pedaes Posted September 7, 2019 Share #21 Posted September 7, 2019 (edited) Advertisement (gone after registration) The last time I looked, changing ISO (same as unloading a 125ASA film and loading a 800ASA film) changed either/or exposure time and aperture. A value difference on the ASA scale has same relationship as EV (ie going from 400ASA to 800ASA has a one stop difference in shutter speed or aperture). That there are other options, such as development time or 'sliders', does not negate the basis principle.Shutter,aperture and Iso all work in combination to achieve correct exposure. Jaapv, I know you know and understand this, so I must be totally missing the point you are trying to make. If the point you are making is changing the ISO 'only' changes the sensitivity of the sensor, I totally agree (same as changing ASA of film). But that does impact on the other exposure perameters for correct exposure. The first article you link to talks about a system to avoid using ISO as an exposure parameter, ergo acknowledging that it is a parameter. Edited September 7, 2019 by pedaes Link to post Share on other sites More sharing options...
Advertisement Posted September 7, 2019 Posted September 7, 2019 Hi pedaes, Take a look here ISO Woes. I'm sure you'll find what you were looking for!
evikne Posted September 7, 2019 Share #22 Posted September 7, 2019 Increasing ISO does not supply the image sensor with more light "for real" as happens when opening the aperture or extending the exposure time. ISO only manipulates the content after it hits the image sensor. Therefore, ISO cannot be considered a true part of the exposure triangle. 1 Link to post Share on other sites More sharing options...
pedaes Posted September 7, 2019 Share #23 Posted September 7, 2019 Just now, evikne said: Increasing ISO does not supply the image sensor with more light "for real" as happens when opening the aperture or extending the exposure time. ISO only manipulates the content after it hits the image sensor. Therefore, ISO cannot be considered a true part of the exposure triangle. OK - I see the subtlety of the debate - you are talking at a factual level of how the sensor/ processor work. Also therefore see point jaapv making, that there may be better? options to achieve same result as changing ISO above base level. Equally though, at a practical level most will accept, for a given light level, if you increase ISO you will reduce other exposure measures to get same outcome. Time to move on! Link to post Share on other sites More sharing options...
Exodies Posted September 9, 2019 Share #24 Posted September 9, 2019 Isn’t the M 240 only ISO invariant in the push and pull regions of the ISO dial? I thought the rest of the scale was achieved by analogue amplifiers. 1 Link to post Share on other sites More sharing options...
sblutter Posted September 12, 2019 Share #25 Posted September 12, 2019 On 9/7/2019 at 10:18 AM, jaapv said: No, it does not change the brightness of the photo, as you can adjust it in postprocessing without quality loss on an ISO invariant camera. This means that you can "underexpose" an image at your desired EV at ISO 200, and pull it up to for instance ISO 3200 in Lightroom etc. without quality loss, provided you have an ISO invariant camera. If you search the forum you'll find various threads discussing this theme for different M models. For instance the M8 had better noise performance used this way. +1 Link to post Share on other sites More sharing options...
lct Posted September 12, 2019 Share #26 Posted September 12, 2019 Sorry to insist but ISO does change the brightness of the photo as shown above. 1 Link to post Share on other sites More sharing options...
pedaes Posted September 12, 2019 Share #27 Posted September 12, 2019 Advertisement (gone after registration) 36 minutes ago, lct said: Sorry to insist but ISO does change the brightness of the photo as shown above. I think you are talking at the practical level of what happens in reality in relation to the recorded image file. We all know that the amount of light hitting the sensor isn't increased by changing the ISO, but changing the ISO does influence the result. Not sure what is important about the semantics! Link to post Share on other sites More sharing options...
evikne Posted September 12, 2019 Share #28 Posted September 12, 2019 (edited) 16 minutes ago, pedaes said: Not sure what is important about the semantics! There is a very important difference between light that actually hits the sensor and brightness that is artificially boosted afterwards. Edited September 12, 2019 by evikne 1 1 Link to post Share on other sites More sharing options...
lct Posted September 12, 2019 Share #29 Posted September 12, 2019 26 minutes ago, evikne said: There is a very important difference between light that actually hits the sensor and brightness that is artificially boosted afterwards. Do you actually see that artificial boost effect in my pics above? How do you explain that clipping can be prevented by changing only isos then? Link to post Share on other sites More sharing options...
jaapv Posted September 12, 2019 Share #30 Posted September 12, 2019 It cannot prevent clipping. Clipping occurs when you choose your exposure parameters i.e. shutterspeed and aperture such that too much light hits the sensor, which overloads the sensels (AKA pixels). In your images you were playing with exposure compensation and you did not equalize the brightness in post, nor did you provide histograms, so they tell us nothing. If you want to compare, take two images with exactly the same exposure (shutter/aperture), no EV compnsation, no Auto-ISO, at different ISO and pull the darker one up to equal brightness in Lightroom. 2 Link to post Share on other sites More sharing options...
evikne Posted September 12, 2019 Share #31 Posted September 12, 2019 (edited) To me, this discussion is mainly about the usefulness of always leaving the ISO at the base setting and just having to concentrate on the two real exposure parameters, aperture and exposure time. I guess those who photograph fully manual have the biggest advantage of this, and even more if they have a screen-less camera. For others, it doesn't matter that much. I do it myself most of the time, even though my M10 maybe isn't fully ISO invariant. Edited September 12, 2019 by evikne 1 Link to post Share on other sites More sharing options...
lct Posted September 13, 2019 Share #32 Posted September 13, 2019 11 hours ago, evikne said: To me, this discussion is mainly about the usefulness of always leaving the ISO at the base setting and just having to concentrate on the two real exposure parameters, aperture and exposure time. Then you don't do auto iso in manual mode. I do personally and i do prevent clipping by simply changing iso when i want to keep the same aperture and shutter speed. Works fine. Link to post Share on other sites More sharing options...
lct Posted September 13, 2019 Share #33 Posted September 13, 2019 11 hours ago, jaapv said: [...] If you want to compare, take two images with exactly the same exposure (shutter/aperture), no EV compnsation, no Auto-ISO, at different ISO and pull the darker one up to equal brightness in Lightroom. Why should i do comparos like this? I did mine already. See my pics above. They show that brightness can be changed by simply changing iso and that clipping is prevented this way. The proof is in the pudding. Link to post Share on other sites More sharing options...
jaapv Posted September 13, 2019 Share #34 Posted September 13, 2019 I'm sorry. I really do my best to explain, but it seems I am unable to instill understanding. Let's leave it at this. Link to post Share on other sites More sharing options...
lct Posted September 13, 2019 Share #35 Posted September 13, 2019 Just now, jaapv said: I'm sorry. I really do my best to explain, but it seems I am unable to instill understanding. I'm not interested in theories that much sorry. In my day to day practice auto iso in manual mode is my favorite exposure technique by far. YMMV. Link to post Share on other sites More sharing options...
jaapv Posted September 13, 2019 Share #36 Posted September 13, 2019 MMDV indeed... Link to post Share on other sites More sharing options...
lct Posted September 13, 2019 Share #37 Posted September 13, 2019 4 minutes ago, jaapv said: MMDV indeed... Sure but what i find interesting in this discussion is that auto iso in manual mode is not taken into account by theories which negate its existence for unknown reasons. Link to post Share on other sites More sharing options...
jaapv Posted September 13, 2019 Share #38 Posted September 13, 2019 It has been mentioned more than a few times on this forum, including this thread. There is nothing wrong with it, but on many cameras it will only help for chimping, as the final result will be no different -in some cases better (and in some cases, like Canon cameras, worse) if you choose the proper exposure values for the scene and shoot at base ISO. Link to post Share on other sites More sharing options...
lct Posted September 13, 2019 Share #39 Posted September 13, 2019 2 minutes ago, jaapv said: It has been mentioned more than a few times on this forum, including this thread. Mentioned by me indeed Link to post Share on other sites More sharing options...
jaapv Posted September 13, 2019 Share #40 Posted September 13, 2019 And me in previous Auto ISO discussions. It all depends on the camera you are using. Link to post Share on other sites More sharing options...
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