Debunking Tony Northrup.

[Meister]

That focal length (and thus the aperture) change with the sensor mounted on them, which is Meister's assertion.

Basically what he says is that a 2.8 lens is not really a 2.8 lens.

I never said that and you know this. Since you have no arguments except for personal attacks you are resorting to misrepresent what I wrote. The focal length and f-stop is a fixed quality of a lens. Neither change. Ever. Everyone knows this and nobody is claiming otherwise. You are starting to lead everybody on a tangent about something that was clear from the beginning. And I am starting to hear a song by Eduard Khil in my head.

 

[Dsching]

That focal length (and thus the aperture) change with the sensor mounted on them, which is Meister's assertion.

Basically what he says is that a 2.8 lens is not really a 2.8 lens.

He didn't say that, nor did anyone else. What is being discussed is the application of what is called the crop factor. The crop factor is used to determine how the same lens will behave when mounted on a camera body with a different sized sensor. To determine this correctly the crop factor has to be applied to both the aperture and focal length.

 

[MCH-1138]

He didn't say that, nor did anyone else. What is being discussed is the application of what is called the crop factor. The crop factor is used to determine how the same lens will behave when mounted on a camera body with a different sized sensor. To determine this correctly the crop factor has to be applied to both the aperture and focal length.

I think we just came full-circle (again). The lens is the lens. It behaves the same, regardless of what sensor is behind it.

 

[leighonigar]

I think we just came full-circle (again). The lens is the lens. It behaves the same, regardless of what sensor is behind it.

Indeed. But the image you produce will not be, because you will have to stand in a different place to capture the 'same' image, changing perspective and dof. With a smaller sensor the pixels will also (probably) be smaller, or at any rate be enlarged more and so the apparent noise will be increased.

 

[kingalexthe1st]

I think we just came full-circle (again). The lens is the lens. It behaves the same, regardless of what sensor is behind it.

Right. And this is where confusion and arguments come from because people try and take stuff that only applies to the lens, and try to apply it to the camera sensor/body. It's only focal length and diameter, and then aperture is calculated by default. Trying to put this in perspective of sensor size adds another element that is not accounted for in the 3 things I mentioned above.

Alex

 

[Meister]

I think we just came full-circle (again). The lens is the lens. It behaves the same, regardless of what sensor is behind it.

Yes, because that's what this thread was all about. All I wanted to proof is that FF DSLRs have magical powers that transform lenses to lower f-stops.

 

[leighonigar]

Unfortunately we as flawed humans need some way of comparing the results you will get with different lenses and bodies. The real numbers don't really do this. You need some common ground. Most of us have settled on '35mm equivalent' conversions. This is where the disagreements arise.

 

[notrack]

...
But it's still worth noting that a lens and its aperture won't change depending on what you put it on. A 1.8 DX lens will still be 1.8 on a full frame, only with black corners, and a 1.8 FX lens will still be a 1.8 lens when mounted on a cropped sensor camera, only with a lot of light wasted. And that's something our friend Meister still doesn't get.

I think we just came full-circle (again). The lens is the lens. It behaves the same, regardless of what sensor is behind it.

Of course the lens physically doesn't change. But that's only half the way, because the image does change. So, if you slap on a smaller sensor camera on your lense, you will only see part of the image.

To get the same image as with the larger sensor, you'll thave to compensate the other parameter.

Move further away from the subject to get everything back in frame. Due to larger distance, you need to open the aperture to get the same dof (and probably to compensate for the light fall-off afaik).

So the lens does't change but you'll have to change it in order to get the same image.

 

[MCH-1138]

Indeed. But the image you produce will not be, because you will have to stand in a different place to capture the 'same' image, changing perspective and dof. With a smaller sensor the pixels will also (probably) be smaller, or at any rate be enlarged more and so the apparent noise will be increased.

Of course the lens physically doesn't change. But that's only half the way, because the image does change. So, if you slap on a smaller sensor camera on your lense, you will only see part of the image.

To get the same image as with the larger sensor, you'll thave to compensate the other parameter.

Move further away from the subject to get everything back in frame. Due to larger distance, you need to open the aperture to get the same dof (and probably to compensate for the light fall-off afaik).

So the lens does't change but you'll have to change it in order to get the same image.

I understand that and agree -- or you could use a different focal length lens to give you the same equivalent focal length as what you had on the full-frame. And I understand and agree that changing either of these (distance to subject or focal length) will affect your depth of field.

But I am referring specifically to the light-gathering ability of a given lens, as used on two different sensors. As others have pointed out, the crop sensor may see less total light (because it has less area), but this does not affect the exposure.

For the record, I don't follow Tony Northrup closely, but I have watched some of his videos and generally enjoy them.

 

[notrack]

Well, I'm not a scientist but the way I understand it has to do with magnification. Afaik noise comes from amplifying what ever is gathered by the sensor. Under identical lighting situation, a smaller area gathers less light than a larger one.

So, to fill your 30 inch display, you'll have less "information" in the first place to bring it up to full size. Either the sensor has the same amount of pixels which leaves less light for each, or you have the same size of pixels but not as many.

So you'll have to open up the aperture to get the same amount of light for each of the smaller pixels (or increase the lighting).

 

[v3rlon]

Indeed. But the image you produce will not be, because you will have to stand in a different place to capture the 'same' image, changing perspective and dof. With a smaller sensor the pixels will also (probably) be smaller, or at any rate be enlarged more and so the apparent noise will be increased.

This is not true. The pixel size is driven by the technology. The sensor size is driven by sensor size.

You could easily make a viable m43 sensor using the same technology with just ~1/4 the pixels.

 

[leighonigar]

This is not true. The pixel size is driven by the technology. The sensor size is driven by sensor size.

You could easily make a viable m43 sensor using the same technology with just ~1/4 the pixels.

You could, but I was talking about real cameras. Almost universally as sensor size decreases so does pixel size.

 

[Meister]

This is not true. The pixel size is driven by the technology. The sensor size is driven by sensor size.

You could easily make a viable m43 sensor using the same technology with just ~1/4 the pixels.

Where did he say that you cannot make a m4/3 sensor with larger pixels.

 

[leighonigar]

I should also make clear that I really mean within a particular generation. Comparing a coolpix P990 from 15 years ago with something modern clearly it is not the pixel pitch that will be the main determinant of noise levels and quality.

Most of the current m4/3 cameras have 16mp sensors, this equates to a density which, in a full frame size, would have 64MP of resolution. We will have that at some point, but we don't yet.

Even if you did keep the pixel size the same I'm not sure the overall noise performance would look as good for a given enlargement. Any blotchiness would be enlarged quite a bit more (by the crop factor) and so more visible. Larger sensors have lots of advantages (and some disadvantages, but generally it's not image quality).

 

[Doylem]

I've finished my peanuts; off to take some pix...

 

[juanm]

Well, I'm not a scientist but the way I understand it has to do with magnification. Afaik noise comes from amplifying what ever is gathered by the sensor. Under identical lighting situation, a smaller area gathers less light than a larger one.

Yes, because that's what this thread was all about. All I wanted to proof is that FF DSLRs have magical powers that transform lenses to lower f-stops.

Meister is spot on.

A very educational discussion.

Are you surprised that your well thought out arguments:

"Tony Northrup is your white haired guru."
"The definition of aperture doesn't apply."
"I have lots of experience as a videographer."

Haven't changed my opinions on the laws of physics.

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I don't think you are able to follow my (and the white hair guru's ) line of argument.

The one in which I produce images. It is the images that matter, and that is it as far as photography goes. I cannot actually comment on the physics, except to say that clearly it is the focal ratio or 'aperture' that affects the amount of light falling on a particular area of light-gathering surface. Obviously I am not disagreeing with you on this (I don't think anyone else is either). What follows is a reflection of my experience of image making.

Photographically there is no respect, with the exception of exposure for a given sensitivity, in which f-stops are equivalent with 'equivalent focal lengths' as sensor size changes.

I found the video I was referring to:

https://www.youtube.com/watch?v=DtDotqLx6nA# (At 21:30 and the kicker comes at 22:10)

It makes absolutely no sense.

What if I decide my gold standard is the 4"x5" view camera I had many years ago? Should I then say Canon misleads its customers because when I convert their lenses to a Field camera equivalent, even their F2.8 series are equivalent to a F64?

 

[kingalexthe1st]

I found the video I was referring to:

https://www.youtube.com/watch?v=DtDotqLx6nA# (At 21:30 and the kicker comes at 22:10)

It makes absolutely no sense.

What if I decide my gold standard is the 4"x5" view camera I had many years ago? Should I then say Canon misleads its customers because when I convert their lenses to a Field camera equivalent, even their F2.8 series are equivalent to a F64?

He's thinking about it way too hard. He basically says that because they also show focal length in their '35mm equivalent' (I shudder every time I hear that) that you should also change the aperture to reflect the light gathering ability. He completely misses the wood for the trees though, as I'd put money on everyone using the '35mm equivalent' just to visualise the FoV. Not the light ability of the lens. Suddenly because a company defines the aperture as actual focal length / lens diameter, as they're supposed to, then people scream bloody murder and call them liars.

Alex

 

[Edge100]

Imagine how fast the Internet would run if we just settled this type of discussion once and for all. So much wasted bandwidth...

 

[Reality4711]

Duh??

I found the video I was referring to:

https://www.youtube.com/watch?v=DtDotqLx6nA# (At 21:30 and the kicker comes at 22:10)

It makes absolutely no sense to me. (Only 30+ years earning my living with a camera - any camera!)

In the first few minutes 12/35mm f2.8 full frame lens does NOT perform as a 24/70mm f2.8 lens on a 2 times crop sensor/camera. ???

My old olympus E3 plus with 12/60 mm lens gave exactly (within limit of me being able to stand exactly in the same place and a fixed subject) the same image size (not shape) as my canon 5D with a 24/105 mm ef lens with olympus set at 50mm and canon at 100mm. So what am I missing??


It is only field of view he is on about I assume all other things being infinitely variable

 

[Meister]

I found the video I was referring to:

https://www.youtube.com/watch?v=DtDotqLx6nA# (At 21:30 and the kicker comes at 22:10)

It makes absolutely no sense to me. (Only 30+ years earning my living with a camera - any camera!)

In the first few minutes 12/35mm f2.8 full frame lens does NOT perform as a 24/70mm f2.8 lens on a 2 times crop sensor/camera. ???

My old olympus E3 plus with 12/60 mm lens gave exactly (within limit of me being able to stand exactly in the same place and a fixed subject) the same image size (not shape) as my canon 5D with a 24/105 mm ef lens with olympus set at 50mm and canon at 100mm. So what am I missing??

It is only field of view he is on about I assume all other things being infinitely variable

A 12-35mm f2.8 lens performs on a m4/3 camera as a 24-70 f5.6 lens would perform on a 35mm camera. The crop factor needs to be applied to the FoV, DOV and the overall light gathering ability. of the body-lens combo. In real world usage the light gathering part can be disregarded, because the camera manufaturer already applied the crop factor to the iso rating of the sensor, to make the same iso number look equally bright on different sized sensors. This is provided we are talking about two sensors of different sizes but the same pixelcount.

 

[carlgo]

Mathematically based photography is required for scientific applications, but just gets in the way of anything else. It just scares people away from getting beyond phone and P&S cameras. All you need are the basic concepts of aperture, ISO and shutter speed and some actual practice.

Funny that Rockwell has the opposite approach, tells people to just get back to basics and not worry about the technicals or equipment and so he gets reamed by the techno-photographers.

Ok, now to check out the woman people are gushing about...

 

[leighonigar]

I found the video I was referring to:

https://www.youtube.com/watch?v=DtDotqLx6nA# (At 21:30 and the kicker comes at 22:10)

It makes absolutely no sense.

What if I decide my gold standard is the 4"x5" view camera I had many years ago? Should I then say Canon misleads its customers because when I convert their lenses to a Field camera equivalent, even their F2.8 series are equivalent to a F64?

Do you know many manufacturers of lenses for 4x5 who advertise focal length based on '35mm equivalence' and, moreover, do so to amateurs who might not know any better?

I don't have the time to watch that entire video (though oddly I am finding the time to post) but the section I did watch (the one you mention) makes sense. What don't you like about it? The formula is an excellent teaching aid which gives you the right numbers, so, what's not to like?

 

[Meister]

Mathematically based photography is required for scientific applications, but just gets in the way of anything else. It just scares people away from getting beyond phone and P&S cameras. All you need are the basic concepts of aperture, ISO and shutter speed and some actual practice.

This thread is about how companies advertise their lenses, not photography as art.

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Funny that Rockwell has the opposite approach, tells people to just get back to basics and not worry about the technicals or equipment and so he gets reamed by the techno-photographers.

Rockwell makes some good points in that regard. That's why he is successful.

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Do you know many manufacturers of lenses for 4x5 who advertise focal length based on '35mm equivalence' and, moreover, do so to amateurs who might not know any better?

Exactly!

 

[Reality4711]

Too much thinking can cause lack of direction or something

A 12-35mm f2.8 lens performs on a m4/3 camera as a 24-70 f5.6 lens would perform on a 35mm camera. The crop factor needs to be applied to the FoV, DOV and the overall light gathering ability. of the body-lens combo. In real world usage the light gathering part can be disregarded, because the camera manufaturer already applied the crop factor to the iso rating of the sensor, to make the same iso number look equally bright on different sized sensors. This is provided we are talking about two sensors of different sizes but the same pixelcount.

If what you are saying is that I am right and that the camera manufacturer did the hard maths/science for me then fine.

I am grateful to you both.

However if any of this dispute made an ounce of difference to my ability to capture; produce and sell an image I would probably put a bit of my brain towards the discussion but as far as I can devine multiple cameras and lens combinations in my hands have produced in excess of 300,00 images that I am reasonably happy with and 1 in 5 that are marketable. So I don't think I will bother with reading this thread any more.

NB:- I am not dismissing anyones knowledge/education/enthusiasm for this and all the other technological wrangling that goes on but it is the photographers eye that is the final arbiter and as long as mine is happy so am I; whether or not the numbers add up or not - "expose for the soul" - someone better than I said that, but I only remember the image he was talking about - sorry.

 

[Reality4711]

Just a thought.

You may call this 'dumbing down' for the masses.

If so in this case I'm all for it. Who in Gods name when buying their first DSLR kit needs to know the aperture equivalents for a large format camera and their old IXUS from the back of the cupboard.

Let the journey start before the knowledge (lack of) and the theory get in the way.

Oh I realise its a discussion on marketing speak but come on. If you know that much that you can spot the gentle smoothing you really don't need the sales pitch!