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05-07-2016, 12:15 PM   #121
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QuoteOriginally posted by Enigmaticca Quote
My K-1 arrived this morning. It is with much relief that I can report that the following Sigma lenses works perfectly:
  • 24-70mm F2.8 IF EX DG HSM - "8 255" (Generic Sigma)
Can you comment on the IQ and AF accuracy using this lens?

05-07-2016, 05:13 PM   #122
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This is the Sigma 70-200 that I use 90% of the time. Is it one that is working with the K1? Sorry I'm so confused with all the different variations of this lens.

Sigma 70-200mm F2.8 EX DG APO Macro HSM II Lens Reviews - Sigma Lenses - Pentax Lens Review Database

Thank you
Jim
05-07-2016, 07:31 PM   #123
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QuoteOriginally posted by jbrowning Quote
Is it one that is working with the K1?
There seem to be reports of it working on the K-1, and reports of it not working. It seems like a case of try it and see.

I am also a 70-200 HSM II owner, so when I get a K-1 it will be the first lens I test.
05-07-2016, 08:19 PM   #124
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There has also been at least one post saying that a firmware update already available fixes the problem.

So the variable reports might depend on how old the lens is and what firmware version is installed.

05-07-2016, 08:59 PM   #125
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Tested all of the following on day one and they all work perfectly on initial go around:

Sigmas: 70-200 HSM DG 2.8, 17-50 2.8 DC, 50 DG 1.4, 24-70 DG 2.8, 50-500 Bigma
Bower 8mm fisheye
Super Albinar 28 2.8 (old school)

An interesting point: I've had many troubles with focusing issues on the 24-70 2.8. The lens has had a troubled life. It first arrived with the wrong firmware, identifying itself as a 70-200. I sent it in for repair and also complained that it wouldn't focus properly (at distance in particular) on either my K5iis or K3 (even trying to tweak it with in camera profiles). Sigma reprogrammed it and said there were no issues with focusing, yet they persisted and I set the lens aside.

Curiously, near as I can tell so far, the focusing issues have gone away under the K-1! I used it for about two dozen or so shots and they all look spot on. For example..

Last edited by gryhnd; 05-08-2016 at 10:05 AM. Reason: fixed 20-200 to 70-200
05-07-2016, 09:24 PM   #126
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I have an older Sigma 70-200/2.8 APO EX DG which works fine with my K1. This is the non macro with an aperture ring version.
05-08-2016, 09:22 AM   #127
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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.

Last edited by Mock; 05-08-2016 at 09:36 AM.
05-08-2016, 10:04 AM   #128
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QuoteOriginally posted by Mock Quote
After mounting the lens, it would frequently lose contact with the pins on the lens mount.
Did you clean the lens contacts? This happens to me often on lenses I use a lot. Just requires proper maintenance. Another poster said the same thing and all works now after I mentioned it.

I just use a q-tip with some isopropanol.

05-08-2016, 10:18 AM   #129
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QuoteOriginally posted by gryhnd Quote
Did you clean the lens contacts? This happens to me often on lenses I use a lot. Just requires proper maintenance. Another poster said the same thing and all works now after I mentioned it.

I just use a q-tip with some isopropanol.
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.

Last edited by Mock; 05-08-2016 at 03:38 PM.
05-09-2016, 08:57 AM   #130
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Just tried my Tamron SP AF 17-50mm f/2.8 XR Di II LD, bit surprised to discover that lens was meant for APS-C to begin with. I have my K1 set to full frame and with the Tamron , I got the dark circle - turning on auto crop mode allowed the camera to recognize the lens as an APS-C lens. The 17-50 will remain permanently with my K5iis, so looking for a wide angle for the K1, preferably an FA or even A older prime (24, 28)
05-09-2016, 09:12 AM   #131
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QuoteOriginally posted by theEight Quote
Just tried my Tamron SP AF 17-50mm f/2.8 XR Di II LD, bit surprised to discover that lens was meant for APS-C to begin with. I have my K1 set to full frame and with the Tamron , I got the dark circle - turning on auto crop mode allowed the camera to recognize the lens as an APS-C lens. The 17-50 will remain permanently with my K5iis, so looking for a wide angle for the K1, preferably an FA or even A older prime (24, 28)
As far as I know all of the 16 or 17 to 50 lenses are APSC.
05-09-2016, 09:23 AM   #132
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QuoteOriginally posted by UncleVanya Quote
As far as I know all of the 16 or 17 to 50 lenses are APSC
That's the case. With a focal length of less than 24mm and a full-frame image circle a lens is considered an ultra-wideangle lens, and those beasts are both expensive and seldom to be seen.

The ultimate for Pentax users used to be the 12-24/4.5-5.6 from Sigma, but for some reasons Sigma ceased their specific kind of Pentax support* with the second iteration of this lens (that added HSM, Sigma's name for what Pentax names SDM).

Which I consider a pity; I would very much like to get a full-frame complement for my APS-C 8-16/4.5-5.6 HSM, which I used on my K-5 without any problems whatsoever. That lens is compatible with the K-1, but definitively shows it's smaller image circle (and it's fixed lens-shade) on the K-1's full-frame sensor, as can be seen here:




*) we all know about the woes with Sigma's reverse-engineered implementation of the K-bayonet, especially with the 70-200/2.8 DG Macro II HSM ...
05-09-2016, 09:45 AM   #133
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QuoteOriginally posted by funktionsfrei Quote
That lens is compatible with the K-1, but definitively shows it's smaller image circle (and it's fixed lens-shade) on the K-1's full-frame sensor, as can be seen here:
And ditto their 17-50, and the Bower 8mm (which looks horrid FF, lol).
05-09-2016, 04:00 PM   #134
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My Sigma lenses quick check with K-1:

Sigma 24-70/2.8 EX DG HSM .... It works fine both live view and viewfinder - If your crop setting is in AUTO, K-1 thinks this lens is CROP, ... Change your crop setting to FF and it works fine.
Sigma 70-200/2.8 APO EX DG OS HSM .... It works fine both live view and viewfinder - If your crop setting is in AUTO, K-1 thinks this lens is CROP, ... Change your crop setting to FF and it works fine.
Sigma 12-24 4.5 EX DG .... it works fine in both Live view and viewfinder
Sigma 15 2.8 DG Fisheye 180 degrees .... it works fine in both Live view and viewfinder

I hope it helps
05-10-2016, 02:37 AM   #135
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QuoteOriginally posted by Raffwal Quote
Can you comment on the IQ and AF accuracy using this lens?
Unfortunately I have yet to have the opportunity to get a proper play with that lens. It will need some forward AF adjustment and my initial impression with regards to IQ has been unconvincing thus far
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