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07-17-2016, 11:43 AM   #61
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Yes. Spent a lot of time with focusing charts. Not sure why they don't calibrate lenses at the factory(?) The Sigma is set to -4 but I understand the USB dock can adjust focusing at different focal lengths - which I guess can mean the lens can be out of focus at one end and in at the other.
I'm not sure whether to get a dock or send the lens away to Sigma as it doesn't focus near to in Live View.

07-17-2016, 12:53 PM   #62
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Not all sigma's are supported by the dock. Only newer models. You cannot calibrate a lens at the factory. ( Well you can to the specification of the mount), because there is sample variation between camera and lens. It is to be calibrated for the camera lens combination. Your live view problem probably won't be solved by the dock.
07-18-2016, 06:39 AM   #63
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Thanks - I suspected the dock wouldn't be the answer for me.
I think mine is compatible. It is the HSM version but not the newer Contemporary. They only seem to mention the docks being for (c) lenses, but I think I read mine can have firmware updates. (I have no idea how many firmware updates there are to see if that is worthwhile. ) But it looks like I'll be sending my lens to Sigma.
07-18-2016, 06:47 AM   #64
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It is compatible with these lenses (as far as they are being made for Pentax):

Compatible lens (as of April, 2016)
20mm F1.4 DG HSM
24mm F1.4 DG HSM
35mm F1.4 DG HSM
30mm F1.4 DC HSM
18-35mm F1.8 DC HSM
50-100mm F1.8 DC HSM
24-105mm F4 DG OS HSM / DG HSM
50mm F1.4 DG HSM
17-70mm F2.8-4 DC MACRO OS HSM / DC MACRO HSM
18-200mm F3.5-6.3 DC MACRO OS HSM / DC MACRO HSM
18-300mm F3.5-6.3 DC MACRO OS HSM / DC MACRO HSM
150-600mm F5-6.3 DG OS HSM
120-300mm F2.8 DG OS HSM
150-600mm F5-6.3 DG OS HSM

07-18-2016, 04:38 PM   #65
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QuoteOriginally posted by stevebrot Quote
...it just occurred to me that I have not heard of any problems with the K-500...go figure...
Apparently it can happen,
QuoteOriginally posted by NS_Sailor Quote
Got my K500 back from being repaired today after having the aperture control replaced. I was lucky to have an extended warranty if not the repair would have cost $318.00CAD
07-19-2016, 10:03 AM   #66
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QuoteOriginally posted by D1N0 Quote
It is compatible with these lenses (as far as they are being made for Pentax):

Compatible lens (as of April, 2016)
20mm F1.4 DG HSM
24mm F1.4 DG HSM
35mm F1.4 DG HSM
30mm F1.4 DC HSM
18-35mm F1.8 DC HSM
50-100mm F1.8 DC HSM
24-105mm F4 DG OS HSM / DG HSM
50mm F1.4 DG HSM
17-70mm F2.8-4 DC MACRO OS HSM / DC MACRO HSM
18-200mm F3.5-6.3 DC MACRO OS HSM / DC MACRO HSM
18-300mm F3.5-6.3 DC MACRO OS HSM / DC MACRO HSM
150-600mm F5-6.3 DG OS HSM
120-300mm F2.8 DG OS HSM
150-600mm F5-6.3 DG OS HSM
So nothing earlier? That would mean buying a dock would not be much use to me. The lens is on its way back to Sigma. Hopefully they can fix it.
07-19-2016, 10:37 AM   #67
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QuoteOriginally posted by stevebrot Quote
BTW...it just occurred to me that I have not heard of any problems with the K-500...go figure...


Steve
FWIW, I have a K-500 since september 2014 with almost 10 000 clicks. No problem so far, but I certainly will post on PF if I notice something looking like aperture failure...
08-27-2016, 06:17 AM   #68
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My shutter count is a bit over 5000 now. Got the SIgma lens repaired with some slight improvement. Started to like the camera a bit more and then yesterday and got two dark frames.
Not as dark as previous examples so not sure if this is shutter or aperture issue. The aperture thing confuses me. If the default position is open then shouldn't a failure to operate it properly result in overexposure?

08-27-2016, 02:13 PM   #69
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QuoteOriginally posted by Oricman Quote
The aperture thing confuses me. If the default position is open then shouldn't a failure to operate it properly result in overexposure?
The movement of the aperture actuator lever is to stop the lens down. How far it stops down is the task of the controller. In theory, failure of that component might result in any number of behaviors (e.g. over or underexposure, imprecision or a mix depending on the current sign of the zodiac). In terms of the common failure of the controller block seen on the K-30/K-50, the behavior is severe underexposure that is often intermittent. For some users of those cameras there have also been concomitant problems with mirror control. Some users have claimed shutter failure secondary to the aperture problems.


Steve
08-28-2016, 07:10 AM   #70
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Maybe I was envisaging a lens with aperture ring? If am aperture ring was used then the camera shouldn't be able to underexpose. Might be a solution for some?
09-10-2016, 05:27 PM   #71
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Anyone know if the new k70 uses the same old aperture block ???
10-14-2016, 03:42 AM   #72
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It looks like there is now a K-S2 with aperture block failure listed in the marketplace (only 1700 shots since April 2015):
https://www.pentaxforums.com/forums/24-photographic-equipment-sale/331774-sal...nly-black.html
10-15-2016, 07:59 AM   #73
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Yes, I think the Ks1, Ks2 are known to have the same problem being pretty similar to K30/ K50.

I've had a few more failures but I've found shooting in Raw means I can retrieve the image - just.
10-16-2016, 11:43 AM   #74
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QuoteOriginally posted by Oricman Quote
Anyone know if the new k70 uses the same old aperture block ???
Apparently the specific part felt to be at fault has been heavily used by Pentax over the years.
QuoteOriginally posted by athlonus Quote
For sure *ist, K-X, K-R, K10D models have two useful identical solenoids, one for the flash pop up up and the other for the aperture control. I have not checked any film SLRs but they (which were produced since 90's) are very likely to use the same part.
This makes me think that the issue is more with bad batches of the part than with anything else. I know this isn't a solution, at least not right now, but this issue would decline in appearance in any case as KAF4 lenses become more common, since their aperture control is apparently completely different.
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