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Olympus announces E-420
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You're dead wrong. The sensor size only comes into play in DoF, which is why you can't get shallow DoF with a P&S camera. f/2.8 is f/2.8 is f/2.8 as far as metering is concerned, regardless of sensor size. If that wasn't the case, a P&S would need a fucking fast lens to be usable in any condition.
Nope. While the sensor will capture the same amount of light per unit area (everything else being equal), a smaller sensor with a smaller area captures less light. This has nothing to do with metering. A P & S needs a fucking fast lens to even approach the performance of the worst SLR for this reason. It's not that the sensor pixels suck so bad, it's that there's not nearly as much area.
Hence, you're dead wrong.
The relation for exposure and aperture is this:
N^2 / t = LS / L
N is the f-number
t is the exposure time
L is the scene's luminance
S is the ISO speed
K is the light meter's calibration constant
Note that none of the variables have anything to do with sensor size or sensor area.
But let's do some thought games also.
You have a 50mm f/2.8. By your definition, if you slap this onto a small digicam with a "crop factor" sensor of 5x, you'll basically be running around with a nearly unusably dark f/16 lens? So if a FF SLR with this lens can take a picture using 1/200s, this same lens on a 5x sensor would need a shutter speed of 1/6 second to get the same exposure as the FF SLR?
Fardringle
Diamond Member
Hehe. I'd LOVE to have the physical aperture size of an f/2.8 50mm prime SLR lens on a point and shoot camera. You'd be able to use shutter speeds in 5 digits and still have an extremely bright picture. 😛
In Punchkin's defense (did I actually just type that? 😉), I suspect he meant to say that the E-420's pancake lens might act like an f/5.6 lens (as far as light-gathering goes) on a full frame camera because it has a physically smaller aperture hole designed to work with the camera's smaller sensor and wouldn't pass enough light to the full frame sensor. That doesn't change the fact that what he actually said is wrong.
Here's another thought example:
You're in a pretty consistent thunderstorm. Imagine that the rain pelting down is analogous to photons of light pelting down.
You put an open box out under the rain that is 1m x 1m.
You put a second open box out under the rain that is 10m x 10m.
You exposure each box to the rain for 10 seconds and then the rain stops.
Each box will contain the same depth of water. The boxes are sensors of different sizes, and the depth of the water is the "exposure" of the picture. Hence, the exposure is the same for both boxes, regardless of their size difference. Sure, the 10m x 10m box has 100x the VOLUME of water of the 1m x 1m box, so this is where you might say that it "gathers" more water (light). However, this has nothing to do with the actual exposure.
You're in a pretty consistent thunderstorm. Imagine that the rain pelting down is analogous to photons of light pelting down.
You put an open box out under the rain that is 1m x 1m.
You put a second open box out under the rain that is 10m x 10m.
You exposure each box to the rain for 10 seconds and then the rain stops.
Each box will contain the same depth of water. The boxes are sensors of different sizes, and the depth of the water is the "exposure" of the picture. Hence, the exposure is the same for both boxes, regardless of their size difference. Sure, the 10m x 10m box has 100x the VOLUME of water of the 1m x 1m box, so this is where you might say that it "gathers" more water (light). However, this has nothing to do with the actual exposure.
You are confusing yourself by talking of exposure. Instead, realize that the 5X camera with this "fast" lens, which is not truly fast on that format, will give results equivalent to a FF camera with a stopped-down lens in both aperture and noise, shutter speed, other technology etc. being equal.
In other words, you are failing to realize that swooning over an f/2.8 on the 4/3 format is disregarding the effect of the format itself on the image. An f/2.8 lens on a 2X camera behaves like an f/5.6 lens of double the focal length on full frame, in angle of view, depth of field and the resulting image.
Note that though you would have to use a higher ISO on the full-frame camera, it has a large advantage in this regard to start with-- you can use higher ISOs without the same noise penalty.
foghorn67
Lifer
Originally posted by: Fardringle
In Punchkin's defense (did I actually just type that? 😉), I suspect he meant to say that the E-420's pancake lens might act like an f/5.6 lens (as far as light-gathering goes) on a full frame camera because it has a physically smaller aperture hole designed to work with the camera's smaller sensor and wouldn't pass enough light to the full frame sensor. That doesn't change the fact that what he actually said is wrong.
It would be a pointless, dumb argument if that was the case. Who cares if it would be 5.6 on a FF? It would be a small image circle since it's made for a sensor twice as small.
punchkin fell into another hole he made.
He has still yet to prove why it has the same light gathering abilities as a 5.6 on a FF, why there is no aperture conversion factor in crop formats (except dof), and he has yet to provide any links on a Canon Rebel Xsi review.
Originally posted by: Fardringle
Hehe. I'd LOVE to have the physical aperture size of an f/2.8 50mm prime SLR lens on a point and shoot camera. You'd be able to use shutter speeds in 5 digits and still have an extremely bright picture. 😛
In Punchkin's defense (did I actually just type that? 😉), I suspect he meant to say that the E-420's pancake lens might act like an f/5.6 lens (as far as light-gathering goes) on a full frame camera because it has a physically smaller aperture hole designed to work with the camera's smaller sensor and wouldn't pass enough light to the full frame sensor. That doesn't change the fact that what he actually said is wrong.
Nope. You have failed to understand what I wrote. I meant to say that an f/2.8 25mm lens on a 2X crop camera behaves as an f/5.6 50mm lens on a full frame camera. The combo is not "fast".
Originally posted by: foghorn67
Originally posted by: Fardringle
In Punchkin's defense (did I actually just type that? 😉), I suspect he meant to say that the E-420's pancake lens might act like an f/5.6 lens (as far as light-gathering goes) on a full frame camera because it has a physically smaller aperture hole designed to work with the camera's smaller sensor and wouldn't pass enough light to the full frame sensor. That doesn't change the fact that what he actually said is wrong.
It would be a pointless, dumb argument if that was the case. Who cares if it would be 5.6 on a FF? It would be a small image circle since it's made for a sensor twice as small.
punchkin fell into another hole he made.
He has still yet to prove why it has the same light gathering abilities as a 5.6 on a FF, why there is no aperture conversion factor in crop formats (except dof), and he has yet to provide any links on a Canon Rebel Xsi review.
You've continued to misunderstand. The camera/lens combo has the same light-gathering capability.
Don't let me dissuade you-- by all means, buy this "fast" lens and go shoot in low-light conditions, then report back.
Do you have Asperger's syndrome? Seriously?
An f/2.8 lens on a 2X camera behaves like an f/5.6 lens of double the focal length on full frame, in angle of view, depth of field and the resulting image.
You're going to have to work on reading that whole sentence as a sentence, instead of just each phrase in isolation, to understand the sentence.
foghorn67
Lifer
Like Hell. Get off your high horse, and admit you are flat out wrong, or worded your argument in the poorest manner. I have shot FF for 15 years. I have shot 1.6 crop for a few years.
I am aware of the crop factor, DOF, and forced perspective that comes into play. But you made a dumb 5.6 argument.
Nope, not at all. For instance, you wrote before: "He has still yet to prove why it has the same light gathering abilities as a 5.6 on a FF".
It's not just the lens, it's the lens/camera combo that gathers light and records it. If you still don't understand that a sensor four times as large, everything else being equal, gathers four times the light-- there's no reaching you. And that's really fine with me.
randomlinh
Lifer
ah, another wonderful punchkin debate. Although, in this case it just sounds like everyone is talking about the lens, and he's talking specifically about the lens+sensor.
foghorn67
Lifer
Your 5.6 argument is broken. Even Oly says 4/3rds is lower than 1/2 a stop. You are talking way out of scale here.
You can scour the internet if you want to compare images of a FF exposure vs. a 4/3 exposure (assuming the Tv is the same) will show you that it's closer to a 1/3 stop. Which is almost negligible in digital photography.
Heck, for example, prime lenses vs. zooms have this much of a difference on the same format, and people don't really notice.
Fardringle
Diamond Member
Punchkin, I think we do understand perfectly what you said. You are saying that with all other factors equal, you will have to use f/2.8 on a crop factor camera in order to maintain the same shutter speed and exposure as f/5.6 on a full frame camera. That is simply not true and it is how we know that you are wrong. If that is not what you are intending to say, then you need to read your own posts and word them better because that is what you are saying.
As a side note, I have to say that I love reading these forums. Apart from the ability to gain knowledge from people who REALLY know what they are doing, it also provides an excellent source of entertainment when people that don't know what they are talking about continue to argue what are usually small and insignificant points against the ones that do know what they are talking about.
As a side note, I have to say that I love reading these forums. Apart from the ability to gain knowledge from people who REALLY know what they are doing, it also provides an excellent source of entertainment when people that don't know what they are talking about continue to argue what are usually small and insignificant points against the ones that do know what they are talking about.
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