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Sony G and GM Lens Resolution on different bodies

  
 
foto16
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p.2 #1 · p.2 #1 · Sony G and GM Lens Resolution on different bodies


philip_pj wrote:
Here we see the same lens tested using the same procedure, on a 21mp sensor and a 50mp sensor. It's pretty analogous to Sony's low/high setup of 24mp and 61mp. The lens is Canon's 24-105, an EF lens.


This is very interesting. When people move from a 21MP sensor to a 50MP sensor, they assume since they will more than double (2.38x) their MP, there is also the same whopping improvement in image details (and crop-ability). However, as the test charts show, even at f8 in the center, your new resolution is less than 2.38x of the old sensor. Taking account of the worsening of the border and corner performance, one can perhaps estimate crudely the gain in actual resolution/details:

At 21MP, the average linear resolution (center, border, extreme) at f8 is (3181+2834+2792)/3=2935.666667.
At 50MP, the average linear resolution (center, border, extreme) at f8 is (4506+3719+3333)/3=3852.666667.

The new linear resolution is 3852.666667/2935.666667=1.312x of the smaller sensor, or 1.312^2=1.722x the area of the smaller sensor, which is equivalent to a 21x1.722=36MP sensor.

So taking into consideration the lens, by moving from a 21MP sensor to a 50MP sensor, you only move from 21MP to 36MP in real details, far from what the sensor MP count suggests. We often hear people say "even if I use the crop mode of my 61MP camera, I can still get 26MP details." But this is untrue. You get a 26MP file, but the real resolution gain is complete different from what the sensor MP count suggests (Of course the calculation above based on the LW/PH is for illustrative purposes only. Real world shooting is more complicated.)



Nov 22, 2023 at 09:09 PM
NonDecaf
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p.2 #2 · p.2 #2 · Sony G and GM Lens Resolution on different bodies


foto16 wrote:
This is very interesting. When people move from a 21MP sensor to a 50MP sensor, they assume since they will more than double (2.38x) their MP, there is also the same whopping improvement in image details (and crop-ability). However, as the test charts show, even at f8 in the center, your new resolution is less than 2.38x of the old sensor. Taking account of the worsening of the border and corner performance, one can perhaps estimate crudely the gain in actual resolution/details:

At 21MP, the average linear resolution (center, border, extreme) at f8 is (3181+2834+2792)/3=2935.666667.
At 50MP, the average linear resolution (center,
...Show more

There isn't any downside from the OP's point of view. IMHO, As long as you're not at the diffraction limit for the lens, more MP/finer pixel pitch on the sensor is always going to be better (with obvious caveats w.r.t read noise improvements for smaller pixel sizes).



Nov 23, 2023 at 01:33 AM
aCuria
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p.2 #3 · p.2 #3 · Sony G and GM Lens Resolution on different bodies





Yes, But now you are introducing contrast values. Earlier we discussed resolution only. When including contrast there are more unknown parameters. For example, what is the resulting resolution when measuring the 135mm lens together with the sensor at a certain contrast level. The most common value describes the LP/mm value at 50% contrast. Questions, questions... IMA-test is not a good tool in my experience as even the slightest increase of contrast in the image make IMA-test show a big difference in "resolution".

So, we have what we have. Over to the formula:

Ah... I thought the formula was (1/image_resolution) = (1/lens_resolution)
...Show more


Resolution and contrast, is the same thing! The MTF chart which we use to judge resolution is ultimately plotting contrast values.

If the contrast is low, the maybe you can distinguish a black strand of hair against a white sky, but you won’t be able to see the detail in fine white lace against the bride’s white dress, or distinguish the individual vanes of a bird’s feather from each other

The formula is from the film days and is ultimately an approximation, you can see the formula mentioned here:

https://www.bobatkins.com/photography/technical/multipliers.html



Nov 23, 2023 at 03:00 AM
aCuria
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p.2 #4 · p.2 #4 · Sony G and GM Lens Resolution on different bodies


foto16 wrote:
This is very interesting. When people move from a 21MP sensor to a 50MP sensor, they assume since they will more than double (2.38x) their MP, there is also the same whopping improvement in image details (and crop-ability). However, as the test charts show, even at f8 in the center, your new resolution is less than 2.38x of the old sensor. Taking account of the worsening of the border and corner performance, one can perhaps estimate crudely the gain in actual resolution/details:

At 21MP, the average linear resolution (center, border, extreme) at f8 is (3181+2834+2792)/3=2935.666667.
At 50MP, the average linear resolution (center,
...Show more

This is because MP is describing surface area… it has always been a bit of a scam

It’s the same way with viewfinder resolution, they describe it in millions of pixels as opposed to “800x600” which is more accurate

Going from a A7iv to RV the difference is at most 30% with perfect optics, just take the ratio of the pixel heights. this means going from an 8x12” print to 10.4x15.6” print (8*1.3=10.4)

In practice it’s even less than this, because it depends on the lens used

Sonys cameras do approximately 83, 100, 110, 120, 130 lp/mm for the 7iii, 7iv, Riii, A1, RV. It’s very deliberate



Nov 23, 2023 at 03:23 AM
 


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foto16
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p.2 #5 · p.2 #5 · Sony G and GM Lens Resolution on different bodies


NonDecaf wrote:
There isn't any downside from the OP's point of view. IMHO, As long as you're not at the diffraction limit for the lens, more MP/finer pixel pitch on the sensor is always going to be better (with obvious caveats w.r.t read noise improvements for smaller pixel sizes).


Agree there is no downside going to higher MP camara in the sense that it won't capture less details, if the higher cost is not a concern. If you need to assess whether paying a higher cost is worthwhile for you (an individual choice), then it's better to know all the facts (including how much a gain you are going to get for the cost you pay) instead of relying solely on the manufacturer's marketing.

Noise is a downside if you printing larger and crop, two of the main motivations for paying for a high MP. I've even seen posts on the forum "soon we will have no need for long lenses or zoom lenses, I can crop as much as I can." The whole-image noise performance of a higher MP camara is not worse than a lower MP camera as long you print at the same size and do not crop. However, as soon as you start to print larger and/or crop, the noise performance will get worse since you are magnifying more and/or use a smaller area of the FF sensor. You also lose DOF control the more you crop.

My overall take is that if money's no object, I will always take the higher MP camera. But I will set a limit in terms of cropping and printing, way more conservative than what the nominal MP count suggests. If cost is a concern, the buyer should know even a 24-33MP can print really large and possesses the ability to crop a lot, sufficient for the typical photographic need.






Nov 23, 2023 at 10:51 AM
Jonas B
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p.2 #6 · p.2 #6 · Sony G and GM Lens Resolution on different bodies


philip_pj wrote:
[...]Data represent wide open aperture at the shared max aperture for Leica and Cosina for such lenses of f2. An interesting feature of these APO lenses is that they barely improve on stop-down nor do they change much in cross-frame performance.
[...]


If I had been into landscapes i certainly would have bought the Voigtländer 50/2.0 APO. Now I'm not that critical about even "sharpness" across the field.
Sometimes it gets too bad though. I have owned the Summilux-M 35/1.4 ASPH (pre-FLE). Great lens as I got many beatiful images - but it couldn't make an image sharp from the left to right when needed. Another example is the Sigma 35i. I had no luck with that lens. Here is cluttered comparison between sample 1 and 2 of the 3 different copies I tried thinking one shouldn't give up.







So, OK, I gave up. Maybe I should have made another attempt later as i noticed the three copies (bought from three different stores) all were pretty close to each other if comparing serial numbers. The point however, even if not very critical about even performance from corner to corner midzone dips sometimes can be too much.



Nov 23, 2023 at 02:43 PM
Jonas B
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p.2 #7 · p.2 #7 · Sony G and GM Lens Resolution on different bodies


aCuria wrote:
Resolution and contrast, is the same thing! The MTF chart which we use to judge resolution is ultimately plotting contrast values.

If the contrast is low, the maybe you can distinguish a black strand of hair against a white sky, but you won’t be able to see the detail in fine white lace against the bride’s white dress, or distinguish the individual vanes of a bird’s feather from each other

The formula is from the film days and is ultimately an approximation, you can see the formula mentioned here:

https://www.bobatkins.com/photography/technical/multipliers.html


Of course contrast and resolution is the same thing. The whole thread is about contrast, or micro-contrast rather, no? It was just nice having a simplified discussion leaving everything about contrast values, CA, "corner sharpness", vignetting, SA and all other aberrations aside.

Thank you for the link! As we now have two different formulas I have to look a little closer at this. In my mind t all worked out so nicely with the more simple formula...




Nov 23, 2023 at 02:43 PM
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