Help with a Pentax FA 28-105mm

Darius4522 · 10-15-2009, 12:53 AM

Hi everyone.

I was the successful eBay bidder for a Pentax SMC FA 28-105mm f4-5.6 lens, which arrived today. It works brilliantly, but I am puzzled by one control, which I have not seen before.

On the left hand side is a slide control with two points - P and A - and at the A point there's a slider to move the control to AS. I have no clue as to what they do. There is also a black button which, again, I have no idea about.

Naturally, the lens arrived minus a manual.

Can anyone provide me with some advice as to what the button and the slide controller do? I only have one other FA lens (50mm f1.4) and this button/slide controler is not present.

hinman · 10-15-2009, 02:06 AM

Originally posted by Darius4522

Hi everyone.

I was the successful eBay bidder for a Pentax SMC FA 28-105mm f4-5.6 lens, which arrived today. It works brilliantly, but I am puzzled by one control, which I have not seen before.

On the left hand side is a slide control with two points - P and A - and at the A point there's a slider to move the control to AS. I have no clue as to what they do. There is also a black button which, again, I have no idea about.

Naturally, the lens arrived minus a manual.

Can anyone provide me with some advice as to what the button and the slide controller do? I only have one other FA lens (50mm f1.4) and this button/slide controler is not present.

Those should be the power zoom control from the Pentax power zoom series. As far as I know, the power zoom is totally absent in Pentax dSLR.

Someone please chimp in for correction. I don't think any switch in the P/A with A<->AS changes on the 'P' (for power zoom) setting will do anything for you except the power zoom ring that can engage in zooming small steps automatically. On the zoom ring, there is a pull up and down toggle. In the power zoom engaged setting, a small left or right will engage the zooming without you turning the zoom ring. Regarding the sub-switch in A<->AS, it is likely related to certain enhanced features in power zoom as in zoom focusing and others odd ball features that I can't remember the purpose. Look up for Pentax Power Zoom to see the detail if you are curious. I think it is an no-op when the switch is in either A or AS position as power zoom is not supported in Pentax dSLR.

I used to have the power zoom in Pentax FA 28-80mm power zoom f/3.5-4.7 and hence the vague memory of those funny switches and the power zoom ring.

Thanks,
Hin

flyer · 10-15-2009, 02:10 AM

power zoom works (partially) with the K10D, K20D, K7 and (I think) K200D. It has only the basic zoom in-zoom out, and nothing more.

Darius4522 · 10-15-2009, 03:32 AM

Thanks to both of you. I did find the following links:

Pentax Lens Power Zoom

http://www.mosphotos.com/PentaxLensesExplained.html

10-15-2009, 12:53 AM	#1
Darius4522 Inactive Account Join Date: Jan 2007 Location: Adelaide, Australia Photos: Gallery Posts: 155	Help with a Pentax FA 28-105mm Hi everyone. I was the successful eBay bidder for a Pentax SMC FA 28-105mm f4-5.6 lens, which arrived today. It works brilliantly, but I am puzzled by one control, which I have not seen before. On the left hand side is a slide control with two points - P and A - and at the A point there's a slider to move the control to AS. I have no clue as to what they do. There is also a black button which, again, I have no idea about. Naturally, the lens arrived minus a manual. Can anyone provide me with some advice as to what the button and the slide controller do? I only have one other FA lens (50mm f1.4) and this button/slide controler is not present.

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10-15-2009, 02:06 AM	#2
hinman Veteran Member Join Date: Oct 2006 Location: Fremont, CA Photos: Albums Posts: 3,473	Originally posted by Darius4522 Hi everyone. I was the successful eBay bidder for a Pentax SMC FA 28-105mm f4-5.6 lens, which arrived today. It works brilliantly, but I am puzzled by one control, which I have not seen before. On the left hand side is a slide control with two points - P and A - and at the A point there's a slider to move the control to AS. I have no clue as to what they do. There is also a black button which, again, I have no idea about. Naturally, the lens arrived minus a manual. Can anyone provide me with some advice as to what the button and the slide controller do? I only have one other FA lens (50mm f1.4) and this button/slide controler is not present. Those should be the power zoom control from the Pentax power zoom series. As far as I know, the power zoom is totally absent in Pentax dSLR. Someone please chimp in for correction. I don't think any switch in the P/A with A<->AS changes on the 'P' (for power zoom) setting will do anything for you except the power zoom ring that can engage in zooming small steps automatically. On the zoom ring, there is a pull up and down toggle. In the power zoom engaged setting, a small left or right will engage the zooming without you turning the zoom ring. Regarding the sub-switch in A<->AS, it is likely related to certain enhanced features in power zoom as in zoom focusing and others odd ball features that I can't remember the purpose. Look up for Pentax Power Zoom to see the detail if you are curious. I think it is an no-op when the switch is in either A or AS position as power zoom is not supported in Pentax dSLR. I used to have the power zoom in Pentax FA 28-80mm power zoom f/3.5-4.7 and hence the vague memory of those funny switches and the power zoom ring. Thanks, Hin

10-15-2009, 02:10 AM	#3
flyer Veteran Member Join Date: Jan 2008 Location: Ste-Anne des Plaines, Qc., Canada Posts: 2,013	power zoom works (partially) with the K10D, K20D, K7 and (I think) K200D. It has only the basic zoom in-zoom out, and nothing more.

10-15-2009, 03:32 AM	#4
Darius4522 Inactive Account Join Date: Jan 2007 Location: Adelaide, Australia Photos: Gallery Posts: 155 Original Poster	Thanks to both of you. I did find the following links: Pentax Lens Power Zoom http://www.mosphotos.com/PentaxLensesExplained.html

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