Poita
14-02-2012, 10:09 AM
The clouds finally cleared enough last night to get my first go at using the Pentax Astrotracer on the night sky.
Basically Pentax has a GPS add on for their newer DSLRs that purports to allow you to take long exposures of the night sky, just using a tripod.
No tracking mount, no barn doors, just calibrate the camera and shoot for up to five minutes and the camera will do the tracking by moving its sensor internally.
That is the theory anyway.
My setup was a manfrotto Jr tripod, a Pentax K-r DSLR and the OGPS-1 GPS module.
First, after not being able to find the menu items in the instructions, I realised had to apply a firmware update to the camera to get it to recognise the GPS module.
Once I had that sorted, I took it all outside.
It is pretty straightforward, you set the ISO you want to shoot at, select GPS from the menu and then calibrate, which requires you to turn the camera at least 180 degrees through each axis. I nearly dropped the damn thing twice, but it seemed to calibrate okay.
The you select Astrotrace, and the amount of minutes you wish to shoot for (note to Pentax, please backlight your buttons!!).
You then focus and press the shutter release and the camera does the rest.
I chose a 5 minute exposure, just using the 18-55 kit lens at 18mm and F4.0
The clouds had started to roll in, and the light pollution from my backyard isn't fantastic. I pointed the camera to the sky, took a guess as to the focus (backed off from infinity a smidgeon) and pulled the trigger.
I could hear the sensor moving inside the camera, and five minutes later, i heard the shutter close. What I didn't realise was that long-exposure-noise-reduction was turned on, so I had another five minutes to wait whilst it shot its dark frame.
Then the battery went flat in the GPS unit :roll eyes: it turns out the GPS doesn't turn off when the camera does, so I had it on all day.
But still, I did get a single image out of it. There is a bit of star trailing, but it does seem to work. Maybe more calibration would improve things a bit, I'm keen to give it another go.
If anyone wants to download the raw image to take a look it is on
http://www.mudgee.net/ot/kr.DNG (http://www.mudgee.net/ot/kr.DNG.zip)
I've attached an extreme crop of the jpeg image, no processing other than setting the black level quickly.
Basically Pentax has a GPS add on for their newer DSLRs that purports to allow you to take long exposures of the night sky, just using a tripod.
No tracking mount, no barn doors, just calibrate the camera and shoot for up to five minutes and the camera will do the tracking by moving its sensor internally.
That is the theory anyway.
My setup was a manfrotto Jr tripod, a Pentax K-r DSLR and the OGPS-1 GPS module.
First, after not being able to find the menu items in the instructions, I realised had to apply a firmware update to the camera to get it to recognise the GPS module.
Once I had that sorted, I took it all outside.
It is pretty straightforward, you set the ISO you want to shoot at, select GPS from the menu and then calibrate, which requires you to turn the camera at least 180 degrees through each axis. I nearly dropped the damn thing twice, but it seemed to calibrate okay.
The you select Astrotrace, and the amount of minutes you wish to shoot for (note to Pentax, please backlight your buttons!!).
You then focus and press the shutter release and the camera does the rest.
I chose a 5 minute exposure, just using the 18-55 kit lens at 18mm and F4.0
The clouds had started to roll in, and the light pollution from my backyard isn't fantastic. I pointed the camera to the sky, took a guess as to the focus (backed off from infinity a smidgeon) and pulled the trigger.
I could hear the sensor moving inside the camera, and five minutes later, i heard the shutter close. What I didn't realise was that long-exposure-noise-reduction was turned on, so I had another five minutes to wait whilst it shot its dark frame.
Then the battery went flat in the GPS unit :roll eyes: it turns out the GPS doesn't turn off when the camera does, so I had it on all day.
But still, I did get a single image out of it. There is a bit of star trailing, but it does seem to work. Maybe more calibration would improve things a bit, I'm keen to give it another go.
If anyone wants to download the raw image to take a look it is on
http://www.mudgee.net/ot/kr.DNG (http://www.mudgee.net/ot/kr.DNG.zip)
I've attached an extreme crop of the jpeg image, no processing other than setting the black level quickly.