[dnas]

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:


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.

I wasn't debating ANYTHING TO DO WITH RESOLUTION, so don't accuse me of that. I don't disagree with that, and I didn't disagree with that. (except for the part about needing a 35-100/2.0, because the f-stop has nothing to do with the resolution)

Your statement:

And for equal light gathering capabilities, they need half the f-stop figure.

It is wrong, and if it is wrong, surely I have a right to point that out, if it is included in the discussion.

[falconeye]

except for the part about needing a 35-100/2.0, because the f-stop has nothing to do with the resolution

I stopped debating this, but for the record of war reporters out there ...

You said a 70-200/4 lens projects as many photons onto the entire surface of an FF sensor as a 35-100/4 lens projects onto the entire surface of a FourThirds sensor.

While I said a 70-200/4 lens projects as many photons onto the entire surface of an FF sensor as a 35-100/2 lens projects onto the entire surface of a FourThirds sensor (which is my statement you just quoted and you insist to be wrong).

[kevinschoenmakers]

dnas, it's way more time-efficient to just admit falconeye is the king of optics :P

[Aristophanes]

because the f-stop has nothing to do with the resolution)

Diffraction says otherwise:

Luminous landscape

[cateto]

I must be wrong, as I thought this thread was about the possibility that Pentax could join the miro4/3 standard.

May I politely suggest people to stop hijacking threads? If there are fancy discussions about DoF or difraction or whatever, why not starting another thread?

Besides, are there moderators here?

[Laurentiu Cristofor]

While I said a 70-200/4 lens projects as many photons onto the entire surface of an FF sensor as a 35-100/2 lens projects onto the entire surface of a FourThirds sensor (which is my statement you just quoted and you insist to be wrong).

How is the total amount of photons relevant? It only matters how many photons reach a fixed area (a photosite in the end). The 35-100/2 would let through as many total photons as the 70-200/4, but there would be twice as many reaching a 4/3 photosite (assuming same photosite density), which would make the lens faster according to my baggage of definitions.

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"?

My impression was that camera size is determined by whatever recording medium technology is available, then by needs for storing more of that medium or for making the camera size smaller. It's a compromise. The resulting side-effects are examined by the marketing department and then they put the bird/studio/street spin on the product. I have a hard time believing 4/3 were introduced because they wanted thicker DOF, but it's a good way to market that result.

[falconeye]

May I politely suggest people to stop hijacking threads? If there are fancy discussions about DoF or difraction or whatever, why not starting another thread?

You're absolutely right.

How is the total amount of photons relevant? It only matters how many photons reach a fixed area (a photosite in the end). The 35-100/2 would let through as many total photons as the 70-200/4, but there would be twice as many reaching a 4/3 photosite (assuming same photosite density), which would make the lens faster according to my baggage of definitions.

So, what shall I do? End the debate? Or answer a very last question?

With the permission of cateto, one last answer and I drop out of the discussion in this thread. I may have to write a blog article to explain in more detail, actually...

So, my last answer: I wrote explicitely "photons onto the entire surface of a xxx sensor".

This is the relevant measure as it defines image quality. e.g., level of noise.

If #pixels is the same, it also means "photons reaching a photosite". Then it is obvious.

If however pixel pitch is the same, it means that four times as many photons would reach a 4/3 photosite (as you correctly point out, except it is 4x, not 2x). But because the FF image would have four times as many pixels, you would first scale it down to 50% size and then compare images side by side. And you'll find that then noise then is identical despite the higher photon current per pixel for 4/3. You may also think in terms of binning four pixels into one.

In the end, if you think it thru, pixels or their pitch don't not enter the equation at all. It's all about the total number of photons forming an image. Replace sensor by film and it is still true.

And now I'll drop out of the OT discussion.

BTW, I have to catch up with my colleagues and can't continue on this battlefield:

570MP camera built by Fermilab physicists. Who says physicists don't take photos too?
[source: Wired.com]

P.S.
It seems to be a mirrorless interchangeable lens design

---

Last edited by falconeye; 05-04-2010 at 03:41 PM.

[Aristophanes]

My impression was that camera size is determined by whatever recording medium technology is available, then by needs for storing more of that medium or for making the camera size smaller. It's a compromise. The resulting side-effects are examined by the marketing department and then they put the bird/studio/street spin on the product. I have a hard time believing 4/3 were introduced because they wanted thicker DOF, but it's a good way to market that result.

35mm was an accident, but an elastic enough size to persist for many purposes, even as digital FF. It's still arbitrary. there is no metric that says any size is universally "best" for any given situation, but some are better than others.

Aesthetics from ISO "grain" to bokeh to DOF, and above all, colour rendition, are what makes photography what it is a medium (content notwithstanding). Like the "Golden Rule" there are standards universally accepted as pleasing to the eye, not necessarily in complete opposition to the jarring or unique, but on average, the norm. This is especially true of photos of people and objects with an inherent beauty, like flowers. For those we usually (not always) demand certain clarity or renditions. Camera designers specifically make sure that lenses and formats can achieve those effects.

You only have to look at the 645D and see where the tripod mount is to understand the settings it will be used in. Smaller cameras are designed to be "hand-held", and top-of-the-line FF's tripod or at least monopod beasts unless you have a chiropractor retained. 4/3 was developed knowing that this would not be a "studio" camera, but a walkaround format based on form factor, right up the Olympus alley traditionally. The rationale for 4/3 was actually to save cost of the sensor through use of an open format design to challenge Canikon. At that time Kodak was a bigger player than it is now. It didn't catch on. Pentax is highly unlikely to alter its lens systems for M4/3 just to get a marginally smaller form factor and all the other disadvantages a smaller senor brings. T

This whole argument is actually summarized on the 4/3 Wikipedia entry under "Disadvantages":

Four Thirds system - Wikipedia, the free encyclopedia

[dnas]

I stopped debating this, but for the record of war reporters out there ...

You said a 70-200/4 lens projects as many photons onto the entire surface of an FF sensor as a 35-100/4 lens projects onto the entire surface of a FourThirds sensor.

While I said a 70-200/4 lens projects as many photons onto the entire surface of an FF sensor as a 35-100/2 lens projects onto the entire surface of a FourThirds sensor (which is my statement you just quoted and you insist to be wrong).

No I DID NOT SAY THAT. You seem to enjoy saying things that I did not say.

I said that the SAME LENS for any given 10mm x 10mm square, whether it's a full frame or 4/3, the same number of photons will fall onto the same area.

Here is the proof of what I said:

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.

What you say above it correct about the number of photons, but there is one thing you haven't taken into account: Standard calibration.

ANY camera with any sensor must be calibrated. This takes a standard (in this case the amount of light) and calibrates the sensor to this standard. So if you have a Canon 5D (FF, 12M pixel) or a 450D (APS-C, 12M pixel), and you use a Canon 200mm 2.8 L (FF), then it will work with both cameras. And both cameras WILL KNOW that wide open, the lens is F2.8 This is fact.

According to your logic, the lens on the 450D would need to be 125mm F1.75, in order for the SAME number of photons to fall on the whole smaller APS-C sensor..... and you'd be right.
HOWEVER, the sensor is NOT CALIBRATED by the number of photons falling on the WHOLE SENSOR, it is calibrated by the number of photons per unit area. This is TRUE, because the same lens (Canon 200mm 2.8 L, FF) must work on both the Canon 5D (FF, 12M pixel) and a 450D (APS-C, 12M pixel).

The calibration occurs in the sensitivity of the sensor. Because there are only 25% the number of photons hitting each pixel on the APS-C sensor, the gain on the sensor (sensitivity) is boosted. So at the standardized 100 ISO, the light cast onto each sensor by the Canon 200mm 2.8 L will yield the same result so far as exposure goes, on the final image. If it was calibrated to total number of photons on the WHOLE sensor, the 450D result would be darker by two stops.

That is why this statement is correct:
"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


That's why your statement is incorrect:

And for equal light gathering capabilities, they need half the f-stop figure.

[dnas]

Diffraction says otherwise:

Luminous landscape

I was referring to the F-stop before the diffractive limit (you knew that), which was why I was using F2.8 in my examples, not F11 or F16.

[dnas]

Anyway, getting back to the topic.

I think there are some questions that need to be asked, to determine if Pentax should join micro 4/3:

1. When Auto Focus was introduced 1981 with the Pentax ME-F, and then the Nikon F3AF, did you think it was just a gimmick that was not really needed?

2. When mainstream DSLR cameras were introduced about 10 years ago, did you think that they would effectively replace film SLRs?

3. Will DSLRs with mirrors still be around in 20 years time?

4. Will MILC/EVIL cameras outnumber DSLR cameras in 5 years time? Or 10 years time?

5. Will electronic shutters mostly replace mechanical shutters(used in DSLRs today) within the next 10 years?

My answers, to be honest would be:
1. I thought AF was a gimmick.
2. Yes, I thought DSLRs would mostly replace film SLRs but in 10 years, not 5 years.
3. I think mirrors will be in just Pro cameras in 10 years time.
4. I think MILC/EVIL cameras will outnumber DSLR cameras in 5 years time.
5. I think electronic shutters will mostly replace mechanical shutters within the next 10 years


Based on my answers, then it makes logical sense that Pentax HAS TO introduce MILC/EVIL cameras.
Pentax has something like 4% of the DSLR market. With micro 4/3, Olympus and Panasonic had 20.2% of the total "DSLR" sales (interchangeable lens cameras, including DSLR & MILC/EVIL) in Japan in March 2010.
Two years ago, Panasonic and Olympus combined had around 4% of the DSLR market. The MILC/EVIL sales have eaten into the market share of Canon, Nikon & Sony.

I'm sorry to say it, but I think Pentax will never get much more DSLR market share than it has already, even though they make some great DSLRs.

So in my view, Pentax needs to get onto MILC/EVIL as soon as possible. Developing a new standard would be too costly, so I think they need to go with micro 4/3. Having 3 companies on board with micro 4/3 will make sure that the standard will remain robust.

And you imagine the lenses that Pentax could contribute!!!

[falconeye]

What you say above it correct about the number of photons, but there is one thing you haven't taken into account: Standard calibration.

Of course I did. It is in my post about lens equivalence. Of course you shoot the FF camera at 4x the ISO setting compared to the FT camera. Who cares about the nominal ISO step? It's just a text string in the EXIF data. Image quality is all we have to care about. And, e.g., ISO100 at FT and ISO400 at FF have equal noise by definition.

[Aristophanes]

I was referring to the F-stop before the diffractive limit (you knew that), which was why I was using F2.8 in my examples, not F11 or F16.

No, I did not know that. You have a tendency to make absolute and general statements that are factually incorrect as falconeye has pointed out.

For Pentax to go to M4/3 would require a complete reworking of their engineering and entire lens assembly system. Got a spare $40 million?

The M4/3 standard goes completely against the grain (literally) of low-noise, high-ISO photography that has won kudos for Pentax lately and has merit equal to that concocted by M4/3. It also fits in with their lens array.

There is no need to reduce the sensor size and lose the sunk costs of the lens legacy and be a latecomer to a small party. Pentax can go to EVIL with APS-C and retain much of their current advantages without the small sensor sacrifices. Samsung and Sony are. Pentax buys sensors from both. The main advantage of EVIL is a shorter register and therefore form factor, but those gains are marginal at best. Don't confuse people buying lots of the latest thing with a business plan. M4/3 is yet another Olympus attempt to set-up what is effectively a proprietary format (xD cards as well) to differentiate the brand and distribute capital costs. Olympus has a great system all together, but it's an also-ran as well in the Canikon universe. For Canikon to make an EVIL APS-C is, frankly, trivial. That they are NOT doing so with haste shows their measure of the market in sum is perhaps better judged than others.

[dnas]

Of course I did. It is in my post about lens equivalence. Of course you shoot the FF camera at 4x the ISO setting compared to the FT camera. Who cares about the nominal ISO step? It's just a text string in the EXIF data. Image quality is all we have to care about. And, e.g., ISO100 at FT and ISO400 at FF have equal noise by definition.

You are talking about noise, and yes for the equivalent noise performance, ISO100 at FT and ISO400 at FF have equal noise(all other things being equal).

However, I was not talking about the ISO setting, I was talking about the nominal calibration gain of the sensor. This is set by the design, not the user.

You are diverting from the question of F-stop of the lens.


No matter what you say, based on the calibration of Canon 5D (FF, 12M pixel) and a 450D (APS-C, 12M pixel), your statement is incorrect:

And for equal light gathering capabilities, they need half the f-stop figure.

This statement is correct:
"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

[dnas]

For Pentax to go to M4/3 would require a complete reworking of their engineering and entire lens assembly system. Got a spare $40 million?

The M4/3 standard goes completely against the grain (literally) of low-noise, high-ISO photography that has won kudos for Pentax lately and has merit equal to that concocted by M4/3. It also fits in with their lens array.

There is no need to reduce the sensor size and lose the sunk costs of the lens legacy and be a latecomer to a small party. Pentax can go to EVIL with APS-C and retain much of their current advantages without the small sensor sacrifices. Samsung and Sony are. Pentax buys sensors from both. The main advantage of EVIL is a shorter register and therefore form factor, but those gains are marginal at best. Don't confuse people buying lots of the latest thing with a business plan. M4/3 is yet another Olympus attempt to set-up what is effectively a proprietary format (xD cards as well) to differentiate the brand and distribute capital costs. Olympus has a great system all together, but it's an also-ran as well in the Canikon universe. For Canikon to make an EVIL APS-C is, frankly, trivial. That they are NOT doing so with haste shows their measure of the market in sum is perhaps better judged than others.

Of course, you have your opinion, which was why I asked those questions.

"For Pentax to go to M4/3 would require a complete reworking of their engineering and entire lens assembly system. Got a spare $40 million?"

Olympus & Panasonic combined had LESS market share (DSLR) than Pentax, and yet both tooled up for what looks like a very successful venture.