Astrotracer shows trails, what am I doing wrong?

honey bo bo · 01-03-2016, 08:20 PM

Originally posted by Sagitta

By that same token, don't set up right next to your car (similar reasons). You have to remember that part of what makes the tracker tick is being able to lock on to the magnetic pole - if anything interferes in that, then you won't get decent results as things won't track true.

The O-GPS1 uses the WGS 84 system (World Geodetic System) 4 satellites and actually tracks true North not magnetic north. In the instructions they say to do a calibration prior to using Astrotracer and I believe it should be a precise calibration to get all the info from the satellites. Further this calibration takes care of any magnetic interferance in the area .
See "O-GPS1 Pentax GPS Unit Review" on this forum.

Gimbal · 01-04-2016, 05:11 AM

The GPS part in the O-GPS1 doesn’t need any calibration, it’s a normal GPS. And just like any other GPS it has no idea of how it’s orientated. All it can figure out is where it is, how fast it is mowing and in what direction it is mowing.

The calibration is for the magnetic compass and the accelerometers in the camera. These sensors tell the camera in what direction it’s pointed, angle up/down and angle of tilt left/right.

honey bo bo · 01-04-2016, 06:26 AM

Originally posted by Gimbal

The calibration is for the magnetic comp

Originally posted by Gimbal

The GPS part in the O-GPS1 doesn’t need any cali

So are you saying you don't have to calibrate the O-GPS1 to use the astrotracer and that it is locking in on magnetic north ? Completely contrary to what I'm reading! I'm confused!

P.S check your spelling we are not talking about mowing hay.

Gimbal · 01-04-2016, 07:00 AM

Originally posted by honey bo bo

So are you saying you don't have to calibrate the O-GPS1 to use the astrotracer and that it is locking in on magnetic north ? Completely contrary to what I'm reading! I'm confused!

P.S check your spelling we are not talking about mowing hay.

You still have to calibrate since the astrotracer function needs the data from the accelerometers and the magnetic compass to know where you are aiming, and the position data from the GPS to know where you are.

Sagitta · 01-04-2016, 05:39 PM

Originally posted by Gimbal

You still have to calibrate since the astrotracer function needs the data from the accelerometers and the magnetic compass to know where you are aiming, and the position data from the GPS to know where you are.

This.

This is the reason I can't use my unit down along the banks of the Kennebec here in town. There ince was a factory that dumped a stupid amount of slag into the river, as well as tenement housing which was bulldozed back in the 1960's in the name of urban renewal. All that iron and steel from the factory waste and the houses was basically buried and forgotten about. To add to things, the town then went in and ripped things up in the early 2000's to install sewers and itilities in the (so far) failed hope of creating development in the plot, which added sewer and electric lines underground on top of everything else.

The end result is that I have yet to be able to use the O-GPS reliably there, despite it working just about everywhere else.

EDIT: Said magnets are actually a part of the camera and not the unit - these are the magnets that control the in-body shake reduction system in the camera. I suppose technically the SR could get thrown off if you tried shooting with enough steel around you to affect the system as well, but I don't know if anyone has ever tested that out.

skogpingvin · 01-16-2016, 12:54 AM

Originally posted by photographerclare

Also, my camera makes a clicking sound when it is taking long exposure shots, I don't know if this is normal. Here is my best attempt so far (I have not been able to recreate it).

Has anyone been able to solve this one?

I'm getting the same clicking from my K-3 II when taking AstroTracer shots when I use longer lenses. I thought it might have been the OS on the Sigma 150-500 I used, but it happens on an old Tokina 70-220 as well, but not on the shorter ones like the Pentax SMC 85. The clicking is associated with poor tracking, and I'm thinking it's causing a shake, but I've no idea, really.

I live in Melbourne where there's lots of light pollution, so the shots I'm getting are pretty poor, but here's one of the standard Orion Nebula. Looks like that's what everyone starts with!

Grey Area · 01-16-2016, 08:35 AM

Astrotracer on...not that you'd think so. 55mm lens, 60s exposure, calibrated ok. Sometimes it works, sometimes it don't...

skogpingvin · 01-16-2016, 03:33 PM

My shorter lenses seem to work pretty well. I do notice that after a while the calibration goes off and needs to be re-done. These two shots were taken within about 30 minutes. The Pleides shot (with the satellite) has nice round stars, but the Small Magellenic Cloud (which isn't to be called SMC here, it seems, as that acronym is taken) has trails. My problem is the longer lenses, which I do know pushes the AstroTracer's abilities a bit.

slartibartfast01 · 01-19-2016, 04:56 PM

When I use the astrotracer on my K50 with a Tamron 70-200 f2.8 zoom I consistently see trails but the strange thing is that the trails are not in the direction you would see if the astrotracer was turned off. They are at almost 90 degrees to this direction. It seems to track the apparent movement of the stars perfectly but the effect is spoiled by this unwanted motion. The electronic compass seems to be reasonably accurate and stable so what else can go wrong?

jamas79 · 02-07-2016, 12:02 PM

I have been using an astro tracer with K-5 and FA 300/4.5. My experience this far is:

- Stready tripod is necessary
- Do a precise calibration
- No longer exposure than 20s
- Cord shutter and 2s mirror lockup
- Beware of angle

Focus is still an big issue for me

But sometimes it all fails anyway for reasons still unknown.

jamas79 · 02-07-2016, 11:29 PM

This is an unedited frame of M3. Even with 20s star begins to show trails. Focus is not perfect either.

https://onedrive.live.com/redir?resid=F737011014D7C7F!7908&authkey=!ADv9k70E...g<br /> <br />

honey bo bo · 02-08-2016, 07:50 AM

the attached was taken on Bulb @ 20s - see EXIF - Tripod of course - No GPS - caught a meteor(luck)

skogpingvin · 02-09-2016, 01:46 AM

Originally posted by realitarian

One more.

Hurrumph. My shots look pretty much like yours. I think I've got a reasonable handle on the AstroTracer - involving the "precise calibration waltz" that you have to do. It's no problem, it's normally dark so few people will see you doing it. My real problem is sharpness of focus, even with mirror-up focusing. I've tried a number of lenses, starting with the old kit lens (DA 18-55 f/5.6). It's a decidedly average lens, but it's close to the right focal length. The other lenses range from an old 85mm f1.8 with an M42 screw mount, which looks promising. I've also tried the Sigma 150-500 f/6.7 stepped down to f/8 which is the sweet spot for the Sigma - but I've not made it work properly, even with good calibration. I think it's so heavy it wobbles the tripod slightly - I haven't tried locking the mirror up, I'll have to give that a go.

jamas79 · 02-09-2016, 04:56 AM

What camera and tripod do you use?

skogpingvin · 02-10-2016, 01:49 AM

Originally posted by Digitalis

I agree, AF systems on DSLRs aren't designed for or capable of accurately focusing on night sky objects.

This should be done with Live view if possible, the true infinity focus point will sometimes be drastically different from what is marked on the lens.

With this setup:

I was able to get this by pointing my camera straight up:

Pentax K5IIs - Sigma 18-35mm f/1.8 @ f/1.8 18mm, Pentax O-GPS - 30s ISO 800 - no bias frames or DFS used.

With the above image I used magnified live view and I focused on the brightest stars in the central portion of the image.

Wow! And that's straight up - it shows that the AstroTracer really can do it!

And living Down Under helps there - people in the Northern Hemisphere really don't get a good look at the Galactic Core.

Smugly living in Melbourne...

01-04-2016, 05:39 PM	#65
Sagitta Veteran Member Join Date: Feb 2011 Location: Maine Photos: Gallery Posts: 3,081	Originally posted by Gimbal You still have to calibrate since the astrotracer function needs the data from the accelerometers and the magnetic compass to know where you are aiming, and the position data from the GPS to know where you are. This. This is the reason I can't use my unit down along the banks of the Kennebec here in town. There ince was a factory that dumped a stupid amount of slag into the river, as well as tenement housing which was bulldozed back in the 1960's in the name of urban renewal. All that iron and steel from the factory waste and the houses was basically buried and forgotten about. To add to things, the town then went in and ripped things up in the early 2000's to install sewers and itilities in the (so far) failed hope of creating development in the plot, which added sewer and electric lines underground on top of everything else. The end result is that I have yet to be able to use the O-GPS reliably there, despite it working just about everywhere else. EDIT: Said magnets are actually a part of the camera and not the unit - these are the magnets that control the in-body shake reduction system in the camera. I suppose technically the SR could get thrown off if you tried shooting with enough steel around you to affect the system as well, but I don't know if anyone has ever tested that out. Last edited by Sagitta; 01-04-2016 at 05:46 PM.

01-16-2016, 12:54 AM	#66
skogpingvin Junior Member Join Date: Jan 2016 Location: Melbourne Photos: Albums Posts: 30	AstroTracer causes K-3 II to make clicking sounds Originally posted by photographerclare Also, my camera makes a clicking sound when it is taking long exposure shots, I don't know if this is normal. Here is my best attempt so far (I have not been able to recreate it). Has anyone been able to solve this one? I'm getting the same clicking from my K-3 II when taking AstroTracer shots when I use longer lenses. I thought it might have been the OS on the Sigma 150-500 I used, but it happens on an old Tokina 70-220 as well, but not on the shorter ones like the Pentax SMC 85. The clicking is associated with poor tracking, and I'm thinking it's causing a shake, but I've no idea, really. I live in Melbourne where there's lots of light pollution, so the shots I'm getting are pretty poor, but here's one of the standard Orion Nebula. Looks like that's what everyone starts with! Attached Images

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01-03-2016, 08:20 PM	#61
honey bo bo Veteran Member Join Date: Apr 2014 Posts: 768	Originally posted by Sagitta By that same token, don't set up right next to your car (similar reasons). You have to remember that part of what makes the tracker tick is being able to lock on to the magnetic pole - if anything interferes in that, then you won't get decent results as things won't track true. The O-GPS1 uses the WGS 84 system (World Geodetic System) 4 satellites and actually tracks true North not magnetic north. In the instructions they say to do a calibration prior to using Astrotracer and I believe it should be a precise calibration to get all the info from the satellites. Further this calibration takes care of any magnetic interferance in the area . See "O-GPS1 Pentax GPS Unit Review" on this forum.

01-04-2016, 05:11 AM	#62
Gimbal Pentaxian Join Date: Apr 2007 Location: Sweden Posts: 2,106	The GPS part in the O-GPS1 doesn’t need any calibration, it’s a normal GPS. And just like any other GPS it has no idea of how it’s orientated. All it can figure out is where it is, how fast it is mowing and in what direction it is mowing. The calibration is for the magnetic compass and the accelerometers in the camera. These sensors tell the camera in what direction it’s pointed, angle up/down and angle of tilt left/right.

01-04-2016, 06:26 AM	#63
honey bo bo Veteran Member Join Date: Apr 2014 Posts: 768	Originally posted by Gimbal The calibration is for the magnetic comp Originally posted by Gimbal The GPS part in the O-GPS1 doesn’t need any cali So are you saying you don't have to calibrate the O-GPS1 to use the astrotracer and that it is locking in on magnetic north ? Completely contrary to what I'm reading! I'm confused! P.S check your spelling we are not talking about mowing hay.

01-04-2016, 07:00 AM	#64
Gimbal Pentaxian Join Date: Apr 2007 Location: Sweden Posts: 2,106	Originally posted by honey bo bo So are you saying you don't have to calibrate the O-GPS1 to use the astrotracer and that it is locking in on magnetic north ? Completely contrary to what I'm reading! I'm confused! P.S check your spelling we are not talking about mowing hay. You still have to calibrate since the astrotracer function needs the data from the accelerometers and the magnetic compass to know where you are aiming, and the position data from the GPS to know where you are.

01-16-2016, 08:35 AM	#67
Grey Area Junior Member Join Date: Nov 2015 Location: Huddersfield, West Yorks. Photos: Gallery \| Albums Posts: 25	Astrotracer on...not that you'd think so. 55mm lens, 60s exposure, calibrated ok. Sometimes it works, sometimes it don't...

01-19-2016, 04:56 PM	#69
slartibartfast01 Pentaxian Join Date: May 2015 Photos: Gallery Posts: 1,931	When I use the astrotracer on my K50 with a Tamron 70-200 f2.8 zoom I consistently see trails but the strange thing is that the trails are not in the direction you would see if the astrotracer was turned off. They are at almost 90 degrees to this direction. It seems to track the apparent movement of the stars perfectly but the effect is spoiled by this unwanted motion. The electronic compass seems to be reasonably accurate and stable so what else can go wrong?

02-07-2016, 12:02 PM	#70
jamas79 Guest	I have been using an astro tracer with K-5 and FA 300/4.5. My experience this far is: - Stready tripod is necessary - Do a precise calibration - No longer exposure than 20s - Cord shutter and 2s mirror lockup - Beware of angle Focus is still an big issue for me But sometimes it all fails anyway for reasons still unknown.

02-07-2016, 11:29 PM	#71
jamas79 Guest	This is an unedited frame of M3. Even with 20s star begins to show trails. Focus is not perfect either. https://onedrive.live.com/redir?resid=F737011014D7C7F!7908&authkey=!ADv9k70E...g<br /> <br />

02-09-2016, 01:46 AM	#73
skogpingvin Junior Member Join Date: Jan 2016 Location: Melbourne Photos: Albums Posts: 30	Originally posted by realitarian One more. Hurrumph. My shots look pretty much like yours. I think I've got a reasonable handle on the AstroTracer - involving the "precise calibration waltz" that you have to do. It's no problem, it's normally dark so few people will see you doing it. My real problem is sharpness of focus, even with mirror-up focusing. I've tried a number of lenses, starting with the old kit lens (DA 18-55 f/5.6). It's a decidedly average lens, but it's close to the right focal length. The other lenses range from an old 85mm f1.8 with an M42 screw mount, which looks promising. I've also tried the Sigma 150-500 f/6.7 stepped down to f/8 which is the sweet spot for the Sigma - but I've not made it work properly, even with good calibration. I think it's so heavy it wobbles the tripod slightly - I haven't tried locking the mirror up, I'll have to give that a go.

02-09-2016, 04:56 AM	#74
jamas79 Guest	What camera and tripod do you use?

02-10-2016, 01:49 AM	#75
skogpingvin Junior Member Join Date: Jan 2016 Location: Melbourne Photos: Albums Posts: 30	Originally posted by Digitalis I agree, AF systems on DSLRs aren't designed for or capable of accurately focusing on night sky objects. This should be done with Live view if possible, the true infinity focus point will sometimes be drastically different from what is marked on the lens. With this setup: I was able to get this by pointing my camera straight up: Pentax K5IIs - Sigma 18-35mm f/1.8 @ f/1.8 18mm, Pentax O-GPS - 30s ISO 800 - no bias frames or DFS used. With the above image I used magnified live view and I focused on the brightest stars in the central portion of the image. Wow! And that's straight up - it shows that the AstroTracer really can do it! And living Down Under helps there - people in the Northern Hemisphere really don't get a good look at the Galactic Core. Smugly living in Melbourne...