Time of exposition versus ISO value

[Panama Hat & Camera]

Folks,
First of all, I apologise for my big mistake (the use of word "exposition" instead of "exposure"). Although my English is very poor (I know), sometimes my excess of confidence make me write without the use of a dictionary.
Really in some latin languages (Portughese, Spanish, French etc ) "exposition" and "exposure" are translated by only one word ("exposição" in Portughese; "exposición" in Spanish; "exposition" in French).
I already knew the word "exposure" but I thought that "exposure" and "exposition" were synonyms. The original title of the thread was " 'Time value' versus 'ISO value' ", but I changed it because "time value" is a expression used in Canon cameras and I tried a more neutral text (I am a Canon and Nikon user).

Because Antonio never mentioned trying to capture a scene's dynamic range, he wanted to know the difference between choosing ISO settings and how would it affect his final image. I would have suggested he capture an image with both settings, post the two images on this forum and then either find the difference for himself or have someone point it out to him; if there is a noticeable difference to be found.

I would like to thank the various answers posted and I accept the suggestion of John. I will try to capture four images with both settings: two with my Nikon D5300 (dynamic range of 13.9 EV) and two with my Canon SX50HS (dynamic range of 11.2 EV) to see the differences between the photos of the same set.
Best regards,
Antonio.

[DanK]

Antonio,

You have no reason to apologize. Your postings in English are clear. I cannot write as well in either of the two languages I have studied. And I think most of us understood what you meant. It's interesting that in English, "exposition" means two things completely unlike "exposure," when that is not true in some other languages.

I think the whole thread can be summed up in three sentences. (1) Boosting ISO, which simply amplifies both signal and noise, will cause the image to lose quality. It cannot improve quality. (This assumes no motion, etc.) (2) In many cases, this difference in quality will not be noticeable at all.

The smaller you display the images, the less likely it is that you will see the differences.

Dan

[Mike Buckley]

Antonio,

You have no reason to apologize.

Exactly.

[Loose Canon]

Antonio, English is also my second language!

I don't have a first!

[Inkanyezi]

I think it is impossible to answer such a multifaceted question as the original post, mainly because "image quality" is not a simple concept. Of course, if we boil it down to one property, as noise, it becomes a bit simpler, but I tend to see photography as a visual art, and noise in the electronically created image is only one property. Just as in the film age with its grain, it is a property that we have to cope with to some extent. Often a noisier image may be preferred before one that is free of noise, but also lacks detail.

Dynamic range of course is another can of worms. Sometimes we wish we had more of it, sometimes it is not an issue at all.

With a camera as SX50HS, I think there is a possibility to have a live histogram, a histogram that shows the dynamic range of the scene even before the picture is taken.

The histogram sometimes can be a powerful tool, as well as the blinkies. With the CHDK plugin for the firmware of the Canon compacts, we have them for both highlights and shadows. Thus we can easily see where we might lose not only highlight detail, but also important shadow detail, if we crank up ISO. And keeping in mind that photography is not purely a technical exercise, but a visual art, we are also free to bury details in deep shadow, when it might give the image more sting.

And when it comes to languages, I am a bit confused, as my mother tongue is Swedish, but I have hardly spoken any other language than Spanish in my home for about fifteen years, and for a long time French was my "second" language. I guess Swedish will always be my first, and presently, Spanish is second. I guess English might have the third place, a tad above the ones in fallow. I notice whenever I have to speak French, that it's rusty. And even if I am rather versed in English, I make mistakes, like when I wrote "facetious" instead of "faceted", which perhaps made a few people smile.

So, language is for communication, and if we won't dare to make mistakes, we would surely lose a lot.