Longshadow Loc: Audubon, PA, United States

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Longshadow Loc: Audubon, PA, United States

Acountry330 Loc: Dothan,Ala USA

I am no expert. Your cameras sensor stores 24 megapixels of light information. Your lens allows light to your sensor. So how does your lens only allow 9 megapixels of light to your sensor? Is there some kind of light constrictor in your lens? Just my humble way of thinking. Happy Shooting.

Strodav Loc: Houston, Tx

If I got this right, DxOMark measures the sensor resolution that is used by a lens, which is always less than the full resolution of the sensor. Say you smear Vaseline on your lens and take a shot of a high resolution scene. All you would only need is a 1 pixel sensor to get the right gray level because you are not going to see any of the detail at all. Now, say, you have an OK lens, nice and clean, and take a shot of the same scene. You are obviously going to need a higher resolution sensor to capture the detail, but you still aren't going to get all the detail in the image because of the poor quality of the glass. The better the glass, the higher resolution sensor you will need to see the detail, but no lens that I know of can use the full resolution of a modern dslr sensor. So, looking at a D7100 24mp camera the Nikkor 105mm f1.4 utilizes about 19mp, but the Nikkor 105mm f2 utilizes about 12mp of the 24mp sensor. So, Tony is basically generalizing DxOMark camera/lens tests. There are other factors to consider. A lens does not behave uniformly. It can be very sharp in the center and not so sharp on the edges, CA, vignetting, f stop, distance all can affect performance. Not always, but more expensive lenses generally perform better than less expensive lenses. Also remember not all scenes have fine detail so even less expensive glass on a decent camera can accurately reproduce the scene.

Bobspez Loc: Southern NJ, USA

I don't understand the 9MP comment either, but he is comparing the 18-55 kit lens to an $800 Sigma 18-35 f1.8 lens. He is saying the Sigma is much sharper and better in low light. Well of course.
Your link should end with a 0 instead of an O ...
https://www.youtube.com/watch?v=fmWBW8aZSS0

Thanks for replying.

Strodav Loc: Houston, Tx

From DxOMark.com: "The score represents the sharpness performance of a lens-camera combination averaged over its entire focal length and aperture ranges and is computed as follows:

For each focal length and each f-number sharpness is computed and weighted across the image field, with the corners being less critical than the image center. This results in a number for each focal length / aperture combination. We then choose the maximum sharpness value from the aperture range for each focal length. These values are then averaged across all focal lengths to obtain the DxOMark resolution score that is reported in P-MPix (Perceptual Megapixels).

It’s worth noting that for lenses with a wide zoom range the differences between sharpness at different focal lengths can be quite significant. For most lenses, sharpness in P-Mpix is typically between 50% and 100% of the sensor pixel count, and differences smaller than 1 P-MPix are usually not noticeable. The best resolutions are usually achieved by prime lenses at apertures between f/2.8 and f/8."

Longshadow Loc: Audubon, PA, United States

A "measurement" of lenses that did not need to be contrived.

ka5ysy

I’m still trying to fathom his statement that the aperture of my MFT Olympus pro lenses is not what M.Zuiko says they are... 🤔

Ronald540 Loc: Sandy Utah

Perceptual Megapixels, P-MPix for short, can be described as the “equivalent” number of megapixels when using a particular lens. ... This means that the resulting photos are equal in sharpness to an 18-megapixel camera shooting with an optically perfect lens.
https://www.dxomark.com/About/In-depth-measurements/Measurements/Sharpness
https://www.dpreview.com/articles/8671938754/dxomark-introduces-perceptual-mpix-score-for-lenses
My lens on a Nikon D750 is a 24-120 f/4 perceptual Sharpness 14mp.
My 24-70 f2.8 is only 17mp closer match to the 24mp sensor.
On the 810 it is 21mp.
Good glass is always better than a new camera...
Tony was for years an engineer for Microsoft. Has written all of their books used in the MCSE coursed of which I am one. His math has always been sound.
At almost 80 I still teach in the IT field, so I guess I am a fan of Tony Northrup.
What does this have to do with photography; it depends on your perception.
It’s just math.
The question is can you tell with your eye???
Cheers ron

Longshadow Loc: Audubon, PA, United States

Some people can make ANYTHING seem logical, believable is another story.

Architect1776 Loc: In my mind

mgoldfield

Perhaps we should take a look at the Dxomark report. Clearly lenses are not usually rated in MP; however, I've seen film rated with MP equivalents so their might be some merit to this information.

We all know there are differences in the resolving power of lenses. It seems reasonable that a lens with limited resolving power could compromise the capability of a digital sensor.

Personally, I have found Tony Northrup's information to be useful. Take a look at his credentials.
There are one million subscribers to his YouTube channel, and his book is the No. 2 best selling book about digital photography on Amazon with over 2,000 positive reviews.

Can his huge success be a fluke. I would like to see the video you reference.

M. Goldfield

mgoldfield

On the mark!

BebuLamar

Actually I do not think Tony Northrup is wrong on most of the stuff he said that many people said he was wrong. However, I do not think his success is because people learned from him because as you can see way too many people think he is wrong or confused about what he said. I can't put a finger on it but his success come from something else. Perhaps a husband and wife team?