focusing differences

TaoMaas · 01-04-2017, 08:51 AM

What are the focusing differences between a K10D and a K-01? My camera club received a donation of Pentax gear recently and they're trying to decide how much it's all worth. One of the lenses is an FA 50mm f2.8. On my K-01, it focuses at infinity, but totally loses it on close stuff. However, on my K10D, the lens seems to work fine. WTH?

Edited to add: Hmmm...okay...maybe this lens has more problems than I thought.

**BigMackCam** · 01-04-2017, 10:13 AM

Well, the K10D is using a phase detect AF module... the K-01 uses contrast detect AF from the sensor, so an entirely different AF system.

I'm not sure why the FA50 f/2.8 would have problems on one and not the other. If it's focusing fine on the K10D, I doubt there's a problem with the lens.

EDIT: See this thread from almost four years ago... doesn't specifically mention the FA50 f/2.8, but does mention the f/1.4:

https://www.pentaxforums.com/forums/138-pentax-k-01/216535-k-01-fa-50-1-4-hunting.html

Adam · 01-04-2017, 01:03 PM

Originally posted by TaoMaas

What are the focusing differences between a K10D and a K-01? My camera club received a donation of Pentax gear recently and they're trying to decide how much it's all worth. One of the lenses is an FA 50mm f2.8. On my K-01, it focuses at infinity, but totally loses it on close stuff. However, on my K10D, the lens seems to work fine. WTH?

Edited to add: Hmmm...okay...maybe this lens has more problems than I thought.

Lenses with a long throw struggle in contrast detect autofocus mode, so this is actually not that surprising. You'd get better results with the FA 50mm F1.4.

TaoMaas · 01-04-2017, 02:35 PM

I guess I'm going to have to play with this lens a bit more because it seems very inconsistent. I've got the FA100mm f2.8 macro and don't seem to have this problem with it. I think this gear may have been sitting for a long, long time because some of the other lenses have sluggish apertures. Too bad. There's some nice stuff in the kit. Besides this FA 50mm macro, there's an M50mm f1.7, an M 35mm (not sure of the aperture), an ME and an MX, as well as an assortment of 3rd party lenses of the era. Thanks for the replies.

01-04-2017, 08:51 AM	#1
TaoMaas Pentaxian Join Date: May 2007 Location: Oklahoma City Photos: Gallery \| Albums Posts: 3,574	focusing differences What are the focusing differences between a K10D and a K-01? My camera club received a donation of Pentax gear recently and they're trying to decide how much it's all worth. One of the lenses is an FA 50mm f2.8. On my K-01, it focuses at infinity, but totally loses it on close stuff. However, on my K10D, the lens seems to work fine. WTH? Edited to add: Hmmm...okay...maybe this lens has more problems than I thought.

01-04-2017, 01:03 PM	#3
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,608	Originally posted by TaoMaas What are the focusing differences between a K10D and a K-01? My camera club received a donation of Pentax gear recently and they're trying to decide how much it's all worth. One of the lenses is an FA 50mm f2.8. On my K-01, it focuses at infinity, but totally loses it on close stuff. However, on my K10D, the lens seems to work fine. WTH? Edited to add: Hmmm...okay...maybe this lens has more problems than I thought. Lenses with a long throw struggle in contrast detect autofocus mode, so this is actually not that surprising. You'd get better results with the FA 50mm F1.4. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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01-04-2017, 10:13 AM	#2
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,690	Well, the K10D is using a phase detect AF module... the K-01 uses contrast detect AF from the sensor, so an entirely different AF system. I'm not sure why the FA50 f/2.8 would have problems on one and not the other. If it's focusing fine on the K10D, I doubt there's a problem with the lens. EDIT: See this thread from almost four years ago... doesn't specifically mention the FA50 f/2.8, but does mention the f/1.4: https://www.pentaxforums.com/forums/138-pentax-k-01/216535-k-01-fa-50-1-4-hunting.html

01-04-2017, 02:35 PM	#4
TaoMaas Pentaxian Join Date: May 2007 Location: Oklahoma City Photos: Gallery \| Albums Posts: 3,574 Original Poster	I guess I'm going to have to play with this lens a bit more because it seems very inconsistent. I've got the FA100mm f2.8 macro and don't seem to have this problem with it. I think this gear may have been sitting for a long, long time because some of the other lenses have sluggish apertures. Too bad. There's some nice stuff in the kit. Besides this FA 50mm macro, there's an M50mm f1.7, an M 35mm (not sure of the aperture), an ME and an MX, as well as an assortment of 3rd party lenses of the era. Thanks for the replies.