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#31
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Meaning of ISO value in digital photography?
On 06/15/2018 07:11 PM, Carlos E.R. wrote:
On 2018-06-15 22:18, Jim-P wrote: On Thu, 14 Jun 2018 19:47:36 -0700, Savageduck wrote: On Jun 14, 2018, Ken Hart wrote (in article ): On 06/14/2018 08:05 PM, Savageduck wrote: On Jun 14, 2018, Jim-P wrote (in article ): In the film days, we used the "Sunny-16" rule: Set the shutter speed equal to the ISO (then "ASA"). In bright sunshine, use f/16. Slightly cloudy- use f/11, open shade- f/8, full shade- f/5.6. This technique would usually give a good exposure. Combine that with the "focal length equals shutter speed" rule: The longer the focal length, the faster the shutter speed to give acceptable hand-held images. For a 200mm lens, you use a shutter speed of 1/250 second. Example: 100mm lens calls for 1/100 second minimum. Set the ISO also at 100, and use the "Sunny-16" rule. Then refer to SD's exposure triangle, three paragraphs down... Let us start by asking, what camera are you using? It would still be good to know what camera the OP is using. I am using a smartphone camera. Although it is not as high quality as a DSLR the principles should be the same and I am interested in understanding them before taking my photography further. The smartphone model is a Moto G5 Plus with a Sony IMX362 Exmor RS camera module which is also used in the Nokia 7 and Samsung S7 Edge https://phoneproscons.com/794/moto-g...enfone-3-zoom/ I recall that old Sunny 16 rule and the thing which strikes me most about it now is how slow the shutter speeds were in the old days. 1/250 was one of the faster speeds I would use for day to day photography years ago but my current smartphone often uses speeds of 1/1000 or 1/2000 which is fantastic because by hand steadiness is not what it used to be. My old SLR had 1/2000 The mechanics had a trick that allowed high effective shutter speed while the shutter in fact moved relatively slowly, at 1/60 or thereabouts. And old trick, actually. It opened a slit on the rectangle, and the slit travelled the length of the aperture. If the slit was 1/5, the effective speed was the actual speed multiplied by 5. That is the standard way a focal plane shutter works (worked) for speeds typically over 1/60 second. The first curtain would start to open, and before it was all the way open the second curtain would start to close. To use electronic flash, you could not sync at a speed where the shutter was not totally open. Vertical travel focal plane shutters usually sync'ed at a faster speed because they had less distance to travel. The shutter tester I use to test my cameras provides a readout of the shutter speed and each curtain speed. Typically, for my Canon FX cameras, the curtain speed is in the neighborhood of 12msec. If there a difference in the speeds of the two curtains, one side of the frame will be over- or under-exposed. When you photograph a subject moving across the frame (such as a fast car), the subject will be either compacted or stretched in length, depending on direction of travel. -- Ken Hart |
#32
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Meaning of ISO value in digital photography?
On 2018-06-16 16:58, Ken Hart wrote:
That is the standard way a focal plane shutter works (worked) for speeds typically over 1/60 second. The first curtain would start to open, and before it was all the way open the second curtain would start to close. To use electronic flash, you could not sync at a speed where the shutter was not totally open. Vertical travel focal plane shutters usually sync'ed at a faster speed because they had less distance to travel. It was around 1/200s by around 1990 or so for a lot of SLR's, my Maxxum 9 went to 1/300 for sync; 7D to 1/250; a900 to 1/250 or 1/300 (don't recall offhand). 1/60 is quite old as far as sync speeds go ... -- "2/3 of Donald Trump's wives were immigrants. Proof that we need immigrants to do jobs that most Americans wouldn't do." - unknown protester |
#33
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Meaning of ISO value in digital photography?
On 06/16/2018 05:13 PM, Alan Browne wrote:
On 2018-06-16 16:58, Ken Hart wrote: That is the standard way a focal plane shutter works (worked) for speeds typically over 1/60 second. The first curtain would start to open, and before it was all the way open the second curtain would start to close. To use electronic flash, you could not sync at a speed where the shutter was not totally open. Vertical travel focal plane shutters usually sync'ed at a faster speed because they had less distance to travel. It was around 1/200s by around 1990 or so for a lot of SLR's, my Maxxum 9 went to 1/300 for sync; 7D to 1/250; a900 to 1/250 or 1/300 (don't recall offhand). 1/60 is quite old as far as sync speeds go ... My cameras are 1964-69 vintage, so "quite old" is fairly accurate! The Maxxum 9 was a vertical shutter. The shutter has less distance to travel vertically (24mm opposed to 36mm for horizontal), so it would have a faster sync speed. The reviews I found for that camera put it in the late 1990's. -- Ken Hart |
#34
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Meaning of ISO value in digital photography?
On 6/14/2018 11:10 PM, Savageduck wrote:
On Jun 14, 2018, Ken Hart wrote (in article ): On 06/14/2018 03:29 PM, Savageduck wrote: Snip Any given sensor will have a base sensitivety, or ISO. Typically ISO 200, or ISO 100 depending on manufacturer. Really? I've never looked into that, but I would have thought that the base sensitivity would be closer to the mid-point of the camera's ISO setting range. But that's just electronics design practice. Yup! Take the Nikon D800 which has a base of ISO 100, and the D810 which has been reduced to ISO 64. Any increase in ISO is an increase of signal gain from the sensor. Both of those cameras are capable of dealing with very high ISO settings without producing noticeable noise. In the APS-C world the D500 has a base of ISO 100, and can be cranked up to ISO 51,200, and extended to an unthinkable ISO 1,640,000. So they say. However, I have found the noise on my D500 at 51,000, to be significant. However the noise at a higher ISO will also increase with higher contrast lighting conditions. My APS-C Fujifilm X-T2 on the other hand can shoot from a base ISO 200 to ISO 12800, and can be extended down to ISO 160, 125, & 100, or up to ISO 25,600, and ISO 51,200. These are worth a read: https://www.bhphotovideo.com/explora...aphy/tips-and- solutions/understanding-exposure-part-4-iso https://www.jmpeltier.com/2018/02/13/what-is-extended-iso-native-iso/ This one is a real simplification: https://photographylife.com/what-is-iso-in-photography -- PeterN |
#35
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Meaning of ISO value in digital photography?
On 6/15/2018 3:00 PM, John McWilliams wrote:
On 6/14/18Â*Â* PDT 9:16 PM, PeterN wrote: On 6/14/2018 10:26 PM, Ken Hart wrote: Both you and the Duck are correct. It all boils down to what type of image the photographer is looking to make. I use auto ISO when I want to use a fixed shutter speed, and a fixed aperture. As for setting an upper limit, there are times when a really noisy image is preferable to no image at all. I would very much prefer a very noisy and grainy image of the abominable snow man, to no image at all. I've set my Canons to ISO 200 and keep it there* as I want the feedback from aperture or shutter speed telling me when I am on the edge of insufficient light. * There are some exceptions! Most of us have different photographic interests. I use auto ISO primarily for high speed sync, and some landscape. i consider auto ISO only as another tool which I use mostly to get a desired effect. some use auto ISO for panos.When it comes to photo art, i think that the image maker should use tools that he is comfortable using. And if he has the interest, see if an alternative method would produce a result closer to the result the maker seeks. Several weeks ago I started working on an image about 9:30 AM. I just couldn't get quite the look I wanted. I kept trying different tools. I finally got a bit hungry, and walked away from the computer. It was after 11:00 PM. -- PeterN |
#36
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Meaning of ISO value in digital photography?
On 6/15/2018 7:49 PM, Jim-P wrote:
snip I wonder what the cost is for a point and shoot giving pictures a notch above a smartphone. If you like smart phone photography, by all means you should continue with it. There are some photo artists who do a lot of good work with smart phones. This year NECCC is having a lot of time devoted to the smart phone. Tony Sweet, also is a smart phone enthusiast, as well as being a highly talented artist and a good person.. https://www.slickpic.com/blog/interview-tony-sweet/ I have not specifically answered your question, because there is no answer. Some smart phones can be expensive,n while some P&S cameras can be very cheap, or priced higher than a smart phone. It's whatever you prefer working with. -- PeterN |
#37
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Meaning of ISO value in digital photography?
On Jun 16, 2018, PeterN wrote
(in article ): On 6/14/2018 11:10 PM, Savageduck wrote: On Jun 14, 2018, Ken Hart wrote (in article ): On 06/14/2018 03:29 PM, Savageduck wrote: Snip Any given sensor will have a base sensitivety, or ISO. Typically ISO 200, or ISO 100 depending on manufacturer. Really? I've never looked into that, but I would have thought that the base sensitivity would be closer to the mid-point of the camera's ISO setting range. But that's just electronics design practice. Yup! Take the Nikon D800 which has a base of ISO 100, and the D810 which has been reduced to ISO 64. Any increase in ISO is an increase of signal gain from the sensor. Both of those cameras are capable of dealing with very high ISO settings without producing noticeable noise. In the APS-C world the D500 has a base of ISO 100, and can be cranked up to ISO 51,200, and extended to an unthinkable ISO 1,640,000. So they say. However, I have found the noise on my D500 at 51,000, to be significant. However the noise at a higher ISO will also increase with higher contrast lighting conditions. Here is my X-T2 maxed out at an extended ISO 51,200. At 100% the noise is obvious, but in general it is possible to capture an interpretable image even at that high ISO. That D500 ISO 1,640,000 would be an impossible mess on the X-T2. This is an SOOC JPG, out of the X-T2 @ ISO 51,200, XF16mm f/1.4 @ f/4, 1/58 second, no PP NR applied. https://photos.smugmug.com/photos/i-9xMDs8m/0/5814404e/O/i-9xMDs8m.jpg My APS-C Fujifilm X-T2 on the other hand can shoot from a base ISO 200 to ISO 12800, and can be extended down to ISO 160, 125, & 100, or up to ISO 25,600, and ISO 51,200. These are worth a read: https://www.bhphotovideo.com/explora...aphy/tips-and- solutions/understanding-exposure-part-4-iso https://www.jmpeltier.com/2018/02/13/what-is-extended-iso-native-iso/ This one is a real simplification: https://photographylife.com/what-is-iso-in-photography -- Regards, Savageduck |
#38
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Meaning of ISO value in digital photography?
On Fri, 15 Jun 2018 17:34:57 -0700, Savageduck wrote:
On Jun 15, 2018, Jim-P wrote (in article ): On Fri, 15 Jun 2018 13:46:46 -0700, Savageduck wrote: On Jun 15, 2018, Jim-P wrote (in article ): On Thu, 14 Jun 2018 19:47:36 -0700, Savageduck wrote: On Jun 14, 2018, Ken Hart wrote (in article ): On 06/14/2018 08:05 PM, Savageduck wrote: On Jun 14, 2018, Jim-P wrote (in article ): On Thu, 14 Jun 2018 14:26:40 -0400, PeterN wrote: On 6/14/2018 1:48 PM, Jim-P wrote: In film cameras, ISO referrs to the sensitivity to light of the emulsion. Manufacturers formulate different film emulsions with different sensitivites tarding increased grain with increased ISO speed. In a digital camera, presumably the sensor does not adjust itself to have greater sensitivity. Or does it? So what is happening in a digital camera when I choose a greater ISO setting? Is more amplification being used? I tried to understand this page but it got far too technical.... https://photography.tutsplus.com/art...-technical-exp lo ration--photo-11963 I am going to try to give you a simplified, non-technical explanation. As with most generalities it is not 100% technically accurate, but should serve as a guideline. ISO is a measurement of the light sensitivity of the sensor. Digital ISO is adjustable in many cameras. And yes, it is a matter of adjusting the amplification. If you are using a wider lens opening, and slower shutter speed, you will be able to use a lower ISO. Digital noise is one of the undesired artifacts in the image. Higher ISO will result in more digital noise, and lessor image quality. Many of the newer high quality sensors are designed to work at a higher ISO, with less noticeable noise, and reduction in image quality. There are some of us here who do not object to noise, while others have serious objections. The point at which noise becomes objectionable often comes down to a matter of taste and personal preferences. Thanks. This makes me wonder what ISO I should set, if I don't leave it on auto. In the film days, we used the "Sunny-16" rule: Set the shutter speed equal to the ISO (then "ASA"). In bright sunshine, use f/16. Slightly cloudy- use f/11, open shade- f/8, full shade- f/5.6. This technique would usually give a good exposure. Combine that with the "focal length equals shutter speed" rule: The longer the focal length, the faster the shutter speed to give acceptable hand-held images. For a 200mm lens, you use a shutter speed of 1/250 second. Example: 100mm lens calls for 1/100 second minimum. Set the ISO also at 100, and use the "Sunny-16" rule. Then refer to SD's exposure triangle, three paragraphs down... Let us start by asking, what camera are you using? It would still be good to know what camera the OP is using. I am using a smartphone camera. Although it is not as high quality as a DSLR the principles should be the same and I am interested in understanding them before taking my photography further. The smartphone model is a Moto G5 Plus with a Sony IMX362 Exmor RS camera module which is also used in the Nokia 7 and Samsung S7 Edge https://phoneproscons.com/794/moto-g...y-imx362-rear- camera-same-amazing-sensor-as-in-xplay-6-and-zenfone-3-zoom/ There is nothing wrong in using a smartphone camera. However, you are going to have limitations which you will not find in modern DSLR, or mirrorless digital cameras (MILC). Even with third party photo apps for your smartphone you are going to have limitations of physical sensor size, and adjustability of the exposure triangle. The next question is; are you intending to add a modern digital camera to your current photography kit? I need to work out how to get the best from my smartphone first. I'm new to smartphones but they take surprisingly good pictures which are almost as good as my point and shoot. They are aso very forgiving and don't need lots of setting up. If it meets your needs there is little point looking for something else, but if you want more you should consider something other than a compact/P&S camera. I wonder what the cost is for a point and shoot giving pictures a notch above a smartphone. There are some excellent compact, or P&S cameras from most of the manufacturers such as Canon, Nikon, Panasonic, Sony, etc, prices, and performance vary. The big issue with the P&S cameras is, they are being killed off by smartphones. The big advantage to a dedicated camera rather than a phone camera is ergonomics. No matter how much one might argue, a smartphone is awkward to use as a camera due to its unavoidable phone shape. Personally, if one is only considering a compact/P&S camera as an upgrade from a smartphone, consider what you are going to be doing with your photography, it might be better to stick with the smartphone. Otherwise, I would suggest moving to a mirrorless camera with, or without interchangeable lenses. They can be more expensive than a smartphone, but your photographic experience will be more enjoyable. I an unabashed fan of the Fujifilm mirrorless cameras, and for somebody wanting something reminiscent of the analog days, a great fixed focal length camera is the Fujifilm X100F. https://www.dpreview.com/reviews/fujifilm-x100f https://www.techradar.com/reviews/fujifilm-x100f-review I currently own several Fujifilm bodies and a bag full of lenses. https://www.dropbox.com/s/5yeyllbh2jd8g0a/IMG_2527e.jpg To get some idea of what is out there in the compact camera range check out dpreview: https://www.dpreview.com That's some serious looking gear in the camera bag! The Fuji X100F camera is a fancier than I was considering. I was thinking of something more along the lines of a Panasonic Lumix DMC-TZ70 but not for some time yet. |
#39
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Meaning of ISO value in digital photography?
In article , Jim-P wrote:
In film cameras, ISO referrs to the sensitivity to light of the emulsion. Manufacturers formulate different film emulsions with different sensitivites tarding increased grain with increased ISO speed. In a digital camera, presumably the sensor does not adjust itself to have greater sensitivity. Or does it? So what is happening in a digital camera when I choose a greater ISO setting? Is more amplification being used? Short answer: yup. ISO for film and "ISO" for digital sensor has very little in common. -- Sandman |
#40
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Meaning of ISO value in digital photography?
On 2018-06-20 11:17, Whisky-dave wrote:
On Wednesday, 20 June 2018 09:12:40 UTC+1, Sandman wrote: In article , Jim-P wrote: In film cameras, ISO referrs to the sensitivity to light of the emulsion. Manufacturers formulate different film emulsions with different sensitivites tarding increased grain with increased ISO speed. In a digital camera, presumably the sensor does not adjust itself to have greater sensitivity. Or does it? So what is happening in a digital camera when I choose a greater ISO setting? Is more amplification being used? Short answer: yup. ISO for film and "ISO" for digital sensor has very little in common. I thought they had quite a lot in common as it stands for International Standards Organization which covers light sensitivity of a sensor or film doesn't matter which. That's what it means by a standard, previously film was ASA which was american while Europe used DIN , so a new standard was created for everyone with digital or film and it was called ISO not to be confused with ios of course. I would think that a film camera loaded with film of a certain iso rating and a digital camera adjusted to that same iso rating do a similarly lighted photo when adjusted to the same diaphragm and shutter speed, so that a photographer can adjust both with the same settings using the same handheld light measurement instrument. -- Cheers, Carlos. |
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