K-3 II Astrotracer Weirdness

really hoping someone can help with this: K-3II with Asahi Takumar SMC 200mm F/4 lens. so, calibration "appeared to have gone well", but the resultant image [F/4, iso800, 20sec] appears to have "doubled" every star in the image. strange though, because I next took a quick capture of the Moon [F/22, iso100, 0.7sec] appears nicely in focus. I used a Bahtinov to get focus for the first star image!







and, a crop of the first image:

The purple is chromatic aberation! Try closing down you f stop... go to f5 - f8...

As for the double star.... did you correct calibrate the tracer and did you by anychance catch the tripod??

When I used one I found it was a bit hit and miss on lenses over about 100mm. I got rid of it and bought a Sky-Watcher Star Adventurer 2i Pro.

hi, yes, correctly calibrated. no, didn;t bump/catch the tripod (catching/bumping the tripod would result in a "line" between each "double-star"?

this is almost as if it captured the whole image twice - it's like a double-exposure?

It has been a while since I used my astro tracer.

But how sturdy is your tripod, and tripod head? If you have a tv aerial in the image, you are shooting at a lowish angle. By any chance, did you shoot anything nearer the zenith? And if so, did you have the same problem?

Gary

hi Gary, all is very steady.
Not really a lowish angle - just very close to the house!

I've been told elsewhere that it could be that I need to tell the camera that the 200mm takumar is 300mm (crop factor)? will try that, but can;t see how it creates "double stars"

Are you using a wired cable release to trip the shutter, so not physically touching the camera.

I am not sure that the using the crop factor is going to do anything, but I am opening to learning something new. It looks as if you getting two images on the same image. Everything sounds normal, that is the shutter only opens and closes once by listening to the camera?

What happens if you use a different shutter speed? Shorter, or longer? Move away from the house if possible. Maybe your gps unit can't lock onto enough satellites in different directions. Try in a more open area.

Let us know how you get on.

Gary

yep, using a wired shutter release

my feeling exactly - it looks like a double-exposure - is there a Pentax menu setting that does this?

the moon image is fine - so shorter exp definitely works fine

Yes... where you have the four control buttons surround the circular button. The top middle one above ok.




These are your shooting modes. Multi Exposure is on the right.

I'm thinking this has something to do with Multi-Exp Mode and Interval Shooting. Is there a way to completely disable both. At present M/Exp is set to "sunlight" and "3" - I cannot find a way to disable this completely.
Self Timer = 2s,
Mirror Lockup = is on

Yes... use the left button to move the selected mode to the single green square. This should put it on single shot.

You may have to use the up button as well.

cheers

It might be worth using Mirror Lock Up. This can help to reduce shutter shake. Especially on longer focal length lenses.

I use it a lot for shooting when my camera is attached to a telescope.

there's two options

MUP
and
MUp with a little "symbol"

First one is Mirror Up using shutter release (use with your cable release) and the other is Mirror Up using a Remote conttol.

The camera will start beeping. You then have about a minute to take the picture.

thank you - so I'm using the first option