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12-21-2014, 08:40 PM   #1
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Interval Composite Glitch

Last week I tried to do some interval composite star trails. My K-3 would not do it if I used a 30-second shutter speed. 25 seconds? fine. Not 30. Anyone else having this issue? Is this a glitch or an intentional design ... thing?

12-21-2014, 09:47 PM   #2
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Working as designed. The interval is shutter speed + pause between frames. Thus, the interval will always need to be larger than the shutter speed. Longest shutter speed is 30 seconds so you won't be able to use it.
12-22-2014, 12:36 AM   #3
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So, I can't set it to 30-second exposure with a two-second interval but I can do a 25-second exposure with a two-second interval, because the latter is only 27 total seconds? Why it would be designed that way makes zero sense but is an even better argument for why Pentax needs to update the firmware to make a zero-lag option for the interval shooting modes.
12-22-2014, 06:59 AM   #4
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Easiest way around this is to put it in remote mode with continuous shooting, set your exposure time to 30 seconds, hit the shutter and let the camera fire away. Make sure that you turn off all lens corrections, shadow/highlight correction, etc. as the extra processing inserts a delay between shots in both interval and continuous shooting mode.

12-22-2014, 07:30 AM   #5
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QuoteOriginally posted by K David Quote
So, I can't set it to 30-second exposure with a two-second interval but I can do a 25-second exposure with a two-second interval, because the latter is only 27 total seconds? Why it would be designed that way makes zero sense but is an even better argument for why Pentax needs to update the firmware to make a zero-lag option for the interval shooting modes.
You can! - but the interval may need to be 33 or 34 seconds rather than 32. I just tried it out on my K-3: Works fine with 30s exposure and 33s interval.
12-22-2014, 07:44 AM   #6
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This is correct as well, but I tend to use the continuous shooting workaround anyway for star trails since a), the camera fires the shutter the instant it is ready rather than waiting the extra 2-3 seconds between frames, resulting in a smoother appearance of your merged trail, and b) even with the increased interval, I've found that on long sequences the body will occasionally skip a frame here or there unless you bring the interval out to 35 seconds or so.

QuoteOriginally posted by Stone G. Quote
You can! - but the interval may need to be 33 or 34 seconds rather than 32. I just tried it out on my K-3: Works fine with 30s exposure and 33s interval.
12-22-2014, 01:57 PM   #7
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QuoteOriginally posted by K David Quote
even better argument for why Pentax needs to
And you are sure that it works differently with other cameras? This sort of logic is pretty common unless you expecting something different. After all, it is nice to know that 10 intervals of 30s = 300s regardless of the actual exposure times.


Steve

Last edited by stevebrot; 12-22-2014 at 02:03 PM.
12-22-2014, 04:00 PM   #8
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It works this way because it has worked this way since the dawn of interval timing. An interval is... an interval. Every X seconds you trigg an event. If the event takes longer it will finish and wait for next trigger. Therefor you will need to calculate a new interval or event duration. Changing it would make it really weird for me.

---------- Post added 12-23-14 at 12:02 AM ----------

Also remember that the camera needs to save the file to the SD-card and get ready to shoot again so do not make the pause to narrow.

12-22-2014, 10:23 PM   #9
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I suppose that what I don't understand is that if I choose a between-shot interval of two seconds and the camera works fine at a 25-second or slower exposure and doesn't work fine with 30-second exposures, why? What's odder still is that this only happens this way with interval composite. With straight-up interval shooting, it will take a 30-second exposure and then another every two seconds until it hits 2,000 (or the sensor overheats.) This is limited to 30-second exposures on interval composite.
12-23-2014, 03:25 AM   #10
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QuoteOriginally posted by K David Quote
I suppose that what I don't understand is that if I choose a between-shot interval of two seconds and the camera works fine at a 25-second or slower exposure and doesn't work fine with 30-second exposures, why? What's odder still is that this only happens this way with interval composite. With straight-up interval shooting, it will take a 30-second exposure and then another every two seconds until it hits 2,000 (or the sensor overheats.) This is limited to 30-second exposures on interval composite.
Please tell me what you have set for time in interval and how many pictures have you set it to take? When I read your first post again I suspect you have set your interval to 2 seconds and shutter speed to 30s. Is that so?

You need to set the interval time to be > or = shutter speed + paus time+ camera image processing time
12-23-2014, 11:35 AM   #11
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QuoteOriginally posted by Tjompen1968 Quote
You need to set the interval time to be > or = shutter speed + paus time+ camera image processing time
Your understanding is correct. I'm going to try it with these settings tonight and see if I can figure it out. I know I'm doing something wrong, but I just don't know what.
12-23-2014, 11:40 AM   #12
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QuoteOriginally posted by Tjompen1968 Quote
You need to set the interval time to be > or = shutter speed + paus time+ camera image processing time
Turn off preview and AF and auto exposure to make the pause time minimal.


Steve
01-03-2015, 12:55 AM   #13
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So I've been testing my camera in interval composite mode some more. Here's what I've found.

When setting the time between frames, that's the time that lapses between each image (and is in addition to the shutter time.) I tested this by trying multiple-second exposures with both a two-second interval and the exposure+2 seconds. In each case, the interval (when it worked) what the number of second I input and did not take into account the shutter duration. So a 10-second shutter speed with a 2-second delay would be 12 seconds from shutter-up to shutter-up. With a 12-second duration, it was 22 seconds between. So that's how the K-3 is working, to remove any confusion about that.

I had a 32GB 95MBs San Disk SD card in the camera for the tests, the same card I've used for more than a year. I've also tried these tests with a brand new 64 GB 95 MBs San Disk SD card. The results were the same.

Not on;y will the camera only take a single photo on 30-second shutter speeds with interval composite mode, on no shutter speed could I get it to take more than two images. So it's a fair question, how many did I have it set to take? 3, 5, and 10. At no point would my K-3 take more than two interval composite shots at any shutter speed any more.

Also, after trying to take an interval composite with a 30-second exposure (and only a 30-second exposure), the camera goes back to the main screen instead of continuing the composite. The control wheels are then unresponsive (full manual mode) and I have to turn the K-3 off and then on again to regain function control.

My firmware is current (1.11.). This issue happens regardless of the image capture mode, image file type (jpg or raw+), and any of the other myriad settings I've tried.

So, can I ask a favor of people with a K-3?

Can you set your K-3 to interval composite mode (the shooting mode furthest on the right) and select any of the blending modes (it does not matter -- this issue is happening regardless of blending mode.)
You can select to save the process, or not, this issue occurs regardless.
Set your shutter speed for anything (2 seconds, 5 seconds, doesn't matter) and then your interval for 2 seconds (or 3 or 5 -- for me if I select 2 seconds I get two exposures, with any other interval I get three exposures -- even though I have the number of exposures set to 5 or 10.)
Let me know if your K-3 stops taking photos before it is supposed to or if it keeps going, please. I'm trying to figure out if this is a my-camera issue or a firmware or software issue.

Thank you all for your input, help, and insight. At this point, I am 100% certain that something is not working correctly. I just need to figure out what.


Edit: Interval shooting is also behaving the exact same way (not functioning correctly).

Edit 2: On a whim, I tried setting it to take 2,000 exposures. It kept on going past the previous limits where it stopped. So I tried it at 1,000 exposures. It kept on going then, too. So it looks like the problem is using interval composite mode with very few exposures.

It would still be good to know if other people's K-3s work like this.

Last edited by K David; 01-03-2015 at 01:07 AM.
01-03-2015, 02:13 AM   #14
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As for the 30seconds exposure that ends up with an unresponsive camera, usually that means that the function "slow shutter speed noise reduction" (at least that is what it is called on the K5) is on.
What is does is that it takes another 30 seconds exposure with the shutter closed to record sensor noise, which it then subtracts from the image. This is also known as dark frame subtraction. For the user that means that the camera is unresponsive while the second exposure is in progress. This second exposure is as long as the first one, so for a 60 minutes exposure, the camera will be unresponsive for yet another 60 minutes after the first exposure. Not always that fun, I have this function off.
01-03-2015, 12:59 PM   #15
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QuoteOriginally posted by Gimbal Quote
As for the 30seconds exposure that ends up with an unresponsive camera, usually that means that the function "slow shutter speed noise reduction" (at least that is what it is called on the K5) is on.
That setting is off on my K-3. Interestingly, the unresponsiveness goes back to the info screen, not to a blank screen. And some functions respond, like the menu button, but other's don't, like the command wheels.
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