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#181
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Finally got to the point where no new camera holds my interest (waiting for specific offering)
On Thu, 10 Jan 2019 10:32:22 -0500, nospam
wrote: In article , Eric Stevens wrote: This illustrates the disadvantage of not using the language with precision. As I said, all my lenses make use of f/numbers which are a measure of stops. Your thoughts have jumped the rails and are now talking about the intervals of Exposure Value of which the camera is capable. The exposure value may be used to set lens aperture, shutter speed or ISO. They are not identical to stops. EV's are equivalent to stops for any purpose related to exposure. I can change exposure value without changing the stop setting. you are confusing f/stop with stop. 'stop' is an abreviated way of referring to an obsolete way of changing lens aperture. It's use as a reference to lens aperture is now normal. -- Regards, Eric Stevens |
#182
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Finally got to the point where no new camera holds my interest (waiting for specific offering)
On Thu, 10 Jan 2019 03:51:41 -0800 (PST), Whisky-dave
wrote --- snip --- This illustrates the disadvantage of not using the language with precision. As I said, all my lenses make use of f/numbers which are a measure of stops. Your thoughts have jumped the rails and are now talking about the intervals of Exposure Value of which the camera is capable. The exposure value may be used to set lens aperture, shutter speed or ISO. They are not identical to stops. they absolutely are. So I double the shutter speed. I have halved the exposure value but I haven't affected the stop setting. Exposure value is really a measure of the brightness irrespective of the shutter speed or aperature. Which is why sensor can have EV values which aren;t referenced to shutter speeds or stops. Exposure value is a measure of the total quantity of light falling on the sensor. i.e its a function of lens aperture and length of time of exposure. If you look at the table here. https://en.wikipedia.org/wiki/Exposure_value example EV 10 10 1/1000 1/500 1/250 1/125 1/60 1/30 If you are referring to Table 1 it shows "Exposure times, in seconds or minutes (m), for various exposure values and f-numbers" The shutter speed columns are headed with a corresponding F number: EV 1.0 1.4 2.0 2.8 4.0 5.6 10 1/1000 1/500 1/250 1/125 1/60 1/30 It all makes perfect sense once you take the two separate parameters into account. so changing the shutter speed has NO effect on the EV. It doesn't if you make the corresponding change in the lens aperture as well. See up above a 1/1000 doubling that is 1/500, you can even double it again it's still the same EV value of 10 Because the aperture has gone from 1.0 to 1.4 to 2.0 respectively. What will change is that the shutter will open for twice as long allowing more light onto the sensor or the film or even the human eye. The shutteer will open for twice as long allowing light to fall on it for longer. But the lens will be stopped down to halve the illumination of the sensor. 2 x 1/2 = 1. No change. -- Regards, Eric Stevens |
#183
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Finally got to the point where no new camera holds my interest (waiting for specific offering)
On Thu, 10 Jan 2019 07:46:00 -0500, Alan Browne
wrote: On 2019-01-10 04:22, Eric Stevens wrote: On Tue, 08 Jan 2019 10:28:28 -0500, nospam wrote: In article , Eric Stevens wrote: It may be hair-splitting but none of my lenses are calibrated in EVs. They most definitely are, and probably 1/2 or 1/3 steps of EV as well, or possibly very fine steps in speed priority or auto modes. I bow to your superior knowledge of my equipment. your equipment is nothing special. many people have the same stuff. for modern lenses, it's user selectable at 1, 1/2 or 1/3 stops. not all options may be available on all cameras. it appears that nikon no longer offers 1 stop anymore (there's no reason to) but older nikon slrs did. i assume canon, pentax, etc., are similar. examples: https://www.imaging-resource.com/PRODS/D7000/screens/DSC_0211.jpg https://1.img-dpreview.com/files/p/a...ages/Captures/ d1x_41.gif http://www.steves-digicams.com/2004_reviews/d70/d70_custom_menu2.jpg for older lenses with a mechanical aperture ring (manual lenses and early autofocus), the aperture ring will normally click at 1 stop increments, sometimes 1/2 stop. occasionally, it's both on the same lens, i.e., the widest and smallest are 1 stop, rest 1/2 stop. there is no point in 1/3 stops since the mechanics aren't good enough. some lenses, such as mirror lenses, have only one f/stop, with no adjustments to be made, although they sometimes accept an nd filter in the back. This illustrates the disadvantage of not using the language with precision. As I said, all my lenses make use of f/numbers which are a measure of stops. Your thoughts have jumped the rails and are now talking about the intervals of Exposure Value of which the camera is capable. The exposure value may be used to set lens aperture, shutter speed or ISO. They are not identical to stops. they absolutely are. So I double the shutter speed. I have halved the exposure value but I haven't affected the stop setting. If you want to continue arguing to the contrary I will be happy to leave you to it. Reciprocity games. "Introduction to photography 101." You are still missing the point: lens aperture, shutter speeds or ISOs are not identical to stops. -- Regards, Eric Stevens |
#184
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Finally got to the point where no new camera holds my interest (waiting for specific offering)
On Thu, 10 Jan 2019 07:43:24 -0500, Alan Browne
wrote: On 2019-01-10 04:12, Eric Stevens wrote: On Wed, 9 Jan 2019 08:36:24 -0500, Alan Browne wrote: Its amazing what Google can produce. This is DxO's own account of the situation at: https://www.dxomark.com/dxomark-came...ol-and-scores/ "Dynamic range corresponds to the ratio between the highest brightness a camera can capture (saturation) and the lowest brightness it can capture (which is typically when noise becomes more important than the signal — that is, a signal-to-noise ratio below 0 dB). A value of 12 EV is excellent, with differences below 0.5 EV usually not noticeable. Dynamic range is an open scale." This appears to confirm that the situation is as I deduced: they are not testing the dynamic range as recorded in a raw file. They are testing the range that a camera can capture. i.e. it is the dynmaic range of the sensor. It is not the dynamic range of the raw file. It doesn't actually say that, however. How, specifically, are they bypassing the raw file to get the data? By measuring not the data in the file but the range of brightness that the camera can capture from their test set up. And where _specifically_ are they getting that data? What is the probe point? What is the probe? Read the URL. The use multiple light sources, each of different calibrated illuminance. It's rather like photographing an gray-scale wedge. -- Regards, Eric Stevens |
#185
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Finally got to the point where no new camera holds my interest (waiting for specific offering)
On Fri, 11 Jan 2019 16:52:47 +1300, Eric Stevens
wrote: On Thu, 10 Jan 2019 07:39:32 -0500, Alan Browne wrote: On 2019-01-10 04:05, Eric Stevens wrote: On Tue, 8 Jan 2019 08:31:05 -0500, Alan Browne wrote: On 2019-01-08 03:54, Eric Stevens wrote: On Mon, 07 Jan 2019 23:42:07 -0500, nospam wrote: In article , Eric Stevens wrote: But a moot point IMO. I doubt the sensor mentioned has 14 bits of DR in the first place. Esp. once you account for noise. Well, DxO measure 14.3 but what exactly that means is unknown. But if they made that specific statement then I would expect they must have grounds. it means their test methodology is worthless or they're intentionally lying. Or that you have failed to understand what they are doing. Your other post ends with a statement to the effect that DxO don't say what their algorithms are doing, so nospam certainly didn't fail anything. nospam will fail to understand what they are doing if he doesn't know what they are doing. That applies to everyone. In the end physics is physics and there is no way they are getting more DR than the sensor offers. Not even the bit depth of it. According to nospam they are claiming a DR of 14.3 for the sensor of the D800. As they said in the link that I posted which has somehow got snipped "Maximum dynamic range is the greatest possible amplitude between light and dark details a given sensor can record ...". 1. A 14 bit sensor cannot, possibly, record 14.3 DR. Please read what I am about to write and give it deep consideration before you reply. _There_is_no_such_thing_as_a_14_bit_sensor_! Or a 12 bit for that matter. The sensors which we are considering are *analog* devices which are not digital in their operation. 12 or 14 bits only come into it after the analog signal is stripped from the sensor and (only then) passed through an analogue to a digital convertor (ADC). A 14 bit ADC can output 16,384 distinct numerical values and the analog output of the sensor has to be mapped to this range. It doesn't matter what the Dynamic Range of the sensor may be. It has to be mapped to the numerical scale of the output of the ADC. It is perfectly feasible to map an analogue dynamic range to 14 bits (o12 (or 8)). Not withstanding what else has been written in this thread the choice of the number of bits used to encode the sensor's output does not affect the _sensor's_ dynamic range. But the issue is not the sensor's DR, it's the camera's DR. The output of the camera is the output of the ADC - not the sensor, and that ADC is limited to 14 stops as designed. The problem is clearly DXO's testing methods. No matter how you look at this, you have to be able to imagine all kinds of sources of inaccurate measurements, especially if they are slight. I have to agree with nospam and Alan. You can't get DR outside of the limits of the ADC because that is the output you see, but you can certainly get test results outside of that limit. |
#186
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Finally got to the point where no new camera holds my interest(waiting for specific offering)
On 1/10/2019 11:36 PM, Eric Stevens wrote:
On Thu, 10 Jan 2019 07:46:00 -0500, Alan Browne wrote: On 2019-01-10 04:22, Eric Stevens wrote: On Tue, 08 Jan 2019 10:28:28 -0500, nospam wrote: In article , Eric Stevens wrote: It may be hair-splitting but none of my lenses are calibrated in EVs. They most definitely are, and probably 1/2 or 1/3 steps of EV as well, or possibly very fine steps in speed priority or auto modes. I bow to your superior knowledge of my equipment. your equipment is nothing special. many people have the same stuff. for modern lenses, it's user selectable at 1, 1/2 or 1/3 stops. not all options may be available on all cameras. it appears that nikon no longer offers 1 stop anymore (there's no reason to) but older nikon slrs did. i assume canon, pentax, etc., are similar. examples: https://www.imaging-resource.com/PRODS/D7000/screens/DSC_0211.jpg https://1.img-dpreview.com/files/p/a...ages/Captures/ d1x_41.gif http://www.steves-digicams.com/2004_reviews/d70/d70_custom_menu2.jpg for older lenses with a mechanical aperture ring (manual lenses and early autofocus), the aperture ring will normally click at 1 stop increments, sometimes 1/2 stop. occasionally, it's both on the same lens, i.e., the widest and smallest are 1 stop, rest 1/2 stop. there is no point in 1/3 stops since the mechanics aren't good enough. some lenses, such as mirror lenses, have only one f/stop, with no adjustments to be made, although they sometimes accept an nd filter in the back. This illustrates the disadvantage of not using the language with precision. As I said, all my lenses make use of f/numbers which are a measure of stops. Your thoughts have jumped the rails and are now talking about the intervals of Exposure Value of which the camera is capable. The exposure value may be used to set lens aperture, shutter speed or ISO. They are not identical to stops. they absolutely are. So I double the shutter speed. I have halved the exposure value but I haven't affected the stop setting. If you want to continue arguing to the contrary I will be happy to leave you to it. Reciprocity games. "Introduction to photography 101." You are still missing the point: lens aperture, shutter speeds or ISOs are not identical to stops. At this point my old physics professor would ask for dimensional analysis. What's the dimensional analysis of "EV" vs "stop" ? -- == Later... Ron C -- |
#187
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Finally got to the point where no new camera holds my interest (waiting for specific offering)
In article , Eric Stevens
wrote: In the end physics is physics and there is no way they are getting more DR than the sensor offers. Not even the bit depth of it. According to nospam they are claiming a DR of 14.3 for the sensor of the D800. As they said in the link that I posted which has somehow got snipped "Maximum dynamic range is the greatest possible amplitude between light and dark details a given sensor can record ...". 1. A 14 bit sensor cannot, possibly, record 14.3 DR. Please read what I am about to write and give it deep consideration before you reply. _There_is_no_such_thing_as_a_14_bit_sensor_! Or a 12 bit for that matter. The sensors which we are considering are *analog* devices which are not digital in their operation. 12 or 14 bits only come into it after the analog signal is stripped from the sensor and (only then) passed through an analogue to a digital convertor (ADC). A 14 bit ADC can output 16,384 distinct numerical values and the analog output of the sensor has to be mapped to this range. It doesn't matter what the Dynamic Range of the sensor may be. It has to be mapped to the numerical scale of the output of the ADC. It is perfectly feasible to map an analogue dynamic range to 14 bits (o12 (or 8)). Not withstanding what else has been written in this thread the choice of the number of bits used to encode the sensor's output does not affect the _sensor's_ dynamic range. the sensor's dynamic range is not what's being measured. dxo is reporting the dynamic range of various *cameras*. and even if you ignore the 14 bit issue, their numbers are highly suspect. the nikon d800 and d800 are identical cameras, the only difference being the lack of an anti-alias filter on the d800e, something which does not affect dynamic range (only aliasing). thus, the results should be *the* *same* (other than alias artifacts on high frequency content). dxo claims that the d800 has 14.4 stops dynamic range and the d800e has 14.3 stops. other test results also differ between the two cameras. they also claim that the d800e has a higher low light iso, again, with the same sensor, which is *opposite* to what one would expect if it has less dynamic range. that alone shows something is very, very wrong with their tests, and to your point, is *not* a measure of the sensor itself. https://www.dxomark.com/Cameras/Nikon/D800 https://www.dxomark.com/Cameras/Nikon/D800E |
#188
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Finally got to the point where no new camera holds my interest (waiting for specific offering)
In article , Eric Stevens
wrote: It may be hair-splitting but none of my lenses are calibrated in EVs. They most definitely are, and probably 1/2 or 1/3 steps of EV as well, [1] --- or possibly very fine steps in speed priority or auto modes. I bow to your superior knowledge of my equipment. Do your lenses have stops? Yes. Exactly. So they are indeed calibrated in EV. ([1] above). No. EVs can be deduced. See https://en.wikipedia.org/wiki/Exposure_value "In photography, exposure value (EV) is a number that represents a combination of a camera's shutter speed and f-number, such that all combinations that yield the same exposure have the same EV (for any fixed scene luminance)." from that link, Exposure value is also used to indicate an interval on the photographic exposure scale, with a difference of 1 EV corresponding to a standard power-of-2 exposure step, commonly referred to as a stop. it would be wise to learn the basics of photography so that you actually understand what it is you're reading before commenting further. It might be commonly referred to as a stop but that is just plain sloppy usage. it's not sloppy at all. in fact, it's exactly correct. On that basis you might as well call the shutter speed a stop or even the ISO a stop. the *difference* is called a stop, aka 'interval on the photographic exposure scale': Exposure value is also used to indicate an interval on the photographic exposure scale, with a difference of 1 EV corresponding to a standard power-of-2 exposure step, commonly referred to as a stop. iso 800 is one stop more sensitive than iso 400. 1/250th is one stop less light than 1/125th. f/4 is one stop more light than f/5.6. I initially mentioned this topic in passing when I referred to sloppy writing. I didn't call for examples. unfortunately for you, examples were provided and they show that you don't understand it. |
#189
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Finally got to the point where no new camera holds my interest (waiting for specific offering)
In article , Eric Stevens
wrote: EV's are equivalent to stops for any purpose related to exposure. I can change exposure value without changing the stop setting. No ****. That's sort of the point. It's my point. Stops aren't exposure values. Exposure values are not stops. they are. Lets leave it at that. ok, but you saying so doesn't make it correct. |
#190
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Finally got to the point where no new camera holds my interest (waiting for specific offering)
In article , Eric Stevens
wrote: This illustrates the disadvantage of not using the language with precision. As I said, all my lenses make use of f/numbers which are a measure of stops. Your thoughts have jumped the rails and are now talking about the intervals of Exposure Value of which the camera is capable. The exposure value may be used to set lens aperture, shutter speed or ISO. They are not identical to stops. EV's are equivalent to stops for any purpose related to exposure. I can change exposure value without changing the stop setting. you are confusing f/stop with stop. 'stop' is an abreviated way of referring to an obsolete way of changing lens aperture. It's use as a reference to lens aperture is now normal. doing so is what you call 'sloppy'. you're confusing stop, f/stop and aperture and also ev. |
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