Re: [darktable-dev] Lens correction with FF lenses used on APS-C
Hi, Am 24.02.19 um 13:32 schrieb Florian W: > 1 This reasoning is mixing description of digital features with analog > ones . A lens quality and specs is not defined by MP resolution (rather > by like purity of the glass, glass curvature homogeneity, CoC, TCA, and > so on). You are right, things work a bit differently on the optics side before the sensor. Hence my use of "oversimplyfing it a bit". But the resolution of an optical system can still be measured (see e.g. Optical transer function [1]), and you can specify how much contrast you expect to see in details and what level of details you expect to still be visible. It's hard to make exact quantitative statements like "this lens has an optical transfer function which gives enough contrast for x line pairs per millimeter, and that would be enough for an x megapixel sensor of this and this size". Especially because glass quality even differs within the same manufacturing batch. But for example with my blurry 70-300 it's easy to judge that it would probably be sharp enough for a 12 to 16 megapixel sensor, but nothing better. > 2 Some of the lenses we're talking about were developed and (partially) > targeted to FF cameras having a sensor with less MP than a current APS-C > (for example in Canon, the 6D is a 2012 FF with 20MP). > > If the reasoning is valid, a lens released at times of FF with 24MP or > higher wouldn't be a good match to the previous cameras with less MP. > Which doesn't seems to be the case. > > What I mean by this is that at some point, to ensure a lens will perform > well on FF cameras that will be released the following decade, one can > assume that the optical manufacturing quality is probably one order of > magnitude above the quality required to fit the current camera sensor > capabilities. Maybe explaining why you can see problems in older lenses. I'm not saying that I see a general problem with older lenses, and I already noted that your prime lenses probably won't cause much of problem. There's simply a very, very wide range of lenses out there, and the pricing, engineering and manufacturing decisions can lead to extremely different optical properties. There are some prime lenses from the 1980s which are still extremely sharp on today's sensors, but primes are easy. Most have just seven or eight glass elements. My Nikon 24-70/2.8 on the other hand has 20 lens elements in 16 groups. The older Canon 70-200/2.8 has 23 lenses in 19 groups. Even the Nikon 16-35/4 has 17 lens elements. Obviously it is much harder to keep the optical resolution at the same level when light has to pass through that many pieces of glass and the lens still has to be affordable. So there are FF lenses out there which will give good results on APS-C bodies, but not all will. And you can easily end up getting worse image quality with a FF lens on an APS-C body when you expected a better one because the FF lens was more expensive and is supposed to be better. Also manufacturers don't generally design lenses so thewy will work perfectly with cameras released a decade later. They will design the current top model so it has enough room to still be good on the next model, but they still want you to buy the new "sharper than ever" lens every five years. cheers, Simon [1] https://en.wikipedia.org/wiki/Optical_transfer_function ___ darktable developer mailing list to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org
Re: [darktable-dev] Lens correction with FF lenses used on APS-C
dxomark.com website seems to have relevant numbers, see for example Nikon lens mentioned by Sturm Flut: https://www.dxomark.com/Lenses/Nikon/AF-S-Nikkor-24-70mm-f-2.8G-ED-mounted-on-Nikon-D750__975 https://www.dxomark.com/Lenses/Nikon/AF-S-Nikkor-24-70mm-f-2.8G-ED-mounted-on-Nikon-D7100__865 Interestingly enough on D810 number is higher than on D750 even though sensor's physical dimensions are the same, probably due to the absence of optical low-pass filter: https://www.dxomark.com/Lenses/Nikon/AF-S-Nikkor-24-70mm-f-2.8G-ED-mounted-on-Nikon-D810__963 On Sun, 24 Feb 2019 13:32:54 +0100 Florian W wrote: > Thanks for the details Simon. > > I also thought about it a bit and had a reasoning similar to yours, that > basically something designed for a specific acquisition chain will probably > perform worse on an acquisition chain farther from its spec. > > However thinking about it more deeply, 2 things are still boggling my mind. > > 1 This reasoning is mixing description of digital features with analog ones > . A lens quality and specs is not defined by MP resolution (rather by like > purity of the glass, glass curvature homogeneity, CoC, TCA, and so on). > > 2 Some of the lenses we're talking about were developed and (partially) > targeted to FF cameras having a sensor with less MP than a current APS-C > (for example in Canon, the 6D is a 2012 FF with 20MP). > > If the reasoning is valid, a lens released at times of FF with 24MP or > higher wouldn't be a good match to the previous cameras with less MP. Which > doesn't seems to be the case. > > What I mean by this is that at some point, to ensure a lens will perform > well on FF cameras that will be released the following decade, one can > assume that the optical manufacturing quality is probably one order of > magnitude above the quality required to fit the current camera sensor > capabilities. Maybe explaining why you can see problems in older lenses. > > Please feel free to point any mistake in this reasoning. > > Maybe are we lucky enough that someone working in the optical lenses or > cameras industry is part of this mailing list and provide us some insights > about it :) > > Florian Wernert > Software engineer INSA > In-training Neuroscience researcher > https://www.linkedin.com/in/wernertflorian > > > > Le sam. 23 févr. 2019 à 18:12, Sturm Flut a > écrit : > > > Hi, > > > > Am 23.02.19 um 16:34 schrieb Florian W: > > > Thanks for your answers guys. > > > > > > Simon, I'm curious to know why to you it's not the best idea ? > > > > (oversimplifying it a bit) > > > > Full-frame lenses are designed to deliver their full sharpness across > > the whole full-frame image circle. If I put a full-frame lens on my > > APS-C D7100, I am basically expecting it to deliver 24 megapixels within > > the smaller APS-C image circle the sensor is cropping out. That means I > > expect the lens to deliver about 24*2,25 = 54 megapixels over the whole > > full-frame image circle. Which not that many standard lenses will do. > > > > If put my standard 24-70/2.8 on a Nikon D850 and (let's say) it only > > delivers 40 megapixels of actual resolution instead of the ~46 the > > sensor wants, that's not going to be a catastrophe. If I put it on a > > camera with a lower resolution sensor, e.g. the 24 megapixel sensor in > > the D750, there is zero problem. But if I put the same lens on the > > D7100, the cropped area will only get around 40 / 2,25 = 17 megapixels. > > That's suddenly 30% less than what the sensor needs. And not every lens > > will even deliver these 40 megapixels. Good APS-C and especially > > Micro-Four-Thirds lenses are expensive and hard to make because they > > have to be very sharp within the smaller image circle. > > > > Prime lenses are usually sharper to begin with, so with your 50/1.8 and > > 28/2.8 it might not be that much of an issue. But I can clearly see the > > problem with my 24-70/2.8, and especially with the good old 70-300/4.5-5.6. > > > > cheers, > > Simon > > > > ___ > darktable developer mailing list > to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org > ___ darktable developer mailing list to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org
Re: [darktable-dev] Lens correction with FF lenses used on APS-C
Thanks for the details Simon. I also thought about it a bit and had a reasoning similar to yours, that basically something designed for a specific acquisition chain will probably perform worse on an acquisition chain farther from its spec. However thinking about it more deeply, 2 things are still boggling my mind. 1 This reasoning is mixing description of digital features with analog ones . A lens quality and specs is not defined by MP resolution (rather by like purity of the glass, glass curvature homogeneity, CoC, TCA, and so on). 2 Some of the lenses we're talking about were developed and (partially) targeted to FF cameras having a sensor with less MP than a current APS-C (for example in Canon, the 6D is a 2012 FF with 20MP). If the reasoning is valid, a lens released at times of FF with 24MP or higher wouldn't be a good match to the previous cameras with less MP. Which doesn't seems to be the case. What I mean by this is that at some point, to ensure a lens will perform well on FF cameras that will be released the following decade, one can assume that the optical manufacturing quality is probably one order of magnitude above the quality required to fit the current camera sensor capabilities. Maybe explaining why you can see problems in older lenses. Please feel free to point any mistake in this reasoning. Maybe are we lucky enough that someone working in the optical lenses or cameras industry is part of this mailing list and provide us some insights about it :) Florian Wernert Software engineer INSA In-training Neuroscience researcher https://www.linkedin.com/in/wernertflorian Le sam. 23 févr. 2019 à 18:12, Sturm Flut a écrit : > Hi, > > Am 23.02.19 um 16:34 schrieb Florian W: > > Thanks for your answers guys. > > > > Simon, I'm curious to know why to you it's not the best idea ? > > (oversimplifying it a bit) > > Full-frame lenses are designed to deliver their full sharpness across > the whole full-frame image circle. If I put a full-frame lens on my > APS-C D7100, I am basically expecting it to deliver 24 megapixels within > the smaller APS-C image circle the sensor is cropping out. That means I > expect the lens to deliver about 24*2,25 = 54 megapixels over the whole > full-frame image circle. Which not that many standard lenses will do. > > If put my standard 24-70/2.8 on a Nikon D850 and (let's say) it only > delivers 40 megapixels of actual resolution instead of the ~46 the > sensor wants, that's not going to be a catastrophe. If I put it on a > camera with a lower resolution sensor, e.g. the 24 megapixel sensor in > the D750, there is zero problem. But if I put the same lens on the > D7100, the cropped area will only get around 40 / 2,25 = 17 megapixels. > That's suddenly 30% less than what the sensor needs. And not every lens > will even deliver these 40 megapixels. Good APS-C and especially > Micro-Four-Thirds lenses are expensive and hard to make because they > have to be very sharp within the smaller image circle. > > Prime lenses are usually sharper to begin with, so with your 50/1.8 and > 28/2.8 it might not be that much of an issue. But I can clearly see the > problem with my 24-70/2.8, and especially with the good old 70-300/4.5-5.6. > > cheers, > Simon > ___ darktable developer mailing list to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org
Re: [darktable-dev] Lens correction with FF lenses used on APS-C
In the database (in liblensfun-data package, file slr-canon.xml for Canon), you will find the various bodies / lenses. For each lens, there is a comment like: This allows you to know how the lens was calibrated. J-L Le sam. 23 févr. 2019 à 19:31, David Vincent-Jones a écrit : > On my system the camera and correct lens is found by default which is > what I want! > > David > On 2019-02-23 9:12 a.m., Sturm Flut wrote: > > Hi, > > Am 23.02.19 um 16:34 schrieb Florian W: > > Thanks for your answers guys. > > Simon, I'm curious to know why to you it's not the best idea ? > > (oversimplifying it a bit) > > Full-frame lenses are designed to deliver their full sharpness across > the whole full-frame image circle. If I put a full-frame lens on my > APS-C D7100, I am basically expecting it to deliver 24 megapixels within > the smaller APS-C image circle the sensor is cropping out. That means I > expect the lens to deliver about 24*2,25 = 54 megapixels over the whole > full-frame image circle. Which not that many standard lenses will do. > > If put my standard 24-70/2.8 on a Nikon D850 and (let's say) it only > delivers 40 megapixels of actual resolution instead of the ~46 the > sensor wants, that's not going to be a catastrophe. If I put it on a > camera with a lower resolution sensor, e.g. the 24 megapixel sensor in > the D750, there is zero problem. But if I put the same lens on the > D7100, the cropped area will only get around 40 / 2,25 = 17 megapixels. > That's suddenly 30% less than what the sensor needs. And not every lens > will even deliver these 40 megapixels. Good APS-C and especially > Micro-Four-Thirds lenses are expensive and hard to make because they > have to be very sharp within the smaller image circle. > > Prime lenses are usually sharper to begin with, so with your 50/1.8 and > 28/2.8 it might not be that much of an issue. But I can clearly see the > problem with my 24-70/2.8, and especially with the good old 70-300/4.5-5.6. > > cheers, > Simon > ___ > darktable developer mailing list > to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org > > > ___ > darktable developer mailing list to unsubscribe send a mail to > darktable-dev+unsubscr...@lists.darktable.org > ___ darktable developer mailing list to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org
Re: [darktable-dev] Lens correction with FF lenses used on APS-C
On my system the camera and correct lens is found by default which is what I want! David On 2019-02-23 9:12 a.m., Sturm Flut wrote: Hi, Am 23.02.19 um 16:34 schrieb Florian W: Thanks for your answers guys. Simon, I'm curious to know why to you it's not the best idea ? (oversimplifying it a bit) Full-frame lenses are designed to deliver their full sharpness across the whole full-frame image circle. If I put a full-frame lens on my APS-C D7100, I am basically expecting it to deliver 24 megapixels within the smaller APS-C image circle the sensor is cropping out. That means I expect the lens to deliver about 24*2,25 = 54 megapixels over the whole full-frame image circle. Which not that many standard lenses will do. If put my standard 24-70/2.8 on a Nikon D850 and (let's say) it only delivers 40 megapixels of actual resolution instead of the ~46 the sensor wants, that's not going to be a catastrophe. If I put it on a camera with a lower resolution sensor, e.g. the 24 megapixel sensor in the D750, there is zero problem. But if I put the same lens on the D7100, the cropped area will only get around 40 / 2,25 = 17 megapixels. That's suddenly 30% less than what the sensor needs. And not every lens will even deliver these 40 megapixels. Good APS-C and especially Micro-Four-Thirds lenses are expensive and hard to make because they have to be very sharp within the smaller image circle. Prime lenses are usually sharper to begin with, so with your 50/1.8 and 28/2.8 it might not be that much of an issue. But I can clearly see the problem with my 24-70/2.8, and especially with the good old 70-300/4.5-5.6. cheers, Simon ___ darktable developer mailing list to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org ___ darktable developer mailing list to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org
Re: [darktable-dev] Lens correction with FF lenses used on APS-C
Hi, Am 23.02.19 um 16:34 schrieb Florian W: > Thanks for your answers guys. > > Simon, I'm curious to know why to you it's not the best idea ? (oversimplifying it a bit) Full-frame lenses are designed to deliver their full sharpness across the whole full-frame image circle. If I put a full-frame lens on my APS-C D7100, I am basically expecting it to deliver 24 megapixels within the smaller APS-C image circle the sensor is cropping out. That means I expect the lens to deliver about 24*2,25 = 54 megapixels over the whole full-frame image circle. Which not that many standard lenses will do. If put my standard 24-70/2.8 on a Nikon D850 and (let's say) it only delivers 40 megapixels of actual resolution instead of the ~46 the sensor wants, that's not going to be a catastrophe. If I put it on a camera with a lower resolution sensor, e.g. the 24 megapixel sensor in the D750, there is zero problem. But if I put the same lens on the D7100, the cropped area will only get around 40 / 2,25 = 17 megapixels. That's suddenly 30% less than what the sensor needs. And not every lens will even deliver these 40 megapixels. Good APS-C and especially Micro-Four-Thirds lenses are expensive and hard to make because they have to be very sharp within the smaller image circle. Prime lenses are usually sharper to begin with, so with your 50/1.8 and 28/2.8 it might not be that much of an issue. But I can clearly see the problem with my 24-70/2.8, and especially with the good old 70-300/4.5-5.6. cheers, Simon ___ darktable developer mailing list to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org
Re: [darktable-dev] Lens correction with FF lenses used on APS-C
Thanks for your answers guys. Simon, I'm curious to know why to you it's not the best idea ? Le sam. 23 févr. 2019 16:19, Sturm Flut a écrit : > Hi, > > it does, as long as lensfun can find the lens in its database. I've been > using full-frame-only lenses on both my Nikon D750 (full-frame) and > D7100 (APS-C) for years. > > (It's not the best idea, though, so I'm about to replace the D7100 with > a second full-frame body). > > cheers, > Simon > > > > Am 23.02.19 um 14:42 schrieb Florian W: > > Hi, > > I happen to use on my Canon 750D (APC-C) 2 lenses designed for full > > frame (Canon EF 50mm f/1.8 STM and Canon EF 28mm f/2.8 IS USM) > > I wondered if the lens correction module takes into account that the > > camera is full frame or APS-C to apply the proper correction ? > > > > Can someone tell me ? > > Thanks > > > > > ___ > > darktable developer mailing list to unsubscribe send a mail to > > darktable-dev+unsubscr...@lists.darktable.org > ___ darktable developer mailing list to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org
Re: [darktable-dev] Lens correction with FF lenses used on APS-C
Hi, it does, as long as lensfun can find the lens in its database. I've been using full-frame-only lenses on both my Nikon D750 (full-frame) and D7100 (APS-C) for years. (It's not the best idea, though, so I'm about to replace the D7100 with a second full-frame body). cheers, Simon Am 23.02.19 um 14:42 schrieb Florian W: > Hi, > I happen to use on my Canon 750D (APC-C) 2 lenses designed for full > frame (Canon EF 50mm f/1.8 STM and Canon EF 28mm f/2.8 IS USM) > I wondered if the lens correction module takes into account that the > camera is full frame or APS-C to apply the proper correction ? > > Can someone tell me ? > Thanks > > ___ > darktable developer mailing list to unsubscribe send a mail to > darktable-dev+unsubscr...@lists.darktable.org ___ darktable developer mailing list to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org
Re: [darktable-dev] Lens correction with FF lenses used on APS-C
I believe it does. Changing body type (full-frame instead of aps-c) changes geometry. Body type description is nothing more than just a file in /usr/share/lensfun/version_1 with cropfactor parameter being the only meaningful information used for geometry calculaton. Timur. On Sat, 2019-02-23 at 14:42 +0100, Florian W wrote: > Hi, > I happen to use on my Canon 750D (APC-C) 2 lenses designed for full > frame (Canon EF 50mm f/1.8 STM and Canon EF 28mm f/2.8 IS USM) > I wondered if the lens correction module takes into account that the > camera is full frame or APS-C to apply the proper correction ? > > Can someone tell me ? > Thanks > > _ > __ darktable developer mailing list to unsubscribe send a mail to > darktable-dev+unsubscr...@lists.darktable.org ___ darktable developer mailing list to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org
