Pentax K70 /Pentax 17-70 SDM Issues


cvhennessy

Link Posted 08/06/2020 - 18:02
Hi.
I've recently bought a K70 secondhand from Wex and over the weekend received a Pentax 17-70 SDM lens I bought on ebay. I've found an odd problem in that photos with this lens are constantly overexposed by in excess of a stop. This happens in all metering modes. The other 2 pentax lenses I own do not have this issue and exposure compensation corrects it which indicates that the aperture is shutting down, just not enough. Unfortunately I don't have any other bodies to test the lens on, though I've owned lots of Pentax kit in the past. I've cleaned all the contacts off and upgraded the firmware to the latest version but to no avail. Anyone have any ideas? To me it looks like a lens issue but its difficult to be certain.

cvhennessy

Link Posted 08/06/2020 - 19:01
I think I may have identified the issue. The aperture arm is very stiff and has no spring

HarisF1

Link Posted 08/06/2020 - 22:21
You're best off returning it - with the 17-70 also have the SDM failure to worry about at some point. A lens like the 18-135mm or the 16-85mm would do fine.

jeallen01

Link Posted 08/06/2020 - 22:59
HarisF1 wrote:
You're best off returning it - with the 17-70 also have the SDM failure to worry about at some point. A lens like the 18-135mm or the 16-85mm would do fine.

Or a version of the Sigma 17-70 which is pretty good AND reliable (and which has replaced my 18-135) - one is available on the forum, albeit from Croatia
K-3 II, K-3 and a K-70 from SRS (having now relegated the K-30 /"K-50" to a backup body), & some Sigma and Pentax lenses (and a lot of old 35mm gear!)
Last Edited by jeallen01 on 08/06/2020 - 23:00
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