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11-14-2017, 10:15 AM - 1 Like   #1
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Pentax KP Long Exposure performance

Heya,

I'm back! Just got a KP with 35mm macro ltd to go along with my 4x5" setup. Camera battery still charging but going to try out long exposure performance soon. What are your thoughts about it? Have you done long exposures with KP? Really interested to see how long it goes without the need for LENR. Fuji X-T20 is capped at ~1 minute @ base ISO without horrible white dot escalation in dark areas of the frame. I also put the camera in freezer to see how it works...frozen. Going to simulate cold environments and long series with intervalometer running until it pops (the battery I hope).

11-14-2017, 11:24 AM   #2
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Putting your new camera in the freezer... you're just asking for condensation issues regardless of weather sealing.

I'd imagine you can go way longer than one minute, my K3 does well with multi minute exposures!
11-14-2017, 12:03 PM   #3
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I've often done exposures between 2-4 minutes with both a K-500 and a K-3. The KP can certainly do as well if not better.
11-14-2017, 12:09 PM   #4
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QuoteOriginally posted by bobbotron Quote
Putting your new camera in the freezer... you're just asking for condensation issues regardless of weather sealing.


IIRC, the freezer is mild considering where he intends put the camera.


Steve

11-14-2017, 12:23 PM   #5
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Indeed. First run in freezer caused some mild issues, constant whirring sound while live view is enabled. K-1 did not do that. Now camera is in ziplock bag warming up slowly on its own and I'm off to go exposing something with it. I have one extra battery, Hähnel branded, which I inserted for 100 exposure interval test in the freezer and it almost died during the last frames. Hope the original is at least a bit better.
11-14-2017, 01:01 PM   #6
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QuoteOriginally posted by MJKoski Quote
100 exposure interval test in the freezer
Guess why Ricoh added the interval shooting mode. Before they did so, we could shoot anything inside the freezer from outside without opening the door, but now we can.
11-14-2017, 01:02 PM   #7
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QuoteOriginally posted by MJKoski Quote
Indeed. First run in freezer caused some mild issues, constant whirring sound while live view is enabled. K-1 did not do that. Now camera is in ziplock bag warming up slowly on its own and I'm off to go exposing something with it.
With some silicone desiccant or rice? Isn't there a significant risk of condensation forming on the cold, air-exposed surfaces of internal components? I'd have thought you'd want to use - at the very least - a camera bag, rather than a sealed zip-lock bag, so the temperature can rise slowly whilst still allowing the camera to breathe. My method of bringing a camera from fairly cold back to room temperature is to leave it in my padded shoulder-bag for a while.

I'm not criticising, here... If the zip-lock bag is a better method, then I've learned something!
11-14-2017, 02:09 PM   #8
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I got huge desiccant "bag" in there. 100g in weight.

11-14-2017, 02:28 PM   #9
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QuoteOriginally posted by MJKoski Quote
I got huge desiccant "bag" in there. 100g in weight.
Good man!! I'd have experienced nightmares if you hadn't said something like that
11-14-2017, 03:52 PM - 6 Likes   #10
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It is made of pantyhose and silica based cat sand. Works very well and is able to soak huge amounts of moisture. They are also very cheap to make. But, that aside, I took 8min and 2x4min exposures @ ISO100 just a moment ago without LENR. Now I have to say I am impressed with this little wonder - the photos have only like 10-20 bright spots which are easy to remove. And this is with 2 stop push!!! This is like better what K-1 does at similar times or about the same. I have never seen anything like this with APS-C camera. Now I am going to get the D-BG7 grip with K-1 battery to get more live view usage out of it.

--

Here is the 8 minute one. No LENR, 1 stop push!



This is superb performance. I suspect there is some kind of spatial filtering method done to RAW file without asking the user anything but it works rather well. Not as aggressive as Sony "optimizations".

Last edited by MJKoski; 11-14-2017 at 04:39 PM.
11-14-2017, 04:54 PM   #11
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No experience with the KP yet, but its on the short list to replace my K-30.

I've been out with my K-30 at -30F to -40 degrees for a couple hours at a time (Iditarod, Yukon Quest, dog mushing races, snowmobile races, northern lights, the Fairbanks Ice Art championships, and more) and both the camera and lenses performed flawlessly. My assumption would be that the KP and K1 should be equally if not more up to the task...
11-15-2017, 12:34 AM   #12
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It was -2C out there where I took that above photo. I used live view for ~10min to compose few shots and took 8min and 2x4min exposures without LENR -> battery 0% (Pentax original) and camera shutdown. That small battery is not going to make it very far in Finnish winter, so the grip is necessary. This morning, I put the battery back in and it showed about 75% capacity. Sony style it is.
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New findings. I set up interval composite of 30 images and did two series. One series with 30second exposures and one series with 10 second exposures. All NR settings were disabled in-camera. When exposure was set to 30 seconds, camera paused for few seconds between images (interval was set to minimum = instant). With 10 second exposures camera kept on ticking frame after frame with no delay. It seems that KP is doing some kind of filtering to the image after long exposures even if no NR settings are enabled. Not sure where the time limit is but looks like 30 seconds or so. Just like Sony's spatial filtering with A7mk1 and mk2 series. This explains why it does multiminute exposures with "better" quality than K-1.

This might be Pentax equivalent of Sony's star eater.
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