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05-03-2010, 03:10 PM   #181
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QuoteOriginally posted by AndrewG NY Quote
Gee, I wonder if the industry will embrace this one?



Oh, nice. Put 'Camera' in the acronym so we can start seeing people redundantly write 'MILC Camera'.
I think the point is that not all camera's we designate 'EVIL' are actually EVILs, because they lack the EV. But yeah, neither acronym is really perfect.

05-03-2010, 03:38 PM   #182
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QuoteOriginally posted by kevinschoenmakers Quote
But yeah, neither acronym is really perfect.
In Germany, the term "system camera" seems to gain acceptance.

Originally, it was used as "Spiegellose Systemkamera" ("mirrorless system camera") and people started to drop the "mirrorless". "system camera" is also used to mean "mirrorless system camera" or SLR, so context is required. There is no commonly accepted abbreviation yet (but SLR was never abbreviated neither (Spiegelreflex).
05-03-2010, 03:42 PM   #183
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QuoteOriginally posted by falconeye Quote
A good start to read may be
https://www.pentaxforums.com/forums/459034-post21.html "Case A".
Thanks for that.

I'm still getting over the 100MP FF possibility and agonizing whether to upgrade my Mac Pro with 7 terabyte drive this would require.

What's the theoretical possible with APS-C?
05-03-2010, 03:45 PM   #184
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Its usually preferable to say what something is (EVF) not what it is not (mirrorless).

We'll probably have to wait for Canon to make up its mind

Although Sony and Samsung appear to have the jump on an APS-C EVILDSLRMILC

QuoteOriginally posted by falconeye Quote
In Germany, the term "system camera" seems to gain acceptance.

Originally, it was used as "Spiegellose Systemkamera" ("mirrorless system camera") and people started to drop the "mirrorless". "system camera" is also used to mean "mirrorless system camera" or SLR, so context is required. There is no commonly accepted abbreviation yet (but SLR was never abbreviated neither (Spiegelreflex).


05-03-2010, 05:21 PM   #185
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QuoteOriginally posted by Aristophanes Quote
I'm still getting over the 100MP FF possibility and agonizing whether to upgrade my Mac Pro with 7 terabyte drive this would require.

What's the theoretical possible with APS-C?
Since this post (more than a year old) I learned that the lens isn't the only limitation. Ability to focus precisely and deshake are mandatory to go to high resolutions and the mechanical precision with smaller lenses may be insufficient to focus precisely enough.

So, this may be academic. Anyway, the very best 35mm lenses outresolve 2Ám pixels (as found in a LX3) and would resolve ~100 MP (APS-C) and ~200 MP (FF). But only in the center region of the lenses. I already used a Zeiss 50mm lens at f/4 to resolve 1.5Ám details with decent contrast in a bee's eye, so the numbers are real (you have to turn the lens around and put in front of another lens for doing stuff like this...). But like I said, the practical limits are lower. I like to claim 40MP for APSC and 100MP for FF.
05-03-2010, 05:24 PM   #186
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QuoteOriginally posted by falconeye Quote
It is.

I hope my hard earned reputation saves me from explaining it yet another time

Just a hint for you ... a photon not hitting the front lens element will have a hard time to ever reach the sensor ... don't confuse iso with signal.


QuoteOriginally posted by Aristophanes Quote
Believe falconeye.

The f-stop is proportional to the sensor size, so if the sensor is smaller, then the f-stop measure is of a lesser physical diameter as well, meaning less light hitting the sensor.

In other words: f-stop is relative to sensor size. The focal length is a constant.

"crop factor" = cropped # of photons. Just because it is "Micro" 4/3, does not mean the photons are micro as well
This is not correct.

F-stop is not a function of sensor size, it is a function of the lens. It is a measure of the effective aperture, to regulate the amount of light passing to the inside of a camera. The light intensity is measured as light per unit area. This means that the light falling on, say, a 10mm x 10mm area is the same regardless of sensor area, for a given F-stop number and external light intensity. So if an F2.8 lens, wide open, exposes that 10mm x 10mm area of a FF sensor or a 4/3 sensor, the resulting area has exactly the same light intensity & exposure.

You are making the mistake of comparing the image circle size. For example, a FF F2 lens must throw a larger image circle than a 4/3 F2 lens. So while the light intensity over the area of the FF sensor is the same as the light intensity(light per unit area) over the area of the 4/3 sensor, the FF lens must cover the full area of the FF sensor. So the lens must be larger to accommodate the larger image circle, even though the F-stop number is the same.

For a 4/3 sensor:
"The 'crop factor' does affect the apparent depth of field of the taken image: with the magnification of 2, the DOF is effectively doubled (again, it is important to note that this perceived effect is due to the FOV 'crop'; the same depth of field is present, but you are viewing it at twice the magnification).

It is important to note that neither the light gathering ability of the lens, nor any of its traits are actually affected: a 50mm f2 lens on a 4/3rds body has the same f-stop as a 50mm lens on a 35mm camera. But the 4/3rds sensor only records the equivalent field of view of a 100mm lens."
From here:
Four Thirds - Camerapedia.org
05-03-2010, 05:29 PM   #187
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QuoteOriginally posted by dnas Quote
So 200mm F2.8 will provide the same light gathering capability on a FF as on a 4/3 sensor.
However, it is the DEPTH OF FIELD that differs, even though the same 200mm F2.8 is used.
Not quite. The lens does not know whether a FF sensor or 4/3 sensor or piece of film is at the end of its light path and thus treats all photons equally.

Imagine taking a photo with a FF camera, then removing the lens, lifting the mirror and masking the sensor with tape so that the exposed area is 4/3 sized. Put the lens back on and take a photo. The Depth of Field is the same.

What has changed though is the Field of View. So now your well-composed image is now horribly cropped. And now you have to go to a lens with a wider FOV to compensate for the smaller sensor - 100mm on 4/3 in your example above is equal to 200mm on FF.

But, 200mm F2.8 does not provide the same DOF as 100mm F2.8. Again, this has nothing to do with the size of the sensor at the focal plane but solely with the optical properties of the lens. That is where the DOF differences between sensor sizes lie, at equivalent FOVs, or as more commonly noted, equivalent FLs.
05-03-2010, 05:45 PM   #188
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QuoteOriginally posted by johnmflores Quote
Not quite. The lens does not know whether a FF sensor or 4/3 sensor or piece of film is at the end of its light path and thus treats all photons equally.

Imagine taking a photo with a FF camera, then removing the lens, lifting the mirror and masking the sensor with tape so that the exposed area is 4/3 sized. Put the lens back on and take a photo. The Depth of Field is the same.

What has changed though is the Field of View. So now your well-composed image is now horribly cropped. And now you have to go to a lens with a wider FOV to compensate for the smaller sensor - 100mm on 4/3 in your example above is equal to 200mm on FF.

But, 200mm F2.8 does not provide the same DOF as 100mm F2.8. Again, this has nothing to do with the size of the sensor at the focal plane but solely with the optical properties of the lens. That is where the DOF differences between sensor sizes lie, at equivalent FOVs, or as more commonly noted, equivalent FLs.
I was meaning that the DOF of the RESULTING image is different, because of the cropped image. DOF is related to magnification(FOV) and circle of confusion, as well as aperture. The crop(on a 4/3 sensor) modifies the FOV, so the resulting DOF on the captured image is not the same as it would be on FF with the same FOV and aperture.

05-03-2010, 07:11 PM   #189
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QuoteOriginally posted by falconeye Quote
BTW, of course it doesn't make a FF lens "slower" when used on APS, nor does it gain DOF. It's just a lens.
I know. The DOF is a function of the lens aperture and print size. FF/APS comes into play via sensor surface because the image recorded by the sensor is blown up in the print. I never said APS are different from FF lenses in terms of DOF - I just said the DOF perception will change when using a FF lens on an APS camera. I could have been more precise than stating one particular change, but making a simple statement about DOF is bound to have exceptions. Bob Atkins has written a nice article on DOF.

I have to read more carefully you article on lens equivalence - I've seen discussions around this concept before, but frankly, I don't find the topic very interesting - it's not my goal to use my lenses and get equivalent results as if I had a FF camera. I use them as best I can on the camera I have.
05-03-2010, 07:56 PM   #190
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QuoteOriginally posted by falconeye Quote
Since this post (more than a year old) I learned that the lens isn't the only limitation. Ability to focus precisely and deshake are mandatory to go to high resolutions and the mechanical precision with smaller lenses may be insufficient to focus precisely enough.

So, this may be academic. Anyway, the very best 35mm lenses outresolve 2Ám pixels (as found in a LX3) and would resolve ~100 MP (APS-C) and ~200 MP (FF). But only in the center region of the lenses. I already used a Zeiss 50mm lens at f/4 to resolve 1.5Ám details with decent contrast in a bee's eye, so the numbers are real (you have to turn the lens around and put in front of another lens for doing stuff like this...). But like I said, the practical limits are lower. I like to claim 40MP for APSC and 100MP for FF.
The economic problem here is PP processing power, and RAM, not to mention a law of diminishing returns. Are you going to invest in a a $1 billion fab to make chips for resolution needs that are at best theoretical, and maybe no necessary in a world where scrolling photos en masse is just as competing a priority as pixel peeping. With digital TV we're approaching the limits of what the average human eye can resolve following motion, so on to 3D gimmickry, made necessary when the basis of sales is a supposed never-ending supply of new tech advances.

Maybe we'll just aim a generic box with a super lens at the horizon, and then crop. We'll use our iPad screen to wirelessly select the object we want in the DOF and in-camera Photoshop will simply apply the correct bokeh exactly how we want it (Pentax FA 31mm effect please @ 2.8).

Or maybe it's academic. Thanks.
05-03-2010, 08:03 PM   #191
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@falconeye:

Well, I don't see the need for an elaborate lens equivalence concept that takes into account DOF, so I can't really follow the point you were trying to make in that article. No camera system was designed with a certain DOF in mind for a given focal length in a specific shooting scenario, so why would lens DOF equivalence be important to consider?

I also still don't understand your earlier statement around APS lenses needing to be faster. I would assume you meant to maintain this DOF equivalence, but then I still don't see how you can perceive a faster lens as a disadvantage and not worthy of the price increase.
05-03-2010, 09:26 PM   #192
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QuoteOriginally posted by Laurentiu Cristofor Quote
@falconeye:

Well, I don't see the need for an elaborate lens equivalence concept that takes into account DOF, so I can't really follow the point you were trying to make in that article. No camera system was designed with a certain DOF in mind for a given focal length in a specific shooting scenario, so why would lens DOF equivalence be important to consider?
But that *is* how camera systems are designed, especially the lens roadmaps. Do you think the 645D is going to be sitting in the end zone at the Superbowl? Olympus has specifically targeted the bird photog community in advertising and lens design knowing the extra crop 4/3 sensor gives them a market advantage. Are you going to snub a rangefinder for "street photography"?

Going back to the premise of the thread, the compromise of the M4/3 standard with its short register is that it in order to get the same DOF and wide-angle lenses as bigger sensors, it needs very pricey glass, or pricey microlenses, and so on. What is gained in compactness is lost somewhere else. Which is why I say APS-C is a known compromise with sunk investment costs and quivers of legacy glass, so EVF married to APS-C is a far more likely scenario than Pentax going to M4/3.
05-04-2010, 05:29 AM   #193
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QuoteOriginally posted by dnas Quote
This is not correct.
You didn't follow up the link I gave four posts later. This is a pitty. In the current thread, it is off-topic, so I won't explain at which point exactly you make your mistake in reasoning. I give you a second and third hint now: you have to compare total illumination, not illumination densities. And you cannot consider ISO to be independent of sensor size. And I play nice to you because I do not simply repeat what I already said. Because you are a new member and I want to be friendly.
QuoteOriginally posted by Laurentiu Cristofor Quote
I have to read more carefully you article on lens equivalence - I've seen discussions around this concept before, but frankly, I don't find the topic very interesting
The concept of lens equivalence just helps to understand the real benefit of larger sensors. Or the effect of sensor size at all. Most people cannot understand it correctly before they learn about equivalent lenses. Just look at dnas

So, it's like learning about binary numbers before you can understand computers.
QuoteOriginally posted by Laurentiu Cristofor Quote
Well, I don't see the need for an elaborate lens equivalence concept that takes into account DOF, so I can't really follow the point you were trying to make in that article.
The concept of lens equivalence is universal. That it leads to identical DoF is just by accident and I had to go thru the maths to prove it. It isn't by definition.

The idea behind lens equivalence is to compare cameras with different sensors but with lenses (for a given field of view) which are about the same size, weight and cost. In order not to compare apples to pies.

That the equivalence extends to DoF, noise, diffraction limits etc. is a nice corrolar I didn't anticipate and is my native discovery. In essence, the corrolar says that equivalent lenses lead to an equivalent image quality.

This factors sensor size completely out of the equation and replaces it with lens availability.


Only if you see that the sensor format defines your choice of lenses rather than the image quality then did you understand the influence of format. This is news for many.

Last edited by falconeye; 05-04-2010 at 05:38 AM.
05-04-2010, 06:01 AM   #194
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QuoteOriginally posted by falconeye Quote
You didn't follow up the link I gave four posts later. This is a pitty. In the current thread, it is off-topic, so I won't explain at which point exactly you make your mistake in reasoning. I give you a second and third hint now: you have to compare total illumination, not illumination densities. And you cannot consider ISO to be independent of sensor size. And I play nice to you because I do not simply repeat what I already said. Because you are a new member and I want to be friendly.

I did read that link, and it's related to "the relationship of sensor size and possible resolution". You have used DIFFERENT lenses with the same F-stop to illustrate the relationship between sensor size and resolution, not illumination.

I was referring to the SAME lens used with a FF & a 4/3 sensors, and the light that lands on the sensors. The F-stop is the same, because it is a property of the LENS, not the sensor.

There is no mistake in my reasoning, and I have provided a link. (perhaps you didn't read that??)

"It is important to note that neither the light gathering ability of the lens, nor any of its traits are actually affected: a 50mm f2 lens on a 4/3rds body has the same f-stop as a 50mm lens on a 35mm camera. But the 4/3rds sensor only records the equivalent field of view of a 100mm lens."

From here:
Four Thirds - Camerapedia.org
05-04-2010, 06:48 AM   #195
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QuoteOriginally posted by dnas Quote
I was referring to the SAME lens used with a FF & a 4/3 sensors, and the light that lands on the sensors. The F-stop is the same, because it is a property of the LENS, not the sensor.
Don't let's get diverted. It's off-topic already.

The debate started because you replied to my statement "And for equal light gathering capabilities, they need half the f-stop figure. " (you said it isn't correct).

The full sentence we're debating was:
QuoteQuote:
And good IQ lenses for FT are expensive for a reason. Because they need twice the lp/mm power compared to FF. And for equal light gathering capabilities, they need half the f-stop figure.
So, of course we're talking about different lenses for different cameras. What are you thinking? That I talked about mounting an FF lens to a FourThirds camera which then magically doubles its lp/mm power?

No, I said that say, a 70-200/4 short tele zoom on FF would have to be replaced by a lens of half the f-stop figure on a FourThirds system to yield comparable image quality (comparing noise, DoF etc.). And this is correct (would be the 35-100/2.0 actually).

For the record: For now and in the future, I'll ignore "This is not correct" postings dnas does make. This doesn't mean I accepted the veto
Also, I'll abandon this debate now.
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