[24X36NOW]

Sorry, but I believe you are taking my words out of context.

"If the football field and your house are close together, there is only one possible answer: IT RAINED THE SAME AMOUNT OF WATER PER SQUARE METER OVER BOTH PLACES.

In shorter words: The only way to honestly compare exposure through a given lens and a certain aperture, is to compare similar situations. As I said before: THE SENSOR SIZE HAS NO PART here. What matters is the effective light transmission of the lens (f/stop) and the time frame during the actual exposure (shutter speed). PERIOD."

(The red section is what you deliberately deleted to take my words out of context)

Yes, I said that, but I also said that in order to be valid, such measurement of light should be given over THE SAME AMOUNT of sensor area, like in the football / backyard comparison example.

It takes a little more than a youtube video to bend or even try to change some laws of physics. An believe me, as I work in the editorial production business (book making), there is an old saying that goes like "the media will stand to whatever is put on it..." (which means, that any statement cannont be considered true just because it shows through some broadcast media...

You're knocking down a Strawman - equivalence is NOT ABOUT EXPOSURE.

---------- Post added 10-10-2014 at 09:58 PM ----------

We have digressed rapidly away from my OP, which was to make the point that if you wish to talk or think in terms of full frame/35mm equivalence relative to a crop factor camera, the crop factor needs to be applied to the aperture as well as the focal length. This is merely arithmetic at the end of the day. The f stop is the focal length divided by entrance pupil. To use the example of the 70-200mm f2.8 and work backwards, f2.8 tells us this has an entrance pupil of approx 71mm. Now on apsc we say that this is equivalent to 105-300mm. The entrance pupil is a physical aspect of the lens and can't change - it is still 71mm. 300mm divided by 71mm gives us the full frame equivalent = f4.2. My impression from some of the responses is that some are trying to cling to an inner notion of "no its still f2.8!" which of course it is and always will be 70-200mm f2.8. But: OR 105-300mm f4.2 fullframe equivalent.

Good so far, getting back to topic.

In his video Northrup discusses, with sample pictures, how this is all interlinked with ASA. Since I'm getting out of my depth, not having the technical knowledge to discuss the inner workings of digital cameras, if you would like to take up particular points about these interesting discussions, I suggest you do so with him. However I can't personally see how smaller sensors can match ASA on a smaller photon count ie fewer total photons hitting a smaller sensor) without some internal adjustment (asuming other aspects eg MPx are the same).

D'oh! Fell on your face again. No "internal adjustment" is necessary to account for difference in total light, the difference in sensor size is all that's needed to explain the difference. Ignore the "exposure" arguments - they are nothing but a red herring. There is no difference in light intensity hitting each sensor at a given f-stop of a given lens, but there IS a difference in total light gathered, because there is less area gathering the light on the smaller sensor vs. the larger sensor. It's as simple as that.

---------- Post added 10-10-2014 at 10:07 PM ----------

See, I have to disagree with that. I could be wrong, but I have to disagree.

Yup you could be wrong, and as a matter of fact...

The lens is projecting a certain amount of light at its back, regardless of what size sensor is capturing it - the sensor doesn't change the T-stop of the lens. The image outside of the sensor is wasted if you are using a smaller sensor, but it still helps maintain the overall qualities of the image. The image projected on the sensor is always the same brightness (or as they like to say, the same amount of light is 'sucked in'). You don't 'suck in' less light because the sensor is smaller.

No, you don't "suck in" less light. BUT you do capture less of it when you use a smaller sensor.

The reason why the sensor sizes give different numbers is pixel density, not size. As I pointed out above, dynamic range is already similar for APS-C and FF. SNR will follow and DP's point will be proven wrong, in fact I think it's already being proven wrong...

No, no, NO!! It has nothing to do with the goddamn pixels! It is the SIZE of the imaging area - that's the difference maker, period! With equivalent sensor tech, the advantage of the bigger sensor never "disappears," so get over it.

---------- Post added 10-10-2014 at 10:11 PM ----------

f/2.8 transmits the SAME AMOUNT OF LIGHT with any focal length.

Please, someone put this in simpler words. English is not my native language and I am struggling here.

NO - f2.8 transmits the same intensity of light with any focal length, NOT the same AMOUNT of light. THAT depends on how much image capturing AREA that light intensity is projected on. Bigger sensor = more light.

---------- Post added 10-10-2014 at 10:23 PM ----------

When it's actually the likes of Northrup who should be blamed, for making simple things complicated and pointless. All to appear as "experts".


Add another blatant lie: focal length is not angle of view. He's amazed that the same FL does not give the same angle of view on different formats, which is downright stupid.
FL is precisely defined, the most basic optics notion, and it doesn't even care if the lens is mounted on a camera or another device.

Anyway, even in its most scientifically-sound form "equivalence" is a fraud, a misapplication of existing notions which doesn't really makes sense outside heated forums discussions. The good old system - which "equivalence" seeks to modify - appeared with purpose, it's elegant and universal, instead of that silly mess. Focal length is what it is; basic geometry will allow you to get the angle of view. f-number appeared as FL/aperture - guess why - and together with ISO and shutter speed it works nicely as the exposure triangle. ISO can be seen as "standard sensitivity per square mm", and that worked perfectly in an era where multiple film formats existed - all cut down from the same large film roll. And DOF was a bit subjective - based on a convention regarding print size and viewing distance, not all manufacturers agreeing about the CoC (IIRC Zeiss used tighter values).

Breaking news: digital didn't obsolete optics. You don't have to keep your shutter speed constant and vary the aperture to get the "same" DOF (reasons you're using a certain f-stop might not be those assumed by "equivalence"). You don't increase ISO to get the "same" noise as for a smaller format. You cannot forget about details. And last - but not least - you will crop. This means changing the effective "total light", effective DOF, angle of view.

However... the discussion is pointless. "Equivalence" fans will always assume they're right, and everyone who don't agree with them lacks knowledge and is unable to understand - they don't even care what arguments we might present. Wait, here it is:


P.S. Apologies for repeating what was already said. Well, we're constantly hit with this "equivalence" religion, even when it obviously cannot be applied (see the recent moon example), perhaps it doesn't hurt to put it to its place.

If there is anything "pointless," it's your entire post. You've argued against a long list of things that nobody discussing "equivalence" ever asserted to begin with.

---------- Post added 10-10-2014 at 10:31 PM ----------

Comparing FOV is not equivalence, is geometry
"Equivalence" is nothing more than a very specific, rigid, limited way of comparing different formats; it did not invent the mathematical and physics apparatus it's using, it brings nothing new other than its particular (mis)application.
"Equivalence" is useless because it can be applied only in very few circumstances (e.g. forum fights). "Equivalence" is a fraud because its proponents are attributing to it the math and physics notions, some discovered ages before even photography itself. And because it's claimed to be useful and used in every situation.

No, it's just a counter to the "f2.8 = f2.8 = f2.8" misinformation that comes out of the same mouths as "200mm = 300mm."

---------- Post added 10-10-2014 at 10:39 PM ----------

What a load of crap.

You mean what you say in the rest of your post?!

That lens is f2.8 regardless if it's on a full frame or a crop sensor camera. End of story. It transmits just as much light regardless of body.

Nobody argued that it "transmits less light." Nobody argued the the f-stop "changed," either.

The sensor on a crop camera merely uses less of the circle than a FF would otherwise use, but the light density is the same no matter what.

Intensity yes, total light captured, no.

And as to multiplying but the focal length... that is merely to get field of view, but not any added 'zoom'.

And with the change of FOV comes a change of DOF, which is exactly why you ALSO multiply the f-stop by the crop factor - to determine the relative DOF the same way you multiplied the focal length to get the relative FOV.

Crop has some disadvantages but it certainly does not change the amount of the f stop on any lens.

It doesn't change to focal length, either, yet you managed to see the need for THAT "change."

[filoxophy]

O.M.G...

boriscleto'd this whole thread, as I should have initially.

[JinDesu]

Why compare the D610 to the D7100? They aren't the same sensor.

Compare the D800 to the D7000. Actually, compare the D800 crop mode to the D7000. If full frame makes a difference in light absorbed, the D800 crop mode should show better signal to noise ratio compared to the D7000. I'll guarantee you the difference is minimal.

[jsherman999]

As I mentioned and questioned before in previous posts, in my opinion this assertion about signal to noise is a fallacy, oft repeated, and central to this thread.
Can somebody explain it to me? I am electrical engineer, I can take explanation simple or detailed.

Wombat, if you want a really good discussion on "total light", read the engineers in this thread. The simplified object field "The_Suede" uses as an example a few posts down is a really neat way of illustrating it IMO. (btw that whole thread is... illuminating. ) Here's another one.

---------- Post added 10-10-14 at 09:38 PM ----------

Why compare the D610 to the D7100? They aren't the same sensor.

Because you were trying to say things would be different if we compared 24MP FF to 24MP aps-c. And they wouldn't, really, unless the sensor efficiency was pretty radically different (which it isn't in that comparison.)

Compare the D800 to the D7000. Actually, compare the D800 crop mode to the D7000. If full frame makes a difference in light absorbed, the D800 crop mode should show better signal to noise ratio compared to the D7000. I'll guarantee you the difference is minimal.

D800 in crop mode matches the D7000 almost exactly in every way, exactly as equivalence says it would if it were basically the same pixel tech.

The D800 uncropped gains it's stop advantage because it gathers more total light for the same FOV and exposure, because of the reasons I already explained here.

---

Last edited by jsherman999; 10-10-2014 at 08:59 PM.

[PJ1]

"the DOF/bokeh would vary with the sensor format"


I think the DOF situation was established years ago. I suppose one could calculate that this or that focal length, aperture and sensor combination gave a certain perceived DOF. I think most people who understand camera settings know that only the image plane is actually in focus and the rest of the DOF is only perception. "Equivalence" is a bit fuzzy when applied in that situation. I don't know of anyone who takes DOF as their starting point for planning an image and certainly I know of no one who plans with "stops" of DOF in mind. But I suppose it is possible in some "art" contexts.


I have never heard anyone argue "equivalence" in bokeh before. That is probably because bokeh is an entirely subjective matter and any discussion of "stops" of bokeh is nonsensical.


I agree with the argument of others here that "crop" factors are misleading for those who are new to photography - particularly those whose first camera may have an aps-c sensor. Learn what a lens does on your sensor and that is all there is to it. Chasing some vague idea of "equivalence" to something in another format is just time wasted without pressing the shutter button.

[jsherman999]

"the DOF/bokeh would vary with the sensor format"


I have never heard anyone argue "equivalence" in bokeh before. That is probably because bokeh is an entirely subjective matter and any discussion of "stops" of bokeh is nonsensical.

I tend to agree, as I said earlier in this thread his use of the term "bokeh" in place of DOF is unfortunate.

But "One stop of DOF" really just means "the effect on DOF in the image that one stop of f-ratio change would cause." It's just a contraction, a shorter way of saying the same thing.

I agree with the argument of others here that "crop" factors are misleading for those who are new to photography - particularly those whose first camera may have an aps-c sensor. Learn what a lens does on your sensor and that is all there is to it. Chasing some vague idea of "equivalence" to something in another format is just time wasted without pressing the shutter button.

All very true when staying within the same format. If you only shoot one format and have no intention of buying into another, there's no pressing need to worry about crop factor, equivalence, any of it. (Also no need to wander into the FF forum and throw insults at people who do care about it perhaps? (not you) )

Things change for most folks though if you shoot more than one format or are thinking of purchasing another. Even then, you're not forced to think about equivalence... up to the individual how they go about spending their money.

.

[Ian Stuart Forsyth]

I tend to agree, as I said earlier in this thread his use of the term "bokeh" in place of DOF is unfortunate.

But "One stop of DOF" really just means "the effect on DOF in the image that one stop of f-ratio change would cause." It's just a contraction, a shorter way of saying the same thing.



All very true when staying within the same format. If you only shoot one format and have no intention of buying into another, there's no pressing need to worry about crop factor, equivalence, any of it. (Also no need to wander into the FF forum and throw insults at people who do care about it perhaps? (not you) )


Things change for most folks though if you shoot more than one format or are thinking of purchasing another. Even then, you're not forced to think about equivalence... up to the individual how they go about spending their money.

.

But you have seen firsthand how people that crop within a format still like to say if they crop their 300 2.8 to the fov as a 600m that it will produce an image that looks like a 600 F2.8
and now that we have such high MP counts that we can use a lot of cropping equivalence is also a important part even when you are only using 1 format

[wombat2go]

Wombat, if you want a really good discussion on this, read the engineers

Thank you for providing references that I requested

In Post #1 of your reference was this summary:
Quote:
"This kind of rough calculation helpfully leads quickly to seeing that the micro four thirds camera normal lens, is going to have to be 25mm F/1.0 lens, to "gather the same amount of light" as a full-frame optic. Thus u43 lenses need to be "a lot faster" than their full frame counterparts to get you the same low-light capability."

I can respond, without tech and maths etc , as I am sure any photographer can, by advising that I have adaptors for my Pentax K lenses, typically 1:2.8 28mm etc, so I use them on my Olympus M4/3, my Pentax Ist-ds , my Pentax K-01, and my Pentax MX.
The experience is as it has been documented for 100 years and in dslrs too, that it is independent of format; the u43 lenses work by f/- and shutter the same as on any format, that is , for example "sunny 16" etc.

So in my opinion, the Post#1 in your reference is incorrect.

You referred me to read a post from "The_Suede" from your referenced link, the summary at the end of that post was this:
Quote:
"Light gathering ability = (crop ratio) / (f-stop)
In the end that means that to collect as many photons per second from a certain scene, you need to change f/# with the same factor as you change the crop ratio."

I assume that "collect as many photons per second" means to integrate luminous intensity by exposure time into a sensor well,
over its noise floor,
and assume that "change the crop ratio" means "change format".

I can respond that I disagree, and
again I am sure that any reasonable photographer would disagree with that conclusion. There is a plethora of references that would provide the correct way to set f/- on any format size of dslr, and it is demonstrated that it does not change by format size.

So in my opinion, the information in Post "The_Suede" in your reference is incorrect.

And I would hope you can respond to my queries about your assertion that the sensor well signal-to-noise- ratio is a function of your "Total light" , whatever that means

Regards,

[Ian Stuart Forsyth]

Thank you for providing references that I requested

In Post #1 of your reference was this summary:
Quote:
"This kind of rough calculation helpfully leads quickly to seeing that the micro four thirds camera normal lens, is going to have to be 25mm F/1.0 lens, to "gather the same amount of light" as a full-frame optic. Thus u43 lenses need to be "a lot faster" than their full frame counterparts to get you the same low-light capability."

I can respond, without tech and maths etc , as I am sure any photographer can, by advising that I have adaptors for my Pentax K lenses, typically 1:2.8 28mm etc, so I use them on my Olympus M4/3, my Pentax Ist-ds , my Pentax K-01, and my Pentax MX.
The experience is as it has been documented for 100 years and in dslrs too, that it is independent of format; the u43 lenses work by f/- and shutter the same as on any format, that is , for example "sunny 16" etc.

So in my opinion, the Post#1 in your reference is incorrect.

You referred me to read a post from "The_Suede" from your referenced link, the summary at the end of that post was this:
Quote:
"Light gathering ability = (crop ratio) / (f-stop)
In the end that means that to collect as many photons per second from a certain scene, you need to change f/# with the same factor as you change the crop ratio."

I assume that "collect as many photons per second" means to integrate luminous intensity by exposure time into a sensor well,
over its noise floor,
and assume that "change the crop ratio" means "change format".

I can respond that I disagree, and
again I am sure that any reasonable photographer would disagree with that conclusion. There is a plethora of references that would provide the correct way to set f/- on any format size of dslr, and it is demonstrated that it does not change by format size.

So in my opinion, the information in Post "The_Suede" in your reference is incorrect.

And I would hope you can respond to my queries about your assertion that the sensor well signal-to-noise- ratio is a function of your "Total light" , whatever that means

Regards,

Think of a FF camera using the k5 sensor , if the K5 captured just 1 photon for every pixel the FF would capture the same 1 photon per pixel at the same F stop and shutter speed.
Which camera captured more photons in the final image ? the FF or the cropped camera
Sure each pixel in both cameras captured the same 1 photon . (let make this even simpler) a pixel represents a single data point that recorded a single photon strike,. The cropped camera captured 16mp data points while the FF captured 36mp data points and each data point contained a single photon strike. So the FF has captured 2.25 times more photons( total light), this manifests as less visual noise in the final image. With SNR you have to take into account the size that SNR is representing in the final image For example in a FF 36mp camera that is 1 data point in 36,000,000 where as with the cropped 16mp would be 1 data point in 16,000,000. That SNR data point would have less of an effect on the final FF image.

A very simple test that one could do with your own camera would be to take to 3 photographs.
Photograph #1 with a 35mm lens shot at F2.8 iso 800 1/400
#2 with a 50mm lens at F2.8 iso 800 1/400
#3 50mm lens to F4.2 iso 1800 1/400
Now crop the 35mm images to the same FOV as the 50 images and make 8-10 prints of all 3 photograph’s
Photos 1 and 3 will have the same visual appearance of noise ( same total light was captured by both images)
And image 2 will have the least amount of noise in print ( more total light was captured)

[kh1234567890]

Nope, focal length and aperture do not change. AOV and DOF/bokeh do change, however, and that is what equivalence is about - settings that provide similar images on different formats.

But you have to change the camera to subject distance between the formats to get a similar image, as well as changing your lens for an 'equivalent' one. Focal length does not affect perspective but moving the camera does. So your efforts are doomed from the start unless your subject is just a planar test chart parallel to your sensor plane ...

[Vitalii]

and its going on and on...
if its all about DOF then, guys, you were misleaded. The manufacturers were actually misleading you, your 100-200 f2.8 isn`t really so, its actually a crappy f3.6 on the MF camera, or so.

[Dartmoor Dave]

A very simple test that one could do with your own camera would be to take to 3 photographs. Photograph #1 with a 35mm lens shot at F2.8 iso 800 1/400 #2 with a 50mm lens at F2.8 iso 800 1/400 #3 50mm lens to F4.2 iso 1800 1/400 Now crop the 35mm images to the same FOV as the 50 images and make 8-10 prints of all 3 photograph’s Photos 1 and 3 will have the same visual appearance of noise ( same total light was captured by both images) And image 2 will have the least amount of noise in print ( more total light was captured)

And that, right there, is why this thread is so ridiculous. You're taking one of the most basic, simple facts about photography, something that has been thoroughly understood for nearly 200 years by countless millions of real-world photographers, and pretending that some amazing new principle called "equivalence" has arrived simply because rolls of film of different sizes have been replaced by electronic sensors of different sizes.

Those of us who regularly switch between different formats are fully aware of differences in angle of view, depth of field, and grain/noise from personal experience, and we take those factors into account without having to worry about non-issues such as "equivalence".

The only reason why anyone would try to con people who only use APS-C into worrying about "equivalence" is as a marketing ploy to try to sell them more expensive cameras.

[Kunzite]

If there is anything "pointless," it's your entire post. You've argued against a long list of things that nobody discussing "equivalence" ever asserted to begin with.

Are you by chance protecting "equivalence" because it makes the 24x36 format looks the best of all formats?
If you think that correcting a blatant lie regarding the most basic optics notion is pointless... if you think that "equivalence" should be allowed to claim that it's the one and only Sacred Holder of Knowledge instead of being crystal clear about what it actually brings new and what it doesn't...

No, it's just a counter to the "f2.8 = f2.8 = f2.8" misinformation that comes out of the same mouths as "200mm = 300mm."

You are of course incorrect - and on two counts:
1. It is OK to look after "lenses offering a similar angle of view" on another format, without going through f-stops conversions. What is not OK is to force an entire system of conversions regardless if it's irrelevant or not.
2. "Equivalence" is indeed pushed with every occasion, aggressively so. I was even accused of using it despite claims and evidence to the contrary (which was pretty rude), despite being absolutely impossible for me to do so (didn't had anything to compare with). Recently a discussion about shooting the moon with the 645z slided into an "equivalence" argument, and some silly f/1.4 vs. f/2.8 comparisons were once again being made.

And that, right there, is why this thread is so ridiculous. You're taking one of the most basic, simple facts about photography, something that has been thoroughly understood for nearly 200 years by countless millions of real-world photographers, and pretending that some amazing new principle called "equivalence" has arrived simply because rolls of film of different sizes have been replaced by electronic sensors of different sizes.

Equivalence is a fraud.

[Rondec]

Bossa said earlier that the issue has to do with smaller sensor requiring more magnification when it comes to printing and/or viewing as compared to larger sensors. This is the basic thing. So, of course you will tend to see more noise from your crop sensor than a full frame sensor if you are printing/viewing big enough. You don't need equivalence to tell you that.

As to whether or not you can tell the difference at normal printing sizes/viewing sizes is debatable at this point. It is when you get to the extremes that the differences will be most obvious -- high iso, large (very large) prints, and really narrow depth of field. If someone doesn't photograph in these areas much, then maybe you don't need a larger sensor size.

The whole equivalence thing is useless. It tells people, who know what it means, information that is unimportant and it confuses people, who don't know what it means, because it gives them information they don't understand. Most folks shooting cameras now have never used a film camera, have never used a "full frame" sensor. Equating their lens/sensor combo to some camera that they have never shot and never will shoot doesn't mean anything. Fifteen years ago, it probably did some, as people moved from 24 by 36 film cameras to digital point and shoots.

If I am explaining to someone how to use their camera, I wouldn't mention equivalence once. All they need to know is what is wide, normal and telephoto on the camera they are using and what focal lengths will give them the results they want.

[wombat2go]

So, of course you will tend to see more noise from your crop sensor than a full frame sensor if you are printing/viewing big enough.

The reason bigger sensors or bigger film formats work to provide higher fidelity enlarged images on our screen or print, is mostly due to a lower enlargement of the spread function.
The signal to noise may or may not be worse on a small sensor, depending on its age and cost etc.

The whole fallacy of this thread, I think , is that the proponents kept insisting that signal to noise was related to sensor size, by the incorrect interpretation that signal to noise in each well is somehow related to integrated light on the overall sensor , so a larger sensor is somehow better. That is false in my opinion.