Lens Hype, What is really a good lens?

[donny1963]

yes but i knew i would get an answer like that because i knew my formula would be way over your year to understand but it does explain my theory in full detail to prove what i said.
However, you keep stick with your own idea of what you think is reality, i'm sure it works for you..

lol

It wasn't your formula you copied it from here: Why are larger sensors better at low light?

And that article topic is unrelated to what you have no idea about is being discussed.

Joe

yes but it's my formula that i presented doesn't matter where i got it, i posted the link earlier and you said yes they are others who are with you that are wrong like you are lol

And it has nothing to do with the questions at hand. You posted irrelevant material. You still haven't answered my questions.

Joe

i told you the answer earlier. not going to keep this going..

 

[table1349]

Not an error, full frame vs APSC does effect exposure differently using the same situation , or should i say larger sensors have an advantage over smaller sensors with the amount of light, for instance a med format camera requires 28% less light then a full frame camera to get the same exposure with the same situation. same with full frame vs apsc ..

And how exactly does that alter the degree of background blur?

But wait! Before you try and answer that please confirm this: Describe specifically this advantage in amount of light for a FF sensor. Your saying that at same ISO, shutter speed and ambient light with lenses at same AOV and both at f/2.8 the APSC camera will be exposed less than the FF. Yes or no?

Joe

Intuitively, if you put the same lens with the same settings on both cameras, and if the distance from the lens to the sensor is the same in both cases, then the full frame sensor will collect more light because the sensor is larger and therefore covers more of the circle of light projected by the lens.
pretty simple physics and math, but maybe you and your friends was out skipping school when your teacher was explaining physics and math...

yes the same everything try to make the situation exactly the same, but with one sensor larger then the other..

An APS-C sensor is about 24x15mm, while a Full Frame (FF) sensor is 36x24mm. In terms of area, the APS-C sensor is about 360mm^2, and the FF is 864mm^2. Now, calculating the actual area of a sensor that is functional pixels can be rather complex from a real-world standpoint, so we will assumeideal sensors for the time being, wherein the total surface area of the sensor is dedicated to functional pixels, assume that those pixels are used as efficiently as possible, and assume all other factors affecting light (such as focal length, aperture, etc.) are equivalent. Given that, and given that our hypothetical cameras are both 8mp, then its clear that the size of each pixel for the APS-C sensor is smaller than the size of each pixel for the FF sensor. In exact terms:

APS-C:
360mm^2 / 8,000,000px = 0.000045mm^2/px
-> 0.000045 mm^2 * (1000 µm / mm)^2 = 45µm^2 (square microns)
-> sqrt(45µm^2) = 6.7µm

FF:
864mm^2 / 8,000,000px = 0.000108mm^2/px
-> 0.000108 mm^2 * (1000 µm / mm)^2 = 108µm^2 (microns)
-> sqrt(108µm^2) = 10.4µm

In simpler, normalized terms of "pixel size", or the width or height of each pixel (commonly quoted on photo gear web sites), we have:

APS-C Pixel Size = 6.7µm pixel
FF Pixel Size = 10.4µm pixel

In terms of pixel size, a FF 8mp camera has 1.55x larger pixels than an APS-C 8mp camera. A one-dimensional difference in pixel size does not tell the whole story, however. Pixels have two-dimensional area over which they gather light, so taking the difference between the area of each FF pixel vs. each APS-C pixel tells the whole story:

108µm^2 / 45µm^2 = 2.4

An (idealized) FF camera has 2.4x, or about 1 stop worth, the light gathering power of an (idealized) APS-C camera! That is why a larger sensor is more beneficial when shooting in low light...they simply have greater light gathering power over any given timeframe.

In alternative terms, a larger pixel is capable of capturing more photon hits than a smaller pixelin any given timeframe (my meaning of 'sensitivity').

SNow, the example and computations above all assume "idealized" sensors, or sensors that are perfectly efficient. Real-world sensors are not idealized, nor are they as easy to compare in an apples-to-apples fashion. Real-world sensors don't utilize every single pixel etched into their surface at maximum efficiency, more expensive sensors tend to have more advanced "technology" built into them, such as microlenses that help gather even more light, smaller non-functional gaps between each pixel, backlit wiring fabrication that moves column/row activate and read wiring below the photo-sensitive elements (while normal designs leave that wiring above (and interfering with) the photo-sensitive elements), etc. Additionally, full-frame sensors often have higher megapixel counts than smaller sensors, complicating matters even more.

A real-world example of two actual sensors might be to compare the Canon 7D APS-C sensor with the Canon 5D Mark II FF sensor. The 7D sensor is 18mp, while the 5D sensor is 21.1mp. Most sensors are rated in rough megapixels, and usually have a bit more than their marketed number, as many border pixels are used for calibration purposes, obstructed by sensor filter mechanics, etc. So we'll assume that 18mp and 21.1mp are real-world pixel counts. The difference in light-gathering power of these two current and modern sensors is:

7D APS-C: 360mm^2 / 18,000,000px * 1,000,000 = 20µm^2/px
5DMII FF: 864mm^2 / 21,100,000px * 1,000,000 = 40.947 ~= 41µm^2/px

41µm^2 / 20µm^2 = 2.05 ~= 2

The Canon 5D MkII Full-Frame camera has about 2x the light gathering power of the 7D APS-C camera. That would translate into about one stops worth of additional native sensitivity. (In reality, the 5DII and 7D both have a maximum native ISO of 6400, however the 7D is quite a bit noisier than the 5DII at both 3200 and 6400, and only really seems to normalize at about ISO 800.

See: Canon EOS 7D Review) In contrast, an 18mp FF sensor would have about 1.17x the light gathering power of the 21.1mp FF sensor of the 5D MkII, since fewer pixels are spread out over the same (and larger than APS-C) area.

Please explain in your own words the physics of your plagiarized post. Why are larger sensors better at low light?

The physics of a lens is simple. The same lens will transmit the same amount of light given the exact same conditions no matter what size the sensor. PERIOD! Sensor size has NOTHING to do with the amount of light being transmitted. Only with what it can record. I repeat "Mixing Apples and Oranges will not give you Peaches."

simple terms the size of the sensor that is capable of gathering that light, doesn't matter, if you got the same amount that is transmitted and the final source where it gets transmitted is larger then it's going to collect more isn't it? the smaller source will just collect the limit it's capable of collecting.
the larger source will get MORE which is light where talking about..
when the smaller sensor reaches it's limit of what it can collect, then the rest is just not used..

If you have 2 buckets one hold 20 gal of water and the other only 10, and you throw 50 gals at each one, then the one holding the 20 gal bucket is going to walk off with more water then the one holding the 10 gal.. OMG!!!!!!!!!!!!!!!!!!!!!!!

Lets try a REAL bucket scenario instead of a partial.

55 gallon drum of water = light
1/2 inch diamater hose = f stop
Tall narrow bucket = APS C sensor
Wide shorter bucket = FF sensor

Place the tall narrow bucket under the 55 gallon drum and release water through the 1/2 inch hose for exactly 1 second.
Now place the wide shorter bucket under the the same 55 gallon drum and release water through the same 1/2 inch hose for exactly 1 second.

Now measure the water. Same amount. The way the different size buckets spread the water is the only difference. That water surface is the sensitivity.

NONE of which has anything to do with your original premise about BOKEH.

I quote from YOUR original post:
"many people go out and buy an expensive lens for the wrong reasons, many will go out and buy lets say a Nikon 70-200 2.8 thinking ok they are oging to get sharp pictures and good bokah..
Bokah is a FAD people getting all hyped up thinking the only good portrait is a bokah one, meaning blur the background, but that is simply not true.

First off let me tell you the reason a background may get bokah, (blur) it has to do with many factors, not just a small number aperture like 1,8 or 2.8 it's about how close you are to your subject, and how close your subject is to the background as well, and also your focal length is if using a zoom lens and not a prime lens such as a 50mm 1.8.."

Later on

"that is one of the reason that the background gets soft is because of the amount of light hitting the sensor, so if you got a full frame sensor then more light is factored in the image, rather then a APSC sensor. that is why lower aperture numbers give you a narrower depth of field, it lets more light in the image. so if you use f 3.5 on full frame sensor and use an f 3.5 on APSC sensor the full frame image is going to have more blur even at the same aperture setting."

Horse Apples. There are only 4 factors that effect DOF.

• f/stop
• CCD pixel size
• distance of the object from the lens
• focal length of the lens

Depth Of Field

The Amount of light hitting the sensor has nothing to do with DOF.

 

[Ysarex]

yes but i knew i would get an answer like that because i knew my formula would be way over your year to understand but it does explain my theory in full detail to prove what i said.
However, you keep stick with your own idea of what you think is reality, i'm sure it works for you..

lol

It wasn't your formula you copied it from here: Why are larger sensors better at low light?

And that article topic is unrelated to what you have no idea about is being discussed.

Joe

yes but it's my formula that i presented doesn't matter where i got it, i posted the link earlier and you said yes they are others who are with you that are wrong like you are lol

And it has nothing to do with the questions at hand. You posted irrelevant material. You still haven't answered my questions.

Joe

i told you the answer earlier. not going to keep this going..

Do you mean this; "yes the same everything try to make the situation exactly the same, but with one sensor larger then the other...?

OK, so I'll assume that "yes" at the beginning of that sentence fragment is your answer to this question: "Your saying that at same ISO, shutter speed and ambient light with lenses at same AOV and both at f/2.8 the APSC camera will be exposed less than the FF. Yes or no?"

You're wrong. The exposure would be the same for both sensors. Sensor size is not an exposure determinant. Exposure = ambient light + f/stop + shutter speed.

And, now that that's settled we can move on to how you explain that the same exposure, using the same f/stop and shutter speed, applied to two different sensors can be responsible for a difference in DOF.

Joe

 

[rexbobcat]

Not an error, full frame vs APSC does effect exposure differently using the same situation , or should i say larger sensors have an advantage over smaller sensors with the amount of light, for instance a med format camera requires 28% less light then a full frame camera to get the same exposure with the same situation. same with full frame vs apsc ..

Intuitively, if you put the same lens with the same settings on both cameras, and if the distance from the lens to the sensor is the same in both cases, then the full frame sensor will collect more light because the sensor is larger and therefore covers more of the circle of light projected by the lens.
pretty simple physics and math, but maybe you and your friends was out skipping school when your teacher was explaining physics and math...

This doesn't make sense. The same amount of light is hitting each diode, and the same amount of light is coming through the lens. More surface area doesn't mean that every pixel is somehow getting more light.

 

[unpopular]

I don't need to read whatever formula you're talking about.

Sensors do not gather light. They do not convert light into energy like a photo-voltaic does. It simply does not matter how large the sensel is, the output will never be greater than the reference.

 

[unpopular]

Not an error, full frame vs APSC does effect exposure differently using the same situation , or should i say larger sensors have an advantage over smaller sensors with the amount of light, for instance a med format camera requires 28% less light then a full frame camera to get the same exposure with the same situation. same with full frame vs apsc ..

Intuitively, if you put the same lens with the same settings on both cameras, and if the distance from the lens to the sensor is the same in both cases, then the full frame sensor will collect more light because the sensor is larger and therefore covers more of the circle of light projected by the lens.
pretty simple physics and math, but maybe you and your friends was out skipping school when your teacher was explaining physics and math...

This doesn't make sense. The same amount of light is hitting each diode, and the same amount of light is coming through the lens. More surface area doesn't mean that every pixel is somehow getting more light.

Exactly. If I took two photo diodes of the same material and applied a reference voltage to one leg of each, the measured voltage on the opposite side would be the same under similar lighting conditions.

I could get a reading under lower light with the larger sensor, true, but with an amplifier on the recording side this is no different than adjusting ISO. Yes, the signal is "there" with the smaller sensor (to a point), but it will be drowned out by noise.

But this applies only to the pixel/sensel/photosite (whatever you want to call it), not the overall size of the sensor.

 

[Overread]

If different sized sensors changed the exposure independent of aperture and shutterspeed then handheld light meters wouldn't work

This whole "larger sensor = more light = changed exposure" is a false truth that has arisen in the last few years (glares at people like that Tony chap off youtube).

 

[Tim Tucker]

Donny, you're making a number of false assumptions here that are leading to a lot of false conclusions.

Exposure is not the 'total light collected by a sensor' it is the 'light per sq mm falling on a sensor'. To get identical exposures from two sensors then the light per sq mm has to be the same which means shutter speed and aperture has to be the same. The sensor with more sq mm collects more total light but has the same exposure.

If you measure rainfall on a field then you measure depth only or 'per sq mm'. So regardless of whether your field is 1m sq or 50 acres it still has the same rainfall though the total rain collected by each field is different.

It is a quirk of 'equivalence argumentatives' who say that because noise is a random event you have to assess it as a percentage of the 'total light hitting the sensor' and compare sensors by using equivalent 'total light hitting the sensor' which of course means both cameras will be set for a different exposure.

When comparing our two fields for 'odd shaped raindrops' we can only compare the small field in a downpour against the larger one in light drizzle.

It's purely a way of levelling the field when comparing the noise performance of sensors across different formats. But given that all cameras, well exposed, will give images where you can't see any noise it's kind of a pointless argument, (the effect is invisible to the naked eye).

But this total light argument is being used to 'prove' a number of false ideas.

Like with our fields, it's easy to say that our small field gets wetter and therefore the larger one has the advantage when it rains because it collects more water.

Which is of course ludicrous because you get the same results if you use the same field but compare different capture area sizes, (the same field can be better than itself and all we have to do to get a better crop yield is change the area we measure).

There are a number of really talented pros an amateurs alike on this site, look at some of the posted images. Do you really think they can achieve these results without knowing what they're doing?

EDIT: A lot of this confusion comes from using 'equivalent f-stop' rather than 'f-stop'. There are a lot of relationships between aperture, focal length, sensor size, dof, fov, etc. These relationships change in an exact proportion to one another, and this is what makes exposure, dof, etc predictable.

The whole concept of equivalent f-stop is based on setting constants. Constants that have no bearing or relevance to actual photography and are set exclusively because doing so cancels out a lot of variables and allows you to compare noise performance across different formats. To compare noise performance you keep total light constant along with fov and dof, which means keeping the effective aperture diameter in mm constant (equivalent f-stop), but holding this condition true results in progressive under exposure in exact proportion to increasing sensor size. In reality you cannot take equivalent photos on different formats because all the variables are related, change one and another will change as well. Equivalent f-stop only holds true if exposure varies in exact proportion to sensor size, but exposure is the one thing we keep constant in photography.

 

[Overread]

Mostly I see this argument used to help push that crop sensor cameras are "better" than fullframe (within the same sensor generation)' which goes against the grain of understanding and thus gets talked about a lot. Which gets those saying such a lot of attention - ergo clicks on their videos/sites - ergo money from ads. It also bolsters the view that crop sensor isn't "lesser" and thus lots of people who have crop sensors flock to such stats as a way to defend their camera against the big evil fullframers.

 

[Braineack]

Yeah, but after you apply some misleading made-up bell curves, the crop sensors looks really good on paper!

 

[fmw]

of course you would get more blur in the background with full frame vs crop sensor,

Maybe. It would depend on the lens focal length of the lens, camera to subject difference and the aperture.

if i shoot a portrait using 2.8 with APSC and you do the same thing with 2.8 with a full frame the image with the full frame will have more exposure in it (more light)

Not at the same aperture. The amount of light that reaches the sensor is the same on any lens or format at the same f stop.

your a liar if you say different , and here bokeh is about blur in the background, here is an article about it, so i'm not the only one who says this..

I must be a liar then. Bokeh is about the blur in the out of focus areas. But it is about the appearance of that blur not the amount of it.

Others can decide for them self what is correct.. lol

They always do. No need to be belligerent. You may have the right concept and simply don't explain it properly.

[/QUOTE]

 

[fmw]

and it's mention here by en expert here about the sensor size having a great deal to do with it as well.

I would suggest that it doesn't have a great deal to do with it. It has a little to do with it. What has a great deal to do with it is the requirement to have a shorter lens in order to achieve the same image size and subject distance in the crop camera.

 

[Braineack]

if i shoot a portrait using 2.8 with APSC and you do the same thing with 2.8 with a full frame the image with the full frame will have more exposure in it (more light)

your a liar if you say different...

Dear Sir,

You have no clue what you're talking about.

Signed,
Truth.

 

[astroNikon]

wow, just wow.

Carry on ...

 

[The_Traveler]

There is any interesting phenomenon that, once certain kinds of people commit to a certain stance, then facts that show the opposite just make their commitment stronger.