Misalignment of AF on DA* lens


beakynet

Link Posted 05/07/2010 - 15:30
Has any one else noticed that focus shift on the DA* 16-50 and DA* 50-135 can lock up (feeling very gritty)? Turning to manual focus on the lens makes no difference, however, turning to manual focus on the camera body releases the lens focus shift problem.

To instigate the problem I found that using quick shift through its range and back again fairly fast soon leads to the lock up. Origionally noticed it on my 16-50 and then tested the 50-135 and found the same issue.

Has anyone noticed this with the 300, 200 and 65-250 DA* lenses?

I haven't noticed this with the lens on my 5MZn, not that I have tried this, though I have used the lens on it and did not notice any focus issues.
Bodies: K5IIs, K7, MZ5n, LX, MV
Lenses: DA*16-50, DA18-55WR, DA18-135, DAL35, M50 F2, A50 f1.4, FA50 f1.4, DA*50-135, DA55-300, Tamron 70-300, DFA 100 WR Macro, M135 f3.5, Sigma 120-400 APO DG HSM, Tokina 500 f8.0
Flash: Metz 58, Metz 48
Accessories: BG4, Pentax right angle finder, Pentax mirror adaptor lens, O-ME53 Viewfinder Loupe
Auto 110 System: Auto 110, Winder, 18mm, 24mm, 50mm, 70mm, 20-40mm, AF100P, 1.7x telecon

Anvh

Link Posted 05/07/2010 - 15:46
No never had that problem with those lenses.

The DFA100 however does sometimes turn very heavy after AF focusing and if the lens didn't lock on. simple doing AF focusing again make it turn smoothly again. I think it has something to do with the gears and the quick-shift of that lens.

KAF2 lenses might work differently or the same... I don't know.
Stefan


K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Last Edited by Anvh on 05/07/2010 - 15:47

johnriley

Link Posted 05/07/2010 - 16:04
Is this just something you can induce with extreme use or is it a problem?

Under what circumstances would it occur in normal use?
Best regards, John

col55555ine

Link Posted 05/07/2010 - 20:00
i have noticed this in another forum,they noticed this happening when there battery was less than 3/4 full, they changed battery and seamed to solve this, as i recall they had three spare batteries and each time after the charged started to drop past 3/4 full,same thing happened...
hope this helps....
seams strange but these lenses use alot more power, well atleast its worth a try...
k-5 IIs, Pentax 60-250, 17-70, 100macro WR, 50mm F2,
AF50 F1.4, Siggy 10-20, Siggy 100-300 F4, ..Pentax Af 160 ring flash

beakynet

Link Posted 05/07/2010 - 20:34
johnriley wrote:
Is this just something you can induce with extreme use or is it a problem?

Under what circumstances would it occur in normal use?

This is more under extreme use/movement, however, I noticed that focus was a bit 'sticky' and I often need a second press on the shutter button to get things in focus. One of these occations, I decided to try quick shift to find it wasn't changing the focus and was gritty. I set manual focus on the lens and tried again, no change, so I set mf on the body and it seemed to resolve. The test went from there and I then decided to try with to 50 - 135 to see if it was just the 16 - 50. I don't have any real focussing issues with the 50-135 so was surprised to find the same problem. I wondered if it was something to worry about. Also was it a problem with the lens or the camera screw drive, though I haven't noticed any issues my other screw drive Pentax lenses.
Bodies: K5IIs, K7, MZ5n, LX, MV
Lenses: DA*16-50, DA18-55WR, DA18-135, DAL35, M50 F2, A50 f1.4, FA50 f1.4, DA*50-135, DA55-300, Tamron 70-300, DFA 100 WR Macro, M135 f3.5, Sigma 120-400 APO DG HSM, Tokina 500 f8.0
Flash: Metz 58, Metz 48
Accessories: BG4, Pentax right angle finder, Pentax mirror adaptor lens, O-ME53 Viewfinder Loupe
Auto 110 System: Auto 110, Winder, 18mm, 24mm, 50mm, 70mm, 20-40mm, AF100P, 1.7x telecon
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