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05-12-2015, 12:56 PM   #1
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What is the function of the "A" aperture setting for SMC A 645 lens?

I'm new to the 645Z and have purchased a couple of SMC A lens to use with the camera. How does the "A" aperture setting function with the camera?

Thanks,
Phil

05-12-2015, 12:58 PM   #2
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The A setting allows the camera to set the aperture.
05-12-2015, 01:06 PM   #3
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That's what I was thinking. However, I'm seeing some confusion when manually setting the aperature on the "A" lens, as the info provided by the camera doesn't always agree with the manual setting. I've been assuming that the LCD info should be ignored; or else, I'm doing something wrong. Or, there could be something wrong with the lens.
05-12-2015, 01:06 PM   #4
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QuoteOriginally posted by boriscleto Quote
The A setting allows the camera to set the aperture.
This. Set the lens to A and use the dial to set the aperture. The aperture will stop down when you release the shutter but will stay fully open while framing and focusing. If you want to preview with the aperture stopped down, pull the power button beyond "ON".

05-12-2015, 01:36 PM   #5
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Not sure about 645, but if they are the same as K-mount, then A setting surrenders the aperture choice to the camera. So you can choose the aperture number manually, but the camera won't know what you chose! And then you need to use Av mode (which will not stop down the aperture to your choice, but will shoot wide open. Note that auto ISO or any more other than M defaults to Av), or M mode - where you can use the green button to let the camera stop down meter and select the shutter speed.
With A series lenses, you can push the little lever on the aperture ring and choose A mode. Now the camera has full control over the aperture. So you can choose the aperture on the camera, use Av mode, P mode, and so on. The camera can now continuously meter and even write the aperture into exif. Basically, if your lens has A on aperture ring, you should just always keep it in A.
(note: I speak from experience with K-mount, 645 could be different, so feel free to look for threads on using manual lenses)
05-12-2015, 01:57 PM   #6
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QuoteOriginally posted by Na Horuk Quote
Not sure about 645, but if they are the same as K-mount, then A setting surrenders the aperture choice to the camera. So you can choose the aperture number manually, but the camera won't know what you chose! And then you need to use Av mode (which will not stop down the aperture to your choice, but will shoot wide open. Note that auto ISO or any more other than M defaults to Av), or M mode - where you can use the green button to let the camera stop down meter and select the shutter speed.
With A series lenses, you can push the little lever on the aperture ring and choose A mode. Now the camera has full control over the aperture. So you can choose the aperture on the camera, use Av mode, P mode, and so on. The camera can now continuously meter and even write the aperture into exif. Basically, if your lens has A on aperture ring, you should just always keep it in A.
(note: I speak from experience with K-mount, 645 could be different, so feel free to look for threads on using manual lenses)
You can use the aperture ring on the 645D with no limitations, since the mount isn't "crippled". Even away from A, the camera will know what the aperture value is. However there isn't much of a reason to use the aperture ring except in very specific circumstances.

Adam
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05-12-2015, 02:48 PM   #7
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I found that even in completely manual 'M' mode, the camera was not letting me set the aperture with the dial when on 'A', i.e. it would not 'stick' but would shift up or down by one or two stops, very annoying. So I just use the aperture ring on the lens to set the aperture (like Leica) and the shutter dial to set the speed. I find this very quick and easy and a great way to change the controls with one hand while changing the shutter with the other. Somehow gives me better control, but then that may just be my imagination.

Pradeep
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