Old lenses with A-Ring, but not A setting...

klkitchens · 12-20-2011, 02:33 PM

I've picked up a few on the cheap and they work great except I was assuming that in Av mode, I'd be able to set the aperture via the dial and the camera would read through the lens and adjust the shutter speed based on what light it was getting.

This appears not to be the case. If I shoot f/22 or f/2.5, I get the same shutter speed 1/40 -- which is odd too because the shots seems to come out looking the same -- when one should be brighter than the other if both were shot at 1/40.

Is the camera actually compensating and setting a different shutter speed, even though it's not reporting so?

Is there a way to have the camera make the decision on shutter speed -- or do I have to shoot manual on these lenses?

TIA

vonBaloney · 12-20-2011, 02:36 PM

You have to put the camera in M mode and use the green button. See this:

https://www.pentaxforums.com/forums/pentax-beginners-corner-q/110658-using-ma...x-dslrs-f.html

SOldBear · 12-20-2011, 02:38 PM

To use Av mode, the aperture ring has to be at A. The aperture of the lens is then controlled by the camera body.

If the aperture is at any setting that is not A, you'll need to use manual mode.

Of course this assumes that the lens has pKA mount. Lenses for Ricoh have P aperture setting, but it's not the same as setting A for Pentax.

klkitchens · 12-20-2011, 02:41 PM

Originally posted by vonBaloney

You have to put the camera in M mode and use the green button. See this:

https://www.pentaxforums.com/forums/pentax-beginners-corner-q/110658-using-ma...x-dslrs-f.html

Green button!

Perfect!

vonBaloney · 12-20-2011, 02:55 PM

Originally posted by SOldBear

To use Av mode, the aperture ring has to be at A. The aperture of the lens is then controlled by the camera body.

If the aperture is at any setting that is not A, you'll need to use manual mode.

Of course this assumes that the lens has pKA mount. Lenses for Ricoh have P aperture setting, but it's not the same as setting A for Pentax.

Av mode works (in fact, every mode becomes Av mode) with non-auto aperture manual lenses, i.e. m42 screw-mounts where the lens actually stops down when you turn the ring (which it doesn't on bayonet K-mounts like of the M-series). I find it is actually a bit easier to use m42s than M lenses metering-wise because of this, but green button method is easy enough as well, and might be preferable for most because the aperture stays open. But I often forget to hit the button and I find you have to look at the position of the ring more often to see where you are at.

bjake · 12-20-2011, 05:57 PM

If there is no A setting you have a K or M type lens.I use these quite a bit.I use TV mode,hold the shutter button half way down while focusing to get the focus assist light on,by then the camera will tell you what shutter speed it has selected.If you con't like the speed selected change the aperture ISO setting to get what you think is appropriate.
Jake

12-20-2011, 02:33 PM	#1
klkitchens Veteran Member Join Date: Oct 2011 Location: Allanta, GA Photos: Gallery \| Albums Posts: 480	Old lenses with A-Ring, but not A setting... I've picked up a few on the cheap and they work great except I was assuming that in Av mode, I'd be able to set the aperture via the dial and the camera would read through the lens and adjust the shutter speed based on what light it was getting. This appears not to be the case. If I shoot f/22 or f/2.5, I get the same shutter speed 1/40 -- which is odd too because the shots seems to come out looking the same -- when one should be brighter than the other if both were shot at 1/40. Is the camera actually compensating and setting a different shutter speed, even though it's not reporting so? Is there a way to have the camera make the decision on shutter speed -- or do I have to shoot manual on these lenses? TIA

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12-20-2011, 02:36 PM	#2
vonBaloney Pentaxian Join Date: Oct 2011 Location: Albuquerque, NM Posts: 6,029	You have to put the camera in M mode and use the green button. See this: https://www.pentaxforums.com/forums/pentax-beginners-corner-q/110658-using-ma...x-dslrs-f.html

12-20-2011, 02:38 PM	#3
SOldBear Veteran Member Join Date: Feb 2009 Location: Alameda, CA Posts: 3,206	To use Av mode, the aperture ring has to be at A. The aperture of the lens is then controlled by the camera body. If the aperture is at any setting that is not A, you'll need to use manual mode. Of course this assumes that the lens has pKA mount. Lenses for Ricoh have P aperture setting, but it's not the same as setting A for Pentax.

12-20-2011, 02:41 PM	#4
klkitchens Veteran Member Join Date: Oct 2011 Location: Allanta, GA Photos: Gallery \| Albums Posts: 480 Original Poster	Originally posted by vonBaloney You have to put the camera in M mode and use the green button. See this: https://www.pentaxforums.com/forums/pentax-beginners-corner-q/110658-using-ma...x-dslrs-f.html Green button! Perfect!

12-20-2011, 02:55 PM	#5
vonBaloney Pentaxian Join Date: Oct 2011 Location: Albuquerque, NM Posts: 6,029	Originally posted by SOldBear To use Av mode, the aperture ring has to be at A. The aperture of the lens is then controlled by the camera body. If the aperture is at any setting that is not A, you'll need to use manual mode. Of course this assumes that the lens has pKA mount. Lenses for Ricoh have P aperture setting, but it's not the same as setting A for Pentax. Av mode works (in fact, every mode becomes Av mode) with non-auto aperture manual lenses, i.e. m42 screw-mounts where the lens actually stops down when you turn the ring (which it doesn't on bayonet K-mounts like of the M-series). I find it is actually a bit easier to use m42s than M lenses metering-wise because of this, but green button method is easy enough as well, and might be preferable for most because the aperture stays open. But I often forget to hit the button and I find you have to look at the position of the ring more often to see where you are at.

12-20-2011, 05:57 PM	#6
bjake Veteran Member Join Date: Mar 2011 Location: Eastern Kentucky Posts: 416	If there is no A setting you have a K or M type lens.I use these quite a bit.I use TV mode,hold the shutter button half way down while focusing to get the focus assist light on,by then the camera will tell you what shutter speed it has selected.If you con't like the speed selected change the aperture ISO setting to get what you think is appropriate. Jake