And she points out...
"... this only applies to the D200 (and D80?). I haven't tested the D70-class body, and I already know that the D2H/D2X are a bit better than the D200" She's also only speaking to the "
The brightness curve on the viewfinder" and how it relates to the FoV of the Muti-cam unit at the base of the Mirror-box. A bit unrelated to if one can see changes in DoF when looking through the viewfinder (at wide apertures). By the examples here, obviously we can see DoF affects through the viewfinder even at small apertures.
I thought that you'd be wise enough to get the STRONG hint that this sub-thread had run its course and that there was no point in extending it.
You do seem intent on extending it. Good discussion so I understand.
No, it's YOU that's going out of your way to extend it. But if that's what you're determined to do I'll accommodate you, at least for a short while.
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But you weren't and went further, beyond the pale by putting your own words in Marianne's mouth.
Not sure I understand...Just pointing out what she said and was discussing... looking at the full context.
Nonsense. There's no full context that has anything to do with the inability to see the full brightness through the OVF with very large aperture lenses.
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What appears as bold text inside quote marks is what she wrote, but nothing in that reply said anything about how it relates to the FoV of the Multi-Cam unit at the base of the mirror box.
Actually it does, in the broader context of the original thread she was contributing to, ...as she pointed out "There is a silver lining to this cloud, though:
Illumination to the AF system should continue improving as lens aperture widens, so we can at least have that benefit of fast lenses" I was indeed looking at it from some of the follow ups she posted. That was from 2006 and she really expanded on the topic since that time.
You still don't understand and this is very disappointing. The light that's used by the AF system DOES NOT reach the camera's metering sensor. The system that's responsible for the OVF limitation that is under discussion is the metering sensor, NOT the AF module that contains several AF sensors. The light that reaches the metering sensor is not reflected back towards the AF module.
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Remember in the 2006 thread she's only measuring light level and not DoF.
Then you don't have the faintest understanding of _why_ she was measuring the light level, i.e., the engineer's way of finding a different way of showing that unlike film SLR focus screens (that don't limit brightness), DSLR focus screens prevent light from lenses faster than about f/3.2 from making it past the focus screen to the eye behind the OVF, and those measurements compare the way visual brightness in the OVF changes uniformly and predictably with aperture changes, until the aperture is opened wider than about f/3.5, when the brigtness changes essentially change to zero as the apertures are opened up even more.
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In viewfinder photography, exposure is measured from light falling not on the image sensor but on a ded-icated metering sensor, which may produce results that differ from those obtained during live view.
http://imaging.nikon.com/lineup/dslr/basics/18/02.htm
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This dedicated metering sensor (array) is located in the top of the camera, near the camera's prism. It should NOT to be confused with the AF sensors that are located in the AF module which is found near the bottom of the DSLR's mirror box, which is not in any way near the metering sensor.
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More from Nikon :
Metering (Viewfinder Photography)
Metering is used to measure the brightness of the subject. The camera optimizes exposure by adjusting shutter speed, aperture (f-number), and ISO sensitivity according to the brightness of the subject, which is measured using the camera's built-in metering sensor. The camera does not simply measure the overall brightness of the frame, but measures brightness separately in multiple areas of the frame. The metering mode determines which areas of the frame are used by the camera to measure subject brightness and how the camera sets exposure. Normally the camera uses matrix metering, in which it divides a wide area of the frame into multiple segments and sets exposure based on a variety of information, including subject brightness and color. You can also choose center-weighted metering (in which the camera assigns the greatest weight to the center of the frame) and spot metering (in which the camera meters the area around the selected focus point).
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http://imaging.nikon.com/lineup/dslr/basics/18/01.htm
The above photo is what a metering sensor looks like. This is an AF sensor module which contains phase detect optical elements :
Accurate AF detection is crucial for extremely high-resolution still images in every situation. The 51 sensor points in the D800/D800E's AF sensor module ...
https://www.google.com/imgres?imgur...d=0ahUKEwjWw5vGxJzLAhXG2R4KHWf9CVkQMwgdKAAwAA
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And unlike the metering sensor (which is located at the top of the DSLR, the AF module is (as already noted) located near the bottom of the mirror box, like this :
http://i307.photobucket.com/albums/nn290/CougarWilbur/800px-E-30-CutmodelAF2.jpg
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And now we have another amazing thread where Marianne Oelund extensively describes and shows the makeup of an AF module in several replies. This is from one of her replies :
There are several apertures pertinent to the AF system: Main lens aperture, field lens mask (defines the portion of the image projected onto the AF sensor chip) and separator lens mask (defines areas within the main lens exit pupil from which light can be received by the AF system). The latter two of these have no equivalent in the metering system.
The field masks have to be larger than the AF operating aperture to allow 10 images (2 for each of 5 AF points) on each of 3 vertical detection lines to be detected within the central AF block area via the pair of fixed position vertical operating masks.
There are only four images (and four separator lenses) serving all 15 of the central block of AF points. There are only two images (and two separator lenses) serving each of the lateral blocks of AF points:
Eight images projected onto the AF sensor, by eight separator lenses. Note the image outlines are defined by the field-lens masks.
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In the 51 point AF system there is just one compound lens used wide open on the front of the camera, the simple field lens and what Nikon describe "as a grain of rice size" apparently single element third lens used during AF acquisition.
The "grain of rice size" is the
aperture mask opening in front of each separator lens. Each of the eight openings shown in this photo of the mask is 0.6mm wide and about 1mm long:
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The separator lenses themselves are small, but much larger than the "grain of rice" apertures:
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and it continues, here :
http://www.dpreview.com/forums/post/54838048
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Other posts in this thread have interesting photos of the test equipment that Marianne Oelund used.
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"Effective" viewfinder aperture (different due to optical path/focus screen specifics) is why you see a much wider DoF though the Viewfinder than what the Sensor captures (not sure)...but you still see a subtle (very small) change in DoF (in the viewfinder) when stopping down from real f1.8 to f2.8 aperture using the Pv button.
You're still completely wrong here. I don't know why YOU are seeing these differences, but that may be because you haven't described your setup and methodology in a way that could be accurately duplicated by anyone else. Do that and I think that I might be able to spot what I believe to be your mistakes.
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Also, the D200 and My D7000 have a different viewfinder coverage percentage (affects "effective" aperture?) and differences in Viewfinder magnification may also play a part in seeing "DoF" changes with the Pv button. Must also be optic path differences model to model.
Just grasping at straws here with little to nothing to describe what you're doing. If not for the fact that you remain polite, I'd be tempted to describe your replies as containing "Trump Logic", i.e., "Proof by Assertion".
Now please, please end it. Reply one more time if you must, but realize that I will NOT respond to it.
Unless that is, you finally agree with what I've been saying. I have little hope that this will happen, though.
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That said (to simplify), I believe you are saying that you can not see any difference between f2.8 and f1.8 (in terms of DoF) when using the Pv button and looking through the Viewfinder. I believe you.
Yes.
Understandable, from your point of view
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I'm only saying that I can see a difference (in many shooting conditions)...and for that reason, the Pv button is not useless at wide apertures... for me.
I'll bet that you didn't do what I described, and that if I was standing next to you I'd have been able to point out your mistake(s).
(I normally wouldn't use a smiley in a place like this but it may help to convey my intentions).
If you actually made the bet...you would lose. I don't have a 35mm f1.8 though. Hope it was a small bet
Again, I don't think that we're about to agree on this anytime soon ..
No need as the examples are clear and repeatable to a degree. I can't but might be nice/interesting to set up a resolution target behind the plane of focus and check sharpness/MFT with something like Imatest...at different set apertures with the Pv Button. Seems that would be definitive? Would be interesting to compare FX vs DX bodies also
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My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)
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My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)
