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FE lens on APS-C body (Sony)
- Thread starter Catcher05
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This is a terrible analogy to prove your point. An engine's performance is measured by crank/flywheel horsepower and torque, not the rate that the whole vehicles covers a set distance. Acceleration is a measure of a car as a whole's performance. Crank/flywheel horsepower and torque are the performance measurement of an engine before drivetrain loss, and is measured before being mated to a transmission. Therefore you are actually proving your counterpoint. The engine performance stays the same, just like a lens, while the transmission's performance changes, just like a sensor.
Your audio analogy is worse in that it's incoherent rambling, proving nothing since it's no where close to being apples to apples.
This image very simply shows how ff vs apsc works. Same lens, same focal length, same projected image. The only difference is the sensor itself. The apsc sensor is smaller, therefor only picks up a piece of the projected image. it has nothing to do with pixel density. The lens is static and performing the same job on either body. Optimized for full frame, or optimized for apsc has nothing to do with resolution, pixel density, or focal length. It simply means that it's designed to cover a full frame sensor, or designed to cover an apsc sensor only. To completely throw your argument out the window. please attach old zeiss or leica glass to any modern camera and see how it magically resolves to a beautiful sharp image. Digital wasn't even dreamed of when those lenses started to set standards in sharpness.
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Jerry R
Forum Pro
One picture better then most of the nonsensical responses.
M
mcslsk
Guest
Thank you, I agree.
earlyadapter
Well-known member
While I would entirely agree with the first part of your statement, I think there are 3 provisos:
1. As noted earlier, the central part of the lens may have higher resolution than the outer edges, so the APS-C sensor only sees the 'better' section.
2. The pixel density of a 24MP APS-C sensor is the same as the pixel density of a 54MP FF sensor. If you are using FE lenses that are good for a 54MP FF camera (slightly better than the A7Rii), then you're OK. But I'd guess there are plenty of FE lenses that are not up to that spec, for a range of everyday apertures.
3. There has been some discussion about the impact of the glass ON the sensor, particularly its depth. There may be marginal differences between a6000/6300 and a7 series sensors, which would not optimise the design of any particular FE lens.
But I'm strictly an amateur, so my opinion is worth what you paid for it.....
1. As noted earlier, the central part of the lens may have higher resolution than the outer edges, so the APS-C sensor only sees the 'better' section.
2. The pixel density of a 24MP APS-C sensor is the same as the pixel density of a 54MP FF sensor. If you are using FE lenses that are good for a 54MP FF camera (slightly better than the A7Rii), then you're OK. But I'd guess there are plenty of FE lenses that are not up to that spec, for a range of everyday apertures.
3. There has been some discussion about the impact of the glass ON the sensor, particularly its depth. There may be marginal differences between a6000/6300 and a7 series sensors, which would not optimise the design of any particular FE lens.
But I'm strictly an amateur, so my opinion is worth what you paid for it.....
davect01
Veteran Member
1- A FF lens will get slightly better results on it's native sensor. Duh.
2- That does not mean that you can not get great results using a FF lens on the APS-C sensor.
I love my 28-70mm FE, (I know it is not the 55mm in question), and get some great shots with it on my A6000. That is all I need to know.
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Novice . Former NEX-3, F3, and Now a proud A6000 owner.
http://davesnex-3photos.blogspot.com/
2- That does not mean that you can not get great results using a FF lens on the APS-C sensor.
I love my 28-70mm FE, (I know it is not the 55mm in question), and get some great shots with it on my A6000. That is all I need to know.
--
Novice . Former NEX-3, F3, and Now a proud A6000 owner.
http://davesnex-3photos.blogspot.com/
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Check their test setup definition .
It's clear that for ISO sensitivity variations of the sensors used, differing T stop values will occur when the same lens is mounted on either APSC or FF (or even another APSC camera).
And BINGO: The same difference of 0.2 T Stops can be found when DXO tested the FE35 on either FF or any APSC.
So up to now, everything is understandable and has some relation to reality ;-)
But we are straying from from the thread.....
andrewD2
Veteran Member
1) they can't redefine what T stop means to suit them.
2) why would a lens absorb a higher % of the light before it gets to whatever sensor is behind, it makes no sense.
3) if the OP uses DXO data to make choices I don't think this is off topic.
Andrew
2) why would a lens absorb a higher % of the light before it gets to whatever sensor is behind, it makes no sense.
3) if the OP uses DXO data to make choices I don't think this is off topic.
Andrew
Well, I guess the DXO team is open for suggestions from you how to improve. ;-)
Frankly, how do you want to measure T Stop of a E-mount lens without using a E-Mount camera? Whenever you do, you are dependent on the accuracy of the ISO mapping to sensitvity. You can compare within one sensor class, but it gets difficult in between different sensors.
FingerPainter
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A lens that has a FF image circle and can resolve N MP over the full frame senor with constant edge-to-edge sharpness can only resolve N/2.25 pixels over the APS-C portion of the sensor. Since most lenses are not 2.25 times sharper in the centre than at the edges, a given lens in front of an M MP APS-C sensor will tend to produce an image less sharp than the same lens in front of an M MP FF sensor.
again, It's not the lens that is making that difference. It is the sensor. All a lens does it take light in, flip it, and project it out the back. The exact same lens produces the exact same imagine out of the rear element on any camera it is attached to. How the sensor interprets the data makes the image sharp or soft. A crop sensor is still seeing the same size image, it's just not seeing all of it.
Your equation doesn't take into account pixel density and ignores the fact that a lens is a static, not changing piece of of metal plastic and glass that does nothing buy pass light.
On top of all of this. it's a dumb comparison all together. Size is not the only thing different between any full frame and crop sensor, so trying to compare the sharpness of full frame "camera a" with full frame "lens a" and crop "camera b" with "lens a" is hardly equal, or scientific for that matter. Trowing in a crop "lens b" just makes it that much less equal and scientific.
I need to leave this thread. It's making me forget how little I care about any of it. Good glass is good glass. Maybe that's why i have more legacy glass than e-mount.
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FingerPainter
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OP effectively asked if there was any difference in image quality to be expected from putting an FE lens in front of a APS-C sensor instead of a FF sensor. Sure, the lens sends the same image to the sensor plane, but the result produced by the camera is almost certainly less sharp on the APS-C sensor than on the FF sensor. It doesn't matter that the lens isn't causing the difference.
Yes it does. An M MP FF sensor obviously has a pixel pitch 1.5 times that of an M MP APS-C sensor.
It doesn't ignore that fact. It relies on it.
FingerPainter
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Of course not.
Of course not.
Depends what you think the product of such a multiplication is.
I don't think they state any such thing.
While you are trying to get Richard to amend his article, you should try to get all those camera manufacturers to stop referring to the full frame equivalent focal length of all their lenses intended for use on other than FF sensor cameras.
andrewD2
Veteran Member
The above is quoted from DXO, why does a factor that is a measure of the proportion of the light that makes its way to the sensor care what the sensor is? It is a property of the lens. Most likely the T 1.8 value is an error on the low side one day and T 2 is an error the next. If their T stop measure can be out by 2^0.2 what about their sharpness measurements?
It is pretty obvious to me they don't really understand the finer points of measurement and analysis like error estimation, otherwise they wouldn't quote values to a level of precision they can't measure. Their 4s.f. ISO 'sports' values are hilarious.
Andrew
Jerry R
Forum Pro
Just because Richard, the manufactures, and others use the wrong terminology does not make it right.
Equivalent FOV is correct. Equivalent focal length is not.
Equivalent DOF is only partially correct. Equivalent f stop is not.
Why is Equivalent DOF only partially correct? Although the the depth of focus will be the same the relationship between the objects in the image changes. To get the same FOV with the same lens on two different size sensors you have to be at different distances from the subject.
There are APSC sensors with better resolution than some FF sensors.
As an extreme example are old 6, 8, 10, and 12 meg FF sensor that have less resolution then a 24 meg APSC sensor.
I think the 36meg Sony FF sensor has the same pixel pitch as the 24 meg Sony sensor. Both should have the same resolution.
Equivalent FOV is correct. Equivalent focal length is not.
Equivalent DOF is only partially correct. Equivalent f stop is not.
Why is Equivalent DOF only partially correct? Although the the depth of focus will be the same the relationship between the objects in the image changes. To get the same FOV with the same lens on two different size sensors you have to be at different distances from the subject.
There are APSC sensors with better resolution than some FF sensors.
As an extreme example are old 6, 8, 10, and 12 meg FF sensor that have less resolution then a 24 meg APSC sensor.
I think the 36meg Sony FF sensor has the same pixel pitch as the 24 meg Sony sensor. Both should have the same resolution.
OK, I see what you are getting at. I must have missed something in your earlier posts. My apologies. I would like to add that DXO or some other "test" site mentioned that a thinker anti-alias filter of the a6000/a5100 etc also contributes to a lack of sharpness when compared to a full frame camera. I just see the answer to the OP's question of lens performance as "Then lens does not perform any different, but the sensor does. A FF camera will out perform the crop camera with any given ff lens."
Jerry R
Forum Pro
I am disagreeing with you since you referenced the article.
Manufacturers mark their lenses with the actual focal lengths and f stops not "equivalent ones".
Do you think a lens's focal length changes when it is placed on a smaller sensor?
Quote from Richard's article. This is correct.
"The F-number itself doesn't change with sensor size, just as actual focal length doesn't change with sensor size. However, the situation is essentially the same as with equivalent focal lengths: put a 50mm lens in front of a smaller-than-full-frame sensor and it's still a 50mm lens, but you get a narrower angle-of-view, because you're not capturing the full extent of the circle-of-light the lens is projecting. So we might say the lens is now 'acting as a 100mm equivalent' lens."
--
Sony R1, NEX C3 & 5R + Zeiss 24mm, 16-70, & FE 70-200 Lenses, Nikon V1 + 10-30 & 30-110 lenses.
Manufacturers mark their lenses with the actual focal lengths and f stops not "equivalent ones".
Do you think a lens's focal length changes when it is placed on a smaller sensor?
Quote from Richard's article. This is correct.
"The F-number itself doesn't change with sensor size, just as actual focal length doesn't change with sensor size. However, the situation is essentially the same as with equivalent focal lengths: put a 50mm lens in front of a smaller-than-full-frame sensor and it's still a 50mm lens, but you get a narrower angle-of-view, because you're not capturing the full extent of the circle-of-light the lens is projecting. So we might say the lens is now 'acting as a 100mm equivalent' lens."
--
Sony R1, NEX C3 & 5R + Zeiss 24mm, 16-70, & FE 70-200 Lenses, Nikon V1 + 10-30 & 30-110 lenses.
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Pixel Pooper
Senior Member
And just because you say so doesn't make it wrong.
The FOV is not equivalent, it is the same (when focal length is equivalent).
The DOF is not equivalent, it is the same (when f/stop is equivalent).
Equivalent images are not shot at same focal length from different distances, they are shot at equivalent focal lengths from the same distance.
The 36MP FF sensor has the same pixel pitch as a 16MP APS-C sensor, but they won't have the same resolution unless the FF is cropped to the same megapixels. Here is a quote from the equivalence essay that may help to elucidate this concept:
"The resolution of the lens is typically measured in lp/mm (line pairs per mm on the sensor) whereas the resolution of the photo is measured in lw/ph (line widths per line pairs per picture height). To convert lp/mm to lw/ph, we simply multiply the value by the twice sensor height. For example, let's consider a lens that resolves 50 lp/mm and convert to lp/ph:
mFT: 50 lp/mm · 2 lw/lp · 13.0 mm/ph = 1300 lw/ph
1.6x: 50 lp/mm · 2 lw/lp · 14.8 mm/ph = 1480 lw/ph
1.5x: 50 lp/mm · 2 lw/lp · 15.7 mm/ph = 1570 lw/ph
FF : 50 lp/mm · 2 lw/lp · 24.0 mm/ph = 2400 lw/ph
In terms of the visual properties of the photo, lw/ph is the relevant measure, where a lens on a sensor half the size (one fourth the area) as another must be twice as sharp to resolve as well for a given pixel count and AA filter."
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spytromics
Forum Enthusiast
Thank you for a civil response w/ actual data to back up your point! I've seen amazing shots taken with Kodak disposable cameras. And I've seen terrible shots taken with pro cameras. Everything is a compromise. If we take the argument in this thread to never use a APS-C sensor, then why even use a 35m sensor? Is that too not just a cropped sensor when compared to medium format? While you can use a Hasselblad or Phase One back on a Hasselblad front, I've yet to actually see someone at Disney World with one! Although that would be quite interesting.
Remember too that all of this resolution talk often ignores one key aspect -- your eyes are not perfect and do not have infinite resolution. Take your laser printer at work or at home. Can you really, truly tell a difference between 300 dpi and 600 dpi or 1200 dpi (or the 1200/600 dpi hybrid that some printers do)?
Remember too that neither Ansel Adams or Mathew Brady or many other photographers took their photos with either E or FE lenses! Yet, somehow, their photos are of somewhat acceptable quality. And 10-20 years from now, when we all have 100MP cameras built into our spectacles and instantly linked to everything, we'll still be debating that the 110MP cameras or their lenses are infinitely better. Yet no one mentions the photos themselves.
Remember too that all of this resolution talk often ignores one key aspect -- your eyes are not perfect and do not have infinite resolution. Take your laser printer at work or at home. Can you really, truly tell a difference between 300 dpi and 600 dpi or 1200 dpi (or the 1200/600 dpi hybrid that some printers do)?
Remember too that neither Ansel Adams or Mathew Brady or many other photographers took their photos with either E or FE lenses! Yet, somehow, their photos are of somewhat acceptable quality. And 10-20 years from now, when we all have 100MP cameras built into our spectacles and instantly linked to everything, we'll still be debating that the 110MP cameras or their lenses are infinitely better. Yet no one mentions the photos themselves.
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