[AlexanderS]

Hi everyone!
unfortunately, I am also having trouble with trails using the astrotracer and the ogps1. Maybe someone has any idea or a suspicion (I dug through all posts the search gave me even somehow related to astrotracer issues, but it seems individual case assessment yields more results), or someone lives near Copenhagen in Denmark or Sweden, and I could visit and try my opgs1 unit with your camera, bribes including some hot chocolate/candies .

Here a short summary of all details, and some pictures:
Camera: Pentax K-70, newest firmware
lenses used: Pentax DAL 18-50, Vivitar 55mm macro
Ogps 1
Cullmann travel tripod

Setup:
1. Placing the ogps1 on the camera, turning the fixing lever to the right, seems well-connected
2. Turning on Pentax k 70, turning on gps unit
3. Making calibration, then going into the menu, precise calibration
4. Getting 3D number of satellites
5. Going into bulb mode, turning astrotracer in the info menu on.
6. Turning off everything else, like noise reduction, etc.
7. Lens is manually focused, and I make shots that do not exceed the Pentax provided exposure time scale(when using the vivitar, I enter the focal length in the menu).

To have nothing disturbing the shot, I went in the middle of an absolutely empty parking lot, no metal around me for 20 meters, removed everything metallic and magnetic from my body, clothes, etc. The batteries of both the camera and the gps are fully charged. The compass seems to point correctly, and also without major disturbances.

8. Help! I really really love night photography, and this feature is actually quite important to me! Not that the camera would become worthless without it, but this would hurt....

Attached Images

         

[Auzzie-Phoenix]

There are plenty of things that could be going on here...

1.) Exposure is too long (don't trust "time scales". Trust only tested experimentation results for focal lengths/f stop settings.)
2.) Tripod/head may not be quite sturdy enough.
3.) Wind/vibration (ties in with #2).
4.) Angle could be too steep.

The picture with the building is really bad, as if something had bumped the tripod. Are you using a remote trigger, or are you using the self-timer? If you are using the self timer, the vibrations going to the sensor from the camera body may not be subsiding by the time the timer opens the shutter. As is, the little calibration dance for fine tuning really isn't necessary.

Even with a 10mm lens set wide open, there will be some (minimal) trailing at the 2 minute exposure mark. For the 18-55 at 18mm f/3.5, you really wouldn't want to exceed 1 min 20 sec. The 55mm would be an even shorter time. Trial and error is the best way to find out what works and what doesn't.

Please bear in mind, that the astrotracer function doesn't work well if you exceed a certain camera angle. I believe the consensus was somewhere around 30 degrees of elevation. The anti-shake system wouldn't have the power to move the sensor effectively after a certain angle of incline.

Batteries... make sure they're fresh. GPS requires quite a bit of battery power, so always make sure your batteries are good prior to leaving the house.

[Adam]

You can expect good results in the 30-60 second range, IMO, generally-speaking. This will vary based on your location, focal length, and precision of the calibration.

I would start by taking a photo without the astrotracer as your baseline for comparisons. Then, enable the astrotracer and increase the shutter speed until you start seeing trails. That way you'll be able to determine the longest/optimal shutter speed, and also identify if calibration is an issue.

[k5astro]

Try it on a friends camera. I had one and could not get it to work on my camera. I now have a K-3II with it built in and I still can't get it to work - gave up - I use a Star Adventurer instead - works great.

[AlexanderS]

Hey, thanks for the replies, I did already cut it down to 40 seconds, still trails are visible, and also made comparison shots without tracer turned on....only minimally worse, which is nothing good about the opgs1 to write home about. The tripod might be a bit of an issue, I will dig out my sturdy one (dont like it for the size and weight, but who knows, might help).

Star Adventurer looks great, and the price is almost the same as this crappy opgs1 unit, I want to rather fix the problem at hand, but at least that suggestion is a nice possibility, if all else fails

The biggest issue might be that there are not too many Pentax shooters around, finding someone to test with might be rather wishful thinking...lets see

[Odinz]

I have been using the OPGS1 on my K3 for several years and find it to be hit or miss for me. Sometimes it works and sometimes it doesn't. There are times where I'll shoot maybe a dozen shots from the same position on a clam night with a heavy duty tripod same shutter settings without touching the camera in between shots. Some shots will look great and others will look like I didn't have it on at all. It also appears randomly, I'll get 8 great shots but shots 2,3,6 & 9 will look like I didn't use it at all. It's always done that and I've never been able to figure out why so I always shoot enough to make sure I get the shot.

[Canid]

Shots with Astrotracer ON and OFF for comparison would really help here.


Looking at the building picture, the star trail looks about half the length of the movement at the window - like it's going in the opposite direction (I don't think it would be possible to install it backwards, would it?)

Were these all taken on the same night? Were the batteries in the O-GPS1 unit new?

[MossyRocks]

Are there high voltage wires near by? If so they could be generating a large enough magnetic field to throw it off.

The first picture is the one that confuses me the most as it seems like the sensor is moving in a different direction from the stars as the trails direction changes across the picture.

With the little playing with the astrotracer on my K-3 I have done I have had varying results but nothing like this. I have found that errors do start creeping in but if you get it calibrated correctly using a rule of 2000 (time=2000/focal length) seems to prevent any trails with the lenses I have used it with and you get really nice point stars. I haven't played enough to get a better number but in the 3 times I have used it that seemed to provide some good results.

[jbinpg]

I suggest you turn on the Astrotracer in the menu before you do the calibrations. Should make a difference.

[AlexanderS]

Shots with Astrotracer ON and OFF for comparison would really help here.


Looking at the building picture, the star trail looks about half the length of the movement at the window - like it's going in the opposite direction (I don't think it would be possible to install it backwards, would it?)

Were these all taken on the same night? Were the batteries in the O-GPS1 unit new?

Hey,
the batteries are new, Eneloop, and opposite isnt possible, otherwise it wouldnt fit into the hotshoe. If I get a cloudless chance, I might try it again soon. My biggest issue is that I live basically in the middle of light pollution itself, have to cycle quite a way for decent levels.

---------- Post added 05-04-18 at 12:03 PM ----------

I suggest you turn on the Astrotracer in the menu before you do the calibrations. Should make a difference.

Will try that(can you tell me what difference that would make, just keen interest), although I think I have not even turned it off the last couple of times....lets see

[SSGGeezer]

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[GodsPetMonkey]

I thought I had previously posted my quick guide to the astrotracer, but I can’t find it any more, so I’ll try to recreate it.

(I haven’t used the OGPS, just the built in GPS on the K3II and the K1, but the actual operation is the same)

0. Make sure the camera has the right focal length for your lens - manual lenses will need this manually inputted!
1. Hook up and turn on the GPS
2. Switch the bulb mode.
3. Enable Astrotracer (from memory you can’t precise calibrate until it’s enabled in the menus)
4. Do a precise calibration. This calibrates the compass, not the GPS, so avoid magnetic fields - think power lines, anything iron (so basically metal), keep in mind what is underground as well as above. Even a small error in the calibration can have a big impact given th precision needed for the astrotracer.
5. Do another precise calibration. My first is never as good as my second.
6. Attach the camera to your sturdy tripod, point at some nice part of the sky. Avoid windy areas, and avoid photographing near the celestial poles (ie. straight north or south).
7. Take a test shot; 30 seconds, 1600 ISO, wide open is a good start. If the image is washed out, decrease ISO, if you see trails, recalibrate! Repeat until you have something you like. Your first image will probably be a mess.
8. Adjust exposure time up, increase ISO to compensate. When you get too much trailing, decrease exposure time or see if more calibration helps.

Astrotracer, and astrophotography generally is an art that involves a lot of patience and trial and error. My general experience is that I don’t go over 60 seconds with the astrotracer, and longer lenses mean shorter exposures (so typically 30 seconds at 100mm). There are exceptions, given the right conditions, but you just need to play and tweak to find out where they lie.

[awscreo]

Hey, thanks for the replies, I did already cut it down to 40 seconds, still trails are visible, and also made comparison shots without tracer turned on....only minimally worse, which is nothing good about the opgs1 to write home about. The tripod might be a bit of an issue, I will dig out my sturdy one (dont like it for the size and weight, but who knows, might help).

Star Adventurer looks great, and the price is almost the same as this crappy opgs1 unit, I want to rather fix the problem at hand, but at least that suggestion is a nice possibility, if all else fails

The biggest issue might be that there are not too many Pentax shooters around, finding someone to test with might be rather wishful thinking...lets see

Maximum I could achieve without trails in center of the frame with a 14mm lens at 2.8 on k-1 was 90s. Anything over gave me trails at pixel peeping level. I usually used 60s and was fine with results. Although, due to extreme fov corners of the image showed some trailing.

[Adam]

Hey, thanks for the replies, I did already cut it down to 40 seconds, still trails are visible, and also made comparison shots without tracer turned on....only minimally worse, which is nothing good about the opgs1 to write home about. The tripod might be a bit of an issue, I will dig out my sturdy one (dont like it for the size and weight, but who knows, might help).

Star Adventurer looks great, and the price is almost the same as this crappy opgs1 unit, I want to rather fix the problem at hand, but at least that suggestion is a nice possibility, if all else fails

The biggest issue might be that there are not too many Pentax shooters around, finding someone to test with might be rather wishful thinking...lets see

In that case this sounds like a calibration issue. It does take a bit of patience (and care) to get it to work right, but once it does the results are super rewarding.

I would recommend calibrating while sitting down, turning the camera slowly, one axis at a time.

[k5astro]

In that case this sounds like a calibration issue. It does take a bit of patience (and care) to get it to work right, but once it does the results are super rewarding.

I would recommend calibrating while sitting down, turning the camera slowly, one axis at a time.

You could be right. I started to get the distinct impression that I just didn't have the magic touch!