Astrotracer and two countdowns


Link Posted 01/11/2015 - 09:16
Two countdowns with Astrotracer

Recently got a K3II and loving it. I have never done any astro photography before, but last night was lovely and clear so thought I would give it a go.

Followed the brief instructions in the manual and get odd behaviour. After firing the shutter (remote or 3s delay) the timer counts down the correct dialled in amount and the immediately starts another countdown with a 'nr' in the lcd display and a unrelated number of seconds countdown. only after this second countdown completes does the camera become responsive.

Anyone any thoughts?
Thanks for your help


Link Posted 01/11/2015 - 09:26
Seems i am able to answer my own question!
wasn't googling the right words.
I have 'Slow shutter speed NR' turned on and this is what is causing it.
So not a Astrotracer problem, just a general Bulb option


Link Posted 01/11/2015 - 09:29
"nr" no doubt means "noise reduction". Known as dark frame subtraction, the second exposure will be the same length as the first one. The noise in this second exposure is analysed by the camera and then the pattern deducted from the main exposure. In this way, random noise on long exposures is removed.

If anyone knows more than that specifically relating to the astrotracer, then hopefully they will tell us in due course.

Hope that helps!
Best regards, John


Link Posted 01/11/2015 - 09:34
You should be able to turn off the noise reduction dark frame in the settings on the camera, just as you can on cameras without built in astrotracers.
I use K5ii with the original astrotracer and have NR turned off.


Link Posted 01/11/2015 - 10:53
It's in the Rec. Menu 3 .... 'Slow Shutter Speed NR'. The choices are Auto, On or Off.

The auto (default) choice applies at un-defined conditions, so impossible to know when it will operate exactly ... Temperature is considered as well as ISO and Time Value.

The On setting only applies the NR to exposure times of 1 minute or more. Off is off, but I'd be cautious.... The combination of long exposure plus hot sensor temperature may not be pretty without NR.
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Last Edited by McGregNi on 01/11/2015 - 10:54


Link Posted 01/11/2015 - 23:22
Assume/hope this is on the JPG only?


Link Posted 02/11/2015 - 08:04
richandfleur wrote:
Assume/hope this is on the JPG only?

No the NR dark frame is also on RAW. If it weren't it would greyed out in the menu when DNG/PEF was set.
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