canon G1X: big sensor fixed lens camera

[ElFenix]

What do you mean?

Lenses same diameter

Both set to 1x zoom

Same view angle = same light

but those lenses aren't the same diameter.

and "1x zoom" is neither here nor there. do you mean at their widest? at their widest angle the canon has a much larger diameter than the fuji.

 

[Throckmorton]

but those lenses aren't the same diameter.

and "1x zoom" is neither here nor there. do you mean at their widest? at their widest angle the canon has a much larger diameter than the fuji.

What lenses aren't the same diameter? Do you not get the concept of a hypothetical question? In this case, the huge sensor camera has a SMALLER diameter lens than many cameras with tiny sensors.

By 1x I mean "35mm equivalent"... Are you being intentionally obtuse? It's not "neither here nor there" because it means the field of view is exactly the same which means the total amount of light is the same if the lens diameter is the same.

I specifically said the lenses are at the same diameter. I'm presenting a scenario where the objective lens is the same diameter, the field of view is the same, and the sensors are different sizes. Do you really not get what I'm saying? With those conditions, the same amount of light is hitting each pixel even though they're different sizes. So how does that affect quality?


OK, let me boil this down and pose a simpler question. One pixel is 10x as big as another pixel. Both of them receive 15 photons during an exposure. Which gathers more light?

 

[IronWing]

I use a G9 at work and it has been the best all around field camera I've encountered: compact, rugged, one hand shooting, good image quality, good macro. This looks like a worthy replacement should the G9 die. The only spec that makes me nervous is the 7.9" macro range. I like to take really closeup closeups. Of course that is measured from the sensor so maybe 7.9" isn't as long as it seems.* The lens could be wider as well but 28mm is okay. And 1.5" is a lot of sensor to like.










* That's what she said.

 

[TanisHalfElven]

OK, let me boil this down and pose a simpler question. One pixel is 10x as big as another pixel. Both of them receive 15 photons during an exposure. Which gathers more light?

Your asking a bad question. A pixel 10 times as small would collect the same amount of light only if other factors were 10 times better.
And even in that case high ISO noise would be worse on the smaller sensor

 

[ElFenix]

What lenses aren't the same diameter? Do you not get the concept of a hypothetical question? In this case, the huge sensor camera has a SMALLER diameter lens than many cameras with tiny sensors.

By 1x I mean "35mm equivalent"... Are you being intentionally obtuse? It's not "neither here nor there" because it means the field of view is exactly the same which means the total amount of light is the same if the lens diameter is the same.

I specifically said the lenses are at the same diameter. I'm presenting a scenario where the objective lens is the same diameter, the field of view is the same, and the sensors are different sizes. Do you really not get what I'm saying? With those conditions, the same amount of light is hitting each pixel even though they're different sizes. So how does that affect quality?


OK, let me boil this down and pose a simpler question. One pixel is 10x as big as another pixel. Both of them receive 15 photons during an exposure. Which gathers more light?

i think you're the one being intentionally obtuse. i've been talking about the canon G1X vs other cameras (in particular the fuji x10) just about the whole time. you said "the lens isn't any bigger than other cameras." which is simply incorrect.

your question assumes away the important differences. such as the fact that the canon G1X does have a larger lens than similar cameras, in particular the fuji x10.

but to answer your intentionally crippled question, if you hold the absolute aperture and shutter speed constant then yes, it's going to be the same.
http://forums.dpreview.com/forums/read.asp?forum=1029&message=21440105
(if you look at those pictures carefully you'll see the big advantage of larger sensors)

and in fact, i already answered that question.
http://forums.anandtech.com/showpost.php?p=32841227&postcount=22

"1x zoom" means absolutely nothing without context. a 24-70 lens and a 70-200 lens are both roughly 2.8x zooms, but they have vastly different FoVs when set to their respective widest and longest positions. no one has ever used "1x" to mean 35 mm equivalent. but guess what? the light intensity of the 200/2.8 is the same as the 24/2.8. that's why we use f-stops rather than absolute apertures, makes figuring exposure easy.

if the objective lens is the same diameter, the fov is the same, and the sensor of one camera is smaller, then you're using a larger f-stop on the smaller sensor. and that's fine if that's available. but out in the real world that's not always available. like in the comparison between the canon G1-X and the Fuji x10, for which i've already done the math and shown you that when both lenses are set to widest end and fastest apertures, the canon captures 8x more light than the fuji.

you don't seem to be able to get your head around the fact that the canon does in fact have a larger lens at the wide end than competing compact cameras.

 

[JohnnyRebel]

BTW, on the G1X sensor size, Thom Hogan wrote:

Their press materials all use the term "near APS-C" in terms of size. The sensor is not close at all. It is "near m4/3" (262 mm squared area versus 243, with APS-C being somewhere above 350 depending upon whose definition you accept). Still a large sensor, but it's actually about about two-thirds of a stop smaller than APS-C (see my sensor size article on sansmirror.com for what I mean by that).

Now I'm off to read his article on sensor size and see if it all finally makes sense.

http://www.sansmirror.com/articles/pick-a-size.html

JR

 

[ElFenix]

hey, thom is thinking of sensor size in terms of stops

 

[Throckmorton]

i think you're the one being intentionally obtuse. i've been talking about the canon G1X vs other cameras (in particular the fuji x10) just about the whole time. you said "the lens isn't any bigger than other cameras." which is simply incorrect.

your question assumes away the important differences. such as the fact that the canon G1X does have a larger lens than similar cameras, in particular the fuji x10.

but to answer your intentionally crippled question, if you hold the absolute aperture and shutter speed constant then yes, it's going to be the same.
http://forums.dpreview.com/forums/read.asp?forum=1029&message=21440105
(if you look at those pictures carefully you'll see the big advantage of larger sensors)

and in fact, i already answered that question.
http://forums.anandtech.com/showpost.php?p=32841227&postcount=22

"1x zoom" means absolutely nothing without context. a 24-70 lens and a 70-200 lens are both roughly 2.8x zooms, but they have vastly different FoVs when set to their respective widest and longest positions. no one has ever used "1x" to mean 35 mm equivalent. but guess what? the light intensity of the 200/2.8 is the same as the 24/2.8. that's why we use f-stops rather than absolute apertures, makes figuring exposure easy.

if the objective lens is the same diameter, the fov is the same, and the sensor of one camera is smaller, then you're using a larger f-stop on the smaller sensor. and that's fine if that's available. but out in the real world that's not always available. like in the comparison between the canon G1-X and the Fuji x10, for which i've already done the math and shown you that when both lenses are set to widest end and fastest apertures, the canon captures 8x more light than the fuji.

you don't seem to be able to get your head around the fact that the canon does in fact have a larger lens at the wide end than competing compact cameras.

I'm trying to get you to see that there's nothing inherent to a bigger sensor that lets it capture more light per pixel. That's why I gave you a hypothetical scenario-- I have no idea why you're choosing to compare to other existing cameras rather than address my point. It's the lens that gathers light and focuses it onto the sensor. What is stopping a manufacturer from building a fixed lens camera with a large diameter objective lens and a smaller sensor? The difference is just geometric

 

[vbuggy]

BTW, on the G1X sensor size, Thom Hogan wrote:



Now I'm off to read his article on sensor size and see if it all finally makes sense.

http://www.sansmirror.com/articles/pick-a-size.html

JR

Assuming he's given us a better and more accurate insight into the relative performance, that does mean that the Canon will at least match the Fuji in terms of effective DOF and overall light collecting ability at the tele end.

It doesn't change the fact that it will (assuming the actual images obtained are also a relative percentage of APS-C, quality wise) still destroy the Fuji at the wide -> mid ends. For $200 more (for me, a little more as I had to pay a small restocking fee for the X10 in the end)? I'll take it, thank you ma' am.

 

[JohnnyRebel]

Assuming he's given us a better and more accurate insight into the relative performance, that does mean that the Canon will at least match the Fuji in terms of effective DOF and overall light collecting ability at the tele end.

It doesn't change the fact that it will (assuming the actual images obtained are also a relative percentage of APS-C, quality wise) still destroy the Fuji at the wide -> mid ends. For $200 more (for me, a little more as I had to pay a small restocking fee for the X10 in the end)? I'll take it, thank you ma' am.

+1

 

[JohnnyRebel]

What is stopping a manufacturer from building a fixed lens camera with a large diameter objective lens and a smaller sensor?

And that is the $1,000,000 question.

This question has an answer.

Your assumption is that the Camera/Lens companies just don't realize this. I submit that is not it. There is a reason. I don't know if it is physics, technology, economics or nostalgia but to make your argument you have to find out what that reason is. It's hard to imagine that a company like Nikon has that level of incompetence. If you are right, I guarantee Kodak would make the camera you describe and save themselves from bankruptcy.

IF you REALLY believe what you are saying, why haven't you sought out some venture capital and formed a start-up?

JR

 

[ElFenix]

I'm trying to get you to see that there's nothing inherent to a bigger sensor that lets it capture more light per pixel. That's why I gave you a hypothetical scenario-- I have no idea why you're choosing to compare to other existing cameras rather than address my point. It's the lens that gathers light and focuses it onto the sensor. What is stopping a manufacturer from building a fixed lens camera with a large diameter objective lens and a smaller sensor? The difference is just geometric

i never said there's anything inherent in the sensor, of course it's the lens aperture, but because we're using stops as shorthand for lens aperture we have to realize that a 50/2 in front of a 35mm sensor is letting in way more light than a 25/1.4 in front of a 4/3 sensor. and the easiest way to compare is to think of sensor stops. that makes everything relative and uses the same easy shorthand that photographers are used to.

who said anything about light per pixel?

the reason i'm comparing existing cameras is that your original point was comparing this camera to existing cameras!

The sensor pixels are bigger but the lens isn't any bigger than other cameras so it's not gathering any more light... how does that affect things?

What is stopping a manufacturer from building a fixed lens camera with a large diameter objective lens and a smaller sensor?

physics, mostly. you can't just make faster and faster lenses.

take for comparison the 4/3 35-100 f/2. the range makes it equivalent to the canon 70-200 lineup. but the absolute aperture makes it equivalent to the 70-200 f/4. and on top of that, the 4/3 lens weighs more and is physically larger than the 70-200 f/2.8

 

[Throckmorton]

i never said there's anything inherent in the sensor, of course it's the lens aperture, but because we're using stops as shorthand for lens aperture we have to realize that a 50/2 in front of a 35mm sensor is letting in way more light than a 25/1.4 in front of a 4/3 sensor. and the easiest way to compare is to think of sensor stops. that makes everything relative and uses the same easy shorthand that photographers are used to.

who said anything about light per pixel?

the reason i'm comparing existing cameras is that your original point was comparing this camera to existing cameras!




physics, mostly. you can't just make faster and faster lenses.

take for comparison the 4/3 35-100 f/2. the range makes it equivalent to the canon 70-200 lineup. but the absolute aperture makes it equivalent to the 70-200 f/4. and on top of that, the 4/3 lens weighs more and is physically larger than the 70-200 f/2.8

Oh yeah, you're right I did compare it to existing cameras. But it really doesn't have an especially big objective lens. It looks smaller than most superzooms'.

I didn't say anything about a faster lens. I said focus the same amount of light onto a smaller sensor. All it takes is changing lens geometry.

You know how a projector lets you adjust size, so you can have a big dim image or a small bright one? Like that, but think of the projection screen as the sensor. The total light doesn't change.

 

[ElFenix]

I didn't say anything about a faster lens. I said focus the same amount of light onto a smaller sensor. All it takes is changing lens geometry.

uh, doesn't work that way. you need a faster lens to have more light. just think about it: which can put more light on a sensor, a 50/1.4 or a 50/2?

 

[Throckmorton]

uh, doesn't work that way. you need a faster lens to have more light. just think about it: which can put more light on a sensor, a 50/1.4 or a 50/2?

I didn't say more light. I said the same amount of light on a smaller sensor... All you have to do is redirect the light rays toward the center at a steeper angle. Like the projector example.

The same amount of light is coming out of the projector no matter what the size of the image is on the screen.

 

[TanisHalfElven]

uh, doesn't work that way. you need a faster lens to have more light. just think about it: which can put more light on a sensor, a 50/1.4 or a 50/2?

i think he might mis-understanding the words faster.
Faster here referes to larger aperture

 

[Throckmorton]

i think he might mis-understanding the words faster.
Faster here referes to larger aperture

No, I'm not misunderstanding. I'm talking about concentrating the exact same amount of light onto a smaller sensor, NOT more light.

 

[TanisHalfElven]

No, I'm not misunderstanding. I'm talking about concentrating the exact same amount of light onto a smaller sensor, NOT more light.

Its not so simple. You can concentrate the light all you want. Two things that come to mind immedietaly are:
1. Your lens and glass quality will have to go up a lot becuase the smaller "screen" means any imperfections will be more obvious.
2. diffraction will begin to play even more important role and the smaller more concentrated pixel won't be able to actually resolve the detail.

 

[ElFenix]

No, I'm not misunderstanding. I'm talking about concentrating the exact same amount of light onto a smaller sensor, NOT more light.

that makes the lens faster. same amount of light over a smaller area results in a higher light intensity. which is faster, because f-stops are intensity.

they actually do use magnifying groups. technically a telephoto lens is a lens with a magnifying group, which makes the lens physically shorter than its focal length (not all long focal lenses are telephoto). but there's only so much they can do with that before they start introducing more problems than they're fixing.