Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-20-2011, 05:20 PM   #1
Senior Member




Join Date: Mar 2011
Location: Melbourne
Posts: 128
Interval Shooting for star trails on k-r

Iím experimenting with star trails at the moment, and Iím trying to work out if you can use interval shooting for this on a k-r. Iím hoping have I can set my camera up so that it is doing 30sec exposures, and then set the interval at 1s and do 120 or so photos. From doing a quick play I canít seem to get it to do want I want. Has anyone done this before, if so how?
Thanks

10-20-2011, 05:31 PM   #2
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
Sounds like you've run into DFS (dark frame subtraction) aka Slow Shutter Speed Noise Reduction. After any exposure longer than about 1/3 second or so, the camera takes another exposure of equal duration, but with the shutter closed -- a "dark frame". Blending these, the camera eliminates non-random noise generated during the image exposure.

For interval shooting with long exposures, you need to set the interval to a second or two longer than the exposure. So, a 30-second exposure, then a 32-second interval, then repeat. Good luck!
10-20-2011, 05:38 PM   #3
Pentaxian
v5planet's Avatar

Join Date: Jan 2010
Location: Seattle
Photos: Albums
Posts: 1,913
QuoteOriginally posted by RioRico Quote
Sounds like you've run into DFS (dark frame subtraction) aka Slow Shutter Speed Noise Reduction. After any exposure longer than about 1/3 second or so, the camera takes another exposure of equal duration, but with the shutter closed -- a "dark frame". Blending these, the camera eliminates non-random noise generated during the image exposure.

For interval shooting with long exposures, you need to set the interval to a second or two longer than the exposure. So, a 30-second exposure, then a 32-second interval, then repeat. Good luck!
I'm not sure if you can turn off the dark frame subtraction Rico is talking about. In the K-7 menu is it referred to as something along the lines of, "Long Exposure Noise Reduction ON||OFF". Note: for all cameras made before the K-5, I believe, it cannot be turned off for exposures longer than 30".

Regarding the interval shooting itself: a one second gap seems like it should be plenty, but I have noticed when doing interval shooting on my K-7 for star trail frames, that the process stops before all the frames are taken. This seems to have something to do with the camera being unable to process and write the data to the SD card before the next frame begins. Seemingly, if this process lags, the interval shooting stops. Creating a gap of longer than 1 second between exposures though can easily introduce a few pixels' worth of space in the star trails themselves between every set of frames. If you have access to a remote that can be locked into position (improvising, if necessary), this may be a better solution, as the camera will immediately start taking the next exposure once it can, rather than running the risk of hitching somewhere between frame 20 and 30.
10-20-2011, 06:13 PM   #4
Senior Member




Join Date: Mar 2011
Location: Melbourne
Posts: 128
Original Poster
Thanks for the replies. I do have the the long exposure noise reduction turned off (It comes back to life straight after taking a picture), but I was using 1 second intervals, so I'm guessing that is the issue. I was thinking that it would do the interval from the end of one image to the start of the next, but obviously it does it from the start of one to the start of the next. I'll try it with an interval of 32secs and see how that goes.
Cheers

10-23-2011, 10:44 AM   #5
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,484
QuoteQuote:
I'm not sure if you can turn off the dark frame subtraction Rico is talking about. In the K-7 menu is it referred to as something along the lines of, "Long Exposure Noise Reduction ON||OFF". Note: for all cameras made before the K-5, I believe, it cannot be turned off for exposures longer than 30".
You can turn off DFS on the K10d. K20d and K7 do not have the option. It was put back on the K5. I don't know if the Kr will allow it or not. At any rate, Rico is correct. To do interval shooting, you must set your interval to include the Exposure. It is a simple timer from what I understand and will simply fire the shutter at each interval. So if you are doing 1 second exposures and you want a 1 second (the minimum you can select) time between the exposures, you set for a 2 second interval. If you set it too short, the camera will attempt to fire the shutter when it is already open (which will do nothing) and then wait for the next 'interval'. The result is going to be missed shots in the desired sequence as it is the number of Attempts that the camera counts for interval shooting, not the actual recorded photos.

10-23-2011, 10:14 PM   #6
Senior Member




Join Date: Mar 2011
Location: Melbourne
Posts: 128
Original Poster
Thanks for the replies. I had a play last night doing 15 second exposures. I first tried 15sec interval, but that missed every other picture, then tried 16secs but that missed one every 3, ended up going to 17secs which worked well for me over 20 images. Also you can turn off the long exposure noise reduction on the k-r, its in the second tab in the menu.
Cheers
10-25-2011, 01:41 AM   #7
Veteran Member
DaveHolmes's Avatar

Join Date: Jul 2010
Location: Yorkshire
Posts: 1,501
https://www.pentaxforums.com/forums/pentax-dslr-discussion/162237-pentax-kx-dfs-success.html
Might be of use... Involves playing in De-Bug mode...
10-25-2011, 01:43 AM   #8
Veteran Member
DaveHolmes's Avatar

Join Date: Jul 2010
Location: Yorkshire
Posts: 1,501
Sorry... Just realised you're shooting on K-r...
May not be helpful after all...
My bad... Apologies...

12-02-2011, 03:30 AM   #9
Junior Member




Join Date: Jun 2011
Location: Italy
Posts: 29
QuoteOriginally posted by JeffJS Quote
You can turn off DFS on the K10d. K20d and K7 do not have the option. It was put back on the K5. I don't know if the Kr will allow it or not. At any rate, Rico is correct. To do interval shooting, you must set your interval to include the Exposure. It is a simple timer from what I understand and will simply fire the shutter at each interval. So if you are doing 1 second exposures and you want a 1 second (the minimum you can select) time between the exposures, you set for a 2 second interval. If you set it too short, the camera will attempt to fire the shutter when it is already open (which will do nothing) and then wait for the next 'interval'. The result is going to be missed shots in the desired sequence as it is the number of Attempts that the camera counts for interval shooting, not the actual recorded photos.

I am having trouble shooting star trails with interval shooting on the K5. I set up 30 sec shutter with a 20 sec interval and it works for about 8 shots but then just stops. I use to do 3 sec intervals but I have upped the interval time trying to fix the problem. In your post were you saying that the k5 has DFS or that it has the ability to turn it off?
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!
camera, interval, k-r, pentax help, photography, star, star trails, trails
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Night Even More Star Trails jswillems Photo Critique 10 02-10-2011 06:06 AM
Night More Star Trails jswillems Photo Critique 8 01-24-2011 02:25 PM
star trails mikedy Troubleshooting and Beginner Help 2 11-16-2010 08:54 AM
Night Star Trails TOUGEFC Post Your Photos! 2 06-14-2010 04:30 AM
K-7 Interval settings for Star Trails? LeDave Troubleshooting and Beginner Help 6 12-29-2009 03:19 AM



All times are GMT -7. The time now is 08:53 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