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<blockquote data-quote="JonB" data-source="post: 66286" data-attributes="member: 3047"><p>Here is the thing - most of the time I see dentists submit images that are underexposed. Probably 9 times out of 10. Add to that that sometimes even I get under exposed images, due to any number of reasons - incidence of light, low batteries, ambient light - who knows. While your suggestions are good ones - they are one way ( a good way) to skin a cat that we already have on the rack. I always tell people to check their histogram to see if their exposures are good - and with that to be sure your right hand side of the histogram has more information than the left hand side. Simple as that. </p><p></p><p>If you have edited many digital images either from Nikon or Canon, you will know that underexposed images always have digital noise. Noise obscures color every time. As good as the Nikon is at low noise at high ISO, and as good as Canon is on this - it has nothing to do with the noise introduced by underexposure. You can get crummy images out of either platform if underexposed. <img src="/forums/images/smilies/test/idea.gif" class="smilie" loading="lazy" alt="Idea" title="Idea Idea" data-shortname="Idea" />lly perfect exposure is the best option... that even the best of us absolutely must deal with underexposure occasionally.</p><p></p><p>Now the reason for overexposure of digital images is simple and one you can research on just about any good online photography forum or thread dealing with digital images. The fact is - there is far more clean digital information recorded in an overexposed image than there is in an underexposed image. If you shoot in RAW - as I always do - and you should, then you have far more latitude in bringing the exposure down to perfect and bringing out those details that are already there. There is no such rescue path for an underexposed image. Please note - I am not suggesting we try to rescue an image that is totally blown out on the right side of the histogram. I said put the hump to the right side of the middle and you will always get good useable and accurate enough images.</p><p></p><p>It is a myth that ceramists can reliably get "colour and value" from any digital image. That is for any number of reasons. How many dental technicians use a monitor calibrator? I doubt very many even know they exist. How many who do - actually use them correctly? How many are trying to calibrate an iMac screen (next to impossible) and how many have invested in color accurate monitors that cost nearly $10,000 just for the screen? I think claiming someone is getting colour accurate images are barking in the wind - with all due respect. We may get close - but accurate? A myth!</p><p></p><p>Add to that that if your doctors are submitting prints from their computers, or if you are doing what I once did, printing them on high quality paper through a very color accurate and calibrated professional Epson printer, and finding that "colour accurate" is a myth, you will soon enough find the best we can hope for is an approximation of color and value with a great deal of valuable information about surface texture, characterization, facial features and architecture and so on.</p><p></p><p>I do not believe I have ever heard anyone say they can pick a shade from a digital image alone. The nuances of color, the way the light is transferred through the enamel and dentin, the way natural light bounces through a tooth structure which is very unlike how a twin light or a ring light blows light through them in a very unnatural fashion. As you suggest, finding the correct kelvin temp is a help... but it is like juggling oil under water. Kelvin temps are dependent upon a consistent distance between subject and light source, battery power, flash tube condition and life, flash lens color, lens coatings and glass, as well as the capability of the camera body being used - with the sensor technology incorporated - that has the best algorithms for colour accuracy. </p><p></p><p>As to your focal distance recommendations - which are probably quite good (i haven't tried them to know) but you have left out some critical information that would render them useful. Actually focal distance is somewhat irrelevant except for framing the subject. But because you are not also telling us how to extrapolate that distance for using a 100mm or a 50mm macro or a 60mm macro or even a 180mm macro - since people have all kinds of lenses and not always a particular one by one particular brand - we'll leave that aside. Using an ƒ45 stop will get nose to molar depth of field, but doesn't affect colour or value at all and even has nothing to do with exposure when all of the other parameters are not taken into account. ISO? who knows... flash power/guide number? good question... is that on AV? don't say... what shutter speed are you getting if in AV mode at ƒ45... cause if you're shooting with a 105mm with a crop factor body that actually bumps the effective focal length to over 150mm - you have to have a shutter speed of 1/160 or there abouts to keep from having camera shake blur. (which renders the image virtually useless) </p><p>Now in my experience, to have an aperture at ƒ45 and a shutter speed of 1/160 or faster - I've got to blow an awful lot of light on the subject... and a camera capable of high speed shutter sync to get an image at all. Yes we can skin cats all day, but the old Occam's Razor - must be applied - "other things being equal, a simpler explanation is better than a more complex one." We are trying to help people from all skill levels achieve the near unachievable. So keeping it simple and easy as pie may not stroke the ego, but it will get great results. Results matter and doing it without spending all day experimenting makes money for the already underpaid dental technician (no matter what you charge for your restorations!)</p><p></p><p>The most important thing to take away from all of this is: Check your histograms!</p></blockquote><p></p>
[QUOTE="JonB, post: 66286, member: 3047"] Here is the thing - most of the time I see dentists submit images that are underexposed. Probably 9 times out of 10. Add to that that sometimes even I get under exposed images, due to any number of reasons - incidence of light, low batteries, ambient light - who knows. While your suggestions are good ones - they are one way ( a good way) to skin a cat that we already have on the rack. I always tell people to check their histogram to see if their exposures are good - and with that to be sure your right hand side of the histogram has more information than the left hand side. Simple as that. If you have edited many digital images either from Nikon or Canon, you will know that underexposed images always have digital noise. Noise obscures color every time. As good as the Nikon is at low noise at high ISO, and as good as Canon is on this - it has nothing to do with the noise introduced by underexposure. You can get crummy images out of either platform if underexposed. Ideally perfect exposure is the best option... that even the best of us absolutely must deal with underexposure occasionally. Now the reason for overexposure of digital images is simple and one you can research on just about any good online photography forum or thread dealing with digital images. The fact is - there is far more clean digital information recorded in an overexposed image than there is in an underexposed image. If you shoot in RAW - as I always do - and you should, then you have far more latitude in bringing the exposure down to perfect and bringing out those details that are already there. There is no such rescue path for an underexposed image. Please note - I am not suggesting we try to rescue an image that is totally blown out on the right side of the histogram. I said put the hump to the right side of the middle and you will always get good useable and accurate enough images. It is a myth that ceramists can reliably get "colour and value" from any digital image. That is for any number of reasons. How many dental technicians use a monitor calibrator? I doubt very many even know they exist. How many who do - actually use them correctly? How many are trying to calibrate an iMac screen (next to impossible) and how many have invested in color accurate monitors that cost nearly $10,000 just for the screen? I think claiming someone is getting colour accurate images are barking in the wind - with all due respect. We may get close - but accurate? A myth! Add to that that if your doctors are submitting prints from their computers, or if you are doing what I once did, printing them on high quality paper through a very color accurate and calibrated professional Epson printer, and finding that "colour accurate" is a myth, you will soon enough find the best we can hope for is an approximation of color and value with a great deal of valuable information about surface texture, characterization, facial features and architecture and so on. I do not believe I have ever heard anyone say they can pick a shade from a digital image alone. The nuances of color, the way the light is transferred through the enamel and dentin, the way natural light bounces through a tooth structure which is very unlike how a twin light or a ring light blows light through them in a very unnatural fashion. As you suggest, finding the correct kelvin temp is a help... but it is like juggling oil under water. Kelvin temps are dependent upon a consistent distance between subject and light source, battery power, flash tube condition and life, flash lens color, lens coatings and glass, as well as the capability of the camera body being used - with the sensor technology incorporated - that has the best algorithms for colour accuracy. As to your focal distance recommendations - which are probably quite good (i haven't tried them to know) but you have left out some critical information that would render them useful. Actually focal distance is somewhat irrelevant except for framing the subject. But because you are not also telling us how to extrapolate that distance for using a 100mm or a 50mm macro or a 60mm macro or even a 180mm macro - since people have all kinds of lenses and not always a particular one by one particular brand - we'll leave that aside. Using an ƒ45 stop will get nose to molar depth of field, but doesn't affect colour or value at all and even has nothing to do with exposure when all of the other parameters are not taken into account. ISO? who knows... flash power/guide number? good question... is that on AV? don't say... what shutter speed are you getting if in AV mode at ƒ45... cause if you're shooting with a 105mm with a crop factor body that actually bumps the effective focal length to over 150mm - you have to have a shutter speed of 1/160 or there abouts to keep from having camera shake blur. (which renders the image virtually useless) Now in my experience, to have an aperture at ƒ45 and a shutter speed of 1/160 or faster - I've got to blow an awful lot of light on the subject... and a camera capable of high speed shutter sync to get an image at all. Yes we can skin cats all day, but the old Occam's Razor - must be applied - "other things being equal, a simpler explanation is better than a more complex one." We are trying to help people from all skill levels achieve the near unachievable. So keeping it simple and easy as pie may not stroke the ego, but it will get great results. Results matter and doing it without spending all day experimenting makes money for the already underpaid dental technician (no matter what you charge for your restorations!) The most important thing to take away from all of this is: Check your histograms! [/QUOTE]
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