Need help with exposure question

[AlanKlein]

The issue about using the triangle to determine exposure came up before invariant sensors. Since 99.9% if cameras are not invariant,

That depends on how you're going to define ISO invariance. You can have a machine measure it and get your figure above or you can measure it visually like this guy did and get a pretty good list of cameras: ISO Invariance: What it is, and which cameras are ISO-less

Fortunately you have an opportunity in this thread to back up your 99.9% figure by going to post #61 in this thread: Need help with exposure question and explaining what to look at in those two photos that makes it obvious why the ISO 100 photo (underexposed 3 stops) is worse than the ISO 800 photo that was "properly exposed." If you can't do that then your 99.9% figure is bogus as far as real world usage is concerned.

then you still need to enter the appropriate ISO. If not, what am I missing?

Can't imagine. Something about still not understanding why the Exposure Triangle is wrong and confuses people?

Joe

Then set your ISO at 100 for all shots and let it rip.

 

[n614cd]

The issue about using the triangle to determine exposure came up before invariant sensors. Since 99.9% if cameras are not invariant,

That depends on how you're going to define ISO invariance. You can have a machine measure it and get your figure above or you can measure it visually like this guy did and get a pretty good list of cameras: ISO Invariance: What it is, and which cameras are ISO-less

Fortunately you have an opportunity in this thread to back up your 99.9% figure by going to post #61 in this thread: Need help with exposure question and explaining what to look at in those two photos that makes it obvious why the ISO 100 photo (underexposed 3 stops) is worse than the ISO 800 photo that was "properly exposed." If you can't do that then your 99.9% figure is bogus as far as real world usage is concerned.

then you still need to enter the appropriate ISO. If not, what am I missing?

Can't imagine. Something about still not understanding why the Exposure Triangle is wrong and confuses people?

Joe

Then set your ISO at 100 for all shots and let it rip.

Actually for years with Canon 6D, I have found ISO 100 with the image under exposed according to the JPEG to be the best when post processing. I only raise the ISO when the combination of shutter and aperature cannot get within 2 EV of optimal.

I just never understood why until now...

Tim

Sent from my SM-J737T using Tapatalk

 

[n614cd]

Anyone have any idea how the Sigma Foveon Sensor handles ISO? I like the concept of the technology, but since it is from a small company not sure it can really compete....

Tim

Sent from my SM-J737T using Tapatalk

 

[AlanKlein]

How do you know when to raise the iso because you need it verses when you can allow the exposure to be darker and not raise the ISO? When do you ignore when the light meter is telling you?

 

[Ysarex]

The issue about using the triangle to determine exposure came up before invariant sensors. Since 99.9% if cameras are not invariant,

That depends on how you're going to define ISO invariance. You can have a machine measure it and get your figure above or you can measure it visually like this guy did and get a pretty good list of cameras: ISO Invariance: What it is, and which cameras are ISO-less

Fortunately you have an opportunity in this thread to back up your 99.9% figure by going to post #61 in this thread: Need help with exposure question and explaining what to look at in those two photos that makes it obvious why the ISO 100 photo (underexposed 3 stops) is worse than the ISO 800 photo that was "properly exposed." If you can't do that then your 99.9% figure is bogus as far as real world usage is concerned.

then you still need to enter the appropriate ISO. If not, what am I missing?

Can't imagine. Something about still not understanding why the Exposure Triangle is wrong and confuses people?

Joe

Then set your ISO at 100 for all shots and let it rip.

I did. I bought a Fuji XE-2 in November of 2013. It took me 7 months to figure it out, do the testing and to actually develop enough confidence in the camera being functionally ISO invariant, but in July 2014 I made the switch. I remember the photos. here they are:

For the first couple months I used the camera adjusting ISO as needed. But I knew I had purchased a camera that was supposed to be ISO invariant so I started testing it. I had just finished a series of tests when I took this photo. After taking the photo on the left I decided I wanted to take it again at a smaller f/stop. Given the shutter speed that meant raising the ISO but I had just run tests to convince myself that ISO on this camera didn't do anything of real value and instead of raising the ISO I turned the EC dial instead. On the XE-2 it was faster and more direct to turn the EC dial to change the exposure. That was it. I kept the camera until May of 2016 and never changed the ISO again. Anytime I needed a different EV for a photo I just turned the EC dial.

Now here's two questions for you: Are you ever going to come up with an answer about the two photos noted above in post #61? What can you see that's different in the ISO 100 photo that separates it from the ISO 800 photo?

And a related question: Here's a 100% enlargement of a section of both photos above in this post.

The one taken with the EC set to -2 (EV 13) has noticeably more noise than the one taken at EC +.3. Isn't the noise supposed to be the same since they were both shot at ISO 200?

Joe

 

[Ysarex]

How do you know when to raise the iso because you need it verses when you can allow the exposure to be darker and not raise the ISO? When do you ignore when the light meter is telling you?

Most people decide to raise ISO when they can't get a fast enough shutter speed to either take a hand-held photo or stop action in the subject. A faster shutter speed reduces exposure. If you can't compensate for the reduced exposure from the shutter speed by changing the f/stop then you have to settle for the reduced exposure.

If your camera is not ISO invariant and/or
If you want a well-exposed JPEG to view and use:
You have to raise the ISO to brighten the reduced exposure.

If your camera is ISO invariant and
You couldn't care less about the JPEGs created by the camera:
You can just reduce the exposure and ignore the ISO setting.

Reducing exposure reduces SNR. Raising ISO does not compensate for the SNR loss. In a non-ISO invariant camera raising ISO can prevent shadow data loss from swamping in read noise.

As for ignoring the light meter, I use the light meter in my cameras but I almost never take a photo with the EC on my camera set to 0.

Joe