't exposure required to just protect HLs from blowing different for different developers? …and isn't it different from past developers to the modern versions of them? Another thing… isn't exposure relevant to the lens flare resistance? I mean a prone to flare lens limits mid tone contrast, while a flare resistant lens improves it… obviously the later is easier to expose for HLs, since the first one will lead to a dull/unprintable image… Now coming back to the subject… aren't "fat pixel" backs better with lenses when wide open? And… (especially with the Kodak sensor) don't the "fat pixel" backs have more contrasty (and linear) mid tones in their raw (which is exactly what some people call the "fat pixel magic")?
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BernardLanguillier

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Re: Ten Years after….
« Reply #84 on: February 20, 2014, 03:06:03 AM »

Bernard,
There are so many errors in your post, and we are so far off the topic of his thread that I propose to respond by starting another thread on the whole subject of misunderstanding of the multiple ISO 12232 defined measures of (1) exposure index, (2) recommended MINMUM usable exposure index based on highlight handling and (3) recommended MAXIMUM exposure index based on shadow handling ... Along with your persistent failure to see he difference between how much exposure the SENSOR gets and how much that signal I s subsequently AMPLIFIED in order to produce the raw levels. Meanwhile, I suggest reading a bit about ISO 12232: there is a decent Wikipedia page.

Sure, no problem.

Cheers,
Bernard
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eronald

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Re: Ten Years after….
« Reply #85 on: February 20, 2014, 08:06:52 AM »

Now why again are you all beating this horse cadaver?

Edmund
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BJL

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Re: Ten Years after….
« Reply #87 on: February 20, 2014, 01:10:53 PM »

Sure, no problem.

Cheers,
Bernard

Here is it: mostly some facts on what the two most relevant standards organizations (the International Organization for Standardization [ISO] and the Camera and Imaging Products Association [CIPA]) say about measuring and reporting on exposure index, sensitivity etc.: http://www.luminous-landscape.com/forum/index.php?topic=87439.msg711760#msg711760

Not that this is very likely to change opinions on how MFD backs should operate, but at least I hope to stop people making flatly false claims about what ISO says, what the "ISO speed" of a camera means, and so on.
« Last Edit: February 20, 2014, 01:14:22 PM by BJL »
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Theodoros

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Re: Ten Years after….
« Reply #88 on: February 20, 2014, 01:49:40 PM »

Here is it: mostly some facts on what the two most relevant standards organizations (the International Organization for Standardization [ISO] and the Camera and Imaging Products Association [CIPA]) say about measuring and reporting on exposure index, sensitivity etc.: http://www.luminous-landscape.com/forum/index.php?topic=87439.msg711760#msg711760

Not that this is very likely to change opinions on how MFD backs should operate, but at least I hope to stop people making flatly false claims about what ISO says, what the "ISO speed" of a camera means, and so on.
You are right of course on what the setting for ISO should be… but, (why there is always a but in engineering?  ???) with digital, things get a bit more complicated… a sensor receives light on all its surface and that includes corners... ;D (you see where I'm getting at… but its more  ;)), then there is the fact that people use different focal lengths…. and then… (especially) the older backs are designed to be used with different cameras and different batch of lenses with each one of them… Now these different lenses have also different rear (last) element too and quite often it differs in size…. Remember when Sinar increased the noted sensitivity on their E-motion backs by one stop (on 22, 54lv, 75 & 75lv) without altering anything on signal amplification?  :) Guess why?  ::) …. The 22mp backs are among the best in DR if exposed right… and what "right" is, should be found from the owner depending on the scene… If he masters the sensitivity with respect to the situation and the distribution of light across the scene (which he should if he is a photographer), the results can be excellent.
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BJL

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Re: Ten Years after….
« Reply #89 on: February 20, 2014, 02:09:17 PM »

You are right of course on what the setting for ISO should be… but, (why there is always a but in engineering?  ???) with digital, things get a bit more complicated ...
What are you talking about? The standards ISO 12232-2006 and CIPA DC-004 that I mention are all specifically for Digital Still Cameras, so how can digital make things "a bit more complicated"?
And since the topic is exposure index, ISO speed, and ISO speed latitude, your talk about different focal lengths and back designs is irrelevant.

P. S. There is of course at least one argument for still using a 22MP sensor back: cost. It is the least expensive way to get a format as big as 48x36mm, which has some advantages over smaller formats like 44x33mm, like less of the enforced cropping of the image from lenses designed for 645 format.
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Theodoros

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Re: Ten Years after….
« Reply #90 on: February 20, 2014, 02:44:02 PM »

What are you talking about? The standards ISO 12232-2006 and CIPA DC-004 that I mention are all specifically for Digital Still Cameras, so how can digital make things "a bit more complicated"?
And since the topic is exposure index, ISO speed, and ISO speed latitude, your talk about different focal lengths and back designs is irrelevant.

P. S. There is of course at least one argument for still using a 22MP sensor back: cost. It is the least expensive way to get a format as big as 48x36mm, which has some advantages over smaller formats like 44x33mm, like less of the enforced cropping of the image from lenses designed for 645 format.
What I'm talking about is that photons are not received evenly across the sensor area (and this is affected by lenses and their design too), while sensitivity is an average on the whole sensor area….
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DavidP

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Re: Ten Years after….
« Reply #91 on: February 20, 2014, 04:53:29 PM »

I found Moire to be a huge issue with the P-25 sensor with the type of photography I do. Mostly in clothing, always seemed  to be popping up and could be very difficult to clean up. With the later backs it has become almost a non issue. If you are shooting things with fabric you would be better off with the D800
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Theodoros

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Re: Ten Years after….
« Reply #92 on: February 20, 2014, 05:07:11 PM »

I found Moire to be a huge issue with the P-25 sensor with the type of photography I do. Mostly in clothing, always seemed  to be popping up and could be very difficult to clean up. With the later backs it has become almost a non issue. If you are shooting things with fabric you would be better off with the D800
True… fabric structure pro work is where "fat-pixel" backs should be avoided… Well, nothing is perfect in this world.  :D
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tho_mas

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Re: Ten Years after….
« Reply #93 on: February 20, 2014, 05:46:29 PM »

How do they compare with film?
I have yet to see a digital file that is as film-like as the P21+... especially at somewhat higher ISO. I mostly use a P45. But when I shoot the P21+ again and again I am very impressed by its very nice look.

Are those 22mp "fat pixel" backs that people used to buy (at those days) at prices similar to a good quality family car still worth buying?
Currently I have a P45 and P21+ (on Contax 645 and Cambo WRS), a Sony A7R, a Panasonic GH2 and GH3 (well, actually just sold the GH3) and some pocket cameras. If I had to choose only one single system today I'd most likely choose a tech cam with a 33MP or 39MP back. (Or, of course, a more recent back... but that was not the initial question...).
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Theodoros

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Re: Ten Years after….
« Reply #94 on: February 21, 2014, 02:58:15 AM »

I have yet to see a digital file that is as film-like as the P21+... especially at somewhat higher ISO. I mostly use a P45. But when I shoot the P21+ again and again I am very impressed by its very nice look.
Currently I have a P45 and P21+ (on Contax 645 and Cambo WRS), a Sony A7R, a Panasonic GH2 and GH3 (well, actually just sold the GH3) and some pocket cameras. If I had to choose only one single system today I'd most likely choose a tech cam with a 33MP or 39MP back. (Or, of course, a more recent back... but that was not the initial question...).

As I stated before, I would also choose a Dalsa 33mp sensor as my first choice… but that's not "ten years after" yet! I believe your P21+ is also a "fat pixel" (9μm) back that only has different image area size (it's 33x44 …no?), it has micro lenses and it's a stop more sensitive… I wouldn't be surprised if it behaves like a 22mp back, with more contrasty mid tones and great colour information in the deep shadows that is what you call "film like" presentation and others call it the "fat pixel magic".
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