Auto ISO + focal length logic

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bfitzgerald
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Auto ISO + focal length logic

Unread post by bfitzgerald »

Bit puzzled by this, but the Programming seems flawed in some ways.

As we know it's focal length aware (which is good)
But seems overly keen to try to maintain a higher shutter speed than you probably need
For example if I shoot on the beercan with say 210mm f4/f4.5 in aperture priority the camera raises the ISO level to try to get 1/400 second shutter.
Now that might be ok if you were not using steady shot, but unfortunately it makes no difference to the ISO logic.

I think using the above settings with steady shot a more appropriate ratio would be say 1/200 second or 1 to 1. Without steady shot I think 1/400 is more than you need, unless you shake like crazy 1/300 second should do the job.

Just something I've noticed, but I'm surprised Sony has not at least adjusted the programming to account for stabilisation
I also saw Ken Rockwell's rant about P mode not using the faster aperture lenses, and he's right sure enough I mount an f1.7 of f1.8 lens and even in horribly dim light it refuses to open up beyond f2. Strange, not that I care much I rarely ever use P mode. This seems to be the same on the KM5d too.

I put the 50mm f1.7 on to the film 7 body and P mode, sure enough it opened the lens up to f1.7
David Kilpatrick
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Re: Auto ISO + focal length logic

Unread post by David Kilpatrick »

I have the Nikon D5300 here and it does the same - at 200mm, it raises the auto ISO to keep the shutter speed at 1/320th. What I find really strange is that an auto ISO flash shot, indoors at f/5.6 and very close (head shot of cat!) was set to ISO 2800. ISO 100 would have been quite OK!

David
Mark K
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Re: Auto ISO + focal length logic

Unread post by Mark K »

I am also puzzled by the Nikon way of handling auto ISO....Canon has a better way and now comes A7
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the_hefay
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Re: Auto ISO + focal length logic

Unread post by the_hefay »

Maybe I'm wrong but it seems to me that auto ISO ought to take 3rd place to auto shutter and auto aperture. For example, in A mode it should auto shutter to an acceptable speed and then auto iso to compensate. Or if in S mode it should auto aperture then auto iso. It sounds like what's going is that the ISO is taking 1st place in the priority. I quit using auto ISO a couple years back and so I'm not familiar with what my camera might do with auto iso. I could take some test shots, but alas, I'm to lazy. :)
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classiccameras
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Re: Auto ISO + focal length logic

Unread post by classiccameras »

I have only used auto ISO very occasionally on my A-37/57, but like you not for a long time. I get very pleasing results using a fixed ISO, usually 100-400 range and programme mode. I still have control over shutter speed and aperture. I also use AP quite a lot and mostly manual focus with the aid of focus peaking. I normally leave DRO on auto and tweak the colour temp as I find the pics a tad too warm, I've managed to get a pictures now that are very reminiscent of Kodak Portra/Kodachrome 64 which is very pleasing. I never achieved that with Canikon.
Happy New Year to all.
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