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10-20-2014, 07:32 PM   #136
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QuoteOriginally posted by ElJamoquio Quote
I'm not ducking. You asked the wrong question and I didnt want to embarrass you publicly any more.
Strike three on refusing to stand up for your beliefs- you're out of there!

Looks like the Emperor has no clothes.

Don't worry about little ol' me, EJ, don't be so coy, you've criticized others copiously, so let's hear it.

Just fill in the gap, Total Light Guru - you requested this, remember ...

ISO 200, 1/125, f?

Breathlessly waiting.


Last edited by clackers; 10-20-2014 at 07:39 PM.
10-20-2014, 07:41 PM   #137
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Your premise is already wrong, and I've already answered your question once.
10-20-2014, 07:56 PM   #138
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I thought as much. Did anyone actually believe he was going to commit to an answer to a concrete question?

There seems little left to do in this thread, so I'll follow EJ's example and do a cut-and-run.

Good day to you all!

Last edited by clackers; 10-20-2014 at 08:03 PM.
10-20-2014, 08:51 PM   #139
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QuoteOriginally posted by clackers Quote
I thought as much. Did anyone actually believe he was going to commit to an answer to a concrete question?

There seems little left to do in this thread, so I'll follow EJ's example and do a cut-and-run.

Good day to you all!
Never ask me another question again.

https://www.pentaxforums.com/forums/169-pentax-full-frame/275535-total-light-...ml#post2977653

10-20-2014, 10:30 PM   #140
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QuoteOriginally posted by clackers Quote
Strike three on refusing to stand up for your beliefs- you're out of there!

Looks like the Emperor has no clothes.

Don't worry about little ol' me, EJ, don't be so coy, you've criticized others copiously, so let's hear it.

Just fill in the gap, Total Light Guru - you requested this, remember ...

ISO 200, 1/125, f?

Breathlessly waiting.
Why on earth would you want to use f8 on Q?
At f8 the Q would be severely diffraction limited and most likely give you more DOF than you need.
It would be similar to using K3 with a lens set to f32 (with lenses giving the same FOV).

On 645Z f8 might be too limited in DOF (maybe something you use for portraits).

To reverse the question. If someone is capturing a landscape using 645Z with a 25/4 lens and using exposure settings of: 1/100 f22 ISO200.
What exposure settings would be best used on Q for capturing a landscape and what lens would you use to create a similar image as the one created with 645Z.
10-21-2014, 12:28 AM   #141
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QuoteOriginally posted by ElJamoquio Quote
Your premise is again incorrect. I explained where your conclusions were wrong in theory and gave you empirical data that disproves your hypothesis.
You explained nothing. You disproved nothing. I think it's clear for everyone (equivalentionists excluded) that you're unable to do either.

And let's remind where we started. Your question: "Should a 70-200mm F/2.8 or instead use a 135 F/2 and crop? Which will provide the best SNR? Sharpness?"
Your claim, to have all the necessary elements for an answer. SNR, without accounting for the transmission differences between the lenses (oh, yeah, that would mess with your best ally, photon noise). Sharpness, without accounting for sharpness differences between the lenses, likely not even for the pixel count. With a ~10% crop, such things might impact the result.

And this is a nice way of ending our discussion. Have a good day!
10-21-2014, 07:05 AM   #142
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I think you're clinging to a thin reed

QuoteOriginally posted by Kunzite Quote
You explained nothing. You disproved nothing. I think it's clear for everyone (equivalentionists excluded) that you're unable to do either.

And let's remind where we started. Your question: "Should a 70-200mm F/2.8 or instead use a 135 F/2 and crop? Which will provide the best SNR? Sharpness?"
Your claim, to have all the necessary elements for an answer. SNR, without accounting for the transmission differences between the lenses (oh, yeah, that would mess with your best ally, photon noise). Sharpness, without accounting for sharpness differences between the lenses, likely not even for the pixel count. With a ~10% crop, such things might impact the result.

And this is a nice way of ending our discussion. Have a good day!
Not to prolong this, but you're continuing to rely on that same strawman. No-one says equivalence is capable of telling you everything, and it doesn't make that claim. A lens' T-stop is obviously out of the realm of equivalence, and you should know this by now. Blaming equivalence for not including things like that is not arguing in good faith when you already know it doesn't include things like that. It's arguing for arguing's sake, to try to 'win' a lost point.

It also doesn't tell you the sensor efficiency. It's a tool to be used in conjunction with things like that, not to replace them.

The parameters El J was describing are arguably the most important, by far, in determining SNR for a combo or crop shot on the same sensor - the parameters you can control that deliver the Total light. The T-stop is in the chain as well, but if you consider T-stop without the other parameters as described by equivalence then you're going to get a much less accurate answer than if you do the opposite, depending on how much you crop, etc.
10-21-2014, 07:06 AM   #143
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QuoteOriginally posted by Kunzite Quote
You explained nothing. You disproved nothing. I think it's clear for everyone (equivalentionists excluded) that you're unable to do either.

And let's remind where we started. Your question: "Should a 70-200mm F/2.8 or instead use a 135 F/2 and crop? Which will provide the best SNR? Sharpness?"
Your claim, to have all the necessary elements for an answer. SNR, without accounting for the transmission differences between the lenses (oh, yeah, that would mess with your best ally, photon noise). Sharpness, without accounting for sharpness differences between the lenses, likely not even for the pixel count. With a ~10% crop, such things might impact the result.

And this is a nice way of ending our discussion. Have a good day!

You're missing the forest for the trees, although thankfully you understand the trees.

I've explained equivalence many times. I don't care at all what you think the answer to my rhetorical question was - and yes, it was rhetorical, because I don't care at all what you think the answer is; I know what the answer is.

I have all the necessary elements for an answer, because I know the sharpness differences between the lenses. I know the transmission of each of the lenses. You do have to verify whether a new lens has better or worse transmission than your other lenses - once.

Once again, rhetorical. Rhetorical. Rhetorical. It applied to me, for a given focal length, and my lenses. The real answer is 'hey, if I apply equivalence I get know what the answer is, instead of guessing'. You have the answers for the same trivial questions. You just have to think about it for 10 seconds; or if you ascribe to normhead's philosophy, undergo thousands of hours of training with specific lenses.


Last edited by ElJamoquio; 10-21-2014 at 07:12 AM.
10-21-2014, 08:05 AM   #144
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QuoteOriginally posted by jsherman999 Quote
A lens' T-stop is obviously out of the realm of equivalence, and you should know this by now.
You don't get it, do you? That's precisely the point, that significant factors which are influencing SNR and resolution are out of the realm of equivalence. Yet the claim was made that nothing else is needed (to be accurate, he said that "Should a 70-200mm F/2.8 or instead use a 135 F/2 and crop?" includes all the information required)
Regarding SNR: if we go for the "same total light", the lens with the better transmittance "wins" (at least assuming only photon noise is significant); a factor which we both agree is "out of the realm of equivalence". Resolution is also "out of the realm of equivalence"; with a ~10% crop, both the zoom and the prime has a chance.

At least now ElJamoquio understood his mistake, and tries to add previously unspecified parameters now that I've told him. Even if initially all he said was a 70-200 f/2.8 vs. a 135 f/2.
10-21-2014, 09:38 AM   #145
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QuoteOriginally posted by Kunzite Quote
At least now ElJamoquio understood his mistake, and tries to add previously unspecified parameters now that I've told him. Even if initially all he said was a 70-200 f/2.8 vs. a 135 f/2.
Yes, yes, I was far too stupid to understand t-stop vs f-stop before you demanded more parameters for a rhetorical question. I bow to your brilliance. You are the king of the internet.
10-21-2014, 10:28 AM   #146
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Huh... interesting the way discussions degrade. I love all the paralells we try to draw.

How about this one, lets throw some science at it and see if it sticks:

Think of sensors / photo sites like solar cells on your roof to generate power. They do ya know!

So... now in familiar territory thinking about solar panels and generating electricity, you can understand more surface area or (larger solar panel), more cells equals more energy generated, and our sensors do generate a signal, but it has to be amplified, less amplification needed, less noise and signal loss... that's a very simplistic way to look at it, but sometimes simple is best. You can get into pixel pitch if you want, maybe equate it to the pitch of your roof versus a flat roof, or having solar panels on both sides of the peak of your roof, heh heh.


Donning my asbestos undies as I hit submit,
Eric
10-21-2014, 10:36 AM - 1 Like   #147
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Then how is it that what used to be 80 watt panels are now 120 watt panels at the same size? That's the trouble with trying to get simple, you have to eliminate meaningful parts of the process in your equation, to create simple, and doing that if done too much leads to meaningless conclusions.

The easiest way to comprehend complex systems is to check output rather than theoretical constructs, unless you know the effect of every aspect of the system. Focusing on one element of the system often leads to false conclusions. The thing about this analogy is, no one would ever assume what the output of a solar panel is from its size. They'd look at it's rating. But people want to assume what the noise output of a sensor is from it's size. Why is one obviously stupid, and the other is acceptable?

Last edited by normhead; 10-21-2014 at 11:08 AM.
10-21-2014, 11:03 AM   #148
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QuoteOriginally posted by Erictator Quote
So... now in familiar territory thinking about solar panels and generating electricity, you can understand more surface area or (larger solar panel), more cells equals more energy generated, and our sensors do generate a signal, but it has to be amplified, less amplification needed, less noise and signal loss... that's a very simplistic way to look at it, but sometimes simple is best. You can get into pixel pitch if you want, maybe equate it to the pitch of your roof versus a flat roof, or having solar panels on both sides of the peak of your roof, heh heh.
As long as each panel produces enough power to cook an omelette, I don't care how big they are. I'll choose my pan size and heat setting based on the size of the eggs, not the size of the solar panel. And the quality of the omelette will depend on my skill and experience as a cook, not on the equipment I'm using.

Of course, real cooks use gas.
10-21-2014, 11:09 AM   #149
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QuoteOriginally posted by normhead Quote
Then how is it that what used to be 80 watt panels are now 120 watt panels at the same size?
This would be under the heading of 'same technology'. Sensors of size X from 2006 are much inferior to the same sensors from 2014, correct? There's a parallel here...
10-21-2014, 11:12 AM   #150
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QuoteOriginally posted by normhead Quote
Then how is it that what used to be 80 watt panels are now 120 watt panels at the same size? That's the trouble with trying to get simple, you have to eliminate meaningful parts of the process in your equation, to create simple, and doing that if done too much leads to meaningless conclusions.
But progess doesn't happen in a vaccuum! IF the old 80 watt panel size is now capable of 120 watt because the individual cells are now more productive, then the larger panels will still be based on the newer cells also, and will generate more power too.

QuoteOriginally posted by normhead Quote
The easiest way to comprehend complex ystems is to check output rather than theoretical constructs, unless you know the effect of every aspect of the system. Focusing on one element of the system often leads to false conclusions. The thing about this analogy is, no one would ever assume what the output of a solar panel is from its size. They'd look at it's rating. But people want to assume what the noise output of a sensor is from it's size. Why is one obviously stupid, and the other is acceptable?
I dunno, because a solar panel expert would knows there has been progress and would want to know what generation/type/output panel he was looking at. Panels probably all look alike to most of us, unlike our cherished cameras which we recognize easily. I would never call anyone stupid! And yes, there is always "more to the story" than a simple analogy will give. BUT... some things are constants...and when it comes to gathering light, historically, larger has been better for most things. Show me an F2.8 300mm lens with a 49mm front element. Different set of problems and challenges... and maybe with some super duper tech, someone could somehow pull it off someday, but the point is, sometimes it's easier, or a more "naitive" solution to just go bigger.

All kidding aside...Remember the first big clunky Nikon/Kodak or Nikon/Fuji joint DSLR's? It was like 1.3MP, and I saw one at COMDEX in the 1990's for over $20K Ya... an Iphone with a tiny sensor can blow away what was a $20K camera at the time. At some point, sensor tech will probably get to the point that the size won't matter anymore except for the most extreme and demanding situations. There will probably be a sweet spot, where you will have enough detail to do a billboard size print viewable from 3ft away in a certain size sensor, whatever that will be, and that will become the defacto size and all else goes away except for small devices that need to be pocketable. etc. But for now and the foreseeable future, larger is still notably better for some applications, or no one would ever buy a 645Z or D810, etc.

Eric
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