|
Forum: Pentax K-1 & K-1 II
05-08-2016, 10:18 AM
|
| |
Yeah, I cleaned everything first. I'm starting to suspect something electrical. The Sigma lens has more resistance (~700ohm) across pin 7 than any of my Pentax lenses (~450 ohm). Perhaps the K-1 doesn't supply the lens enough power, I'm going to compare the current from both cameras.
edit: As you would expect they're putting out the same voltage, the K-1 may actually be outputting slightly more on average, but that may come down to the battery being a fuller charge. Gonna check inside the lens for any issues now.
edit: Finally isolated a cause! If I hold the lens lock button down, communication is fine. The lens lock pin is somehow to blame.
OK. A bit of scotch tape over the lens mount hole on the lens fixes the issue, which I also encounter to a lesser extent with my Sigma 400mm f/5.6 APO Tele Macro. For a short while my Sigma 105 Macro wouldn't work either, but it has since returned to normal. I still can't say what the issue is definitely. I think the tape is pushing back the lens-lock pin enough, which creates a connection that tells the camera to look at pin 7. Would this be new behaviour for K-mount? I can't imagine this is the cause though, it's not as if Sigma locking-holes are deeper than Pentax ones. Regardless, I've partially filled the hole on my 24-60 with superglue so something pushes against the pin...so far so good.
|
|
Forum: Pentax K-1 & K-1 II
05-08-2016, 09:22 AM
|
| |
I encountered an issue using my Sigma 24-60mm f/2.8. After mounting the lens, it would frequently lose contact with the pins on the lens mount. The aperture would flicker between "--" and my selected one, I also lost AF during the times it was displaying no aperture. So it was losing contact with the data pin, at minimum. Holding the lens in any one position, or pushing it onto the pins did not generate any consistent improvement.
The lens did not exhibit any problems mounted on my K-5. I think the pins Sigma uses on this lens (and others) do not protrude as much as the pins Pentax uses.
I first tried tightening the lens mount screws on the lens, but this did not help, nor would I expect it to since the K-5 had no issues. With hesitation, I then tightened the screws on the lens mount of my K-1, they were all able to tighten about 1/5 of a turn without using much force. After tightening the screws on the K-1, the Sigma 24-60mm functions perfectly, contact with the pins is 100%.
The downside is that I now have to dial in a +1 focus adjustment on my DA* 55, since tightening the mount changes the registration distance ever so slightly, causing that lens to back-focus.
edit: Actually it's happening again now, maybe the pin doesn't connect inside the lens properly. It tends to lose function when zooming.
|
|
Forum: Pentax K-1 & K-1 II
04-30-2016, 04:55 PM
|
| |
Don't the newer ones have HSM and/or OS? That would differentiate them from the basic EX DG I thought. Regardless, I own this one:
 |
|
Forum: Pentax K-1 & K-1 II
04-30-2016, 09:26 AM
|
| |
Tried both the Sigma 105mm f/2.8 DG Macro, and Sigma 400mm f/5.6 APO Tele Macro.
They work better than ever! AF is so confident in this camera, neither lens hunts like they do on my K-5 and *ist DS.
edit: Sigma 24-60 f/2.8 EX DG works - no speed increase on this one, but it works okay. :)
|
