Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-27-2016, 07:24 AM   #1
New Member




Join Date: Mar 2016
Posts: 8
Hello! Ė and a query concerning ASTROTRACER on K3 II

Hello! Iím a long time user of Pentax cameras and have just joined this group.

I began with a Pentax MX which I still have, and progressed via SFX anf Z1 before getting an istD and then a K10D, and now a K3 II.

For a few years I also had a Canon EOS450D which because of lower digital noise levels was significantly better than the K10D for long exposure astrophotography. I recently got rid of the Canon in favour of the K3 II.

Iíve accumulated a good selection of older Pentax lenses and of the newer digital age glass. Itís good to be able to use all of these lenses on the newer cameras.

My first impressions of the K3 II are very pleasing. I have still to explore some of the features and am hoping for some help in understanding the ASTROTRACER facility on the K3 II.

Searching the Internet, I discovered that ASTROTRACER could provide stable images over periods of 90 seconds or so with a 40mm lens. That should translate to approx 9 seconds with my SMC M 400mm f5.6 lens. Given the low noise level of the K3 II, I can use ISO 1600 without any problems. So thatís looking like working out well.

Iím wondering if I could go further. I have a couple of motor driven equatorial telescope mounts (a large and very heavy EQ6 and a more portable EQ3/2). Given careful polar alignment, the EQ6 is capable of producing stable images over periods of 10 minutes or more. The EQ3/2 is less stable. To do better, I would need to set up a secondary astro camera and computer to provide autoguiding.

I donít know how the K3 II does itís calculations wrt GPS, but if instead of the K3 II remaining stationary, it were mounted on a motor driven equatorial mount, would it then detect small errors in tracking and correct these via ASTROTRACER?

If this were the case then this might provide a means of doing LONG exposures without exceeding the travel limits of the sensor in the K3 II.

03-27-2016, 08:27 AM   #2
Pentaxian
Aaron28's Avatar

Join Date: Jan 2015
Location: Huntsville, Al
Posts: 1,070
welcome aboard! the astrotracer uses the shake reduction 'servos' to move the sensor in the body with the aid of the gps calculations.....I would think you use one or the other not both...have not heard anyone doin both
03-27-2016, 09:08 AM   #3
Moderator PEG Judges
Kerrowdown's Avatar

Join Date: Aug 2008
Location: Highlands of Scotland.
Photos: Gallery
Posts: 30,697
I'll just saying welcome to the forum, as I'm not technical enough to even understand the question let alone answer it.
03-27-2016, 10:34 AM   #4
Administrator
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 40,992
QuoteOriginally posted by kenhough Quote
I don’t know how the K3 II does it’s calculations wrt GPS, but if instead of the K3 II remaining stationary, it were mounted on a motor driven equatorial mount, would it then detect small errors in tracking and correct these via ASTROTRACER?
I think the sensor just follows a constant arc for the duration of the exposure. Like Aaron28 said, either or but not both, I believe.


Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)



PentaxForums.com's high server and development costs are user-supported. You can help cover those costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

03-27-2016, 10:45 AM - 1 Like   #5
Senior Moderator
Loyal Site Supporter
Nass's Avatar

Join Date: Aug 2009
Location: The British Isles
Photos: Gallery
Posts: 2,213
QuoteOriginally posted by kenhough Quote
I don’t know how the K3 II does it’s calculations wrt GPS, but if instead of the K3 II remaining stationary, it were mounted on a motor driven equatorial mount, would it then detect small errors in tracking and correct these via ASTROTRACER?
I believe that k3II has an internal table of lens mm vs. sensor rotation Vs. GPS data, and draws its data off that. I don't think it could compensate for being a secondary, incremental rotation driver after an Equatorial Mount unless you could somehow bodge it by telling the camera it had a 3(?)mm lens mounted (ie such a short f/l that its internal table made the movement very little using astrotracer). I can't say I've tried the latter, no idea if it'd work (what's the min. mm settable in the body anyway?) but that's about the only option I could think of...
03-27-2016, 11:38 AM - 1 Like   #6
Moderator PEG Judges
Kerrowdown's Avatar

Join Date: Aug 2008
Location: Highlands of Scotland.
Photos: Gallery
Posts: 30,697
QuoteOriginally posted by Nass Quote
I believe that k3II has an internal table of lens mm vs. sensor rotation Vs. GPS data, and draws its data off that. I don't think it could compensate for being a secondary, incremental rotation driver after an Equatorial Mount unless you could somehow bodge it by telling the camera it had a 3(?)mm lens mounted (ie such a short f/l that its internal table made the movement very little using astrotracer). I can't say I've tried the latter, no idea if it'd work (what's the min. mm settable in the body anyway?) but that's about the only option I could think of...
Wow, I wish I'd studied harder at school...
03-27-2016, 05:09 PM   #7
pjv
Eager To Learn
pjv's Avatar

Join Date: Mar 2015
Location: Melbourne, Australia
Photos: Gallery
Posts: 3,642
Hi kenhough. Welcome to the Pentax forums. Your question is an excellent example of how this site works - ask and it is answered !!!
03-28-2016, 01:40 AM   #8
New Member




Join Date: Mar 2016
Posts: 8
Original Poster
Thanks to all who responded so quickly to my query concerning use of ASTROTRACER on K3 II.
I'm not surprised that there were no positive results. My request was stretching ideas somewhat, but nothing ventured, nothing gained.

As the built-in GPS system is accurate enough to retain star images to pin-point accuracy, I guess that it should in principle also be possible to calculate and implement deviation errors from the true/required tracking arc. Given GPS coordinates, the true tracking arc can be calculated exactly.

If this were to be done, IMHO it would be a significant and probably (another?) unique selling point for the K3 II. Perhaps this could be considered for inclusion in a future firmware update for the K3 II.


Thanks again guys.

Regards

Ken Hough

03-28-2016, 03:55 AM   #9
Junior Member




Join Date: Mar 2016
Location: Midlands
Posts: 43
Its quoted as using horizontal/vertical tilt and facing direction, compass, detected by the magnetic and acceleration sensors are used to calculate the movement of astronomical body. GPS gives it the position on earth including altitude.

Now given the camera takes all these measurements into consideration before it moves the sensor. But does it do this real time of as a singular calculation as the shutter opens.

So if you mount the camera on a EQ mount the camera is going to do one of two things depending on how it decides how to use the position information it gathers.

If the camera calculates in real time while moving the sensor then in theory as the eq mount moves the camera recalculates its position thus reducing the sensor movement and therefor allowing a greater exposure times

If however it calculates the details and them just moves the sensor then the EQ mount will throw the camera out due to its movement.

The only real way to tell is to mount the camera on an EQ mount and try the camera with and without the feature on.
03-28-2016, 05:36 AM   #10
Loyal Site Supporter
TER-OR's Avatar

Join Date: Apr 2009
Location: Dundee, IL
Photos: Gallery | Albums
Posts: 5,417
I don't think the camera fixes points and tracks the points. I think it "knows" where you are on the planet and how to move the sensor to compensate for Earth's rotation at that point. If that's the case, then using Astrotracing on an equatorial mount will give you star trails. Probably backward star trails.
03-29-2016, 06:40 AM   #11
New Member




Join Date: Mar 2016
Posts: 8
Original Poster
Hello! Ė and a query concerning ASTROTRACER on K3 II Read more at: http://www.pentax

Again, thanks for responses to my query.

Perhaps I should have thought more about this before posting.

As ukspeedtraps suggested, the best way to check is to try it out. Will do this as soon as possible.

Regards

Ken Hough
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!
astrotracer, ii, k3, k3 ii, lens, motor, noise, pentax, periods
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Questions re: K-3 II pixel shift and Astrotracer gazelle01 Pentax K-3 102 03-06-2017 06:23 PM
Suggestions and opinions concerning a zoom lens for my K3II candeloromauro Pentax SLR Lens Discussion 13 01-14-2016 08:10 AM
Wired remote on K3 II? tfischer Pentax K-3 3 12-11-2015 09:57 AM
Stupid question ahead concerning Astrotracing & GPS on K3 II MyTZuS Pentax K-3 9 08-16-2015 12:26 AM
Do you see use for an astrotracer either from ogps 1 or K3-II ? Nicolas06 Pentax SLR Lens Discussion 20 05-24-2015 02:15 PM



All times are GMT -7. The time now is 06:46 PM. | See also: NikonForums.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