Full-frame vs. cropped lenses on APS-C camera

normhead · 02-18-2021, 06:04 AM

Originally posted by GUB

Hey Norm if you are still watching - just wanting to say this observation is flawed. The unit lw/ph is one dimensional while describing the 2 times pixel count of the sensor is 2 dimensional. so the equation should be K1 lw/ph (3350) divide by K5 lw/ph (2100) = 1.6 but then squared. Which comes out as 2.5 times the resolution in the K-1 -- very much as Pentaxxoid said.

Your logic is flawed not mine. The K-3 resolution is 2700 lw/ph not 2100.
The 13.3 x 8.8mm sensor of the ZS100 produces the same lw/ph resolution as the 36x24 6D sensor that is 8 times it's size.

How is it possible that an "unbiased" person misses these things?

You limit your theory by using only sensors of the exact same pixel density, when in real life, that's a rare thing. Even just with Pentax, I've had 6 MP, 10 MP, 12 MP, 14 Mp and 24 MP APS-c cameras each of which produce different lw/ph independent of the size of the image circle. I can't see how this would be more obvious.

If your theory was that the image circle was the determining factor if and only if the pixel density is exactly the same then you're on to something. But that's not often a real world scenario. And it's not what the OP stated.

Quote:

The 13.3 x 8.8mm sensor of the ZS100 produces the same lw/ph resolution as the 36x24 6D sensor that is 8 times it's size.

Meditate on this.

Last edited by normhead; 02-19-2021 at 06:43 AM.

**Serkevan** · 02-18-2021, 06:25 AM

Originally posted by redrockcoulee

Useless compared to next to useless?

Yep! It was mostly tongue in cheek - neither would really be usable in that case, I know. But we were talking about different things, sorta... one is a matter of image circle, the other of backwards compatibility. The point is that (assuming the camera works with the lens) the larger the image circle of the lens the more versatile it will be in terms of camera formats. A hypothetical Pentax-M APS-C lens would leave a good portion of the negative black on a film camera even if aperture worked.

**GUB** · 02-18-2021, 12:20 PM

Originally posted by normhead

Now the interesting part.

The K-1 sensor is double the size, but even looking at the k-5, at 2100, that's a 60% increase. More than double the number of pixels, double the area, but only 60% more resolution. With the same lens you can't just cut the resolution in half. Half of the K-1 resolution is 1675 as compared to the measured 2100.

Ummm you are the one using the K-5 to disprove Pentaxxoid. I am just pointing out your maths are not too hot.

swanlefitte · 02-18-2021, 02:36 PM

https://media.giphy.com/media/icgArcntfH5C0/source.gif

Following this thread

**luftfluss** · 02-18-2021, 03:07 PM

Originally posted by swanlefitte

https://media.giphy.com/media/icgArcntfH5C0/source.gif

Following this thread

I tried following this thread, but got motion sickness.

normhead · 02-18-2021, 03:14 PM

Originally posted by GUB

Ummm you are the one using the K-5 to disprove Pentaxxoid. I am just pointing out your maths are not too hot.

I am absolutely under no obligation to provide correct math. I illustrate the points I make quick and dirty, just to get the concepts across. If that's not good enough for you, don't read my work. Or pay me $35 an hour $200 minimum and the math will be perfect.

By the way, the reason I used the K-5 is because I know of no empirical tests done on the K-1 in crop mode, so I used the K-5 for which accurate data is available because they are close. If you'd done the work yourself instead of just throwing out nonsense and letting others correct it for you you'd know that.

Try saying "thank you normheaad for adding some clarification to this issue." I might help you out again sometime, as opposed to ignoring you, which is the way I'm haded right now. Trust me, you can believe as much ignorance as you want, I don't care, as long as you don't try and mislead others on the forum.

**GUB** · 02-18-2021, 03:36 PM

Originally posted by normhead

as long as you don't try and mislead others on the forum.

Others have plenty of opportunity to disagree with me here. No one is misleading anyone.

**Serkevan** · 02-18-2021, 03:48 PM

Originally posted by luftfluss

I tried following this thread, but got motion sickness.

I gave up like 5 pages ago

**Ash** · 02-18-2021, 03:53 PM - **4 Likes**

I would like to remind everyone that providing advice or expertise on a matter should not come at the cost of discord among the membership.

swanlefitte · 02-19-2021, 03:05 AM - **1 Like**

Due to insomnia I just realized and checked that Tony Northrup video. When he shows his comparisons he is doing it on a monitor and lies by omission. He scales each differently. If the ff is scaled at 50%, the m43 is scaled to 75%. The em-10 has 16.1 MP the canon5dii has 21.1 MP. He presents them as being the same while ignoring he is presenting different resizing and using different pixel pitch and these are what creates any difference he shows in the noise and dof.
What he really says is if we pretend different things are similar things we can show that similar things produce different things.

normhead · 02-19-2021, 06:56 AM - **2 Likes**

Originally posted by swanlefitte

Due to insomnia I just realized and checked that Tony Northrup video. When he shows his comparisons he is doing it on a monitor and lies by omission. He scales each differently. If the ff is scaled at 50%, the m43 is scaled to 75%. The em-10 has 16.1 MP the canon5dii has 21.1 MP. He presents them as being the same while ignoring he is presenting different resizing and using different pixel pitch and these are what creates any difference he shows in the noise and dof.
What he really says is if we pretend different things are similar things we can show that similar things produce different things.

He's a master of manipulation and deception. Even with a year of classroom work in lens design photographic theory etc. it took me a while to be able to understand exactly how he was manipulating things. I always knew he was wrong, but it can be difficult to explain exactly why.

It would be great exercise on a photography exam to put his work and grade students on their rebuttals. You can really tell how much a person understands about photography by how quickly they refute nonsense. In Northrups case, he's extremely convincing to the ignorant. He has just enough fact on his side to make his misrepresentations believable to those with a shaky background in photographic science, or any science for that matter.

Of course that's just my opinion. Well really it's my explanation for how people get so involved with Northrup's insanity and their impassioned defences of his half baked theories.

If you can't debunk a Northrup theory, you seriously need to learn critical thought. It's a test.

Traditionally, quoting Northrup is how people lacking an educated background in photography try to win friends and influence their rich uncle.

But it always puts them at odds with people who know their stuff.

And as far as I'm concerned that's the only thing worth knowing about Tony Northrup. If you repeat his theories, you're probably wrong.

**Serkevan** · 02-19-2021, 07:04 AM

Originally posted by swanlefitte

Due to insomnia I just realized and checked that Tony Northrup video. When he shows his comparisons he is doing it on a monitor and lies by omission. He scales each differently. If the ff is scaled at 50%, the m43 is scaled to 75%. The em-10 has 16.1 MP the canon5dii has 21.1 MP. He presents them as being the same while ignoring he is presenting different resizing and using different pixel pitch and these are what creates any difference he shows in the noise and dof.
What he really says is if we pretend different things are similar things we can show that similar things produce different things.

Northrup makes critical errors left and right from what little I've actually seen of his videos... I don't know a lot about photography, but I'd like to believe I know enough about experiment design to realize when someone's approach has the consistency of wet soufflé

.

dbs · 02-19-2021, 03:43 PM

Originally posted by swanlefitte

Due to insomnia I just realized and checked that Tony Northrup video. When he shows his comparisons he is doing it on a monitor and lies by omission. He scales each differently. If the ff is scaled at 50%, the m43 is scaled to 75%. The em-10 has 16.1 MP the canon5dii has 21.1 MP. He presents them as being the same while ignoring he is presenting different resizing and using different pixel pitch and these are what creates any difference he shows in the noise and dof.
What he really says is if we pretend different things are similar things we can show that similar things produce different things.

Or

Lies

More Lies

and Statistics

redrockcoulee · 02-19-2021, 07:58 PM

Originally posted by Serkevan

Yep! It was mostly tongue in cheek - neither would really be usable in that case, I know. But we were talking about different things, sorta... one is a matter of image circle, the other of backwards compatibility. The point is that (assuming the camera works with the lens) the larger the image circle of the lens the more versatile it will be in terms of camera formats. A hypothetical Pentax-M APS-C lens would leave a good portion of the negative black on a film camera even if aperture worked.

As a large format shooter I am well aware of image circle. But if a lens has an image circle is over welding much larger than you would require that all you have done is carried more weight than you needed to.

**Serkevan** · 02-20-2021, 01:56 AM

Originally posted by redrockcoulee

As a large format shooter I am well aware of image circle. But if a lens has an image circle is over welding much larger than you would require that all you have done is carried more weight than you needed to.

That is true, but between FF and APS-C the difference in image circle is small enough that the lens quality is a better predictor of size... The M20/4 isn't bigger than the DA15, for example.

02-18-2021, 03:14 PM	#171
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by GUB Ummm you are the one using the K-5 to disprove Pentaxxoid. I am just pointing out your maths are not too hot. I am absolutely under no obligation to provide correct math. I illustrate the points I make quick and dirty, just to get the concepts across. If that's not good enough for you, don't read my work. Or pay me $35 an hour $200 minimum and the math will be perfect. By the way, the reason I used the K-5 is because I know of no empirical tests done on the K-1 in crop mode, so I used the K-5 for which accurate data is available because they are close. If you'd done the work yourself instead of just throwing out nonsense and letting others correct it for you you'd know that. Try saying "thank you normheaad for adding some clarification to this issue." I might help you out again sometime, as opposed to ignoring you, which is the way I'm haded right now. Trust me, you can believe as much ignorance as you want, I don't care, as long as you don't try and mislead others on the forum. Last edited by normhead; 02-18-2021 at 03:26 PM.

02-19-2021, 06:56 AM - 2 Likes	#176
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by swanlefitte Due to insomnia I just realized and checked that Tony Northrup video. When he shows his comparisons he is doing it on a monitor and lies by omission. He scales each differently. If the ff is scaled at 50%, the m43 is scaled to 75%. The em-10 has 16.1 MP the canon5dii has 21.1 MP. He presents them as being the same while ignoring he is presenting different resizing and using different pixel pitch and these are what creates any difference he shows in the noise and dof. What he really says is if we pretend different things are similar things we can show that similar things produce different things. He's a master of manipulation and deception. Even with a year of classroom work in lens design photographic theory etc. it took me a while to be able to understand exactly how he was manipulating things. I always knew he was wrong, but it can be difficult to explain exactly why. It would be great exercise on a photography exam to put his work and grade students on their rebuttals. You can really tell how much a person understands about photography by how quickly they refute nonsense. In Northrups case, he's extremely convincing to the ignorant. He has just enough fact on his side to make his misrepresentations believable to those with a shaky background in photographic science, or any science for that matter. Of course that's just my opinion. Well really it's my explanation for how people get so involved with Northrup's insanity and their impassioned defences of his half baked theories. If you can't debunk a Northrup theory, you seriously need to learn critical thought. It's a test. Traditionally, quoting Northrup is how people lacking an educated background in photography try to win friends and influence their rich uncle. But it always puts them at odds with people who know their stuff. And as far as I'm concerned that's the only thing worth knowing about Tony Northrup. If you repeat his theories, you're probably wrong. Last edited by normhead; 02-19-2021 at 07:07 AM.

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02-18-2021, 06:04 AM	#166
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by GUB Hey Norm if you are still watching - just wanting to say this observation is flawed. The unit lw/ph is one dimensional while describing the 2 times pixel count of the sensor is 2 dimensional. so the equation should be K1 lw/ph (3350) divide by K5 lw/ph (2100) = 1.6 but then squared. Which comes out as 2.5 times the resolution in the K-1 -- very much as Pentaxxoid said. Your logic is flawed not mine. The K-3 resolution is 2700 lw/ph not 2100. The 13.3 x 8.8mm sensor of the ZS100 produces the same lw/ph resolution as the 36x24 6D sensor that is 8 times it's size. How is it possible that an "unbiased" person misses these things? You limit your theory by using only sensors of the exact same pixel density, when in real life, that's a rare thing. Even just with Pentax, I've had 6 MP, 10 MP, 12 MP, 14 Mp and 24 MP APS-c cameras each of which produce different lw/ph independent of the size of the image circle. I can't see how this would be more obvious. If your theory was that the image circle was the determining factor if and only if the pixel density is exactly the same then you're on to something. But that's not often a real world scenario. And it's not what the OP stated. Quote: The 13.3 x 8.8mm sensor of the ZS100 produces the same lw/ph resolution as the 36x24 6D sensor that is 8 times it's size. Meditate on this. Last edited by normhead; 02-19-2021 at 06:43 AM.

02-18-2021, 06:25 AM	#167
Serkevan Site Supporter Join Date: May 2019 Photos: Albums Posts: 5,976	Originally posted by redrockcoulee Useless compared to next to useless? Yep! It was mostly tongue in cheek - neither would really be usable in that case, I know. But we were talking about different things, sorta... one is a matter of image circle, the other of backwards compatibility. The point is that (assuming the camera works with the lens) the larger the image circle of the lens the more versatile it will be in terms of camera formats. A hypothetical Pentax-M APS-C lens would leave a good portion of the negative black on a film camera even if aperture worked.

02-18-2021, 12:20 PM	#168
GUB Loyal Site Supporter Join Date: Aug 2012 Location: Wanganui Photos: Gallery \| Albums Posts: 5,757	Originally posted by normhead Now the interesting part. The K-1 sensor is double the size, but even looking at the k-5, at 2100, that's a 60% increase. More than double the number of pixels, double the area, but only 60% more resolution. With the same lens you can't just cut the resolution in half. Half of the K-1 resolution is 1675 as compared to the measured 2100. Ummm you are the one using the K-5 to disprove Pentaxxoid. I am just pointing out your maths are not too hot.

02-18-2021, 02:36 PM	#169
swanlefitte Pentaxian Join Date: May 2015 Location: Minneapolis Photos: Gallery Posts: 4,068	https://media.giphy.com/media/icgArcntfH5C0/source.gif Following this thread

02-18-2021, 03:07 PM	#170
luftfluss Site Supporter Join Date: Jun 2011 Location: NJ Photos: Gallery \| Albums Posts: 11,618	Originally posted by swanlefitte https://media.giphy.com/media/icgArcntfH5C0/source.gif Following this thread I tried following this thread, but got motion sickness.

02-18-2021, 03:36 PM	#172
GUB Loyal Site Supporter Join Date: Aug 2012 Location: Wanganui Photos: Gallery \| Albums Posts: 5,757	Originally posted by normhead as long as you don't try and mislead others on the forum. Others have plenty of opportunity to disagree with me here. No one is misleading anyone.

02-18-2021, 03:48 PM	#173
Serkevan Site Supporter Join Date: May 2019 Photos: Albums Posts: 5,976	Originally posted by luftfluss I tried following this thread, but got motion sickness. I gave up like 5 pages ago

02-18-2021, 03:53 PM - 4 Likes	#174
Ash Loyal Site Supporter Join Date: Mar 2007 Location: Toowoomba, Queensland Photos: Gallery \| Albums Posts: 23,920	I would like to remind everyone that providing advice or expertise on a matter should not come at the cost of discord among the membership.

02-19-2021, 03:05 AM - 1 Like	#175
swanlefitte Pentaxian Join Date: May 2015 Location: Minneapolis Photos: Gallery Posts: 4,068	Due to insomnia I just realized and checked that Tony Northrup video. When he shows his comparisons he is doing it on a monitor and lies by omission. He scales each differently. If the ff is scaled at 50%, the m43 is scaled to 75%. The em-10 has 16.1 MP the canon5dii has 21.1 MP. He presents them as being the same while ignoring he is presenting different resizing and using different pixel pitch and these are what creates any difference he shows in the noise and dof. What he really says is if we pretend different things are similar things we can show that similar things produce different things.

02-19-2021, 07:04 AM	#177
Serkevan Site Supporter Join Date: May 2019 Photos: Albums Posts: 5,976	Originally posted by swanlefitte Due to insomnia I just realized and checked that Tony Northrup video. When he shows his comparisons he is doing it on a monitor and lies by omission. He scales each differently. If the ff is scaled at 50%, the m43 is scaled to 75%. The em-10 has 16.1 MP the canon5dii has 21.1 MP. He presents them as being the same while ignoring he is presenting different resizing and using different pixel pitch and these are what creates any difference he shows in the noise and dof. What he really says is if we pretend different things are similar things we can show that similar things produce different things. Northrup makes critical errors left and right from what little I've actually seen of his videos... I don't know a lot about photography, but I'd like to believe I know enough about experiment design to realize when someone's approach has the consistency of wet soufflé .

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02-19-2021, 03:43 PM	#178
dbs Pentaxian Join Date: Jun 2010 Location: Clare Valley S A Photos: Albums Posts: 7,563	Originally posted by swanlefitte Due to insomnia I just realized and checked that Tony Northrup video. When he shows his comparisons he is doing it on a monitor and lies by omission. He scales each differently. If the ff is scaled at 50%, the m43 is scaled to 75%. The em-10 has 16.1 MP the canon5dii has 21.1 MP. He presents them as being the same while ignoring he is presenting different resizing and using different pixel pitch and these are what creates any difference he shows in the noise and dof. What he really says is if we pretend different things are similar things we can show that similar things produce different things. Or Lies More Lies and Statistics

02-19-2021, 07:58 PM	#179
redrockcoulee Pentaxian Join Date: Nov 2009 Location: Medicine Hat Posts: 2,306	Originally posted by Serkevan Yep! It was mostly tongue in cheek - neither would really be usable in that case, I know. But we were talking about different things, sorta... one is a matter of image circle, the other of backwards compatibility. The point is that (assuming the camera works with the lens) the larger the image circle of the lens the more versatile it will be in terms of camera formats. A hypothetical Pentax-M APS-C lens would leave a good portion of the negative black on a film camera even if aperture worked. As a large format shooter I am well aware of image circle. But if a lens has an image circle is over welding much larger than you would require that all you have done is carried more weight than you needed to.

02-20-2021, 01:56 AM	#180
Serkevan Site Supporter Join Date: May 2019 Photos: Albums Posts: 5,976	Originally posted by redrockcoulee As a large format shooter I am well aware of image circle. But if a lens has an image circle is over welding much larger than you would require that all you have done is carried more weight than you needed to. That is true, but between FF and APS-C the difference in image circle is small enough that the lens quality is a better predictor of size... The M20/4 isn't bigger than the DA15, for example.