Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-18-2015, 05:59 PM   #106
Senior Member
mgbirder's Avatar

Join Date: Jun 2010
Location: Cali
Photos: Gallery | Albums
Posts: 235
QuoteOriginally posted by fs999 Quote
Yes an no. Good calibration is very important, but it depends also where you are and in what direction you point.
If 2 mins is the maximum given by the camera, try 1 min 30 or 1 min 45. If no trails then go for 2 mins...
I sometimes can not achieve calibration and just use the O-GPS without it (i have found that it does function, but my exposures can not be as long). I really think 5 min tracking time without star-trails is pretty much impossible. I never go over 2 minutes with my Da 14mm.

It is sometimes pretty frustrating not to be able to calibrate the unit. Is there any consensus about the correct way of calibration (speed, sequence of the different directions...)? Sometimes it calibrates very fast, in other occasions I give up after 4 or 5 tries ;-) and shoot without calibration.

Thanks for the kind comments :-)
The O-GPS is definitely one of the reasons i will keep using Pentax.

01-18-2015, 08:32 PM   #107
Pentaxian
Sagitta's Avatar

Join Date: Feb 2011
Location: Maine
Photos: Gallery
Posts: 3,081
QuoteOriginally posted by mgbirder Quote
I sometimes can not achieve calibration and just use the O-GPS without it (i have found that it does function, but my exposures can not be as long). I really think 5 min tracking time without star-trails is pretty much impossible. I never go over 2 minutes with my Da 14mm.

It is sometimes pretty frustrating not to be able to calibrate the unit. Is there any consensus about the correct way of calibration (speed, sequence of the different directions...)? Sometimes it calibrates very fast, in other occasions I give up after 4 or 5 tries ;-) and shoot without calibration.

Thanks for the kind comments :-)
The O-GPS is definitely one of the reasons i will keep using Pentax.
In my experience its the terrain you're on. My unit works wonderfully out in the sticks or from my apartment window, but works horribly down at the iron-laden shore of the Kennebec River by my house (not that I can use that spot anymore since the town in its wisdom plastered the riverside with streetlights).

I wound up with my best series of shots when I didn't have a tripod at all and had to get creative with rocks and bits of stray clothing to use as a camera support.

No tripod, 90 second exposure, 10mm@f/3.5 and ISO 1600



EDIT: And to show that 'longer' isn't necessarily better, same basic shot, only at 210 seconds. The tracking was spot on, dead center, but you still get insane trailing at the edges when shooting very wide (I assume the same effect would carry through at narrower focal lengths as well, only less pronounced.)

No tripod, 210 second exposure, 10mm, f/3.5, ISO 1600 (only difference from above is the exposure length and the amount of correction needed in post to correct the exposure)

Last edited by Sagitta; 01-18-2015 at 08:46 PM.
01-19-2015, 01:11 AM   #108
Loyal Site Supporter
Loyal Site Supporter
fs999's Avatar

Join Date: Jul 2008
Location: Luxembourg
Photos: Gallery
Posts: 8,587
QuoteOriginally posted by Sage97 Quote
The K5 suggested a max of 5 mins but it was cold and I didn't have my jacket on and I was too excited to go back and grab one.
Was it "Max Trace Duration" or "Exposure Time Preset" ?
You can preset up to 5 mins but it doesn't go over "Max Trace Duration".
I tried yesterday the Orion belt and M42 with my Porst 135mm F1.8 for 3 mins at 1600 ISO without trails...
01-19-2015, 01:42 AM   #109
Site Supporter
Site Supporter
forest_bear59's Avatar

Join Date: Oct 2013
Location: Idstein (near Frankfurt - Germany)
Photos: Gallery
Posts: 147
I simply can't imagine, that full three minutes can be astro-traced at 135mm focal length. But I am in the first carefull experimenting phases with GPS module and my trusted K-r. Are there tables from Ricoh/Pentax for this topic?
Next time we'll have a clear dark sky I will make some tests with the 300mm lens and different times. The results could be used to extrapolate to other focal lengths and I'll know more. The one crucial point for me is to be sure, that calibration has been finished properly. Yesterday I got the information, that calibration was passed successfully when I just had finished two of three axis of rotation. I repeated calibration and it was fine, but a degree of uncertainty always remains ...

01-19-2015, 07:59 AM   #110
Loyal Site Supporter
Loyal Site Supporter
fs999's Avatar

Join Date: Jul 2008
Location: Luxembourg
Photos: Gallery
Posts: 8,587
I found a table with approx times on Ricoh's japaneese site.

ASTROTRACER Tracking Time (approx. in sec.)

K-5
Declination - Focal length
(°)200mm100mmunder 50mm
90300300300
45160290300
0110240300

K-r
Declination - Focal length
(°)200mm100mmunder 50mm
90300300300
4580200300
080170300
01-19-2015, 08:09 AM   #111
Pentaxian
Sage97's Avatar

Join Date: Apr 2012
Photos: Albums
Posts: 3,237
QuoteOriginally posted by fs999 Quote
Was it "Max Trace Duration" or "Exposure Time Preset" ?
You can preset up to 5 mins but it doesn't go over "Max Trace Duration".
I tried yesterday the Orion belt and M42 with my Porst 135mm F1.8 for 3 mins at 1600 ISO without trails...

Max duration was 5 but I only wanted to do a 90 second shot.

I tried again last night about 2 hours away into the canyon. Not much trailing this time for 2.5 mins with a 14 mm but I'm not getting any milk , just tons of stars. I was pointed straight at it anywhere from 30 to 50 degrees.

I see 30 sec shots all over the web that are much better than my results.

Last edited by Sage97; 01-19-2015 at 08:39 AM.
01-19-2015, 11:22 AM   #112
Pentaxian




Join Date: Jun 2010
Location: North Zealand, Denmark
Photos: Gallery | Albums
Posts: 1,516
QuoteOriginally posted by Sage97 Quote
Not much trailing this time for 2.5 mins with a 14 mm but I'm not getting any milk , just tons of stars.

I would guess that you sensor has captured more than that, but capturing the light is only the beginning; next comes post-processing and that preferrably only after stacking.


Would you share some examples with us?

01-19-2015, 11:41 AM - 2 Likes   #113
Pentaxian
Sage97's Avatar

Join Date: Apr 2012
Photos: Albums
Posts: 3,237
QuoteOriginally posted by Stone G. Quote
I would guess that you sensor has captured more than that, but capturing the light is only the beginning; next comes post-processing and that preferrably only after stacking.


Would you share some examples with us?
Ok...but it's my first attempt ever so giggle quietly.



Reading up on stacking/layering/masking right now.
01-19-2015, 11:45 AM   #114
Loyal Site Supporter
Loyal Site Supporter
fs999's Avatar

Join Date: Jul 2008
Location: Luxembourg
Photos: Gallery
Posts: 8,587
Wow ! Superb shot Sage97 ! I can see the milk !

I'm not sure to show mine now...
01-19-2015, 11:48 AM   #115
Pentaxian
Sage97's Avatar

Join Date: Apr 2012
Photos: Albums
Posts: 3,237
QuoteOriginally posted by fs999 Quote
Wow ! Superb shot Sage97 ! I can see the milk !

I'm not sure to show mine now...
Thank you but you always have outstanding pics!
01-19-2015, 02:55 PM   #116
Loyal Site Supporter
Loyal Site Supporter
fs999's Avatar

Join Date: Jul 2008
Location: Luxembourg
Photos: Gallery
Posts: 8,587
Orion belt and M42
K5 IIs • 1600 ISO • Porst Tele 1:1.8/135mm MC AUTO E
Pentax O-GPS1 GPS Unit • 180 sec.



Next time I will better frame
I used a mask with the inversed luminosity in Darker color blend mode, which removes the light pollution.

Last edited by fs999; 01-19-2015 at 03:05 PM.
01-19-2015, 08:23 PM   #117
Pentaxian
Sage97's Avatar

Join Date: Apr 2012
Photos: Albums
Posts: 3,237
QuoteOriginally posted by fs999 Quote
Orion belt and M42
K5 IIs • 1600 ISO • Porst Tele 1:1.8/135mm MC AUTO E
Pentax O-GPS1 GPS Unit • 180 sec.



Next time I will better frame
I used a mask with the inversed luminosity in Darker color blend mode, which removes the light pollution.
Those stars look so sparkly clean. Very nice.
01-20-2015, 08:48 AM   #118
Loyal Site Supporter
Loyal Site Supporter
fs999's Avatar

Join Date: Jul 2008
Location: Luxembourg
Photos: Gallery
Posts: 8,587
Thank you !
11-09-2015, 05:50 PM - 1 Like   #119
New Member




Join Date: Nov 2015
Location: Pismo Beach, CA
Posts: 1
I finally bought the Pentax O-GPS1 GPS Unit & have been spending way too much time on it with my preexisting Pentax K-5 for the past few months. The easiest way for me to get decent photos is off my porch which is a long block from the ocean in Pismo (Shell ) Beach. Even though there is significant light pollution from the main part of Pismo to my left, I happen to live on a narrow strip between the Ocean & the Mountain in back of me, so that it is not too bad. The coast fog, neighbors lights, my lights, weather conditions, moon-light, and the finicky GPS unit all contribute to making it hard to do...especially when I am trying to image Andromeda at almost a 90 degree angle.
Since it seems that my porch is facing South toward the Ocean, the progression of the stars from east to west unfold like clockwork on a dark night. Orion & it's nebula are in the best view very late at night, but the Andromeda galaxy is almost directly overhead early in the evening. I have simple basic equipment, including lens ranging from 14mm to zooms that go to 300mm, a decent tripod from Costco, the K-5, & now the GPS. Since I have had major back surgery, arthritis, & am handicapped, trying to image close to a 90 degree angle becomes painful (& can stay that way for a week), since the preview screen faces the ground.
Like so many others, I have tried to learn & deal with the limitations of this finicky arrangement. I have avoided stacking & done little post processing past what my iMac can do already. Even though I recalibrate, tried darker skies (still near the ocean), tried all kinds of various ISO's, times, & other variables, I think I may have hit a block.
Sometimes I have horrid star tracks, for unclear reasons....but thanks for all the recommendations! Overall, for a total beginner I am so pleased with my personal discovery of the cosmos from my own porch. The star birthing nebula is just as amazing as seeing the remote Andromeda Galaxy from my porch.
I have tried going to a much less light polluted area north of me, near Big Sur, but was limited by Ocean moisture & the hotels lights. I want to try some back country near Paso Robles, CA...but the lack of facilities is a problem.
Anyway, he is a sample of some of my photos, some are clearly over processed, but they sure do look cool. It is amazing what this system will do at 150-300mm with some simple post processing. Since I do not have a current program that can do RAW, I have had to settle for less for now.
Attached Images
       
View Picture EXIF
PENTAX K-5  Photo 
View Picture EXIF
PENTAX K-5  Photo 
View Picture EXIF
PENTAX K-5  Photo 
View Picture EXIF
PENTAX K-5  Photo 
11-11-2015, 02:58 PM   #120
Pentaxian




Join Date: Apr 2007
Location: Sweden
Posts: 2,106
Cool pictures, but you should really try to find a program that can handle the raw format. There is so much more info hidden in the raw files, especially in the dark areas.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
50mm, calibration, camera, dslr, exposure, k-5, k-5 ii, k-5 iis, k5, mystery, pentax, pentax k-5, pictures, star, thanks
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K5 & Pentax GPS Module O-GPS1 DigiMack Pentax K-5 & K-5 II 6 07-29-2018 04:58 PM
I want guidance on Pentax GPS1 Astrophotography in Adirondack mountains. mrjamesabels Photographic Technique 8 10-14-2011 05:21 PM
K2000 & astrophotography DuaneV Pentax DSLR Discussion 6 04-29-2010 09:00 PM
K20D or Samsung P&S? Pix compared. SpecialK Post Your Photos! 8 11-30-2008 05:51 PM
Landscapes from Sossusvlei, Namibia tcom Post Your Photos! 4 01-07-2007 01:53 AM



All times are GMT -7. The time now is 02:32 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top