[NaClH2O]

I took my K-1 out on Sunday in 15F weather. For the first hour I was shooting hand held with the D FA 28-105 lens and had no problem. Battery was fully charged (I pulled the battery off the charger where it had been sitting overnight). After about an hour of hand held shooting I attached my camera to my tripod and immediately experienced a big metering issue. In Tv mode with the Sigma 70-200 EX DG (non macro) lens attached and about 6 stops of ND filter attached, the camera gave me an aperture of 22 with 2 seconds of shutter speed dialed in. However the resultant shot was massively over exposed to pure white. Tried the same shot with the same ND etc in M mode and got the same results. It wasn't a particularly bright day and I was mostly in shade. After about 10 minutes of trial and error I was finally getting decent results with 10 stops of ND filters, plus my CP filter at f/32 and 1 second shutter speed. I was using the tripod mount on the lens. I've taken the K-1 out in winter weather before but never this cold. After about 1/2 hour to 45 minutes of shooting this was the camera started metering normally again, with shot brightness reflecting the numbers listed by the camera. I will admit that I didn't think to try setting the lens to the non-A setting and using it as a manual aperture lens. Has anyone had any problems with K-1 metering in rather cold weather? There was no appreciable wind chill as the wind was almost calm.

NaCl(it's a head scratcher)H2O

[CarlJF]

Could it be that the aperture lever got frozen and stuck in the lens ? Meaning that the metering wasn't done at the aperture expected by the camera, or that the pictures were all taken at full aperture and not closed down as expected ?

[Bob 256]

It's also possible that the lens malfunctioned. The small tab on the back of Pentax lenses is used to drop the aperture to the correct value when the shutter trips and I've seen a lens where an internal cam got stiff and prevented this from happening (it incorrectly set the aperture to full open). That required lens surgery to get the cam loosened up and working again. It's conceivable that cold weather could create a similar problem. Try another lens next time this happens or take the lens off, dial in f22 and see if the tab will open and close the lens (off-camera, the lens should close to f22 and moving the tab will open it). You should also be able to test this with the depth-of-field option while looking through the viewfinder). Not saying this is the problem, but one more possibility.

[Supakatti]

That temperature should not cause any other problems to K-1 but battery drain a tad faster.
Of course, there is other aspects like humidity level causing freezing. When you bring your gear in the house, you should let it dry well, before taking it out in cold again. The possibley remaining water will turn into ice and cause big problems.

[stevebrot]

Was the metered exposure to blame or the actual exposure provided by lens and camera. I suspect sticky/thickend lubricant in the lens actuation or iris mechanism.


Steve

[NaClH2O]

Thanks everybody for your input. I'm thinking that it was the lens. The Sigma is an old lens and the aperture actuator could have gotten frozen, and the default is wide open, which is what the shots were indicating. I don't shoot cold frequently, but often enough that I'm careful about letting gear warm up gradually and without generating too much condensation. Ironically enough the piece of equipment that I have the most problem with is the O-ME53 magnifying eyepiece. There are two lenses in the eyepiece with a space between them and they fog up in the internal space. If I've been shooting outside in the cold and go inside to shoot in the NY Botanical Conservatory, I remove the eye piece and put it in my pocket. After about 1/2 an hour I can use it again,.

NaCl(the little tricks you learn)H2O