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11-18-2013, 03:42 AM   #166
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(I was told what I wrote was completely wrong, so I removed it for the time being. read below for follow-up)


Last edited by tripodquest; 11-18-2013 at 07:06 AM.
11-18-2013, 04:06 AM   #167
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QuoteOriginally posted by tripodquest Quote
It doesn't matter what Pentax makes or doesn't make, FF sensor/film is a lot more unforgiving to lens imperfections than a smaller sensor/110/whatever. In FF resolution you need the lenses to be more perfect to achieve the same IQ/avoid the same deteriorating factors, so a lens that's correctly made for FF (ie. is considered to be a decent lens on FF, and not an absolutely horrendeous lens on FF) will have better IQ on aps-c than an aps-c lens only because to even make a FF lens, you have to be prepared to use more high-quality materials and more precise engineering than if you make "just an aps-c" lens since whichever fault of the lens would be barely noticeable on aps-c would be blatantly obvious on FF. Another point is the reverse: since the differences are harder to detect, even if the FF lens was 15x better in IQ than the aps-c lens, if the latter is on the limit of what aps-c can resolve/"see" then you wouldn't notice a difference. I think that was the point why comparing the two wouldn't be "fair" but correct me if I'm wrong.
Well, I can safely say you're wrong on ALL points. I won't even try to correct you. I hope others have more time at hand because I don't
11-18-2013, 04:22 AM   #168
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QuoteOriginally posted by tripodquest Quote
It doesn't matter what Pentax makes or doesn't make, FF sensor/film is a lot more unforgiving to lens imperfections than a smaller sensor/110/whatever. In FF resolution you need the lenses to be more perfect to achieve the same IQ/avoid the same deteriorating factors, so a lens that's correctly made for FF (ie. is considered to be a decent lens on FF, and not an absolutely horrendeous lens on FF) will have better IQ on aps-c than an aps-c lens only because to even make a FF lens, you have to be prepared to use more high-quality materials and more precise engineering than if you make "just an aps-c" lens since whichever fault of the lens would be barely noticeable on aps-c would be blatantly obvious on FF. Another point is the reverse: since the differences are harder to detect, even if the FF lens was 15x better in IQ than the aps-c lens, if the latter is on the limit of what aps-c can resolve/"see" then you wouldn't notice a difference. I think that was the point why comparing the two wouldn't be "fair" but correct me if I'm wrong.
It is a lot tougher to make good quality APS-C (or for that matter four thirds lenses) due to the higher pixel density. Sticking a horrendous lens on full frame on an APS-C camera will just crop the edges of that image away and concentrate the focus on the center of the image. If the only issue with the lens is that it has weak corners then that may help. But a truly bad lens on full frame will be just as bad or worse (in general) on a crop camera.

Full frame is actually a more forgiving format than the smaller formats.
11-18-2013, 04:26 AM   #169
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QuoteOriginally posted by Rondec Quote
If the only issue with the lens is that it has weak corners then that may help.
Which is why I'm keen on getting the Sigma 24-70mm... a full frame lens with no-so-great edge performance and vignetting but looks fantastic on APS-C cameras haha



11-18-2013, 04:51 AM   #170
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QuoteOriginally posted by Asahiflex Quote
Well, I can safely say you're wrong on ALL points. I won't even try to correct you. I hope others have more time at hand because I don't
Either you take the time or leave the floor to those you have something meaningful to contribute. Arrogance does not make you experienced or respected, it makes you something else entirely.
QuoteOriginally posted by Rondec Quote
It is a lot tougher to make good quality APS-C (or for that matter four thirds lenses) due to the higher pixel density. Sticking a horrendous lens on full frame on an APS-C camera will just crop the edges of that image away and concentrate the focus on the center of the image. If the only issue with the lens is that it has weak corners then that may help. But a truly bad lens on full frame will be just as bad or worse (in general) on a crop camera.

Full frame is actually a more forgiving format than the smaller formats.
Ah... now that you say that, of course that makes more sense. I added "correct me if I'm wrong" for a reason: I wasn't sure if what I said was correct, it was based on something I recently read that seemed to make sense in my head, unfortunately the wrong way around. Thank you for taking the time to correct me

Last edited by tripodquest; 11-18-2013 at 05:29 AM.
11-18-2013, 06:15 AM   #171
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QuoteOriginally posted by Rondec Quote
Full frame is actually a more forgiving format than the smaller formats.
There's a good example of this effect documented by Photozone,
where the Nikon 28/1.8 G earns 2.5 stars on 1", 3-3.5 on APS-C, and 4 on FF.

The corner resolution is at best "good" on 1",
but never less than "very good" on FF.

For various reasons,
including the higher pixel density needed on small formats,
the intuitive concept of "cropping away bad corners"
doesn't necessarily work out in practice.
11-18-2013, 06:25 AM   #172
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QuoteOriginally posted by lytrytyr Quote
There's a good example of this effect documented by Photozone,
where the Nikon 28/1.8 G earns 2.5 stars on 1", 3-3.5 on APS-C, and 4 on FF.

The corner resolution is at best "good" on 1",
but never less than "very good" on FF.

For various reasons,
including the higher pixel density needed on small formats,
the intuitive concept of "cropping away bad corners"
doesn't necessarily work out in practice.
This article also makes a good point: Full Frame vs while it's cheaper for a manufacturer to only cover the FF sensor exactly with no wiggle room (which is the case with cheap lenses), some (better, more expensive (to buy and to manufacture)) lenses cover a larger circle, so there are no "bad corners" on FF.

Maybe someone smarter can explain to me how the aps-c sensor could tell the difference between a lens that couldn't resolve the individual slats in the blinds in the example image, and a lens that can resolve a lot more? Lets say white bb pellets in between the slats just so no one can say "but it resolves the slats... kind of, barely..." I'm not being snarky here, I genuinely want to understand what to me seems impossible to understand even after I accepted that the way I thought it is isn't the way it is. How can the smaller sensor tell the difference when it can't resolve the detail? Smaller pixels also mean less photos detected by each pixel or more noise because each pixel gets more photons than it can handle, doesn't it? Isn't that one of the disadvantages of smaller sensors? Photographer Dennis Manarchy builds supersize 35 foot camera | Mail Online

can any dslr/FF/4/3 or even middle format resolve the individual pores on human skin from a portrait distance? If it can't, how can it measure the resolving limit/sharpness of a lens better than a larger format (sensor or film)? I'm slipping back to my original understanding because it's the only one that seems to make any sense, but I'll happily accept the reverse if someone can explain it to me. I can't understand something no one explains.

Last edited by tripodquest; 11-18-2013 at 06:55 AM.
11-18-2013, 06:59 AM   #173
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QuoteOriginally posted by tripodquest Quote
It doesn't matter what Pentax makes or doesn't make, FF sensor/film is a lot more unforgiving to lens imperfections than a smaller sensor/110/whatever. In FF resolution you need the lenses to be more perfect to achieve the same IQ/avoid the same deteriorating factors, so a lens that's correctly made for FF (ie. is considered to be a decent lens on FF, and not an absolutely horrendeous lens on FF) will have better IQ on aps-c than an aps-c lens only because to even make a FF lens, you have to be prepared to use more high-quality materials and more precise engineering than if you make "just an aps-c" lens since whichever fault of the lens would be barely noticeable on aps-c would be blatantly obvious on FF. Another point is the reverse: since the differences are harder to detect, even if the FF lens was 15x better in IQ than the aps-c lens, if the latter is on the limit of what aps-c can resolve/"see" then you wouldn't notice a difference. I think that was the point why comparing the two wouldn't be "fair" but correct me if I'm wrong.
You have it backwards. Smaller sensors have to be enlarged much more which makes lens quality much more critical.

11-18-2013, 07:05 AM   #174
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QuoteOriginally posted by Winder Quote
You have it backwards. Smaller sensors have to be enlarged much more which makes lens quality much more critical.
See my follow-up question above and please answer it if you can. I really want to understand all these things better, understand why my thinking is backwards. It doesn't seem backwards to me so I need someone to help me understand how and why it's backwards.
11-18-2013, 07:33 AM   #175
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Link to PF Post for Hands-on opinion of the 20~40 at DFW PhotoExpo HERE
"The lens lineup included the 20-40 Limited; that lens on the K3 is just....solid. And fast. And solid. The combo reminds me of my classic Pentax stuff; the 135 1.8 ED on an LX, for example."

Last edited by monochrome; 11-18-2013 at 12:01 PM.
11-18-2013, 07:36 AM   #176
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QuoteOriginally posted by tripodquest Quote
This article also makes a good point: Full Frame vs while it's cheaper for a manufacturer to only cover the FF sensor exactly with no wiggle room (which is the case with cheap lenses), some (better, more expensive (to buy and to manufacture)) lenses cover a larger circle, so there are no "bad corners" on FF.

Maybe someone smarter can explain to me how the aps-c sensor could tell the difference between a lens that couldn't resolve the individual slats in the blinds in the example image, and a lens that can resolve a lot more? Lets say white bb pellets in between the slats just so no one can say "but it resolves the slats... kind of, barely..." I'm not being snarky here, I genuinely want to understand what to me seems impossible to understand even after I accepted that the way I thought it is isn't the way it is. How can the smaller sensor tell the difference when it can't resolve the detail? Smaller pixels also mean less photos detected by each pixel or more noise because each pixel gets more photons than it can handle, doesn't it? Isn't that one of the disadvantages of smaller sensors? Photographer Dennis Manarchy builds supersize 35 foot camera | Mail Online

can any dslr/FF/4/3 or even middle format resolve the individual pores on human skin from a portrait distance? If it can't, how can it measure the resolving limit/sharpness of a lens better than a larger format (sensor or film)? I'm slipping back to my original understanding because it's the only one that seems to make any sense, but I'll happily accept the reverse if someone can explain it to me. I can't understand something no one explains.
I think you are a little confused. If you have a 24 megapixel APS-C sensor, you have very small pixels. In order to have a lens that actually shows pixel level sharpness, you need a lens that has a lot more engineering, than a lens that is used on a 24 megapixel full frame camera. As Winder says, you are enlarging the image more on the smaller sensor and that ends up magnifying tiny aberrations in the lens.
11-18-2013, 07:48 AM   #177
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QuoteOriginally posted by Rondec Quote
I think you are a little confused. If you have a 24 megapixel APS-C sensor, you have very small pixels. In order to have a lens that actually shows pixel level sharpness, you need a lens that has a lot more engineering, than a lens that is used on a 24 megapixel full frame camera. As Winder says, you are enlarging the image more on the smaller sensor and that ends up magnifying tiny aberrations in the lens.
Yes, of course I'm confused, otherwise I'd have an easier time figuring this out. oh, I didn't know normal lenses can't focus/resolve that sharply. Okay. In the text I also read this: "Aberrations (inperfections) in images usually vary with the distance from the center of the frame, in the manner shown in the table below for simple lenses." I think that confused me as well. I didn't understand it the first time, now reading it again it seems to say that the aberrations closer to the edges get worse quicker on FF than on APS-C. Is that correct?
11-18-2013, 08:08 AM   #178
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I think the area where things get a little dicey is in the really wide angle range. These are lenses that often are tough to make for any format. Probably the Sigma 8-16mm is the best of the lot on APS-C, while the Nikon 14-24 f2.8 is the best of the lot on full frame. Borders can get pretty weak and distortion can be a struggle as well. But certainly most people would conclude that full frame has the advantage in these lenses.
11-18-2013, 08:33 AM - 1 Like   #179
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QuoteOriginally posted by tripodquest Quote
Yes, of course I'm confused, otherwise I'd have an easier time figuring this out. oh, I didn't know normal lenses can't focus/resolve that sharply. Okay. In the text I also read this: "Aberrations (inperfections) in images usually vary with the distance from the center of the frame, in the manner shown in the table below for simple lenses." I think that confused me as well. I didn't understand it the first time, now reading it again it seems to say that the aberrations closer to the edges get worse quicker on FF than on APS-C. Is that correct?
I think the point is this: given a constant resolution (MP count), a FF lens on a FF sensor uses more surface area of its glass for each pixel than does an APS-C lens on an APS-C sensor. So if there are impurities in the glass (which I think there will be), the effect of those impurities on the pixel level is easier spotted when using the APS-C setup than when using the FF setup, because the size of those impurities relative to the size of the pixel is bigger on the APS-C setup. So, the necessity for bigger glass in FF lenses gives designers more leeway to get the same optical performance.

It's the same concept as taking a photo at ISO 3200, blowing it up to 100% and seeing all the noise, versus blowing it up to 50% and seeing less noise, because it is more fine-grained.
11-18-2013, 08:41 AM   #180
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QuoteOriginally posted by starbase218 Quote
I think the point is this: given a constant resolution (MP count), a FF lens on a FF sensor uses more surface area of its glass for each pixel than does an APS-C lens on an APS-C sensor. So if there are impurities in the glass (which I think there will be), the effect of those impurities on the pixel level is easier spotted when using the APS-C setup than when using the FF setup, because the size of those impurities relative to the size of the pixel is bigger on the APS-C setup. So, the necessity for bigger glass in FF lenses gives designers more leeway to get the same optical performance.

It's the same concept as taking a photo at ISO 3200, blowing it up to 100% and seeing all the noise, versus blowing it up to 50% and seeing less noise, because it is more fine-grained.
ohh... that makes perfect sense, I finally undestand what was meant and why I had it backwards. Thank you so much for explaining it in detail.
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