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Forum: Pentax Full Frame
08-30-2016, 11:06 AM
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Yes it can, press info button twice to get to the display options, then step to the rightmost option for electronic compass and hit ok.
Note that this will also turn on the GPS.
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Forum: Pentax Full Frame
08-29-2016, 11:46 AM
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It seems impossible to get a better accuracy then +-15 degrees, so I made an experiment.
I turned the camera in the direction where the error was the largest, I then taped a piece of a metal paperclip on top of the prism house in such a way that the error was minimized. Then I turned the camera to the new largest error which where about 90 degrees from the original one and again I taped another piece of the paperclip on top of the prism house in such way so that the error was minimized.
And now the error was down to +-5 degrees in any direction. Success, and I figured that maybe I should do something more portable that could be attached and removed sitting in the flash shoe.
But then I tried a new calibration with the compensation clips still attached, and unfortunately the original error was back. My compensation clips where compensated for.
Back to the drawing board. Hm, maybe an adjustable metal bar on top of the prism house that I can rotate until the compass shows exactly the heading I want... Not pretty but maybe it can improve the astro tracker performance?
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Forum: Pentax Full Frame
08-29-2016, 08:56 AM
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It will compensate for the zoom, unless it's an old lens that doesn't report the focal length camera, in which case you will have to manually enter the focal length.
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Forum: Pentax Full Frame
08-28-2016, 12:47 PM
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I've tried that as well. But this rotating of the body is most probably only for calibrating the 3-axis electronic compass. The position fix is made by the GPS, and a GPS does not need any manual calibration, but an electronic compass do. In fact you can do the calibration process while still being in house without the GPS ever getting a lock. (But of course is should also be done at the photo site, but for practicing purpose you can do it at home in the house.)
---------- Post added 08-28-2016 at 09:51 PM ----------
I fully agree. Or even better a manual deviation table for the complete 360 degree turn.
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Forum: Pentax Full Frame
08-28-2016, 11:58 AM
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That's what I figured as well, and even though I got a slightly different result it wasn't that much better. I still have quite a large variance in precision during a complete 360 degree turn. At some directions it is spot on, at other directions it is slightly behind and yet other directions the compass is way ahead. A little variance is expected but when the error reaches 20 degrees it is way to much. This could happen with the ogps-1 as well but a couple of re-calibrations later one usually could get a really good accuracy.
---------- Post added 08-28-2016 at 09:01 PM ----------
Yes, that is what I do. I usually rotate the first axis while still mounted on the tripod, then hook it off and do the other two "by hand".
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Forum: Pentax Full Frame
08-28-2016, 09:42 AM
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In order to use the astro tracer it's necessary to have the electronic compass calibrated. And even though the calibration process says that the calibration procedure is "OK" the result can differ quite a lot from time to time.
With the ogps-1 on my K-5 i could after a couple of trials get a pretty good accuracy. Usually less then 3 degrees error for most of the directions but often there were one direction that could be up to 5 degrees in error. But all in all quite good.
With the K-1 I have yet to get under 15 degrees in error in the "bad" directions. Usually about 20 degrees in error in some directions and less then 3 in others. Very inconsistent.
But during my tests I also found out that the movable LCD affects the compass with up to 10-15 degrees in some directions depending on the position of the LCD. So moving the LCD in or out turns the compass. This does not happen in all directions though.
So I figured that since I will have the LCD out and tilted when doing astro work I will also have to have the LCD out when calibrating. But while that does give a different result compared to having the LCD tucked in the accuracy didn't improve much.
The procedure I use to check the compass is to first align the tripod head (which have a 360 degrees scale) so that 0 degrees on the scale has the camera pointing to the north. Then I attach the camera and watch the compass heading on the LCD and compares with the scale on the tripod. Turn into different directions and compare. Do not have the camera mounted on the tripod when aligning to the north since the camera body is full of magnets and will affect any compass used to align the tripod.
So the question is, has anyone else checked the accuracy of the built in compass, and did you get at better result?
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