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Old 16th March 2019
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Naughty Nigel Naughty Nigel is offline
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Re: ISO is Fake - Seriously

Originally Posted by Bassman51 View Post
I think the critical issue for us as users is rarely what the absolute ISO number is for a given camera/image, but rather whether the camera is capable of being used to produce images that we find properly exposed.
The true ISO sensitivity of digital cameras only becomes relevant when you need to work with external devices such as exposure meters, studio flash or other cameras.

I have often used my OM4Ti to meter a scene for my Mamiya RZ and have fount it extremely accurate. (The metering head for the RZ is a bit big and heavy to carry very far along disused railway lines.)

My current OM-D E-M1 is also pretty close, but my old Olympus E1 was miles out, especially at higher ISO settings. I know I am cynical about these things but I suspect the noise from the E1 at a true 400 ASA might have had something to do with this.

Likewise I had a Canon PowerShot that was even further out, with an indicated ISO 400 actually being closer to ISO 240; probably for the same reasons.

Oddly enough, I use an exposure meter app on my Sony Z3 and Z3 Compact mobile phones, (which of course have very small sensors), and that is remarkably accurate.

Naughty Nigel

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