ISO settings

[Kelly Grannell]

image resized!

 

[Charade]

oh, and to asnwer the other question, yes the aperture are identical too.

How can that be? Same shutter, same aperture? If you change the ISO, something else (like the shutter or aperture) has to change to keep the exposure the same. It looks like a little positive EV was applied to pics 2 and 3.

 

[Kelly Grannell]

The mistake is in the title. I shot it with aperture priority. No EV change, just ISO.

My apology for the severely misleading title.

 

[Muushka]

Like I said in a post earlier, the more I learn about DSLR, the more I realize I don't know!!! Keep 'em coming!

 

[Charade]

The mistake is in the title. I shot it with aperture priority. No EV change, just ISO.

My apology for the severely misleading title.

But that still doesn't make sense. If you shoot in aperture priority of say F8 and you change the ISO (from 100) to 400, that's 2 stops. The shutter should now change to 1/4 of what it was for the ISO 100 shot. Same thing when going from ISO 400 to ISO 800 except that's one stop. The shutter should now be 1/2 of what it was for the ISO 400 shot.

 

[Kelly Grannell]

That's exactly what I'm saying. The title is wrong, it's supposed to say "same aperture" instead of "same shutter speed".

From my EXIF: f/4 for all shots, EV 0 for all shots, ISO 100/400/800 respectively, Shutter speed 1/30 - 1/120 - 1/240 respectively

 

[Anewman]

Looks like the flash fired. Did it?

 

[Muushka]

OK, now I REALLY DO understand that! Thanks for the clarification.

 

[Kelly Grannell]

Yes, the flash fired.

 

[Anewman]

Yes, the flash fired.

How do I ask this...

So does the flash fire with the same intensity each time or does it help acheive proper exposure by using a different intensity(length) each time depending on settings and available light?

 

[Kelly Grannell]

In theory, it's supposed to be so (I'm using E-TTL mode). However, from my experiment, it doesn't look like it.

 

[Charade]

That's exactly what I'm saying. The title is wrong, it's supposed to say "same aperture" instead of "same shutter speed".

From my EXIF: f/4 for all shots, EV 0 for all shots, ISO 100/400/800 respectively, Shutter speed 1/30 - 1/120 - 1/240 respectively

You can correct the title if it's wrong by editing your original message. But I understand that.

What I'm saying is all the shots should have the same exposure (look the same) if the aperture is constant, the shutter adjusts automatically to make the exposure the correct as the previous ISO. Changing the ISO shouldn't change the exposure as your pictures seem to show that it did.

F4 + 1/30 at ISO100
F4 + 1/120 at ISO400
F4 + 1/240 at ISO 800

are all the same exact exposure.

I'm curious to know why they don't look the same. It looks like +1 and +2 EV were dialed in for shots 2 and 3.

 

[Charade]

In theory, it's supposed to be so (I'm using E-TTL mode). However, from my experiment, it doesn't look like it.

Oops. I should have read this first. It does appear that you're getting more flash at the higher ISO's.

Is it a bug in the camera firmware?

 

[Kelly Grannell]

You can correct the title if it's wrong by editing your original message. But I understand that.

What I'm saying is all the shots should have the same exposure (look the same) if the aperture is constant, the shutter adjusts automatically to make the exposure the correct as the previous ISO. Changing the ISO shouldn't change the exposure as your pictures seem to show that it did.

F4 + 1/30 at ISO100
F4 + 1/120 at ISO400
F4 + 1/240 at ISO 800

are all the same exact exposure.

I'm curious to know why they don't look the same. It looks like +1 and +2 EV were dialed in for shots 2 and 3.

Thanks! I never realized I can change the title. Now I've changed it. To my knowledge, changing ISO should not change the exposure, but I honestly don't know why it turns brighter. I usually don't use internal flash a lot because I tend to use my studio flash where I can completely play with the power, ratio etc. So maybe (just maybe) it's a firmware bug or my sensor is dying (I hope not).

 

[jann1033]

think i might still not quite get digital iso but what would i not be able to take with iso 400 and adjusted shutter/ tripod or aperture that i could with iso 800? basically i think the canon s2/s3 difference comes down to that for me so wondering if it's worth the $100 for that or would i not use it much anyway

 

[Anewman]

think i might still not quite get digital iso but what would i not be able to take with iso 400 and adjusted shutter/ tripod or aperture that i could with iso 800? basically i think the canon s2/s3 difference comes down to that for me so wondering if it's worth the $100 for that or would i not use it much anyway

Imagine an INDOOR/LOW LIGHT situation handheld with your shutter speed TOO SLOW and your aperture is wide open, an extra stop of ISO would allow you to speed up the shutter to avoid motion blur.

It really depends on your style of shooting to determine if it is "worth" the extra money. But there are other minor improvements, 5 vs 6 mp, etc...

I shoot with a Canon 20D and for high school Volleyball and Basketball ISO 800(sometimes 1600 is required) is barely the minimum, and that is shooting with a 85mm F1.8 lens. The S3 lens is at least 1 stop slower at most focal ranges and could be 2.5 stops slower at FULL ZOOM.


Remember that a TRIPOD will not stop your Subject from moving, it will only hold the camera still. If you want to freeze the ACTION only a faster shutter speed will do that, a stop or two in ISO will help obtain that faster shutter speed.

 

[Kelly Grannell]

or to put it simply.

Say with ISO 400 you only get 1/300 shutter speed (not enough for sports piccies), with ISO 800 the shutter speed will become 1/600 (enough for sports piccies).

 

[jann1033]

so does the second "more simply put" post mean you are starting to understand i am a bit dense ?

truthfully thanks...i keep forgetting about the extra mp. and it would probably help with any action type shots then.

 

[Kelly Grannell]

LOL! You're too funny!

 

[JR6ooo4]

ISO 800 means you can take the picture faster than 400, 200 or 100 etc...
Then quality of the ISO 800 then needs to be judged or compared to other cameras or previous models. ie newer / better camera.
Mikeeee