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Seriously, mine won't even give point stars on a 15s exposure with a 50me lens. My flipping Samsung snapcam does a better job. It's almost like its moving the wrong way!

Any suggestions?

I guess the first question is "what are you using it with?" It's supposedly only supported on the K3 and 645Z (however the manual does show the K-5, K-r and 645D with the latest FW??). Second question is "does it go through the calibration procedure and then tell you the calibration was successful? All I can think of.

This isn't the external unit, it's the built in function on the K3-II. Yes, it says calibration has worked. This is why I suspect it may be defective...

While it may be a little time intensive, it really helps if you can fully explain your process, lens used, and any other equipment involved. Then it also helps to see some example photos including the EXIF. Also, have you tried with other lenses like a wider lens? If you have a wider lens, can you get a decent exposure without using the astrotracer? Regarding the 50mm lens (I assume you meant 50mm), are you sure you have proper focus?

What kind of 50mm lens are you using? If its a manual lens, (M-series, A-series etc) you must set the focal length in the pop up menu when you turn on the camera. If you skipped this step and the camera assumes you use another focal length, then it will track at the wrong rate, making star trails.

At work, post later including examples...

I've only ever used the astrotracer with AF lenses.

OK here goes...yes I meant 50mm (curse you autocorrect). To be exact a 50mm Pentax DA 1:1.8 50mm. I get the same problems with the Pentax DA 18-55mm as well - be it at 18mm or 55...I calibrate every time I turn the camera on.

BTW I'm very new at the online posting thing and have no idea how to reduce the image sizes and someone took me to task for it once before - my apologies if they are bigger than convention would permit. All these taken with Astrotracer on and calibrated...

With the 50mm lens

30s, f1.8, ISO 100



15s, f8.0, ISO 12800



With the 18-55m lens (@55mm)

10s, f5.6, ISO 3200



I was really expecting better from such short exposures. Doesn't it claim somewhere that up to two minutes is possible?

I need to find some 18mm shots I guess...but honestly to my mind it seems to make no difference - maybe even make things worse. At some point I'll do some straight comparisons with it turned on and off butall other settings the same...

the o-gps is a mysterious device.....yer results are disappointing and should be much better like 60-90 second exposures with zero trailing would be ideal with a 50mm.....I have experienced the same both with trails of disappoint and times of static bliss.....it usually functions best with a strong battery......typically use 400iso......hopefully next time you will get much better results.....the dang thing can be super frustrating but it can do wonders as well

Astrotracer works well but it has its limitations. First of all, precise calibration is critical for good results. Be sure, if you are using a manual lens or one that doesn't communicate its focal length to the camera that you have the correct focal length set in the menu. Overhead shots work better with minimal trailing and center of the frame is better than the edges.


The max exposure time is complicated. Under ideal conditions 5 minutes is the absolute top. When you set up the device on your camera it will tell you the max exposure time which is usually somewhat less than 5 minutes. Personally I would not exceed half that or the edges trailing will be more pronounced. Wider lenses are more forgiving but longer lenses render more detail; 50mm is a decent compromise.

yes that is quite important for manual lenses and should not be overlooked!

Again, this is the built-in unit on the K3-II, not the external O-GPS1. Most of my lenses are automatic, but if not I always enter the correct focal length. I always do the precise calibration. I don't think the built-in unit gives a suggested maximum exposure, though if someone can show me where it is I'd be very grateful.

My experiences with O-GPS1 and K-5 were that it allowed 10x (regularly) up to max 20x (sometimes) the exposure time of the 500 rule. So with your 50 mm 60- 120 seconds should be expectable. I used 20 seconds with my 200 mm typically. The succes varies with the inclination angle of the cam and the azimut of the stars you shoot at. the higher the declination and the closer to the celestial equator the cam is oriented the more I got trails. And beware of metallic (magnetic) things and electric fields in the near of the camera because the eyact measurement of the magnetic field ist essential for the calculations performed within Astrotracer.

Again...not O-GPS1...K3-II. Maybe the former is better than the latter? Regrettably the latter certainly doesn't seem to provide anywhere near as much information.

I don't think the O-GPS1 is better. Whatever - your results just aren't acceptable and seem to justify a warranty claim. Others with the K-3ii have had and do get much better results, so in your case a hardware failure seems the most plausible cause of your poor results. Such failure could be either in the GPS-unit, in the accelerometers or in the sensor actuators.


A couple of things you should try before you make a claim:


1. Does the GPS unit give you the right co-ordinates? Use a program like Geosetter to verify.
2. Are the compass readings stable or do they flicker erratically?
3. Does the electronic compass show the proper heading (+ some 5 degrees)? Center on a prominent object and verify using Geosetter again.
4. Have you tried to shoot from different locations and in different directions? Strong, local magnetic disturbances can have a very detrimental effect on the Compass, and hence also the Astrotracer functionality.


Good luck. You have every right to expect better results than what you currently are getting.