How can you appreciate 100MP without cropping?

[pippy]

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4 minutes ago, dem331 said:

Won’t it affect OOF and DOF?

Yes, of course.

Sorry; I was only talking about perspective and compression (as stated) so I was wholly wrong in saying that "...there will be no difference whatsoever..." because in some situations - such as the one you mention - images will not look identical.

My apologies to Einst_Stein!

Philip.

[dem331]

9 minutes ago, pippy said:

Yes, of course

Thanks. Not trying to be picky, but I often see cropping equated to changing focal length (not referring to your post) and to me it seems quite different 

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[pippy]

16 minutes ago, dem331 said:

Thanks. Not trying to be picky, but I often see cropping equated to changing focal length (not referring to your post) and to me it seems quite different 

No; you were absolutely right to correct me. Mea Culpa!...........

The subject of perspective / compression crops (Ho!Ho!) up quite often but not usually in the context of DOF/OOF so it was good that you mentioned it here as it is very relevant to this thread.

Philip.

[Einst_Stein]

Thanks for the above clarifications.

If I try to explain in physics, assuming two subjects a and b in different distance, their image in two image plan A and B, if I use focal length L1 and L2, shooting from the same position, focus at a, then the image plane A1 and A2 will be the same, but  image plane B1 and B2 will be different. if I crop the image, there is only one image plain B.

Edited February 16, 2023 by Einst_Stein

[pgk]

1 hour ago, dem331 said:

Won’t it affect OOF and DOF? 
 

If I photograph my wife with a 28mm 50 metres away with my huge sensor and crop to 500mm equivalent and then photograph her with my 500mm lens at F2.8 focussing on her face I think the result will be totally different even though the perspective will be the same.   (I don’t know if it’s 20 or 50 or 100 metres away, but you get my point) 

Try it! The results will be similar at the same aperture (not identical because you are using two different lenses and there will be differences due to technicalities such as pixel size). You will always get the same perspective of a subject from the same viewpoint - lens focal length is irrelevant.  

[dem331]

8 minutes ago, pgk said:

Try it! The results will be similar at the same aperture (not identical because you are using two different lenses and there will be differences due to technicalities such as pixel size). You will always get the same perspective of a subject from the same viewpoint - lens focal length is irrelevant.  

I don’t think so. Please consider that I am not talking about perspective. We all agree that perspective is independent of focal length. I am talking about depth of field. 
 

Try taking a picture of your favourite sports personality from your seat in the stands with a 21 mm and cropping it. Everything will be in focus. Now take it with a long lens. The face will be in focus (if you nail it because you are using a Sony and not an SL2 like I am) and everything one metre behind that will be out of focus. 
 

The resulting photo will be very different. 
 

Try it! 🙂
 

 

 

[pippy]

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1 hour ago, pgk said:

Try it!...

Funnily enough I just have because there is a lot of confusion on these points.

Camera was M Monochrom. Lenses were 28mm / 50mm / 90mm / 135mm. All images exposed at f8. Focus-point was Velux window on front-row house just left of centre. No post-prod because ultimate IQ is hardly relevant here.

First group is uncropped view ( on a very gloomy day!) out of the window of the studio. Top pairing is 28 / 50; lower pairing 90 / 135;

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Next grouping is the cropped view of these same images where the 28, 50 and 90 frames have been cropped to match full-frame of the 135mm;

As can be seen the perspective / compression is unchanged. What can't quite be seen here (because of size constraints) is that the DoF / OoF rendering changes from the 28 to 90. There is a noticeable difference on-screen at full resolution. Perhaps it would have been clearer had I used f4 but hopefully this wee test will be of some use.

Philip.

Edited February 16, 2023 by pippy

[Ko.Fe.]

On 2/13/2023 at 1:10 PM, Einst_Stein said:

I know, I know, you can crop it or “de-stitch” it to make smaller or multiple pictures.  

Oh, yes, I forget you can print it 4 meter x 3 meter or even the size of theater screen. But have your ever really done that? Would you?

Maybe 100 MP is too much, what about 47mp?

I know very few photogs who needs huge files for real. Two, to be exact. They made choice to do some business in large prints.

What happened to both of them, they realized what sensor size is as important as MPs. 

I'm thinking of updating my phone to better camera phone, the model I'm aimed to has ... 108 MP.

Would I be able to print huge from it? No. Mobile phone cameras MPs count is total marketing SCAM.  

From this extreme example, similar is with so called FF and so called MF digital.

So, both photogs choice for large prints cameras was not just hundred MPs, but larger sensor, digital MF cameras. Because image quality comes from the sensor size most.

 

Another aspect of hundreds MPs cameras, regardless sensor size is different size RAW images support in camera.

Any camera with hundreds MPs has processor fast enough to process those huge RAW files.

Taking this fact in account, in terms of large sensor, premium cameras, I'm finding it to be ignorant jerks approach from camera manufacturers who do not include in-camera RAW files resizing, choice of MPs count. 

Cameras where choice of MPs in RAW files is supported are doing it in real time. So, every time some smarts pants is coming with wisdom of using in computer convertor, my reaction - I'm not a looser to waste my valuable time on this.   

[pgk]

1 hour ago, dem331 said:

 I am talking about depth of field.

Depth of field will be the same at the same aperture for a long focal length lens or an equivalent crop from a shorter focal length lens. Any observable differences will be because of magnification, image processing, pixel size, etc.. But not primarily because of a change in the depth of field  (although it may vary marginally depending on the lens design and design objectives). You need to look at the geometry of the image to appreciate this.

Depth of field is a rather widely misunderstood concept.

Edited February 16, 2023 by pgk

[dem331]

1 minute ago, pgk said:

Depth of field will be the same at the same aperture for a long focal length lens or an equivalent crop from a shorter focal length lens. Any observable differences will be because of magnification, image processing, pixel size, etc.. But not primarily because of a change in the depth of field  (although it may vary marginally depending on the lens design and design objectives). You need to look at the geometry of the image to appreciate this.

Take a look at this. I just shot it out of a window. 
 

35 mm APO on SL2 at f2.8 focus on tree trunk in foreground 

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[dem331]

Same photo cropped to 180mm equivalent
 

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Edited February 16, 2023 by dem331

[dem331]

SL2 with 180mm Sonnar at f2.8

 

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[dem331]

I don’t know if you call these differences depth of field or not. But the results are absolutely different

[pgk]

13 minutes ago, dem331 said:

Take a look at this. I just shot it out of a window. 

Given that the enlarged section is unsharp and the point of focus is not definable the test is simply invalid.

[Einst_Stein]

Don't waste your time. 

Cropping is essentially shooting on a smaller sensor with a shorter focal length. Can you get same picture by shooting on a, say, 1/2.3" sensor to match a FF? adjust your focal length and aperture by all means!  

[dem331]

3 hours ago, pgk said:

Given that the enlarged section is unsharp and the point of focus is not definable the test is simply invalid.

yes, for some reason it did not upload properly.  Here is the same photo with the 35 mm cropped to 180 mm equivalent.

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I am sure you can appreciate the difference in the background

[dem331]

12 hours ago, Einst_Stein said:

Can you get same picture by shooting on a, say, 1/2.3" sensor to match a FF?

A very good question that is not that easy to answer.  I would say no, unless you crop the FF image and use the same focal length and aperture for both images, and even then it will depend on the properties (pixel densities or whatever, which I don’t fully understand) of the sensors. 
 

One thing that surprises me is that people that are very keen on shooting at f0.95 or f1.0 are also keen to use extreme crops to explain the need for a 100mp sensor. 

[jaapv]

18 hours ago, dem331 said:

Thanks. Not trying to be picky, but I often see cropping equated to changing focal length (not referring to your post) and to me it seems quite different 

That refers to perspective, and is  100%  correct. However things like resolution and grain will be different. 

[jaapv]

15 hours ago, pgk said:

Depth of field is a rather widely misunderstood concept.

Amen to that! 

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[jaapv]

12 hours ago, dem331 said:

yes, for some reason it did not upload properly.  Here is the same photo with the 35 mm cropped to 180 mm equivalent.

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I am sure you can appreciate the difference in the background

I'm not convinced that you used the same aperture.