Auto ISO and IS?

Hello

I wonder...

Does the auto ISO function of the 40D take in account the what the
focal range of the Lens is, and does it know if the lens uses IS!

Generally speaking yes, camera is aware of the focal length being used as well as it is aware whether the IS has been engaged (at least for the modern IS lenses).
However, I failed in attempt to understand what Auto ISO has to do with that..

Can you elaborate, please?

Overkill wrote in post #4295713
Does the auto ISO function of the 40D take in account the what the
focal range of the Lens is, and does it know if the lens uses IS!

I don't know what IS has to do with automatically determining the ISO. I think they are independent of each other.

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I have noticed that the 40D obeys the 1/focal length rule. So, with my Sigma 30mm f/1.4 I find that it will usually set my shutter to 1/30 and whatever ISO it needs to get the exposure right. Since the camera seems to first obey the shutter speed rule and THEN works out the remaining determinants of exposure (i.e. aperture and ISO), it seems like it is taking focal length into account... Why it does not do 1/(focal length*1.6) since it is a crop-body, frustrates me!

As for IS... I am not sure. I don't think it knows that IS is being used. It would need to know how effective the IS is on each particular lens - e.g. some implementations are 2-stop, newer implementations are 3-stop, etc. and lower the shutter value accordingly. Don't think it's that smart!

EDIT: Well, had a quick look at my shots with my other lenses (e.g. nifty fifty) and it doesn't always seem to obey the 1/focal length rule. Maybe it's just coincidence...? I suppose where the appropriate exposure can be set within the auto ISO range, it does use the rule.

I'm not aware than any Canon camera takes the 1/focal length thumbrule ito account. If you think you've seen that it's most likely coincidence.

Mark

Thanks for confirming, Mark. Would have been cool if they built the logic to use that rule to set the shutter, and then determine aperture and ISO.

AperturePriority wrote in post #4295911
I don't know what IS has to do with automatically determining the ISO. I think they are independent of each other.

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If i want a shot without motion blur from my hand i have to increase the ISO (fast shutter speed)
or engage the IS! So the ISO has a direct link with my IS lenses!!

Overkill wrote in post #4301040
If i want a shot without motion blur from my hand i have to increase the ISO (fast shutter speed)
or engage the IS! So the ISO has a direct link with my IS lenses!!

Alright...point taken...thanks!

However, I interpret "direct link" as being automatic in nature. If I were in Auto ISO mode and I turn off IS, the ISO doesn't automatically change. So, while related, there is no "direct and automatic" link.

To answer the original question in this thread, it appears that the answer would be "no".


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AperturePriority wrote in post #4302713
Alright...point taken...thanks!

However, I interpret "direct link" as being automatic in nature. If I were in Auto ISO mode and I turn off IS, the ISO doesn't automatically change. So, while related, there is no "direct and automatic" link.

To answer the original question in this thread, it appears that the answer would be "no".


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Alright... so id better adjust the ISO by hand than in AUTO mode when shooting pictures with an IS lens..... Esp voor static pictures!