astrophotography with K-7 - issues =(. Please help?

Nass · 12-15-2009, 02:10 PM

Hello,

I've never done any astrophotography before and I'm trying to do a few nice star trails. I'm failing miserably though, can anyone point me in the right direction please?

First, ideally I'd like to do several exposures and stack/merge them. I downloaded a freebie called deepskystacker but I'm having a little issue with my camera. When I set the thing to do interval shooting, every 30 seconds, with an exposure time of 30 seconds set manually, there seem to be gaps between the joined images. Is this because the camera is doing some processing in between and how would I avoid that please?

Secondly, I'd like to do this for exposures longer than 30 seconds but the in-camera limit seem to be 30 seconds. Is there any way around that?

many thanks in advance

wildlifephotog · 12-15-2009, 02:17 PM

You are getting gaps in the trails due to dark frame subtraction by the camera.
The only way to go beyound 30 seconds is to use the bulb mode.
If you take a 5 minute shot, the camera will take about 5 minutes to finish dark frame subtraction. I don't believe anyone has found a way to turn all that off.

Nass · 12-15-2009, 03:22 PM

Thanks wildlifephotog, I've been fiddling with it all night and whilost I've turned off those default noise settings, it still has gaps - even for exposures at 20 seconds and seperated by 20 seconds. So it must be some inbuilt thing - is there no way to turn this off at all for shots below 30 seconds?

I thought that this is what custom setting 18 was supposed to do "slow shutter speed noise reduction" - turn all this sort of stuff off?

Nass · 12-15-2009, 03:44 PM

This seems to be the best I can come up with. These is a quick and dirty 5 20 second exposures merged in HDR via CS3, with setting 18 turned to "off".

Has anyone had any success with this at all?

many thanks

wildlifephotog · 12-15-2009, 05:56 PM

From other threads on this same subject that I've read, no.
It appears the DFS is a separate function that can not be turned off.
If the camera is pausing between shots, then the DFS is automatic.

Wheatfield · 12-15-2009, 08:35 PM

This seems to be something that Pentax doesn't do well. A friend of mine does wonderful star trails with whatever Canon is the flavor of the week.

jezza323 · 12-15-2009, 09:34 PM

i can disable DFS (dark frame subraction) on my K200D, i'd be very suprised if you couldnt on your K7. This is test i did quite a while back, 30 sec exposures.

Wheatfield · 12-15-2009, 09:47 PM

Originally posted by jezza323

i can disable DFS (dark frame subraction) on my K200D, i'd be very suprised if you couldnt on your K7. This is test i did quite a while back, 30 sec exposures.

DFS cannot be disabled on the K20 or K7. The scuttlebut that I heard when the K20 came out was that the Samsung sensor was just too noisy, so Pentax elected to not allow it to be disabled to hide how bad the sensor really is.

Christopher M.W.T · 12-15-2009, 11:08 PM

The K7 is more than capable of doing long exposures cleanly...

I had no problems with my stacked star trails....

This is 16 x 30sec exposures, now the important thing is TURN OFF slow shutter NR, this will effectively turn off DFS for exposures <30secs.

And keep the camera firing continuously.

Nass · 12-16-2009, 02:46 AM

Originally posted by C.W Tsorotes

The K7 is more than capable of doing long exposures cleanly...

I had no problems with my stacked star trails....

This is 16 x 30sec exposures, now the important thing is TURN OFF slow shutter NR, this will effectively turn off DFS for exposures <30secs.

And keep the camera firing continuously.

Tsotores, thanks. By "TURN OFF slow shutter NR" you mean setting 18, is that right?

What do you mean by firing continuously? The shutter option?

Thanks again

Jonson PL · 12-16-2009, 04:08 AM

Here are some other threads that might be helpful :
https://www.pentaxforums.com/forums/pentax-dslr-discussion/77684-k-x-king-lon...ography-2.html

Re: Do you agree with this comparison of the 20D and nikon 700D?: Pentax SLR Talk Forum: Digital Photography Review

https://www.pentaxforums.com/forums/pentax-dslr-discussion/67569-k7-astrophotography.html

https://www.pentaxforums.com/forums/post-your-photos/77417-landscape-star-tra...-exposure.html

https://www.pentaxforums.com/forums/694773-post86.html

https://www.pentaxforums.com/forums/general-photography-techniques-styles/694...questions.html

wildlifephotog · 12-16-2009, 06:53 AM

Nass,
If you enlarge each of the photos in this thread. You'll see there are small gaps in all of them.
These are caused by the delay during the writing to the card.

wildlifephotog · 12-16-2009, 07:33 AM

BTW. I just heard from a Pentax rep. All noise reduction and DFS can be disabled for 30 seconds.

NeverSatisfied · 12-16-2009, 10:19 AM

Originally posted by wildlifephotog

BTW. I just heard from a Pentax rep. All noise reduction and DFS can be disabled for 30 seconds.

You guys have piqued my interest but apparently my K20D only offers "Auto" or "On" for Slow Shutter Speed Noise Reduction. "On" enables it for anything longer than 0.3 seconds, while Auto makes NR "automatically activated according to the situation" - which is useless!!!

C.W. Tsorotes, I like your work-around, impressive photo! Does anyone know of a similar method for the K20D? (Or is it time to buy a K7?

)

Nass · 12-16-2009, 10:20 AM

Originally posted by wildlifephotog

BTW. I just heard from a Pentax rep. All noise reduction and DFS can be disabled for 30 seconds.

hello again - I don't suppose you'd have a name for this rep or where this is written down (ie where he got this from)? If this is so then I must be doing something wrong - I still get those blasted gaps even with everything obvious turned off - so I was thinking about calling the service guys here in the UK to see if they could shed light on this, what I'm doing wrong!!

Cheers

12-15-2009, 02:10 PM	#1
Nass Veteran Member Join Date: Aug 2009 Location: The British Isles Photos: Gallery Posts: 2,402	astrophotography with K-7 - issues =(. Please help? Hello, I've never done any astrophotography before and I'm trying to do a few nice star trails. I'm failing miserably though, can anyone point me in the right direction please? First, ideally I'd like to do several exposures and stack/merge them. I downloaded a freebie called deepskystacker but I'm having a little issue with my camera. When I set the thing to do interval shooting, every 30 seconds, with an exposure time of 30 seconds set manually, there seem to be gaps between the joined images. Is this because the camera is doing some processing in between and how would I avoid that please? Secondly, I'd like to do this for exposures longer than 30 seconds but the in-camera limit seem to be 30 seconds. Is there any way around that? many thanks in advance

12-16-2009, 04:08 AM	#11
Jonson PL Veteran Member Join Date: Dec 2006 Location: Copenhagen Photos: Gallery Posts: 1,842	Here are some other threads that might be helpful : https://www.pentaxforums.com/forums/pentax-dslr-discussion/77684-k-x-king-lon...ography-2.html Re: Do you agree with this comparison of the 20D and nikon 700D?: Pentax SLR Talk Forum: Digital Photography Review https://www.pentaxforums.com/forums/pentax-dslr-discussion/67569-k7-astrophotography.html https://www.pentaxforums.com/forums/post-your-photos/77417-landscape-star-tra...-exposure.html https://www.pentaxforums.com/forums/694773-post86.html https://www.pentaxforums.com/forums/general-photography-techniques-styles/694...questions.html Last edited by Jonson PL; 12-16-2009 at 04:17 AM.

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12-15-2009, 02:17 PM	#2
wildlifephotog Inactive Account Join Date: Nov 2008 Location: USA Posts: 924	You are getting gaps in the trails due to dark frame subtraction by the camera. The only way to go beyound 30 seconds is to use the bulb mode. If you take a 5 minute shot, the camera will take about 5 minutes to finish dark frame subtraction. I don't believe anyone has found a way to turn all that off.

12-15-2009, 03:22 PM	#3
Nass Veteran Member Join Date: Aug 2009 Location: The British Isles Photos: Gallery Posts: 2,402 Original Poster	Thanks wildlifephotog, I've been fiddling with it all night and whilost I've turned off those default noise settings, it still has gaps - even for exposures at 20 seconds and seperated by 20 seconds. So it must be some inbuilt thing - is there no way to turn this off at all for shots below 30 seconds? I thought that this is what custom setting 18 was supposed to do "slow shutter speed noise reduction" - turn all this sort of stuff off?

12-15-2009, 03:44 PM	#4
Nass Veteran Member Join Date: Aug 2009 Location: The British Isles Photos: Gallery Posts: 2,402 Original Poster	This seems to be the best I can come up with. These is a quick and dirty 5 20 second exposures merged in HDR via CS3, with setting 18 turned to "off". Has anyone had any success with this at all? many thanks

12-15-2009, 05:56 PM	#5
wildlifephotog Inactive Account Join Date: Nov 2008 Location: USA Posts: 924	From other threads on this same subject that I've read, no. It appears the DFS is a separate function that can not be turned off. If the camera is pausing between shots, then the DFS is automatic.

12-15-2009, 08:35 PM	#6
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,981	This seems to be something that Pentax doesn't do well. A friend of mine does wonderful star trails with whatever Canon is the flavor of the week.

12-15-2009, 09:34 PM	#7
jezza323 Veteran Member Join Date: Jan 2009 Location: Brisbane Photos: Gallery Posts: 1,421	i can disable DFS (dark frame subraction) on my K200D, i'd be very suprised if you couldnt on your K7. This is test i did quite a while back, 30 sec exposures.

12-15-2009, 09:47 PM	#8
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,981	Originally posted by jezza323 i can disable DFS (dark frame subraction) on my K200D, i'd be very suprised if you couldnt on your K7. This is test i did quite a while back, 30 sec exposures. DFS cannot be disabled on the K20 or K7. The scuttlebut that I heard when the K20 came out was that the Samsung sensor was just too noisy, so Pentax elected to not allow it to be disabled to hide how bad the sensor really is.

12-15-2009, 11:08 PM	#9
Christopher M.W.T Veteran Member Join Date: Jun 2009 Posts: 1,689	The K7 is more than capable of doing long exposures cleanly... I had no problems with my stacked star trails.... This is 16 x 30sec exposures, now the important thing is TURN OFF slow shutter NR, this will effectively turn off DFS for exposures <30secs. And keep the camera firing continuously.

12-16-2009, 02:46 AM	#10
Nass Veteran Member Join Date: Aug 2009 Location: The British Isles Photos: Gallery Posts: 2,402 Original Poster	Originally posted by C.W Tsorotes The K7 is more than capable of doing long exposures cleanly... I had no problems with my stacked star trails.... This is 16 x 30sec exposures, now the important thing is TURN OFF slow shutter NR, this will effectively turn off DFS for exposures <30secs. And keep the camera firing continuously. Tsotores, thanks. By "TURN OFF slow shutter NR" you mean setting 18, is that right? What do you mean by firing continuously? The shutter option? Thanks again

12-16-2009, 06:53 AM	#12
wildlifephotog Inactive Account Join Date: Nov 2008 Location: USA Posts: 924	Nass, If you enlarge each of the photos in this thread. You'll see there are small gaps in all of them. These are caused by the delay during the writing to the card.

12-16-2009, 07:33 AM	#13
wildlifephotog Inactive Account Join Date: Nov 2008 Location: USA Posts: 924	BTW. I just heard from a Pentax rep. All noise reduction and DFS can be disabled for 30 seconds.

12-16-2009, 10:19 AM	#14
NeverSatisfied Veteran Member Join Date: Dec 2007 Location: S.E. Michigan Photos: Albums Posts: 688	Originally posted by wildlifephotog BTW. I just heard from a Pentax rep. All noise reduction and DFS can be disabled for 30 seconds. You guys have piqued my interest but apparently my K20D only offers "Auto" or "On" for Slow Shutter Speed Noise Reduction. "On" enables it for anything longer than 0.3 seconds, while Auto makes NR "automatically activated according to the situation" - which is useless!!! C.W. Tsorotes, I like your work-around, impressive photo! Does anyone know of a similar method for the K20D? (Or is it time to buy a K7? )

12-16-2009, 10:20 AM	#15
Nass Veteran Member Join Date: Aug 2009 Location: The British Isles Photos: Gallery Posts: 2,402 Original Poster	Originally posted by wildlifephotog BTW. I just heard from a Pentax rep. All noise reduction and DFS can be disabled for 30 seconds. hello again - I don't suppose you'd have a name for this rep or where this is written down (ie where he got this from)? If this is so then I must be doing something wrong - I still get those blasted gaps even with everything obvious turned off - so I was thinking about calling the service guys here in the UK to see if they could shed light on this, what I'm doing wrong!! Cheers