"Crop-ability" of images?

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bobn2
bobn2 Forum Pro • Posts: 69,811
Re: "Crop-ability" of images?

Donald B wrote:

bobn2 wrote:

Donald B wrote:

Wu Jiaqiu wrote:

Donald B wrote:

Wu Jiaqiu wrote:

john isaacs wrote:

Wu Jiaqiu wrote:

Donald B wrote:

bobn2 wrote:

Donald B wrote:

bobn2 wrote:

Muster Mark wrote:

bobn2 wrote:

dperez wrote:

More photographers who’s judgement I respect are talking about moving to Olympus. A question came up the other day and I’m trying to figure out the answer.

Nikon D850, 600mm f/4 versus M1X, 300mm f/4.

As I understand it - the lenses are the same equivalent - 600mm. The Nikon shoots at f/8 and ISO 3200 and 1/500. The M1X shoots at f/4 so the DOF is the same, and ISO 800 and 1/500, so the exposure is the same, right?

Wrong! Somewhere along the way you've picked up a wrong idea of what 'exposure' means. It does not mean how light or dark the image is. It means what is the light energy density at the sensor. It is determined by shutter speed, f-number and scene luminance. In your example, since the shutter speed and scene luminance are the same, but the f-number is two stops higher on the Nikon, it will have two stops less exposure. But it will make up for it by having four times the sensor area.

I think he was saying he puts the Nikon at f8 and gets the same results as the Oly at F4. This is correct. He has the Nikon shooting at ISO 3200 and the oly at ISO 800. I don't think your criticism of his understanding is warranted.

I didn't criticise his understanding except for the meaning of 'exposure', which he got wrong. This misunderstanding is unfortunately common. As you say, if he was saying that he gets the same 'results' or lightness, then yes, he's right.

I like this quote "The “Exposure Triangle,” as it is often referred to, is a handy way of interpreting the major components involved in the process of capturing an image.

Yes, I think that the 'triangle' is responsible for people thinking wrongly that the components of exposure are aperture, shutter and ISO.

well think of it like this , to expose a viewable image on the camera rear lcd or evf . the camera requires the correct aperture ,shutter speed and iso now try to argue against that

When invented by Bryan Peterson it was the 'Photographic Triangle'. Whatever the name, it's useless.

iso you say....the rabbit hole beckons

Exposure triangle:

https://www.cambridgeincolour.com/tutorials/camera-exposure.htm

Exposure settings:

https://www.adobe.com/creativecloud/photography/hub/guides/camera-exposure-camera-settings.html

Because when people think of "exposure", they think of the image.

ISO does not change the sensor's sensitivity to light though as per the adobe article, it's wrong

a light meter requires 3 inputs from the user for it to work.

There are lots of kinds of light meter, but I suspect you're talking about one particular type, an 'exposure meter'. Even then, it's not the case. Over the history of photography, exposure meters have come in many shapes and forms. To calculate exposure you need the scene luminance and the EV (combination of shutter speed and f-number). Some meters give you a direct reading of scene luminance and then provide tables to calculate exposure, given different EV values. However, mostly photographers have not been so interested in what is the exposure, they want to match the target exposure specified by the ISO (or before that the ASA or DIN). For hand held meters, you's generally set the target exposure, by means of setting the ISO, and the meter would tell you the EV setting to use, or it would separate it out into f-number and shutter speed. You set one, and it tells you the other. For coupled meters the norm was to display the difference from the target exposure with the selected f-number and shutter speed.

Mostly people who make this mistake of what exposure is have never used a separate exposure meter or if they have, haven't understood what they are doing with it.

Don

does that change your sensor's sensitivity to light?

A gain control controls the sensors sensitivity’s, which I presume is the iso control can’t image its further down the track. Same as gain control on a radio receiver.

Din

I thought my typing was bad, but I usually get my own name right.

Anyhow, the gain control on a radio receiver only affects its sensitivity for an AM radio using a diode detector. The amplitude of the carrier needs to be larger than the diode's forward voltage for the signal to be detected, this 'sensitivity', in the sense of what is the smallest signal that can be detected, can be increased by putting gain in front of the detector stage.

But what if you added a multi element yagi with a 6db gain, if a strong station was close the gain control would then need to decrease the signal, wouldnt that be the same as a bright lens and sunny day ?

You'd need an attenuator, not a gain control.

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bobn2
bobn2 Forum Pro • Posts: 69,811
Re: Exposure vs Exposure
5

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

I think in this case, 'he can talk about Lux all he wants' is shorthand for 'I'm incapable of following the discussion and don't want to admit to it,' and the statement 'No one cares' should have been prefixed with the words 'I hope'.

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john isaacs Veteran Member • Posts: 6,124
Re: Exposure vs Exposure

bobn2 wrote:

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

I think in this case, 'he can talk about Lux all he wants' is shorthand for 'I'm incapable of following the discussion and don't want to admit to it,' and the statement 'No one cares' should have been prefixed with the words 'I hope'.

His definition is useless. His insistence is futile.

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john isaacs Veteran Member • Posts: 6,124
Re: Exposure vs Exposure

bobn2 wrote:

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

I think in this case, 'he can talk about Lux all he wants' is shorthand for 'I'm incapable of following the discussion and don't want to admit to it,' and the statement 'No one cares' should have been prefixed with the words 'I hope'.

You wish.

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gary0319
gary0319 Veteran Member • Posts: 8,898
Olympus severe crop
3

Shot with the 12-100 on E-M1 II.

Full image and crop of same image.

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john isaacs Veteran Member • Posts: 6,124
Re: Exposure vs Exposure

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

It’s the image that matters.

A good image becomes better when exposure is also good.

Perhaps this is why Kodak is no longer in the camera business?

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Iliah Borg Forum Pro • Posts: 28,762
Re: Exposure vs Exposure
6

john isaacs wrote:

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

It’s the image that matters.

A good image becomes better when exposure is also good.

Perhaps this is why Kodak is no longer in the camera business?

No, they are no more in camera business because people who knew what they are doing were replaced by people who literally don't know what exposure is.

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john isaacs Veteran Member • Posts: 6,124
Re: Exposure vs Exposure

Iliah Borg wrote:

john isaacs wrote:

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

It’s the image that matters.

A good image becomes better when exposure is also good.

Perhaps this is why Kodak is no longer in the camera business?

No, they are no more in camera business because people who knew what they are doing were replaced by people who literally don't know what exposure is.

So you work for Kodak?  Interesting.

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bobn2
bobn2 Forum Pro • Posts: 69,811
Re: Exposure vs Exposure
1

john isaacs wrote:

bobn2 wrote:

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

I think in this case, 'he can talk about Lux all he wants' is shorthand for 'I'm incapable of following the discussion and don't want to admit to it,' and the statement 'No one cares' should have been prefixed with the words 'I hope'.

You wish.

I don't wish. I expect I'm right.

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john isaacs Veteran Member • Posts: 6,124
Re: Exposure vs Exposure

bobn2 wrote:

john isaacs wrote:

bobn2 wrote:

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

I think in this case, 'he can talk about Lux all he wants' is shorthand for 'I'm incapable of following the discussion and don't want to admit to it,' and the statement 'No one cares' should have been prefixed with the words 'I hope'.

You wish.

I don't wish. I expect I'm right.

You will be disappointed.

Exposure Triangle.  It is Truth.

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bobn2
bobn2 Forum Pro • Posts: 69,811
Re: Exposure vs Exposure
6

john isaacs wrote:

bobn2 wrote:

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

I think in this case, 'he can talk about Lux all he wants' is shorthand for 'I'm incapable of following the discussion and don't want to admit to it,' and the statement 'No one cares' should have been prefixed with the words 'I hope'.

His definition is useless.

Not very clever, all those people like Hurter and Driffield, ISO, Kodak, Fujifilm, Ilford, Agfa and all the  manufacturers that used and designed their products around that definition of exposure. Or the photographers like Adams that based their practice around it. Of course, it's to be expected, without the help of all those You Tube videos and Web explainers to put them right. I mean, what were they to do? They went to college and learned from people who actually know what they were talking about, and got their qualifications by satisfying examiners that they had learned it all properly. What a useless way of doing it. All that really matters is how many likes you get for your post. That tells you what's right and wrong.

And none of them had even heard of the 'Exposure Triangle', so really, how were they ever going to understand anything?

His insistence is futile.

Not quite as futile as someone who continues an argument in which their every contribution is yet another eloquent demonstration that they haven't a clue what they are talking about. It must be a lack of self-awareness.

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bobn2
bobn2 Forum Pro • Posts: 69,811
Re: Exposure vs Exposure
4

john isaacs wrote:

bobn2 wrote:

john isaacs wrote:

bobn2 wrote:

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

I think in this case, 'he can talk about Lux all he wants' is shorthand for 'I'm incapable of following the discussion and don't want to admit to it,' and the statement 'No one cares' should have been prefixed with the words 'I hope'.

You wish.

I don't wish. I expect I'm right.

You will be disappointed.

No, I won't.

Exposure Triangle. It is Truth.

Clearly you and I have different definitions of the word 'truth'. Except, I see you used a capital letter, so it's not just plain old truth. Does than mean it's something religious?

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Dennis Forum Pro • Posts: 20,497
Re: Exposure vs Exposure
5

john isaacs wrote:

His definition is useless. His insistence is futile.

Funny, before reading about equivalence and exposure in dpreview threads a few years ago, I shared the misconceptions that "f/2.8 is f/2.8" and exposure is the sum of all the "exposure settings". Bobn2 and GB straightened me out. Now, I tend to expose to the right when possible. I ended up switching (actually, quite a few years ago) from a camera that did not offer Auto ISO in M to one that does, because that makes it easier to ensure I'm maximizing exposure in low light. I set shutter speed and f-stop to maximize exposure (always subject to various constraints) and let the camera calculate the ISO to brighten the image according to however I've metered it (metering is still important to avoid blown highlights). I could, at that point, shoot at base ISO and brighten in post processing, but that's now a workflow that interests me (and I want a usable preview image in the camera).

It's a simple, basic concept that has resulted in an improvement in certain aspects of some of my photos.

It's a shame that so many people are so adamantly against the spread of knowledge .

- Dennis
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Iliah Borg Forum Pro • Posts: 28,762
Re: Exposure vs Exposure
4

john isaacs wrote:

Iliah Borg wrote:

john isaacs wrote:

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

It’s the image that matters.

A good image becomes better when exposure is also good.

Perhaps this is why Kodak is no longer in the camera business?

No, they are no more in camera business because people who knew what they are doing were replaced by people who literally don't know what exposure is.

So you work for Kodak?

I was one of their students when knowledgeable people were at the helm.

Interesting.

This thread is about photographic exposure, and not about your rather odd remarks.

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Tony Rogers Senior Member • Posts: 2,067
Re: Exposure vs Exposure

Iliah Borg wrote:

john isaacs wrote:

Iliah Borg wrote:

john isaacs wrote:

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

It’s the image that matters.

A good image becomes better when exposure is also good.

Perhaps this is why Kodak is no longer in the camera business?

No, they are no more in camera business because people who knew what they are doing were replaced by people who literally don't know what exposure is.

So you work for Kodak?

I was one of their students when knowledgeable people were at the helm.

Interesting.

This thread is about photographic exposure, and not about your rather odd remarks.

This sub-thread might be. But the thread was supposed to be about how the number of pixels on the sensor affects the amount of detail in the image and how it affects cropping and possibly about moving to Olympus from Nikon! Just sayin...

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Iliah Borg Forum Pro • Posts: 28,762
Re: Exposure vs Exposure
5

bobn2 wrote:

john isaacs wrote:

bobn2 wrote:

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

I think in this case, 'he can talk about Lux all he wants' is shorthand for 'I'm incapable of following the discussion and don't want to admit to it,' and the statement 'No one cares' should have been prefixed with the words 'I hope'.

His definition is useless.

Not very clever, all those people like Hurter and Driffield, ISO, Kodak, Fujifilm, Ilford, Agfa and all the manufacturers that used and designed their products around that definition of exposure.

Canon, Nikon, Olympus, and Sony are also listed among those responsible for ISO 12232 standard - "Digital still camerasDetermination of exposure index, ISO speed ratings, standard output sensitivity, and recommended exposure index" - https://www.iso.org/news/ref2375.html

Or the photographers like Adams that based their practice around it. Of course, it's to be expected, without the help of all those You Tube videos and Web explainers to put them right. I mean, what were they to do? They went to college and learned from people who actually know what they were talking about, and got their qualifications by satisfying examiners that they had learned it all properly. What a useless way of doing it. All that really matters is how many likes you get for your post. That tells you what's right and wrong.

And none of them had even heard of the 'Exposure Triangle', so really, how were they ever going to understand anything?

His insistence is futile.

Not quite as futile as someone who continues an argument in which their every contribution is yet another eloquent demonstration that they haven't a clue what they are talking about. It must be a lack of self-awareness.

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Iliah Borg Forum Pro • Posts: 28,762
Re: Exposure vs Exposure
3

Tony Rogers wrote:

Iliah Borg wrote:

john isaacs wrote:

Iliah Borg wrote:

john isaacs wrote:

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

It’s the image that matters.

A good image becomes better when exposure is also good.

Perhaps this is why Kodak is no longer in the camera business?

No, they are no more in camera business because people who knew what they are doing were replaced by people who literally don't know what exposure is.

So you work for Kodak?

I was one of their students when knowledgeable people were at the helm.

Interesting.

This thread is about photographic exposure, and not about your rather odd remarks.

This sub-thread might be. But the thread was supposed to be about how the number of pixels on the sensor affects the amount of detail in the image and how it affects cropping and possibly about moving to Olympus from Nikon! Just sayin...

To quote OP:

" The Nikon shoots at f/8 and ISO 3200 and 1/500. The M1X shoots at f/4 so the DOF is the same, and ISO 800 and 1/500, so the exposure is the same, right?"

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bobn2
bobn2 Forum Pro • Posts: 69,811
Re: Exposure vs Exposure
2

Tony Rogers wrote:

So you work for Kodak?

I was one of their students when knowledgeable people were at the helm.

Interesting.

This thread is about photographic exposure, and not about your rather odd remarks.

This sub-thread might be. But the thread was supposed to be about how the number of pixels on the sensor affects the amount of detail in the image and how it affects cropping and possibly about moving to Olympus from Nikon! Just sayin...

You're dead right. Whether what exposure means is really an issue depends on the context.

If Bill and Joe go out photographing and Bill asks Joe 'what exposure are you getting', and Joe answers 'eff five six at two fifty' the conversation is full of technical errors, but then it's colloquial, and they each know what they mean, so no problems.

The context of this discussion is a bit different. The discussion will move from just considering the number of pixels to the image quality given by those pixels, because that is relevant to the discussion. The image quality discussion in turn leads to one about the amount of light, because it is that which in the main determines image quality. So, the OP made a slight error in terms of his understanding of measurements of amount of light, I put in a polite correction, to which he responded positively. That might have been the end of it, except that a couple of people here decided that their misunderstanding of the basics of photography should be imposed on all of us, and pursued a strategy of battering away presumably in the hope that we'd give way.

That is a very common pattern in these kinds of discussion. Some people are very attached not only to their right to be wrong, which of course they have, but also to impose their wrongness on everyone else.

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bobn2
bobn2 Forum Pro • Posts: 69,811
Re: Exposure vs Exposure
1

Iliah Borg wrote:

bobn2 wrote:

john isaacs wrote:

bobn2 wrote:

Iliah Borg wrote:

john isaacs wrote:

He can talk about Lux all he wants. No one cares.

If no one cares, why would Kodak mention lux 70 times on 24 pages of their "Basic Photographic Sensitometry Workbook" brochure?

I think in this case, 'he can talk about Lux all he wants' is shorthand for 'I'm incapable of following the discussion and don't want to admit to it,' and the statement 'No one cares' should have been prefixed with the words 'I hope'.

His definition is useless.

Not very clever, all those people like Hurter and Driffield, ISO, Kodak, Fujifilm, Ilford, Agfa and all the manufacturers that used and designed their products around that definition of exposure.

Canon, Nikon, Olympus, and Sony are also listed among those responsible for ISO 12232 standard - "Digital still camerasDetermination of exposure index, ISO speed ratings, standard output sensitivity, and recommended exposure index" - https://www.iso.org/news/ref2375.html

Yes, but they obviously though better of it, since their marketing people have released helpful explainers which say something different

Anyhow, we're told by Mr Isaacs that there is no standard for ISO, so you must be wrong.

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cameron2 Veteran Member • Posts: 4,074
Re: "Crop-ability" of images?

dperez wrote:

The question I was asked was essentially "Once I take the bird picture, and get it into Lightroom, and crop it down to the bird, WHICH camera is going to give me the most bird pixels so I can crop the least?"

There's another way to imagine the difference: Shooting with a 20mp m43 sensor and a 300mm f4 lens is nearly identical to shooting with an 80mp 35mm sensor and a 300mm f4 lens and then cropping down to the middle 20mp of the 80mp image. This is one of the (technically incorrect) reasons why some people refer to m43 as a "crop format".

The real question is this, though: How much more do you need to crop that remaining 20mp down to get the image that you actually want?

In my test world, it's the D850. In the REAL world, shooting a 600mm I'd have more bird pixels shooting the D500 with the 600 (900mm 35 EQ) followed by the M1X at 400mm (800mm 35 EQ)...

The D850 is 46mp. So if you can fill the frame (no crop required), you have a 2.3x pixel advantage. Given the same light, you also have a 4x light advantage. I'm sure Bob will correct me if my calculations are wrong, but at first glance, that means that you have a 1.74x advantage per pixel (meaning you can shoot at roughly 4x the shutter speed as m43 to achieve the same noise level, or 1.74x the shutter speed as m43 to achieve the same noise per pixel, or shoot at the same shutter speed with less resulting noise).

All that to say that, yes, there are measurable and significant advantages to using larger sensors.

The other area of curiosity - (this one is my curiosity) is the mechanics. I shot a Sony A9 II and an A7r III. In both cases I found that when I put the camera to my eye, there was a delay before the EVF came on. Since I'm watching a bird flying by, I'm used to putting the D500 to my eye, seeing the bird, and shooting. With either Sony I was always behind the bird because of the delay.

Will this happen with the M1X or the E-M1 III?

Yup. The Oly dot sight can help, but it's hard to beat the D500 for speed-to-shot.

I'd strongly suggest that you borrow someone's Oly and lenses to try for yourself before you buy. You have a working setup now, so don't abandon it unless you are certain that what you're switching to will meet your needs. (Also, don't switch to something that you will not enjoy.)

p.s. I have spent a lot of time in Japan, and it's always funny to see 50Kg 85 year old photographers carrying around 20Kg cannons (some of which are Canons) to get their shots. They are happy and contented with their setups, so I know it is possible to do.

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