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Author Topic: D3, 1DsMKIII, D300  (Read 33411 times)
Mark D Segal
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« Reply #80 on: December 13, 2007, 09:57:43 AM »
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Thanks Ray, good to hear it's resolved.
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
brethogan
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« Reply #81 on: December 13, 2007, 06:42:42 PM »
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On first glance, I had assumed that those were hookers, but then I saw your note that they were transvestites. Maybe still hookers, but not the type a normal guy would be interested in. Anyway, I certainly appreciate your humor   .

Bill
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One wonders how much it cost Ray to learn their little secret.
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John Sheehy
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« Reply #82 on: December 13, 2007, 07:34:08 PM »
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Sorry, I didn't see your post until today.

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I suppose in a sense one could describe all ISO settings in digital cameras as fake, or bogus. The sensitivy of the light gathering capacity of the photoreceptors does not change with changing ISO settings.

Not of the photoreceptors, but as far as the product of the camera is concerned, ISOs can be very different in the shadows due to read noise differences.  Trying to use the bottom 1/16th of the sensor's range at ISO 100 instead of at ISO 1600 leads to a relatively poor capture with some cameras.

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At a fundamental level, there is only one ISO sensitivity in a digital camera and only one best and correct exposure for maximum S/N and highest dynamic range.

All ISO settings higher than base ISO (which is ISO 125 for the Canon 5D and ISO 200 for the D3) merely represent the camera's attempts to compensate for underexposure.

The 5D is more like ISO 84.  It actually meters and has enough headroom for the RAW data at ISO 120 when it is set to 100, but it has more headroom available in the sensor for its "ISO 50" (metered for ISO 60, and has only enough headroom to be a minimum of about 84).

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When I set my 5D to ISO 3200, I'm really just sending an instruction to the camera's processor that subsequent shots will be underexposed by 5 stops. If I'm shooting RAW I don't have any control over the way the camera's built-in processor will compensate for such underexposure.

No, but I believe it does use a different amplification at the photosites for ISOs 50, 100, 200, 400, 800, and 1600, with a consequent different in absolute noise floor.

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Another way of looking at this is that fundamentally the difference between the 5D and the D3 is that the 5D will only accept instructions (from the user) on how to deal with 5 stops of underexposure, where as the D3 will accept instructions on how to deal with as much as 7 stops of underexposure. (It's a more advanced robot   ).

True, but in type, they seem to be similar; different ISOs by different gains (at the photosites) for multiple ISOs, unlike all compact cameras and most other Nikons and other brands of DSLR, which only seem to vary gain (if at all) before going into the ADC.

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But I've got my own way of compensating for underexposure, so I think it's perfectly legitimate for me to say the following shot was taken at ISO 256,000.

I don't think you can really say that, because you collected photons multiple times.  There is no real difference (except in read noise) between shooting one frame at 9 seconds and 9 frames at 1 second.  Your ISO is 256000 divided by nine, if you took nine exposures.  I have not yet investigated the difference between additive stacks and median stacks (I just have assumptions, such as median possibly being more accurate when you have a lot of wild, stray, extreme values in your system, and that additive potentially increases bit depth while median does not, meaning that median will be more likely to lead to quantization), but I am pretty certain that it is a bit of a stretch to identify the exposure index of a median stack by an individual exposure.

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That's a total of 10 stops of underexposure, the first 5 handled by the camera's processing and the additional 5 handled by me and photoshop   .

How is this possible considering the 5D only has about 10 stops of DR or less?

ISO 100 has that limitation; the sensor doesn't.  5D ISO 1600 goes about 2.5 stops deeper than ISO 100 for usable signal, in an absolute sense.  If you could get the quality of readout at ISO 100 in its very deepest shadows that you get of the same absolute levels at ISO 1600, you would have an amazing ISO 100.

Then, as I implied, your exposure index is really the sum of the ISOs of the individual shots.

And let's not forget, most of these measures of dynamic range assume 100% pixel view, or nearly so.  These DR values don't mean that you can't separate half a frame that is black from half a frame that is white, but 20 stops below sensor saturation by binning down to two pixels!

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I noticed this defect when I tested my second copy of the 5D. The first copy had unacceptable banding in deep shadows. I returned the camera and found the second one was better regarding the ugly banding, but had this defective corner. I considered returning the second camera, but decided against it on the grounds that possibly all 5D sensors would have one defect or another. This was a budget Full Frame sensor after all.

I'm sure it could be calibrated out, but none of the common converters allow that, AFAIK.  It's probably just a blackpoint issue, and with Canon's blackpoint offset in their RAW files, you could probably calibrate it out without losing anything near black.

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The fourth image is the 100% crop showing a fair amount of noise. What would you say, film at ISO 800?
[a href=\"index.php?act=findpost&pid=159652\"][{POST_SNAPBACK}][/a]

I don't remeber exact film qualities.  Last time I shot film was 1976-1981.
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Ray
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« Reply #83 on: December 13, 2007, 07:35:52 PM »
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One wonders how much it cost Ray to learn their little secret.
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Hardly anything. A few drinks at the most. These guys are usually very willing to be photographed because they are so proud of their transformation.

[attachment=4237:attachment]
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Ray
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« Reply #84 on: December 13, 2007, 08:30:02 PM »
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I don't think you can really say that, because you collected photons multiple times.  There is no real difference (except in read noise) between shooting one frame at 9 seconds and 9 frames at 1 second.  Your ISO is 256000 divided by nine, if you took nine exposures.  I have not yet investigated the difference between additive stacks and median stacks (I just have assumptions, such as median possibly being more accurate when you have a lot of wild, stray, extreme values in your system, and that additive potentially increases bit depth while median does not, meaning that median will be more likely to lead to quantization), but I am pretty certain that it is a bit of a stretch to identify the exposure index of a median stack by an individual exposure.
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John,
Actually they were stacked in mean mode. I haven't done any comparisons between median and mean yet.

I take your point that it really is cheating to pretend that 9 stacked ISO quarter of a million shots constitute a genuine ISO 256,000 shot.

Here's is the first of those 9 shots showing all the striations in their full glory.

Hhmm! This is beginning to look like one of Edmund's underexposed P45+ shots at ISO 800   .

[attachment=4238:attachment]
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John Sheehy
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« Reply #85 on: December 13, 2007, 10:14:39 PM »
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John,
Actually they were stacked in mean mode. I haven't done any comparisons between median and mean yet.

I take your point that it really is cheating to pretend that 9 stacked ISO quarter of a million shots constitute a genuine ISO 256,000 shot.

Here's is the first of those 9 shots showing all the striations in their full glory.

Hhmm! This is beginning to look like one of Edmund's underexposed P45+ shots at ISO 800   .

[attachment=4238:attachment]
[a href=\"index.php?act=findpost&pid=160549\"][{POST_SNAPBACK}][/a]

Yeah, well, I'm getting the impression that the backs, in general, are really only made for base ISO and just offer high ISO as an afterthought.  The Sinar 22MP that someone linked to a RAW from in one of these forums - it performed very well at ISO 25, as you would expect, but I measured only about 38000 photons for it, full-well.  Probably has no microlenses, and the color filters are probably very sharp for good color discrimination (but losing a lot of light).

Your striations are probably fairly removable with a RAW file.

If you link to the RAW of that file, I can show you what can be done with it.
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Ray
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« Reply #86 on: December 15, 2007, 01:06:56 AM »
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Your striations are probably fairly removable with a RAW file.

If you link to the RAW of that file, I can show you what can be done with it.
[a href=\"index.php?act=findpost&pid=160564\"][{POST_SNAPBACK}][/a]

Thanks for the offer, John. However, I'm not subscribed to any site such as ''Yousendit" I could link to.

As Bill suggested, it would be better to use a tripod for a shot like this. I did in fact return last night with my very compact and lightweight Manfrotto and luckily found the temple gates open. (Perhaps some novice was being slack in his duties   ).

Here's a 30 second exposure at ISO 400 and f11, plus a lightened version and a crop of the darkest part, bottom left corner showing surprisingly little noise.

[attachment=4267:attachment]  [attachment=4268:attachment]  [attachment=4269:attachment]

I also took a shorter exposure at ISO 1600 which also shows surprisingly little noise. Phwoar!  

[attachment=4270:attachment]
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Ray
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« Reply #87 on: December 15, 2007, 01:48:59 PM »
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Hi! John,
I've just discovered Yousendit have a free trial option. Below is the link to one of my genuine ISO 256,000 shots, give or take half a stop for error of assessment   .

I'd be interested to learn if your method of removing the striations is as effective as stacking. I imagine that, after removing the striations it would not be possible to get much further benefit from stacking. Would this be right?

 http://www.yousendit.com/download/www/YVJZc2ZFMVhVbS9IRGc9PQ
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Eric Myrvaagnes
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« Reply #88 on: December 15, 2007, 02:27:12 PM »
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That's a gorgeous picture (the one at 30 seconds, f/11, ISO 400). But the lightened one is lightened too much. That probably means you need to get a better laptop (with a calibrated monitor).  
« Last Edit: December 15, 2007, 02:29:19 PM by EricM » Logged

-Eric Myrvaagnes

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Ray
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« Reply #89 on: December 15, 2007, 03:06:51 PM »
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That's a gorgeous picture (the one at 30 seconds, f/11, ISO 400). But the lightened one is lightened too much. That probably means you need to get a better laptop (with a calibrated monitor). 
[a href=\"index.php?act=findpost&pid=160900\"][{POST_SNAPBACK}][/a]

Thanks, Eric. The second one was deliberately lightened to show off the lack of noise and to create that sensation of heaven, where we all go when we die   .

This choice of venue to demonstrate noise issues was particularly appropriate because some of the temples in Chiang Mai are amazingly quiet places. They are usually surrounded by thick, high walls which very successfully block out the noise from a continuous stream of honking, motor revving traffic, just a few feet away in this case.
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Eric Myrvaagnes
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« Reply #90 on: December 15, 2007, 11:16:00 PM »
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... to create that sensation of heaven, where we all go when we die   .
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That's an oversimplification, Ray. There are at least two places we all go when we die. One is Canon Heaven (a.k.a. Nikon Hell), and the other is Nikon Heaven (a.k.a. ... ,    )
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-Eric Myrvaagnes

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Ray
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« Reply #91 on: December 15, 2007, 11:24:08 PM »
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That's an oversimplification, Ray. There are at least two places we all go when we die. One is Canon Heaven (a.k.a. Nikon Hell), and the other is Nikon Heaven (a.k.a. ... ,    )
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Eric,
As long as Nikon lenses are provided, I don't mind which heaven   .
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Rob C
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« Reply #92 on: December 16, 2007, 04:51:02 AM »
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So, then: Superheaven uses Leica glass?

Rob C
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