auto exposure mode in still

[stefanocps]

Hello, i have always used the xt3 for video, and now i am trying to see the various possibility with photo. I am trying to use the Full auto mode (exposure), and while i can see that f and ss would change when moving the camera, the iso is always on the same number

I have set the iso dial do A, and the camera show ISOA1, with the number i have selected as MAX SENSISTIVITY in autoiso settings, AUTO 1

SO for test i set 3200, or 6400 on MAX sensitivity..and iso never change from that value ...it rather change the SS to unusable rate

How does it works?

thanks

[jerryy]

Hopefully, this will help:

https://www.jmpeltier.com/fujifilm-how-to-use-auto-iso/

[stefanocps]

i am tryng but i don't understand

i always have the iso fixed at the  MAX sensitivity

ss go down to 3 or less even if i set minimum shutter speed at 1/250

I tried to simulate the settings as in the post

[stefanocps]

even if i set fixed F ans SS ISo will always remains at that Setting! 

Edited July 29, 2021 by stefanocps

[jerryy]

From the article:

”EXAMPLE: You set an ISO range of 200-3200 and a minimum shutter speed of 1/250 second.  If the image will be underexposed by one stop at 1/250 and ISO3200, the camera will automatically lower the shutter speed to 1/125 second while maintaining ISO3200.”

It sounds like you are actually getting what you are supposed to, the scene you are trying to get an image is so dark, the camera thinks it will be under-exposed for your settings and keeps the ISO at the maximum you have allowed it to go to and then lowers the shutter speed to try to get a good exposure.

Can you post an image along with all of the settings you have put in place, as well as what you thought should happen?

From what you have described so far, kicking the maximum ISO to say 6400 or 8000 will probably work for that scene.

[stefanocps]

mainly what i expect to happen is seeing a change in ISO value, as well as i see F and SS changing

I have these valuein AUTO ISO 1

Default Sensitivity 160

Max Sensitivity  1600

min Shutter speed 1/250

ISOA1 is the one in use now

 

 

Then  i try to point my camera to very dark place and very light place

What i see is the SS changing from all the range..i see it coing down to "1 in the darkest or going up to 640 or more when in light

I hardly F changing, and also ISO never change!

To resume it seems only SS change when going from very dark to very light

 

And as i told you i have tried to set the SS and F to fixed value and leave the ISO in auto and still, i never see ISO changing value when going from dark to light

If i set only SS to a fixed value, i set it to 500, F do change in very light, while it stays in RED at 2.5 in dark and  ISO never change

 

What i expect is to see ISO changing value accordingly to situation, but it is always at the fixed value specified in MAX SENSITIVITY

Edited July 30, 2021 by stefanocps

[jerryy]

ISO 1600 is not that high with a minimum shutter speed of 1/250 depending on the f-stop you can still get very dark images. Try setting the ISO to 6400, the f-stop to 4.0 or 5.6 depending on your lens and see what happens. That trial where you had the ss at 500 can be misleading, that is way too much for a dark setting.

To make sure there is nothing messed up in the camera, try manually setting the following (no auto):

ss 1/180 and leave it here.

f 4.0 — or whatever the widest your lens will do, and leave it here. I see you mentioning 2.5, so use that.

ISO 160 then 640, then 3200 then 8000. Take the four photos, of course of the same scene, as quickly as you can, so that the lighting does not change.

You should have widely differing exposures, if they are all very close, something else is going on.

Edited July 30, 2021 by jerryy

[stefanocps]

i have discovered the trick. The iso shown on the display don't reflect the effective iso used. When hal pressing the shutter, the real used ISO is shown. But only in that moment!